ARTICLE | doi:10.20944/preprints202003.0004.v1
Subject: Social Sciences, Econometrics & Statistics Keywords: monetary; West African countries; trade; economy
Online: 1 March 2020 (03:04:45 CET)
It shows the monetary investigation in west countries the big flow in economy by the gross value change effects, also the value of debt policy with debt management strategies to control the budgetary risk of long-term economy from sustainability. The intellectual policies of inflation, GDP, trade, and services and merchandise trade has effected on the West African country’s monetary policies. The implication of trade by a lag of exchange rate indicators has a positive and significant effect. The estimated results reflect the dynamic implication of trade with liquidity and proper monitoring policies. The GDP, gross value (GVA), debt policies, equity of public administration, trade in service and merchandise trade is positive and significant, all are significant. We suggest the optimum control of liquidity with trade service policy recommendations in different countries. The research method was based on 5 countries from the 16 countries of western African and elaborated by their individual indicators with the least square method. The gross value of debts and public administration controlled the development aim of an entire state with strategic and planned environment for state and reduce the level of inflation in small and enterprise section and the results analyzed the policy makers implement planned in implication of trade with domestic currency and long run endogeneity. The results analyzed the monetary policies affecting the level of growth of an individual country.
ARTICLE | doi:10.20944/preprints202111.0007.v1
Subject: Earth Sciences, Geoinformatics Keywords: African agriculture; Irrigation; Landsat; Remote Sensing; Reservoir.
Online: 1 November 2021 (11:26:45 CET)
Agriculture in Morocco has been extensive until the middle of the 20th century due to the distribution of rainfall and the availability of water. In the middle of the last century hydraulic works were built that allowed the transition to intensive agriculture by the increase of irrigated areas, allowing that in the territories where there is water for irrigation and the climate allows it, the crops adapt to the demands of the market. The objective of the study is to assess by satellite images the land cover between 1985 and 2020, analyzing the changes in cultivation areas, as well as the changes in desert, sub-desert and forest areas of the Oum Er Rbia hydrological basin in Morocco. Landsat satellite images have been used since 1984 by the US government (Aerospace and Geological Agencies). A series of vegetation indices (NDVI, RVI, TNDVI and EVI) have been used; among which TNDVI (Transformed Normalized Vegetation Index) stands out for its better accuracy, which has allowed us to distinguish vegetation in cultivated and forest areas, as well as arid zones. In addition, the study has compared the use of two methodologies to calculate changes in the coverage of the Earth’s surface, has used local image processing from the Sentinel Application Platform tool and has also used the Google Earth Engine tool. The latter being the most optimal, although at the moment it has great limitations. In both methodologies and in the different indices it has been possible to observe during these 35 years as the cultivated area has increased (related to the availability of water by the construction of reservoirs and canals), how plant cover has improved in forest areas, and a range of variations in arid areas.
COMMUNICATION | doi:10.20944/preprints202012.0271.v2
Subject: Biology, Anatomy & Morphology Keywords: osteoarthritis; African elephant; Asian elephant; captivity; housing; mobility
Online: 18 January 2021 (17:30:32 CET)
The African bush and forest elephants, Loxodonta Africana and Loxodonta cyclotis, and the Asian elephant, Elephas maximus, are the largest land-dwelling animals. Elephants need to be highly mobile and active in order to find fresh food and water, and in the case of males, to locate females in estrus for breeding. Asian elephants walk up to 21 km each day and African elephants can walk up to 28 km per day. This high level of mobility in the wild is also important for maintaining an optimum musculoskeletal health. However, most zoo elephants live in restricted spaces and cold climates that require extended periods of indoor confinement are therefore unable to be as physically active. Zoo enclosures for elephants are relatively small with hard surfaces (i.e. concrete, tarmac and hard packed dirt), so they cannot exercise and are forced to stand on unnaturally hard surfaces continually. Physical inactivity in captivity makes them more prone to gaining weight and developing bone and joint diseases such as osteomyelitis, joint ankylosis and osteoarthritis (OA). Many health and welfare problems in captive elephants are likely to be caused by the lack of mobility. This perspective article focuses on the possible link between captivity, mobility, physical inactivity and the development of OA in captive elephants.
Subject: Medicine & Pharmacology, Oncology & Oncogenics Keywords: CYP3A5; androgen receptor; African American; CYP3A5 inhibitors/inducers
Online: 6 March 2020 (03:33:52 CET)
Androgen receptor signaling is crucial for prostate cancer growth and is positively regulated in part by intratumoral CYP3A5. As African American (AA) men often carry the wild type CYP3A5 and express high level of CYP3A5 protein, we blocked the wild type CYP3A5 in AA origin prostate cancer cells and tested its effect on androgen receptor signaling. q-PCR based profiler assay identified several AR regulated genes known to regulate AR nuclear translocation, cell cycle progression and cell growth. CYP3A5 processes several commonly prescribed drugs and many of these are CYP3A5 inducers or inhibitors. In this study, we test the effect of these commonly prescribed CYP3A5 inducers/inhibitors on AR signaling. The results show that the CYP3A5 inducers promoted AR nuclear translocation, downstream signaling and cell growth whereas CYP3A5 inhibitors abrogated them. The observed changes in AR activity is specific to alterations in CYP3A5 activity. Both the inducers tested demonstrated increased cell growth of prostate cancer cells, whereas the inhibitors showed reduced cell growth. Further, characterization and utilization of the observation that CYP3A5 inducers and inhibitors alter AR signaling may provide guidance to physicians prescribing CYP3A5 modulating drugs to treat comorbidities in elderly patients undergoing ADT, particularly AA.
REVIEW | doi:10.20944/preprints202104.0025.v1
Subject: Medicine & Pharmacology, Nutrition Keywords: nutritional guidelines; food pyramid; mushrooms; viral diseases; african foods
Online: 1 April 2021 (14:10:48 CEST)
In Sub-Saharan Africa, despite poverty, chronic hunger and food insecurity, traditional eating has been related to positive health outcomes and sustainability. There is little health research on diet quality based on what African people consume. The defining characteristics of the traditional African cuisine are the richness in herbs and spices, fermented foods and beverages, and healthy and whole ingredients used. However, as countries in this region become more economically developed, there is a shift to “modern” occidental foods rich in saturated fats, sugar and sweeteners. As a result, there are increased incidences of previously unreported ailments due to unbalanced diet. The regular practice of infinite international aid to the region to curb food insecurity has been unsustainable, ineffective and with no end in sight. Local increase in production and productivity is imperative. Protein rich foods in dietary guidelines enhance only those of animal or plant sources while rich protein sources such of mushroom, has been absent in these charts. This article considers the valorisation of traditional African foods and the importance of establishing an African Food-Based Dietary Guidelines (AFBDGs), an unprecedented Food Pyramid, along with the added emphasis on the potential of African mushrooms, which may play a role in shielding Sub-Saharan Africans against the side-effects of a western stylish diet and promote health. It enhances the preventive role of mushrooms in viral diseases and other disorders.
ARTICLE | doi:10.20944/preprints202012.0186.v1
Subject: Medicine & Pharmacology, Allergology Keywords: asymptomatic malaria; Plasmodium falciparum; Dzanga Sangha; Central African Republic
Online: 8 December 2020 (09:40:22 CET)
According to the World Health Organization 94% of global malaria cases and 94% of global malaria deaths have been reported from Africa. Unfortunately, it is difficult to determine the exact prevalence of disease in some African countries due to a large number of asymptomatic cases. The aim of this study was to assess the prevalence of malaria infections in seemingly healthy children living in the Central African Republic (CAR). CareStartTM Malaria HRP2 Pf Ag RDT targeting Plasmodium falciparum was used to test a group of 500 asymptomatic children aged 1-15 years old (330 settled Bantu and 170 semi-nomadic BaAka Pygmies) inhabiting the villages in the Dzanga Sangha region (south-west CAR) in March 2020. 32.4% of asymptomatic Bantu and 40.6% of asymptomatic Pygmy children had a positive result of malaria RDT. The mean age of the study participants with RDT (+) was 8.7 in Bantu and 7.0 years in Pygmies; the mean body temperature was 36.8oC in both groups; the mean haemoglobin level was 10.6 g/dL and 10.1 g/dL, respectively. Our findings allowed us to demonstrate the high prevalence of asymptomatic malaria infections in south-west CAR. RDTs seem to be a useful tool for the detection of Plasmodium falciparum in areas with limited possibilities of using other diagnostic methods, such as light microscopy and molecular biology.
