ARTICLE | doi:10.20944/preprints202011.0318.v1
Online: 10 November 2020 (14:07:18 CET)
Brucellosis is an infectious zoonosis that has huge economic and public health implications globally. The disease is prevalent in humans, livestock and wildlife in Sub Saharan Africa. A cross-sectional study was conducted between 6th May 2017 and 31st July 2020 during which 1712 sera from 177 cattle herds in Southern, Western and Eastern provinces of Zambia was collected and screened against brucellosis. Rose Bengal Test and c-ELISA were used in serial testing for detection of antibodies against Brucella species. Results: A total of 127 animals and 37 herds tested positive, giving an overall individual and herd seroprevalence of 7.42% (CI: 0.61-0.86) and 20.9% respectively. Namwala district recorded the highest seroprevalence (12.2%) while Lundazi had the lowest (0%). A higher seropositivity was observed among female animals (8.5%), those aged between 11 and 17 years (14.1%) and pregnant cows (13.8%). Conclusions: Brucella seroprevalence among traditional cattle in Zambia remains high. It is vital that control programmes against bovine brucellosis are introduced in order to reduce its zoonotic impact on human health and increase animal production.
ARTICLE | doi:10.20944/preprints202105.0760.v1
Subject: Life Sciences, Biochemistry Keywords: Toxoplasma gondii; domestic cat; seroprevalence; Cyprus
Online: 31 May 2021 (12:06:05 CEST)
Toxoplasma gondii is a cosmopolitan protozoon parasite, and the causative agent of toxoplasmosis, one of the most prevalent zoonotic parasitic diseases. Cats, as definitive hosts, are spreaders of the parasite via their faeces, but this occurs only for a very short period in their life. Seropositivity in cats, although not associated with current shedding of the parasite, is indicative of the infection in a cat population and can be used to assess the infection risk for definitive and intermediate hosts in that area. In order to assess the prevalence of infection in cats living in Cyprus, 155 cats, originating from all districts of the country, were examined for the presence of T. gondii antibodies. Additionally, parameters such as age, sex, health status, lifestyle and concomitant infections were statistically assessed as potential risk factors for T. gondii seropositivity. Specific anti-T. gondii antibodies were detected in 50 (32.3%) cats, while the presence of feline immunodeficiency virus antibodies and a history of never having been vaccinated were statistically associated with T. gondii seropositivity on multivariate logistic regression model. This is the first report of T. gondii seroprevalence in cats in Cyprus and indicates that raised public awareness should be considered to prevent infection of animals and humans.
ARTICLE | doi:10.20944/preprints202107.0332.v1
Subject: Life Sciences, Biochemistry Keywords: Taenia solium; seroprevalence; porcine Cysticercosis; Côte d’Ivoire.
Online: 14 July 2021 (12:46:07 CEST)
Abstract : Background : porcine cysticercosis is an endemic parasitic zoonosis in many developing countries. The objective was to estimate the seroprevalence of porcine cysticercosis in traditional pig farms in the departments of Dabou, Aboisso and Agboville where blood samples were taken from pigs and analyzed by ELISA (IgG) and western blot. Data on farming practices and pig characteristics were collected. Categorical variables were compared with the Chi2 test and continuous variables with the Student test. Multivariate logistic regression models were constructed to identify risk factors. Results: A total of 668 pigs were sampled from 116 farms. The seroprevalence of cysticercosis was estimated at 13.2%. Overweight [ORa=2.6; 95%CI(1.3-4.9)] and fat pigs [ORa=2.3; 95%CI(1.0-4.8)] were twice as likely to be seropositive for cysticercosis. This risk was increased in farms using well water for drinking [aOR=2.5; 95%CI(1.0-6.3)] as well as those reporting veterinary care of the animals (ORa=2.9; 95%CI (1.2-7.3)). Conclusions: This study demonstrated the circulation of T. solium in pig farms in southern Côte d'Ivoire.