ARTICLE | doi:10.20944/preprints202011.0639.v1
Subject: Social Sciences, Accounting Keywords: COVID 19; response strategies; African continent; pandemic; innovative solutions
Online: 25 November 2020 (12:53:22 CET)
The ongoing crisis of COVID-19 pandemic that swept across the world, poses serious challenges on health delivery systems particularly in developing countries. In Africa however, the crisis rather inspires and sparks creativity and innovation at the national, institutional, organizational, and individual levels. This paper unravels Africa’s response mechanisms to the virus that might have relatively contributed to the low infection rate of the pandemic within the continent. Some criteria are adopted to assess and assemble the most influential government policies and home-grown innovations from various African countries and territories within the continent. It is found that, some of the innovations do not only help in combating the virus, but also have socio-economic benefits as they substantially complement government efforts in easing the burden of the citizenry as they cope with preventive protocols imposed on them. This study will be helpful in identifying the most significant home-based innovations that can be improved and used to reduce health delivery crises within the continent even after COVID-19.
Subject: Life Sciences, Biochemistry Keywords: African swine fever virus; stability; soil; disinfection; risk mitigation
Online: 29 October 2020 (09:17:20 CET)
Understanding African swine fever virus (ASFV) transmission is essential for strategies to minimize virus spread during an outbreak. ASFV can survive for extended time periods in animal products, carcasses, and the environment. While ASFV genome was found in the environment around infected farms, data on the virus survival in soil are scarce. We investigated different soil matrices spiked with ASFV-positive blood from infected wild boar to see if ASFV can remain infectious in the soil beneath infected carcasses. As expected, ASFV genome detection was possible over the entire sampling period. Soil pH, structure, and ambient temperature played a role for the stability of infectious ASFV. Infectious ASFV was demonstrated in specimens originating from sterile sand for at least three weeks, from beach sand for up to two weeks, from yard soil for one week, and from swamp soil for three days. Virus was not recovered from two acidic forest soils. All risk mitigation experiments with citric acid or calcium hydroxide resulted in complete inactivation. In conclusion, stability of infectious ASFV is very low in acidic forest soils but rather high in sandy soils. However, given the high variability, treatment of carcass collection points with disinfectants should be considered.
Subject: Life Sciences, Biochemistry Keywords: African swine fever virus, Belgium, virulence, clinical course, domestic pigs
Online: 2 August 2021 (13:05:54 CEST)
African swine fever (ASF) is one of the most important and devastating viral diseases in wild boar and domestic pigs worldwide. In the absence of vaccines or treatment options, early clinical detection is key and requires sound knowledge of disease characteristics. To provide practitioners and state veterinarians with detailed information, the objective of the present study was to characterize the ASF virus (ASFV) isolate “Belgium 2018/1” in subadult and weaning domestic pigs. To this end, two animal trials were performed. Trial A included eight subadult domestic pigs and trial B five weaner pigs. In general, clinical signs and pathological lesions were in line with previous studies utilizing highly virulent ASF genotype II viruses. However, in trial A, four subadult domestic pigs survived and recovered pointing to an age dependent outcome. The long-term fate of those survivors remains under discussion and would need further investigations.
BRIEF REPORT | doi:10.20944/preprints202104.0312.v1
Subject: Medicine & Pharmacology, Clinical Neurology Keywords: Tinzaparin; African swine fever; heparin shortage; fraxiparin; neurosurgery; perioperative anticoagulation
Online: 12 April 2021 (14:06:07 CEST)
Background An outbreak of African swine fever (ASF) in China in 2020 has led to an unprecedented shortage of fraxiparin. Most patients, especially those kept in hospital for surgery, are currently treated with prophylactic anticoagulation (AC). In search of alternatives for fraxiparin, we found no sufficient data on alternatives for neurosurgical patients, such as tinzaparin of European origin. We compared fraxiparin and tinzaparin concerning adverse events (bleeding versus thromboembolic events) in neurosurgical patients. Methods Between 2012 and 2018, 517 neurosurgical patients with benign and malignant brain tumors as well as 297 patients with subarachnoid hemorrhage (SAH) were treated in the Department of Neurosurgery, University Hospital Leipzig receiving prophylactic anticoagulation within 48 hours. In 2015, prophylactic anticoagulation was switched from fraxiparin to tinzaparin throughout the university hospital. In a retrospective manner, the frequency and occurrence of adverse events (rebleeding and thromboembolic events) in connection with the substance used was analyzed. Statistical analysis was performed using Fisher’s exact test and the chi-squared test. Results Rebleeding rates were similar in both fraxiparin and tinzaparin cohorts in patients being treated for meningioma, glioma, and SAH combined (8.8 vs 10.3%). Accordingly, the rates of overall thromboembolic events were not significantly different (5.5% vs 4.3%). The severity of rebleeding did not vary. There was no significant difference among subgroups when compared for deep vein thrombosis (DVT) or pulmonary embolism (PE). Conclusion In this retrospective study, tinzaparin seems to be a safe alternative to fraxiparin for AC in patients undergoing brain tumor surgery or suffering from SAH.
ARTICLE | doi:10.20944/preprints202010.0251.v1
Online: 12 October 2020 (15:31:08 CEST)
African swine fever (ASF) is a viral infection of pigs and represents a major threat to animal health and trade. Due to the high tenacity of the causative virus also in carcasses of wild boar, contacts of wild boar with infectious carcasses are regarded an important driver of the so-called habitat cycle. The latter is believed to play a major role in maintaining the present ASF situation in wild boar in Europe. Therefore, search campaigns and timely removal and disposal of carcasses are considered important disease control approaches. If timely disposal is not feasible due to logistic reasons, deterrence of wild boar could be a provisionary option. The performance of seven deterrents (physical and chemical) was tested in a forest near Greifswald, Germany. Carcasses as entities of attraction for wild boar were substituted by luring sites. It could be demonstrated that certain physical (LED-Blinkers, aluminum stripes) and chemical (Wildschwein-Stopp™, Hukinol™) deterrents are capable of reducing significantly the odds of wild boar contacts to one third. It is recommended to carry a choice of the aforementioned, reasonable and easy to apply deterrents, when carcass search campaigns are launched in case of an outbreak of ASF in wild boar.
ARTICLE | doi:10.20944/preprints202004.0178.v1
Subject: Medicine & Pharmacology, Oncology & Oncogenics Keywords: triple negative breast cancer; African Ancestry; RNAseq analysis; oncologic pathways
Online: 12 April 2020 (04:22:51 CEST)
Triple negative breast cancers (TNBCs) are molecularly heterogeneous, and the link between their aggressiveness with African ancestry is not established. We investigated primary TNBCs for gene expression among self-reported race (SRR) groups of African American (AA, n=42) and European American (EA, n=33) women. Using The Cancer Genome Atlas (TCGA) approaches, we analyzed RNA sequencing data to measure changes in genome-wide expression and used logistic regressions to identify ancestry-associated gene expression signatures. To determine global ancestry, GATK best practices were followed for variant calling, and used the 1000 Genomes Project as reference data. We identified >150 African ancestry-associated genes and found that, compared to SRR, quantitative genetic analysis was a more robust method to identify racial/ethnic-specific genes that were differentially expressed. A subset of African ancestry-specific genes that were upregulated in TNBCs of our AA patients were validated in TCGA data. In AA patients, there was a higher incidence of basal-like 2 tumors and altered TP53, NFB1, and AKT pathways. The distinct distribution of TNBC subtypes and altered oncologic pathways show that the ethnic variations in TNBCs are driven by shared genetic ancestry. Thus, to appreciate the molecular diversity of TNBCs, tumors from patients of various ancestral origins should be evaluated.
ARTICLE | doi:10.20944/preprints202003.0352.v1
Subject: Medicine & Pharmacology, Pediatrics Keywords: vaginal; cesarean section; African American women; infant mortality; race/ethnicity
Online: 23 March 2020 (11:21:46 CET)
Objective: Racial/ethnic disparities in infant mortality (IM) continue to persist in the United States, with Black/African Americans (AA) being disproportionally affected with threefold increase in mortality compared to Whites. Epidemiologic data have identified maternal characteristics as risk IM such as eclampsia, maternal education, smoking, maternal weight, maternal SES, and family structure. Understanding the cause of causes including the method of labor and delivery and the racial heterogeneity may facilitate intervention mapping in narrowing the Black White IM risk differences. We aimed to assess the temporal/racial trends and the methods of delivery, mainly vaginal versus cesarean section (C-section) as exposure function of IM. Methods: The United States linked Birth/Infant Death records (2007-2016) were used with a cross-sectional ecologic design. The analysis involved chi squared statistic, incidence rate estimation, and period percent change. Results: Of the 40,445,070 births between 2007 and 2016, cumulative mortality incidence was 249,135 (1.16 per 1000). The IM rate was highest among Black/AA (11.41 per 1000), intermediate among Whites (5.19 per 1000), and lowest among Asian /Pacific Islanders (4.24 per 1000). The cumulative incidence rate difference, comparing vaginal to cesarean procedure was 1.73 per 1000 infants, implying excess IM with C-section. Compared to C-section, there was a 31% decreased risk of IM among mothers with vaginal delivery, rate ratio (RR) = 0.69, 95% CI 0.64-0.74. Racial disparities was observed in the method of delivery associated with IM. Black/AA mothers with vaginal delivery had a 6% decreased risk of IM compared to C-section, RR = 0.94, 95%CI 0.92-0.95, while Whites with vaginal delivery had a 38% decrease risk of IM relative to C-section, RR= 0.68, 95%CI 0.67-0.69, p<0.001. Conclusion: Infant mortality varied by race, with Black/AA disproportionally affected which is explained in part by labor and delivery procedures, suggesting reliable and equitable intrapartum assessment of Black/AA mothers during labor.
ARTICLE | doi:10.20944/preprints201902.0227.v1
Subject: Earth Sciences, Geoinformatics Keywords: Location privacy; GDPR; European Union; inference; privacy cultures; African Union
Online: 25 February 2019 (14:33:17 CET)
The General Data Protection Regulation (GDPR) protects the personal data of natural persons and at the same time allows the free movement of such data within the European Union (EU). Hailed as majestic by admirers and dismissed as protectionist by critics, the Regulation is expected to have a profound impact around the world, including in the African Union (AU). For European–African consortia conducting research that may affect the privacy of African citizens, the question is ‘how to protect personal data of data subjects while at the same time ensuring a just distribution of the benefits of a global digital ecosystem?’ We use location privacy as a point of departure, because information about an individual’s location is different from other kinds of personally identifiable information. We analyse privacy at two levels, individual and cultural. Our perspective is interdisciplinary: we draw from computer science to describe three scenarios of transformation of volunteered/observed information to inferred information about a natural person and from cultural theory to distinguish four privacy cultures emerging within the EU in the wake of GDPR. We highlight recent data protection legislation in the AU and discuss factors that may accelerate or inhibit the alignment of data protection legislation in the AU with the GDPR.
ARTICLE | doi:10.20944/preprints201810.0561.v1
Subject: Mathematics & Computer Science, Computational Mathematics Keywords: Human African Trypanosomiasis (HAT), Mathematical modelling, optimal control, Control measures
Online: 24 October 2018 (09:05:54 CEST)
Human African Trypanosomiasis (HAT) commonly known as sleeping sickness, is a neglected tropical vector borne disease caused by trypanosome protozoa. It is transmitted by bites of infected tsetse fly. In this paper we first present the vector-host model which describes the general transmission dynamics of HAT. In the tsetse fly population, the HAT is modelled by three compartments while in the human population, the HAT is modelled by four compartments. The next generation matrix approach is used to derive the basic reproduction number, R0, and also it is proved that if R0 ≤ 1 the disease free equilibrium is globally asymptotically stable, which means the disease dies out. The disease persist in the population if the value of R0 > 1. Furthermore, the optimal control model is determined by using the Pontryagin’s maximum principle with control measures such as education, treatment and insecticides used to optimize the objective function. The model simulations confirm that the use of the three control measures are very efficient and effective to eliminate HAT in Africa.
ARTICLE | doi:10.20944/preprints201801.0292.v1
Subject: Chemistry, Medicinal Chemistry Keywords: African medicinal plants; Leishmaniasis; natural products; protozoal diseases; Schistosomiasis; Trypanosomiasis
Online: 31 January 2018 (05:28:15 CET)
Parasitic diseases continue represent a threat on a global scale, particularly among the poorest countries in the world. This is particularly because of the absence of vaccines, and in some cases, resistance against available drugs, currently being used for their treatment. In this review emphasis is laid on natural products and scaffolds from African medicinal plants (AMPs) for lead drug discovery and possible further development of drugs for the treatment of parasitic diseases. In the discussion, emphasis has been laid on alkaloids, terpenoids, quinones, flavonoids and narrower compound classes of compounds with micromolar range activities against Schistosoma, Trypanosoma and Leishmania species. Suggestions for future drug development from African medicinal plants have also been provided.
ARTICLE | doi:10.20944/preprints202301.0562.v1
Subject: Life Sciences, Virology Keywords: African swine fever; ASFV; spray-dried porcine plasma; challenge; nutritional intervention
Online: 31 January 2023 (02:21:18 CET)
The objective of this study was to evaluate the potential benefits of feeding spray-dried porcine plasma (SDPP) to pigs infected with African swine fever virus (ASFV). Two groups of twelve weaned pigs each were fed with CONVENTIONAL or 8% SDPP enriched diets. Two pigs (trojans)/group) were injected intramuscularly with the pandemic ASFV (Georgia 2007/01) and comingled with the rest of the pigs (1:5 trojan:naïve ratio) to simulate a natural route of transmission. Trojans developed ASF and died within the first week after inoculation but contact pigs did not develop ASF, viremia or seroconversion. Therefore, three more trojans per group were introduced to optimize the ASFV transmission (1:2 trojan:naïve ratio). Blood, nasal and rectal swabs were weekly harvested and at end of the study, ASFV-target organs collected. After the second exposure, rectal temperature of conventionally fed contact pigs increased >40.5˚C while fever was delayed in the SDPP contact pigs. Additionally, PCR Ct values in blood, secretions and tissue samples were significantly lower (P<0.05) for CONVENTIONAL compared to SDPP contact pigs. Under these study conditions, contact exposed pigs fed SDPP had delayed ASFV transmission and reduced virus load, likely by enhanced specific T-cell priming after the first ASFV-exposure.