ARTICLE | doi:10.20944/preprints202105.0387.v1
Subject: Life Sciences, Biochemistry Keywords: Chikungunya; seroprevalence; clinical presentation; febrile outpatient; Malawi
Online: 17 May 2021 (13:19:32 CEST)
Chikungunya is a mosquito-borne viral disease caused by Chikungunya virus (CHIKV. We conducted this study determine the seroprevalence and clinical presentation of Chikungunya infection among outpatients seeking healthcare in Mzuzu City, Malawi. Blood samples were collected from malaria negative and non-septic febrile outpatients with fevers ≥38 °C, for not more than 5 days. The enzyme- linked immunosorbent assay (ELISA) test was used to detect anti-CHIKV IgM antibodies and its results were used to determine seroprevalence of Chikungunya. A total of 119 serum samples were tested, of these, 73 (61.3%) tested positive for anti-CHIKV IgM antibodies by ELISA. Laboratory requisition forms were used to capture demographic information such as age, sex, clinical signs and symptoms presented by the enrolled patients. Age groups of 1-9, 10- 19, 20- 29, 30- 39, 40- 49, and ≥50 years had 17.8% (n= 13), 12.3 %,( n=9), 15.1%) (n=11), 19.2%; (n=14), 17.8% (n=13) and 17.8% (n=13) proportion of seroprevalence respectively. Most of the CHIKV infected individuals presented with fever (52.05%), joint pain (45.21%) and abdominal pain (42.67%). The presence of anti- CHIKV IgM antibodies suggest the presence of recent CHIKV infection and therefore accurate laboratory assays are highly recommended for CHIKV diagnosis and appropriate management of febrile patients.
ARTICLE | doi:10.20944/preprints202008.0622.v1
Subject: Life Sciences, Biochemistry Keywords: Serology; Seroprevalence; Humoral response; COVID-19; serosurvey; epidemiology
Online: 27 August 2020 (12:47:12 CEST)
Seroprevalence studies suggest that the number of PCR-confirmed COVID-19 cases is significantly smaller than the true number of infections. I study logintidual seroprevalence data from 7 sites across the US, from early April 2020 to June 27. I show that not only COVID-19 seroprevalence does not seem to increase over time, there is no clear association between the number of cases reported during a period and the change in seroprevalence during the same time. I conclude that as they are, seroprevalence studies can only be used in the qualitative sense and distinguish between populations with no COVID-19 exposure, to those populations where the virus had already started spreading.
ARTICLE | doi:10.20944/preprints202105.0766.v1
Subject: Medicine & Pharmacology, Allergology Keywords: Homelessness; SARS-CoV-2; Health inequalities; seroprevalence; Housing conditions
Online: 31 May 2021 (12:15:39 CEST)
Background: Overcrowded housing, as well as inadequate sanitary conditions, contribute to making homeless people particularly vulnerable to the SARS-CoV-2 infection. We aimed to assess the seroprevalence of the SARS-CoV-2 infection among people experiencing homelessness on a large city-wide scale in France, taking into account different community settings. Methods: A consortium of outreach teams in 48 different locations including streets, slums, squats, emergency or transitional shelters and drop-in centres participated in the inclusion process. All participants consented to receive a validated rapid assay for immunoglobulins M (IgM) and G (IgG) antibodies and to answer a questionnaire on medical health conditions, comorbidities, historic of symptoms compatible with COVID-19, with a retrospective calendar of types of accommodation since COVID-19 crisis. Results: From June 01 to August 05, 2020, 1,156 homeless participants were enrolled in the study and tested. Seroprevalence of SARS-CoV-2 IgG/IgM antibodies was 5.6% (95%CI 2.3–7.0), with a range of 2.2% in people living on the streets to 8.1% in people living in emergency shelters (P=0.009). Around one third of the seropositive participants reported symptoms with COVID-19. Compared to the general population in Marseille (3.6%), the homeless population living in the same urban area experienced an significant increased risk of SARS-CoV-2 infection (|z|=3.65 > 1.96). Conclusion: These results highlight the need for organizing regular screening to prevent clusters forming in homeless accommodations and for providing basic resources for health maintenance.