ARTICLE | doi:10.20944/preprints201607.0082.v1
Subject: Arts & Humanities, General Humanities Keywords: Africa, African women, Christianity, Igbo society, patriarchy, post-colonialism, feminism, womanism
Online: 27 July 2016 (04:18:57 CEST)
The African society is one of the societies with rich culture and traditions. Apart from the indigenous religion of Africa, Christianity and Islam are worshiped as the major religions of the African society. Literature reflects a great amount of influence of religions on the existing societies, people and cultures. African literature often mirrors the clash of indigenous religion with Christianity. In the writings of African authors one can find the elements of Christian beliefs and practices. The present paper, however, is focused on the African woman novelist Buchi Emecheta’s selected four novels: Second-Class Citizen (1974), The Bride Price (1976), The Slave-Girl (1977) and The Joys of Motherhood (1979). The paper attempts to discuss the impact of Christianity on the social and cultural aspects of the African society with special focus on African women. The findings reveal the positive as well as negative impacts of the new religion on African people and on the position of African women through the characters present in the selected novels. With the medium of writing and through Christianity, Emecheta seek to educate her society and improve upon the position of the African women.
ARTICLE | doi:10.20944/preprints202111.0252.v1
Subject: Life Sciences, Virology Keywords: African swine fever; male reproductive tract; pathogenesis; virus detection; histopathology; venereal transmission
Online: 15 November 2021 (11:14:35 CET)
African swine fever (ASF) has evolved from an exotic animal disease to a threat to global pig production. An important avenue for wide-spread transmission of animal diseases is the dissemination of viruses through boar semen used for artificial insemination (AI). In this context, we investigated the role of male reproductive organs in ASF. Mature domestic boars and adolescent wild boar inoculated with different ASF virus strains were investigated by means of virological and pathological methods. Additionally, electron microscopy was employed to investigate in vitro inoculated sperm. Viral genome, antigen and infectious virus could be found in all gonadal tissues and accessory sex glands. The viral antigen and viral mRNAs were mainly found in mononuclear cells of the respective tissues. However, some other cell types, including Leydig, endothelial and stromal cells were also found positive. Using RNAScope, p72 mRNA could be found in scattered halo cells of the epididymal duct epithelium which could point to disruption of the barrier. No direct infection of spermatozoa was observed by immunohistochemistry or electron microscopy. Taken together, our results strengthen the assumption that ASFV can be transmitted via boar semen. Future studies are needed to explore excretion dynamics and transmission efficiency.
ARTICLE | doi:10.20944/preprints202301.0564.v1
Subject: Life Sciences, Virology Keywords: African swine fever; ASFV; spray-dried porcine plasma; vaccine; challenge; nutritional interven-tion
Online: 31 January 2023 (02:24:23 CET)
This study aimed to evaluate the effects of feeding spray-dried porcine plasma (SDPP) on the protection afforded by the BA71∆CD2 African swine fever virus (ASFV) vaccine prototype. Two groups of pigs ac-climated to diets without or with 8% SDPP were intranasally inoculated with 105 plaque forming units (PFU) of live attenuated ASFV strain BA71∆CD2 and three weeks later left in direct contact with pigs infected with the pandemic Georgia2007/01 ASFV strain. During the post-exposure (pe) period, 2/6 from the conventional diet group showed a transient peak rectal temperature >40.5ºC before day 20 pe and some tissue samples collected at 20 d pe from 5/6 were PCR+ for ASFV, albeit showing Ct values much higher than Trojan pigs. Interestingly, the SDPP group did not show fever, neither PCR+ in blood nor rectal swab at any time pe and none of the postmortem collected tissue samples were PCR+ for ASFV. Differential serum cytokine profiles among groups at vaccination, and a higher number of ASFV-specific IFNϒ-secreting T-cells in pigs fed with SDPP soon after the Georgia2007/01 encounter, confirmed the relevance of Th1-like responses in ASF pro-tection. We believe that our result show that nutritional interventions might contribute to improve future ASF vaccination strategies.
ARTICLE | doi:10.20944/preprints202208.0051.v1
Subject: Life Sciences, Virology Keywords: African swine fever; vaccination; efficacy; domestic pigs; wild boar; oral vaccine; intramuscular vaccine
Online: 2 August 2022 (08:36:03 CEST)
African swine fever (ASF) is a pandemic threat to the global pig industry and wild suids. A safe and efficacious vaccine could monumentally assist in disease eradication. In the past years, promising live attenuated vaccine candidates emerged in proof-of-concept experiments, among them, “ASFV-G-∆MGF”. In our study, we tested the vaccine candidate in three animal experiments intramuscularly in domestic pigs one orally in wild boar. Further, a macrophage-grown vaccine virus and a virus grown on permanent cells could be employed. Irrespective of the production system of vaccine virus, a two-dose intramuscular immunization could induce close to sterile immunity with full clinical protection against challenge infection. After oral immunization, 50% of the vaccinees seroconverted and all responders were completely protected against subsequent challenge. All non-responders developed ASF upon challenge with two acute lethal infections and two mild and transient courses. The latter results show a lower efficiency after oral administration that would have to be taken into consideration when designing vaccination-based control measures. Our findings suggest that “ASFV-G-∆MGF” could help to contain the disease under an appropriate vaccination campaign. Further research is needed to characterize safety aspects and define possible improvements of oral efficiency.
ARTICLE | doi:10.20944/preprints202112.0320.v1
Subject: Life Sciences, Virology Keywords: African swine fever virus; laboratory diagnosis; commercial real-time PCR; performance; sensitivity; specificity
Online: 21 December 2021 (09:24:26 CET)
African swine fever (ASF) is one of the major threats to pig production, and real-time PCR (qPCR) protocols are integral part of ASF laboratory diagnosis. With the pandemic spread of ASF, commercial kits have risen on the market. In Germany, the kits have to go through an approval process and thus, general validation can be assumed. However, they were never compared to each other. In this study, 12 commercial PCR kits were compared to an OIE recommended method. Samples representing different matrices, genome loads, and genotypes were included in a panel that was tested under diagnostic conditions. The comparison included user-friendliness, internal controls, and the time required. All qPCRs were able to detect ASFV genome in different matrices across all genotypes and disease courses. With one exception, there were no significant differences when comparing the overall mean. The overall specificity was 100 % [95 % CI 87.66 - 100], and the sensitivity was between 95 % and 100 % [95 % CI 91.11 - 100]. As can be expected, variability concerned samples with low genome load. Concluding, all tests were fit for purpose. The test system can therefore be chosen based on compatibility and prioritization of the internal control system.
ARTICLE | doi:10.20944/preprints202007.0747.v1
Subject: Life Sciences, Virology Keywords: African swine fever virus; virulence; pathology; wild boar; domestic pig; macroscopy; histopathology; immunology
Online: 31 July 2020 (13:01:32 CEST)
Endemically infected European wild boar are considered a major reservoir of African swine fever virus in Europe. While high lethality was observed in the majority of field cases, strains of moderate virulence occurred in the Baltic States. One of these, “Estonia 2014”, led to a higher number of clinically healthy, antibody-positive animals in the hunting bag of North-Eastern Estonia. Experimental characterization showed high virulence in wild boar but moderate virulence in domestic pigs. Putative pathogenic differences between wild boar and domestic pigs are unresolved and comparative pathological studies are limited. We here report on a kinetic experiment in both subspecies. Three animals each were euthanized at 4, 7 and 10 days post infection (dpi). Clinical data confirmed higher virulence in wild boar although macroscopy and viral genome load in blood and tissues were comparable in both subspecies. The percentage of viral antigen positive myeloid cells tested by flow cytometry did not differ significantly in most tissues. Only immunohistochemistry revealed consistently higher viral antigen loads in wild boar tissues in particular 7 dpi, whereas domestic pigs already eliminated the virus. The moderate virulence in domestic pigs could be explained by a more effective viral clearance.
ARTICLE | doi:10.20944/preprints202208.0482.v1
Subject: Life Sciences, Molecular Biology Keywords: African buffaloes; bovine tuberculosis; cfp-10; esat-6; hsp65; nontuberculous mycobacteria; rpoB; Syncerus caffer
Online: 29 August 2022 (09:48:58 CEST)
Diagnosis of bovine tuberculosis (bTB) may be confounded by immunological cross-reactivity to Mycobacterium bovis antigens when animals are sensitised by certain nontuberculous mycobacteria (NTMs). Therefore, this study aimed to investigate NTM species diversity in African buffalo (Syncerus caffer) respiratory secretions and tissue samples, using a combination of novel molecular tools. Oronasal swabs were collected opportunistically from 120 immobilised buffaloes in historically bTB-free herds. In addition, bronchoalveolar lavage fluid (BALF; n=10) and tissue samples (n=19) were obtained during post-mortem examination. Mycobacterial species were identified directly from oronasal swab samples using the Xpert MTB/RIF Ultra qPCR (14/120 positive) and GenoType CMdirect (104/120 positive). In addition, all samples underwent mycobacterial culture, and PCRs targeting hsp65 and rpoB were performed. Overall, 55 NTM species were identified in 36 mycobacterial culture-positive swab samples with presence of esat-6 or cfp-10 detected in 20 of 36 isolates. The predominant species were M. avium complex and M. komanii. Nontuberculous mycobacteria were also isolated from 6 of 10 culture-positive BALF and 4 of 19 culture-positive tissue samples. Our findings demonstrate that there is a high diversity of NTMs present in buffaloes, and further investigation should determine their role in confounding bTB diagnosis in this species.
ARTICLE | doi:10.20944/preprints201912.0077.v1
Subject: Earth Sciences, Environmental Sciences Keywords: Sub-Saharan Africa; phosphorus XANES; fertilizer microdosing; African leafy vegetables; synchrotron; sustainability; nutrient stewardship
Online: 6 December 2019 (04:48:26 CET)
This study investigated the speciation, transformation and availability of P during indigenous vegetable production by employing a combination of chemical and spectroscopic techniques. The study focused upon sites in two ecozones of SSA, the Dry Savanna (lna, Benin Republic) and Rainforest (Ilesha, Nigeria). Both sites were cultivated with two indigenous vegetable species; local amaranth (Amaranthus cruentus (AV)) and African eggplant (Solanum macrocarpon (SM)). The soils were treated with 5 t/ha poultry manure and urea fertilizer at the rate of 0, 20, 40, 60 and 80 kg N/ha. Soil samples were collected before planting and after harvest. Phosphorus K-edge X-ray absorption near-edge structure (XANES) spectroscopy was used to determine P speciation in these soils. Quantitative analysis showed that adsorbed and organic P were the two dominant P species in the manure amended Dry Savanna (DS) soils before planting and after harvest in soils cultivated with both AV and SM, with the addition of urea (40 kg N/ha) causing an increase in the organic P form in Dry Savanna soils cultivated with AV. Soils of the Rainforest (RF) cultivated with AV initially had large amounts of apatite P in the manure amended soils prior to planting which was transformed to adsorbed and organic P after harvest. Urea addition to the Rainforest soils shifted the dominant P species from organic P to adsorbed and apatite P, which is likely to limit P availability. Soils cultivated with SM had similar proportions of both organic and adsorbed P forms, with 40 kg N/ha addition slightly increased the proportion of adsorbed P.
ARTICLE | doi:10.20944/preprints202211.0413.v1
Subject: Life Sciences, Virology Keywords: African swine fever virus; early virus detection; artificial insemination; pathogenesis; transmission; boar semen; vertical transmission
Online: 22 November 2022 (09:13:27 CET)
Rapid spread of African swine fever virus (ASFV), causing severe disease with often high fatality rates in Eurasian suids, prevails as a threat for pig populations and dependent industries world-wide. Although advancing scientific progress continually enhances our understanding of ASFV pathogenesis, alternative transmission routes for ASFV have yet to be assessed. Here, we demonstrate that ASFV can efficiently be transferred from infected boars to naïve recipient gilts through artificial insemination (AI). In modern pig production, semen from boar studs often supplies many sow herds. Thus, the infection of a boar stud presents the risk of rapidly and widely distributing ASFV within or between countries. Daily blood and semen collection from four boars after intramuscular inoculation with ASFV strain ‘Estonia 2014’ resulted in detection of ASFV genomes in the semen as early as 2 dpi, in blood at 1 dpi while semen quality remained largely unaffected. Ultimately, after insemination with extended semen, 7 of 14 gilts were ASFV positive by 7 days post insemination, and all gilts were ASFV positive by 35 days post insemi-nation. Twelve out of 13 gilts aborted at the onset of fever. A proportion of fetuses originating from the remaining gilt showed both abnormalities and replication of ASFV in fetal tissues. Thus, we present evidence for the efficient transmission of ASFV to gilts via AI and also to im-planted embryos. These results underline the critical role that boar semen could play in ASFV transmission.
REVIEW | doi:10.20944/preprints202008.0038.v1
Subject: Earth Sciences, Atmospheric Science Keywords: South African Weather Services; radiometric network; climatic zone; Angström-Prescott; Global Horizontal Irradiance; sunshine duration
Online: 2 August 2020 (15:14:49 CEST)
The South African Weather Service (SAWS) manages an in-situ solar irradiance radiometric network of 13 stations and a very dense sunshine recording network; located in all six macro-climate zones of South Africa. A sparsely distributed radiometric network and over a landscape with dynamic climate and weather shifts is inadequate for solar energy studies and applications. Therefore, there is a need to develop mathematical models to estimate solar irradiation for a multitude of diverse climates. In this study, the annual regression coefficients, a and b, of the Ångström-Prescott (AP) model that can be used to estimate global horizontal irradiance from observed sunshine hours were calibrated and validated with observed station data. The AP regression coefficients were calibrated and validated for each of the six macro-climate zones of South Africa using the observation data that spans 2013 to 2019. The predictive effectiveness of the calibrated AP model coefficients was evaluated by comparing estimated and observed daily global horizontal irradiance. The maximum annual relative Mean Bias Error (rMBE) was 0.371 %, relative Mean Absolute Error (rMAE) was 0.745 %, relative Root Mean Square Error (rRMSE) was 0.910 % and the worst-case correlation coefficient (R2) was 0.910. The statistical validation metrics results show that there is a strong correlation and linear relation between observed and estimated solar radiation values. The AP model coefficients calculated in this study can be used with quantitative confidence in estimating daily GHI data at locations in South Africa where the daily observation sunshine duration data is available.
ARTICLE | doi:10.20944/preprints202207.0409.v1
Subject: Life Sciences, Molecular Biology Keywords: QNBC (Quadruple negative breast cancer); AR (Androgen receptor); AA (African American); CA (Caucasian); BC (Breast cancer)
Online: 27 July 2022 (04:07:32 CEST)
Background: We previously found that QNBC tumors are more frequent in African Americans compared to TNBC tumors. To characterize this subtype further, we sought to determine the miRNA-mRNA profile in QNBC patients based on race. Methods: Both miRNA and mRNA expression data were analyzed from TCGA and validated using datasets from the METABRIC, TCGA proteomic, and survival analysis by KMPLOT. Results: miRNA-mRNAs which include FOXA1 and MYC (mir-17/20a targets); GATA3 and CCNG2 (mir-135b targets); CDKN2A, CDK6, and B7-H3 (mir-29c targets); and RUNX3, KLF5, IL1-β, and CTNNB1 (mir-375 targets) were correlated with basal-like and immune subtypes in QNBC patients and associated with a worse survival. Conclusion: Thus, QNBC tumors have an altered gene signature implicated in racial disparity and poor survival.