REVIEW | doi:10.20944/preprints202012.0126.v1
Subject: Medicine & Pharmacology, Allergology Keywords: Covid-19; SARS-CoV-2; coronavirus; seroprevalence; antibody testing
Online: 7 December 2020 (08:19:40 CET)
SARS-CoV-2 continues to widely circulate in populations globally. Underdetection is acknowledged and is problematic when attempting to capture the true prevalence. Seroprevalence studies, where blood samples from a population sample are tested for SARS-CoV-2 antibodies that react to the SARS-CoV-2 virus, are a common method for estimating the proportion of people previously infected with the virus in a given population. However, obtaining reliable estimates from seroprevalence studies is challenging for a number of reasons, and the uncertainty in the results is often overlooked by scientists, policy makers and the media. This paper reviews the methodological issues that arise in designing these studies, and the main sources of uncertainty that affect the results. We discuss the choice of study population, recruitment of subjects, uncertainty surrounding the accuracy of antibody tests themselves, and the relationship between antibodies and infection over time. Understanding these issues can help the reader to interpret and critically evaluate the results of seroprevalence studies.
ARTICLE | doi:10.20944/preprints202009.0324.v1
Subject: Life Sciences, Virology Keywords: MERS-CoV; camel; seroprevalence; transmission; ELISA; RT-qPCR; slaughterhouse
Online: 15 September 2020 (03:54:34 CEST)
Background: MERS-CoV is a zoonotic virus that have emerged in humans in 2012 and caused severe respiratory illness with mortality rate of 34.4%. Since its appearance, MERS-CoV have been reported in 27 countries and most of these cases were in Saudi Arabia. So far, dromedaries are considered to be the intermediate host and the only known source of human infection. Method: This study was designed to determine the seroprevalence and the infection rate of MERS-CoV in slaughtered food-camels in Riyadh, Saudi Arabia. A total of 171 nasal swabs along with 161 serum samples were collected during the winter; from January to April 2019. Nasal swabs were examined by Rapid test and RT-qPCR to detect MERS-CoV RNA, while serum samples were tested primarily using S1-based ELISA Kit to detect MERS-CoV (IgG) antibodies and subsequently by MERS pseudotyped viral particles (MERSpp) neutralization assay for confirmation. Genetic diversity of the positive isolates was determined based on the amplification and sequencing of the spike gene. Results: Our results showed high prevalence (38%) of MERS-CoV infection in slaughtered camels and high seropositivity (70.81%) during the time of the study. These data indicate previous and ongoing MERS-CoV infection in camels. Phylogenic analysis revealed relatively low genetic variability among our isolated samples. When these isolates were aligned against published spike sequences of MERS-CoV, deposited in global databases, there was sequence similarity of 94%. Conclusion: High seroprevalence and high genetic stability of MERS-CoV in camels indicating that camels pose a public health threat. The widespread of MERS-CoV infections in camels increases the risk of future zoonotic transmission into people with direct contact with these infected camels. This study confirms re-infections in camels, highlighting a challenge for vaccine development when it comes to protective immunity.
SHORT NOTE | doi:10.20944/preprints202005.0194.v1
Subject: Mathematics & Computer Science, Probability And Statistics Keywords: Serosurvey; seroepidemiology; seroprevalence; sampling; imperfect diagnostic test; sensitivity; specificity; Coronavirus
Online: 11 May 2020 (12:47:00 CEST)
This brief note aims to explain the scope in conducting large-scale serological surveys of SARS-CoV-2 to define the landscape of population immunity without overlooking the inherent uncertainty steaming from sampling design and diagnostic validity. The note completes with a succinct statistical appendix of simple methods for estimating prevalence from random population samples using imperfect diagnostic tests.
ARTICLE | doi:10.20944/preprints202201.0152.v1
Subject: Medicine & Pharmacology, Other Keywords: SARS-CoV2; COVID-19; homeless people; public health; vulnerable population; Seroprevalence, cohort; residential mobility
Online: 11 January 2022 (17:20:14 CET)
Most vulnerable individuals are particularly affected by the COVID-19 pandemic. This study takes place in a large city in France. The aim of this study is to describe the mobility of the homeless population at the begin-ning of the health crisis and to analyze its impact in terms of COVID-19 prevalence. From June to August 2020 and September to December 2020, 1272 homeless people were invited to be tested for SARS-CoV-2 antibodies and virus in and completed questionnaires. Our data show that homeless populations are sociologically dif-ferent depending on where they live. We show that people living on the street were most likely to be relocated to emergency shelters than other inhabitants. Some neighborhoods are points of attraction for homeless peo-ple in the city while others emptied during the health crisis, which had consequences for virus circulation. People with a greater number of different dwellings reported became more infected. This first study of the mo-bility and epidemiology of homeless people in time of pandemic provides unique information about mobility mapping, sociological factors of this mobility, mobility at different scales and epidemiological consequences. We suggest that homeless policies need to be radically transformed since actual model exposes people to infection in emergency.