ARTICLE | doi:10.20944/preprints201804.0096.v1
Subject: Life Sciences, Virology Keywords: Zika virus; ZIKV; Rhesus macaques; Non-human primates; NHP; infection; natural history; Asian-lineage; African-lineage
Online: 9 April 2018 (03:53:26 CEST)
The establishment of a well characterized non-human primate model of Zika virus (ZIKV) infection is critical for the development of medical interventions. In this study, challenging Indian rhesus macaques (IRMs) with ZIKV strains of the Asian lineage resulted in dose dependent peak viral loads between days 2 and 5 post infection; and a robust immune response which protected the animals from homologous and heterologous re-challenge. In contrast, viremia in IRMs challenged with an African lineage strain was below the assays lower limit of quantitation and the immune response was insufficient to protect from re-challenge. These results corroborate previous observations but are contrary to reports using other African strains obviating the need for additional studies to elucidate the variables contributing to the disparities. Nonetheless, the utility of an Asian lineage ZIKV IRM model for countermeasures development was verified by vaccinating animals with a formalin inactivated reference vaccine and demonstrating sterilizing immunity against a subsequent subcutaneous challenge.
ARTICLE | doi:10.20944/preprints202012.0778.v1
Subject: Life Sciences, Biochemistry Keywords: Alphavirus; chikungunya virus; East Central South African lineage; Indian Ocean sub-lineage; acute febrile illness; viremia; arthritides
Online: 31 December 2020 (09:22:52 CET)
Chikungunya virus is an Alphavirus belonging to the family Togaviridae that is transmitted to humans by an infected Aedes mosquito. Patients develop fever, inflammatory arthritis, and rash during the acute stage of infection. Although the illness is self-limiting, atypical and severe cases are not uncommon, and 60% may develop chronic symptoms that persist for months or even for longer durations. Having a distinct periodical epidemiologic outbreak pattern, chikungunya virus reappeared in Thailand in December 2018. Here, we describe a cohort of acute chikungunya patients who had presented to the Bangkok Hospital for Tropical Diseases during October 2019. Infection was confirmed by real-time RT-PCR using serum collected at presentation to the Fever Clinic. Other possible acute febrile illnesses such as influenza, dengue, and malaria were excluded. We explored the sequence of clinical manifestations at presentation during the acute phase and associated the viral load with the clinical findings. Most of the patients were healthy individuals in their forties. Fever and arthralgia were the predominant clinical manifestations found in this patient cohort, with a small proportion of patients with systemic symptoms. Higher viral loads were associated with arthralgia, and arthralgia with the involvement of the large joints was more common in female patients
ARTICLE | doi:10.20944/preprints202210.0363.v1
Subject: Life Sciences, Molecular Biology Keywords: African buffaloes; bovine tuberculosis; IGRA; IP-10 release assay; M. bovis; nontuberculous mycobacteria; serial testing; specificity; Syncerus caffer
Online: 24 October 2022 (12:09:20 CEST)
Ante-mortem bovine tuberculosis (bTB) tests for buffaloes include the single comparative intradermal tuberculin test (SCITT), interferon-gamma (IFN-γ) release assay (IGRA) and IFN-γ-inducible protein 10 release assay (IPRA). Although parallel test interpretation increases detection of Mycobacterium bovis-infected buffaloes, these algorithms may not be suitable for screening buffaloes in historically bTB-free herds. In this study, the specificities of three assays were determined using M. bovis unexposed herds, and a high specificity diagnostic algorithm developed. Serial test interpretation using the IGRA and IPRA showed significantly greater specificity (98.3%) than individual tests or parallel testing (73%). When the SCITT was added, the algorithm had a 100% specificity. Since the cytokine assays had imperfect specificity, potential cross-reactivity with nontuberculous mycobacteria (NTM) was investigated. No association was found between NTM presence (in oronasal swab cultures) and positive cytokine assay results. As a proof-of-principle, serial testing was applied to high-value buffaloes (n=153) in a historically bTB-free herd. Buffaloes positive on a single test (n=28) were regarded as test negative. Four buffaloes were positive on IGRA and IPRA, and M. bovis infection was confirmed following culling. These results demonstrate the value of using IGRA and IPRA in series to screen buffalo herds with no previous history of M. bovis infection.
ARTICLE | doi:10.20944/preprints202205.0395.v1
Subject: Life Sciences, Virology Keywords: African swine fever; pathogenesis; biomarkers; serum; saliva; virus inactivation; detergent treatment; heat treatment; impact of treatment on biomarkers
Online: 30 May 2022 (11:22:19 CEST)
African swine fever (ASF) is a notifiable viral disease of domestic and wild suids. Despite intensive re-search efforts, the pathogenesis of the disease is still far from being understood. Analysis of biomarkers in different body fluids may supplement traditional pathogenesis studies. As reliable protocols are often es-tablished in laboratories with lower biosafety, reliable inactivation of samples is crucial. The objective of this study was to find a procedure that inactivates the virus while preserving the biomarkers for down-stream analyses. To this means, three different inactivation protocols were employed, namely Tergitol-type NP-40 (NP-40) and polyoxyethylene-p-t-octylphenol (Triton X-100), respectively, and one with 95 °C heating. It could be demonstrated that all samples treated with 0.5% (v/v) concentration of both deter-gents showed absence of virus infectivity. The same was true for heated samples. However, heated serum was not suitable for analyses. Next, the treatment impact on biomarker readouts was assessed. While all protocols had an impact on the detection of biomarkers, correlation was retained. Especially NP-40 could be the desired detergent for more accurate measurements while achieving efficient virus inactivation. Based on these studies, samples can be reliably inactivated for most biomarker analyses and thus broader interdisciplinary cooperation is possible.
ARTICLE | doi:10.20944/preprints202008.0131.v1
Subject: Social Sciences, Political Science Keywords: Pan-Africanism; African Diaspora; human rights; liberation; transformational leadership; civil rights; colonialism; Martin Luther King Jr.; Nelson Mandela
Online: 5 August 2020 (10:48:12 CEST)
The Rev. Martin Luther King Jr. and Nelson Mandela were two of the world's most iconic civil (political) (human) rights advocates and leaders of all time. Both advocated for, and to varying degrees, applied elements of peaceful protests to the achievement of their goals. Both spent time in jail, often concurrently, but eventually forced their respective countries to extend the same rights that white populations had denied Africans and African Americans. For the US, civil rights, voting rights, right to education, housing and housing loans suggested that equality had been achieved, capped in South Africa by the election of Nelson Mandela as the first majority-rule president, and in the US, by Barack Obama’s election to the presidency. Yet the historical over-policing, police mistreatment and more generally, the judicial system’s inordinate ‘targeting’ of African Americans, with egregious cases running from Emmett Till to Rodney King to Walter Scott to Breonna Taylor to George Floyd to Rayshard Brooks and thousands of others shows the danger of such magical thinking. The now-persistent global wave pursuing human rights, civil rights and the right to be treated equally, primarily driven by the loosely-organized Black Lives Matter (BLM) movement, has become the leading voice in pursuit of equality. Riots such as those in LA, protests in Ferguson and everywhere in summer 2020 has ushered new civil rights campaign. In the US and elsewhere, it has morphed to include historical issues such as monuments to colonialism, the US civil war, slavery and slave owners and traders, institutions, companies and people whose wealth and existence has links to slavery. Instructively, the protests persisted even as COVID-19, the hundred-year plague, continues to ravage the world. Lost in the moment is the absence of central leadership and leaders such as MLK or Mandela. Their charisma and effectiveness has been lacking for 50 years. This paper evaluates whether this has led to inconsistent civil and human rights pursuit for equality, or whether perchance, Mandela and MLK were extraordinary, once-in-a-lifetime transformative leaders uniquely selected by history for their time.
ARTICLE | doi:10.20944/preprints202001.0175.v1
Subject: Earth Sciences, Environmental Sciences Keywords: Sub-Saharan Africa; FTIR spectroscopy; fertilizer microdosing; African leafy vegetables; greenhouse gas mitigation; sustainability; tropical agriculture; soil fertility
Online: 17 January 2020 (04:23:44 CET)
Fertility management techniques being promoted in sub-Saharan Africa (SSA) seek to grow indigenous vegetables economically and sustainably. This study was conducted in a phytotron chamber and compared yield, soil carbon (C) speciation and greenhouse gas (nitrous oxide (N2O) and carbon dioxide (CO2)) emissions from SSA soils of two ecoregions; the dry savanna (lna, Republic of Benin) and rainforest (Ife, Nigeria) cultivated with local amaranth (Amaranthus cruentus) under manure (5 t/ha) and/or urea (80 kg N/ha) fertilization. Vegetable yield ranged from 1753 kg/ac to 3198kg/ac in the rainforest, RF, soils and 1281 kg/ac to 1951 kg/ac in the dry savanna, DS, soils. Yield in the urea treatment was slightly higher compared to the manure+urea treatment, but the difference was not statistically significant. Cumulative CO2 emissions over 21 days ranged from 497.06 to 579.47 g CO2 in the RF, and 322.96 to 624.97 g CO2 in the DS, while cumulative N2O emissions ranged from 60.53 to 220.86 mg N2O in the RF, and 24.78 to 99.08 mg N2O in the DS. In the RF samples, the combined use of manure and urea reduced CO2 and N2O emissions but led to an increase in the DS samples. ATR-FTIR analysis showed that the combined use of manure and urea increased the rate of microbial degradation in the soils of the DS, but no such effect was observed in soils of the RF. We conclude that combining manure and urea fertilization has different effects on soils of the two ecoregions, and that RF farmers can reduce agricultural emissions without compromising soil productivity and yield potential.
ARTICLE | doi:10.20944/preprints201910.0235.v1
Subject: Life Sciences, Genetics Keywords: African locust bean; climate change; cluster analysis; genetic intra-specific diversity; polymorphic information content; food and nutrition security
Online: 20 October 2019 (16:01:21 CEST)
African locust bean (Parkia biglobosa (Jacq.) is a multi-purpose economic tree with genetic potentials in sub-Saharan Africa. Its cultivation and production is declining with increased aging and genetically threatened throughout its natural ranges. Research efforts are needed to change the present scenario to sustainable cultivation and utilization, hence this present study. This study was aimed at evaluating genetic diversity and geographical spread relationships of twenty landraces collected from different ecological zones of Nigeria using simple sequence repeat (SSR) markers. Ten SSR markers were screened and five primers (PbL02, PbL03, PbL04, PbL05 and PbL09) were selected based on clear amplification products and reproducible scorable bands. The SSR primers detected a total of 55 alleles ranged from 10 to 14 alleles with a mean of 11. The percentage polymorphisms were high and ranged from 68.75 % in PbL04 to 84.21 % in PbL05 with a mean of 74.16 %. The polymorphic information content (PIC) was in the range of 0.31 in PbL02 to 0.37 in PbL09. The genetic diversity and heterozygosity values ranged from 0.39 to 0.50 and 0.00 to 0.68 while the average genetic distance for all pair wise comparisons was 0.31.The first five Principal Component (PC) accounted for 70.20 % of the total variation out of which PC1 (31.50%) and PC2 (19.20%) extracted 49.70% molecular similarity. The dendrogram resulted in separation of the 19 landraces into three major clusters based on unweighted pair group method with arithmetic average. Cluster I comprised of five landraces: ABNo130 and BENo023; OYNo11, KANo125 and NiNo262 while cluster II had only one (BANo116). Cluster III was diverse comprising 13 landraces: ZANo188, KNNo162, KENo220, GMNo076 and EbNo260, ADNo64, EdNo164, KANo137, KENo217, KwNo270, NiNo241, OsNo206 and PLNo120. The homogeneity of alleles among the studied landraces suggested suspicion of loss of genetic intra-specific variation among the landraces of P. biglobosa which calls for concerted efforts toward better cultivation, conservation, management, utilization and genetic improvement of the species in Nigeria.
ARTICLE | doi:10.20944/preprints202102.0590.v2
Subject: Biology, Other Keywords: African swine fever virus (ASFV); Pork shortage; Alternative meat consumption; Wildlife; Human-animal contact; Zoonotic spillover; SARS-CoV-2
Online: 25 January 2022 (10:01:12 CET)
The spillover of a virus from an animal reservoir to humans requires both molecular and ecological risk factors to align. While extensive research both before and after the emergence of SARS-CoV-2 in 2019 implicates horseshoe bats as the significant animal reservoir for the new human coronavirus, it remains unclear why it emerged at this time. One massive disruption to animal-human contacts in 2019 is linked to the on-going African swine fever virus (ASFV) pandemic. Pork is the major meat source in the Chinese diet. We hypothesize that the dramatic shortage of pork following large-scale culling and restrictions of pig movement (resulting in marked price increases) led to alternative sources of meat and unusual animal and meat movements nationwide, e.g., involving wildlife, and thus greatly increased opportunities for human-sarbecovirus contacts. Pork prices were particularly high in southern provinces (Guangdong, Guangxi, Fujian, Jiangxi, Hunan, and Hubei), where wildlife is farmed and more frequently consumed. Major wildlife farming provinces are spread from Northern to Southern China, which overlaps with horseshoe bat host ranges, potential hosts of the proximal SARS-CoV-2 ancestor, and wildlife sourcing provinces of Wuhan Huanan market and possibly other markets. Trading of SARS-CoV-2 susceptible wildlife in these markets, such as minks, raccoon dogs, foxes and palm civets in Wuhan markets, could have increased the risk of SARS-CoV-2 from an intermediary host. Moreover, large quantities of animals raised for fur could have entered the human food chain undetected and significantly increased risks of animal-human contact. Performing retrospective testing of stored susceptible animals and their meat sold before December 2019 may be helpful in the next stage of tracing the animal origin of SARS-CoV-2 as spillover events are more likely to have taken place in 2019 when China was experiencing the worst effects of the ASFV pandemic.
ARTICLE | doi:10.20944/preprints202012.0634.v1
Subject: Arts & Humanities, Anthropology & Ethnography Keywords: Assistive Technology; Assistive devices; Students with disabilities; Decolonial Approach; South African Higher Education; Disability Staff members; learning; Enable and Constrain
Online: 24 December 2020 (14:46:01 CET)
This paper used the decolonial theory to analyse provision of Assistive Technology and assistive devices at an institution of higher education in South African. It was an empirical study, in which data were collected through interviews with students with disabilities and the Disability Rights Centre staff members. The paper sought to understand the invisible hidden implications of provision of Assistive Technology and assistive devices. The finding was that it is students with disabilities who were provided with Assistive Technology and assistive devices at the institution. The institution provided them through the Centre, to support their learning. However, this way of provision was found to be stigmatising and segregative. Furthermore, while the provision on one hand enabled students with disabilities’ learning, on the other, it constrained it. The argument of the paper is that when provision of Assistive Technology and assistive devices is for a particular group of students it defeats the whole purpose for it is intended, and could hinder rather than promote learning. It is hoped that the paper will contribute to contemporary debate on provision of Assistive Technology and support services for people with disabilities in low resource settings, from a South African context specifically, and in higher education broadly.