ARTICLE | doi:10.20944/preprints202204.0165.v1
Subject: Medicine & Pharmacology, Other Keywords: Coronavirus SARS-CoV-2; seroprevalence; antibodies; nucleocapsid antigen; antigen receptor binding domain; seropositivity; St. Petersburg; volunteers; vaccination
Online: 18 April 2022 (10:42:54 CEST)
Since the detection of the first COVID-19 patient, 2 years have passed, during which more than 287,862,000 people fell ill globally, of which about 1.9% died. Implementation of SARS-CoV-2 control programs required efforts from almost all countries. An important direction in the fight against COVID-19 was the formation of herd immunity, the main tool for managing the pandemic. Study goal: to assess the seroprevalence of antibodies (Abs) to SARS-CoV-2 nucleocapsid (Nc) and receptor binding domain (RBD) in the St. Petersburg population during the COVID-19 pandemic. Materials and methods. A longitudinal cohort randomized monitoring study of Ab seroprevalence (SARS-CoV-2 Nc, RBD) was organized and conducted according to a unified methodology developed by Rospotrebnadzor with the participation of the St. Petersburg Pasteur Institute. For this purpose, a cohort of 1000 volunteers was formed who participated in all five stages of seromonitoring. The cohort was divided into 7 age groups: 1-17; 18-29; 30-39; 40-49; 50-59; 60-69; 70; and older (70+) years. Seropositivity levels (Nc, RBD) were assessed by quantitative and qualitative enzyme immunoassays. During the 2nd year of monitoring, some volunteers were vaccinated with the GamCOVIDVac (84%) or EpiVacCorona (11.6%) vaccines approved in Russia. Statistical processing was carried out using the Excel 2010 software package. Confidence intervals for shares and percentages (95% CI) were calculated using the method of A. Wald and J. Wolfowitz with adjustment (A. Agresti, B.A. Coull). The statistical significance of differences was calculated by z-test, using the appropriate online calculator (p<0.05), unless indicated. Results. There was a trend towards: an increase in Nc seropositivity in stages 1-3 of seromonitoring, with a decrease in stages 4-5 among children and adults. The share of RBD seropositive steadily increased during all 5 stages of seromonitoring. The most frequently found were low anti-RBD Abs levels (22.6-220 BAU/ml). High Ab levels were recorded statistically significantly less frequently. Asymptomatic forms were observed in 84-88% of SARS-CoV-2 seropositive volunteers. By the 5th stage of monitoring, this indicator significantly decreased to 69.8% (95% CI: 66.1-73.4). The monitoring revealed a statistically significant increase in anti-RBD Abs, alongside a statistically significant decrease in the proportion of Nc seropositive. This dynamic was especially characteristic of persons vaccinated with GamCOVIDVac. Conclusion. Prior to the use of specific vaccines, a seroprevalence of anti-Nc Abs was noted. After the introduction of the GamCOVIDVac vaccine in adults, a decrease in the level of anti-Nc Abs was noted due to an increase in the proportion of RBD seropositive persons.
ARTICLE | doi:10.20944/preprints202209.0328.v1
Subject: Medicine & Pharmacology, Other Keywords: SARS-CoV-2; COVID-19; outpatient cohort; seroprevalence; mild infections; asymptomatic cases; COVID-19 contacts; PCR-positivity and symptoms; first year of the pandemic; Hungary
Online: 22 September 2022 (02:08:09 CEST)
We aimed to estimate the proportion of the population infected with SARS-CoV-2 in the first year of the pandemic. The study population consisted of outpatient adults with mild or no COVID-19 symptoms, and was divided into subpopulations with different levels of exposures. Of the subpopulation without known previous COVID-19 contacts 4143, of the subpopulation with known COVID-19 contacts 594 persons were investigated. IgG- and IgA-seroprevalence and RT-PCR positivity were determined in context with COVID-19 symptoms. We hope to have contributed to the understanding of the significance of the asymptomatic and mild infections in the long persistence of the pandemic.