REVIEW | doi:10.20944/preprints202002.0325.v1
Subject: Life Sciences, Microbiology Keywords: Leishmaniases; Chagas disease; Human African Trypanosomiasis; Animal trypanosomiasis; Diagnosis; non-invasive; Meta-analysis; Vector Born diseases; Neglected tropical disease; Diagnosis
Online: 23 February 2020 (13:44:05 CET)
Unicellular eukaryotes of the Trypanosomatidae family include human and animal pathogens that belong to the Trypanosoma and Leishmania genera. Diagnosis of the diseases they caused requires the sampling of body fluids (blood, lymph, peritoneal fluid, cerebrospinal fluid, etc.) or organ biopsies (bone marrow, spleen, etc.), which are mostly obtained through invasive methods. Body fluids or appendages can be alternatives to these invasive biopsies but appropriateness remains poorly studied. To further address this question, we perform a systematic review on clues evidencing the presence of parasites, genetic material, antibodies, and antigens in body secretions, appendages, or the organs or proximal tissues that produce these materials. Paper selection was based on searches in PubMed, Web of Science, WorldWideScience, SciELO, Embase, Google. The information of each selected article (n=333) was classified into different sections and data were extracted from 77 papers. The presence of Trypanosomatidae parasites has been tracked in most of organs or proximal tissues that produce body secretions or appendages, in naturally or experimentally infected hosts. The meta-analysis highlights the paucity of studies on Human African Trypanosomiasis and a the absence on animal Trypanosomiasis. Among the collected data high heterogeneity in terms of the I2 statistic (100%) is recorded. A high positivity is recorded for antibody and genetic material detection in urine of patients and dogs suffering leishmaniasis, and of antigen for leishmaniasis and Chagas disease. Data on conjunctival swab can be analyzed with molecular methods solely for dogs suffering canine visceral leishmaniasis. Saliva and hair/bristle showed a pretty good positivity that support their potential to be used for leishmaniasis diagnosis. In conclusion, our study pinpoints significant gaps that need to be filled in order to properly address the interest of body secretion and hair or bristle for the diagnosis of infections caused by Leishmania and by other Trypanosomatidae parasites.
ARTICLE | doi:10.20944/preprints202209.0186.v1
Subject: Earth Sciences, Atmospheric Science Keywords: mineral dust; north African dust; Saharan dust; Bodélé depression; bias correction; machine learning; aerosol optical depth; chemistry-transport model; aerosols; particulate matter
Online: 14 September 2022 (03:02:59 CEST)
We develop a machine learning (ML) approach for improving the accuracy of the horizontal dis-tribution of the aerosol optical depth (AOD) simulated by the CHIMERE chemistry-transport model over Northern Africa using Moderate-Resolution Imaging Spectroradiometer (MODIS) AOD satellite observations. These observations are used during the training phase of the ML method for deriving a regional bias correction of AODs simulated by CHIMERE. The results are daily maps of regional bias corrected AODs with full horizontal coverage over Northern Africa. We test four types of ML models: multiple linear regression (MLR), random forests (RF), gradi-ent boosting (XGB), and multiple layer perceptron networks (NN). We perform comparisons with satellite and independent ground-based observations of AOD that are not used in the training phase. They suggest that all models have overall comparable performances with a slight advantage of the RF model which expresses less spatial artifacts. While the method slightly underestimates the very high AODs, it significantly reduces biases and absolute errors, and clearly enhances linear correlations with respect to independent observations. This im-provement for deriving the AOD is particularly relevant for high dust pollution regions like the Sahara Desert, which dramatically lack ground-based measurements for validations of chemis-try-transport modeling which currently remains challenging and imprecise.
REVIEW | doi:10.20944/preprints202105.0549.v1
Subject: Life Sciences, Biochemistry Keywords: COVID-19 pandemic; Africa; SARS-CoV-2 virus spread; lower COVID-19 disease burden; African populations; demographic pyramid; trained immunity; government measures
Online: 24 May 2021 (09:56:05 CEST)
COVID-19 differential spread and impacts across regions is a major focus for researchers and policy makers. Africa has attracted tremendous attention due to predictions of catastrophic impacts that have not yet materialized. Early in the pandemic, the seemingly low African case count was largely attributed to low testing and case reporting. However, there is also reason to consider that many African countries got out ahead of the virus early on. Factors explaining low spread include early government mandated lockdowns, community-wide actions, population distribution, social contacts, and ecology of human habitation. While recent data from seroprevalence studies posit more extensive circulation of the virus, continuing low COVID-19 burden may be explained by the demographic pyramid, prevalence of pre-existing conditions, trained immunity, genetics, and broader sociocultural dynamics. Though all these prongs contribute to the observed profile of COVID-19 in Africa, some provide stronger evidence than others. This review is important to expand what is known about the differential impacts of pandemics enhancing scientific understanding and gearing appropriate public health responses. Also, highlighting potential lessons the world may draw from Africa for global health on assumptions regarding deadly viral pandemics given its long experience with infectious diseases.
ARTICLE | doi:10.20944/preprints201811.0334.v1
Subject: Life Sciences, Biochemistry Keywords: human African trypanosomiasis; pteridine reductase 1; PTR1; DHFR; antifolates; anti-trypanosomal agents; molecular dynamics; dynamic residue network analysis; binding free energy; isobologram assay
Online: 14 November 2018 (10:39:01 CET)
Pteridine reductase 1 is a trypanosomatid multifunctional enzyme that provides a mechanism for escape of Dihydrofolate reductase (DHFR) inhibition. This is because PTR1 can reduce pterins and folates. Trypanosomes require folates and pterins for survival and are unable to synthesize them de novo. Currently there are no anti-folate based Human African Trypanosomiasis (HAT) chemotherapeutics in use. Thus, successful dual inhibition of TbDHFR and TbPTR1 has implications in the exploitation of anti-folates. We carried out molecular docking of a ligand library of 5742 compounds against TbPTR1 and identified 18 compounds showing promising binding modes. The protein-ligand complexes were subjected to Molecular dynamics to characterize their molecular interactions and energetics followed by in vitro testing. In this study, we identified five potential TbPTR1 inhibitors that showed low micromolar Trypanosome growth inhibition in in vitro experiments with no significant human cell cytotoxicity. Compounds RUBi004, RUBi007, RUBi014, and RUBi018 displayed moderate to strong antagonism when used in combination with the known TbDHFR inhibitor, WR99210. This gave an indication that the compounds might inhibit both TbPTR1 and TbDHFR. RUBi016 showed an additive effect in the isobologram assay. Our results provide a basis for scaffold optimization for further studies in the development of HAT antifolates.
ARTICLE | doi:10.20944/preprints202205.0403.v1
Subject: Medicine & Pharmacology, Veterinary Medicine Keywords: African elephants; broncholoalveolar lavage; Hain CMdirect V1.0; ku PCR; Mycobacterium tuberculosis complex; non-tuberculous mycobacteria; rhinoceros; rpoB PCR; trunk wash; Xpert MTB/RIF Ultra
Online: 30 May 2022 (16:33:30 CEST)
Since certain Mycobacterium tuberculosis complex (MTBC) members, like M. bovis, are endemic in specific South African wildlife reserves and zoos, cases of clinically important nontuberculous mycobacteria (NTM) in wildlife may be neglected. Additionally, due to the inability of tests to differentiate between host responses to MTBC and NTM, the diagnosis of MTBC may be confounded by the presence of NTMs. This may hinder control efforts. These constraints highlight the need for enhanced rapid detection and differentiation methods for MTBC and NTM, especially in high MTBC burden areas. We evaluated the use of the GeneXpert MTB/RIF Ultra, the Hain CMdirect V1.0, and novel amplicon sequencing PCRs targeting the mycobacterial rpoB and ku gene targets, directly on antemortem respiratory samples from known MTBC-infected and NTM culture-positive African elephants (n=26 animals) and rhinoceros (n=23 animals). Our findings suggest that the Ultra is the most sensitive diagnostic test for MTBC DNA detection directly in raw antemortem respiratory specimens and that the rpoB PCR is ideal for Mycobacterium genus DNA detection and species identification through amplicon sequencing.