Seroprevalence and Risk Factors of Toxoplasma gondii Infection Among Pregnant Women in Shendi, River Nile State, Sudan

1. Introduction

Toxoplasmosis is a globally distributed zoonotic disease caused by the obligate intracellular protozoan parasite Toxoplasma gondii. Members of the family Felidae, particularly domestic cats, serve as the definitive hosts and are the only species capable of shedding unsporulated oocysts into the environment via their feces. These oocysts undergo sporulation and become infectious in soil, water, or feed after 1 to 5 days. Humans and other warm-blooded animals act as intermediate hosts, acquiring infection primarily through the ingestion of sporulated environmental oocysts or via the consumption of raw or undercooked meat containing viable tissue cysts (bradyzoites), particularly from small ruminants like sheep and goats [1,2].

While primary infection in immunocompetent individuals is typically mild or asymptomatic, maternal acquisition of T. gondii during pregnancy poses severe clinical risks due to the risk of vertical transmission. Congenital toxoplasmosis can lead to miscarriage, premature birth, neonatal death, or severe long-term neuro-ophthalmic sequelae such as chorioretinitis, hydrocephalus, and intracranial calcifications [4,5,6].

Maternal exposure triggers an antibody cascade. Because the intracellular parasite is rarely observable by direct microscopy in clinical blood samples, serological screening is the diagnostic standard. Immunoglobulin M (IgM) levels rise rapidly following acute infection and decline over several months, serving as a diagnostic hallmark for recent acquisition [7,8,9,10]. Conversely, specific IgG antibodies appear later, persist for life, and denote chronic or historical exposure [11,12].

Despite historical records documenting toxoplasmosis in Sudan since 1966, there remains a distinct scarcity of contemporary data mapped to localized sub-urban regions like Shendi in the River Nile State. This study addresses this gap by establishing the seroprevalence and assessing the socioeconomic, dietary, and obstetric risk factors of T. gondii exposure among a large cohort of pregnant women

2. Materials and Methods

2.1. Study Area and Design

This cross-sectional, descriptive study was conducted in Shendi city, situated on the east bank of the Nile River in the River Nile State, Sudan. The region serves as an agricultural and trading hub with a high density of livestock. Sampling was executed across a 12-month period spanning from January to December 2025.

2.2. Study Population and Sampling Technique

The target population comprised pregnant women booking or attending routine antenatal care check-ups at major local health institutions, including Shendi University Hospital, Shendi Teaching Hospital, and primary rural-urban antenatal clinics. A convenience sampling method was utilized to enroll 300 consecutive consenting participants across varying maternal age categories (<20, 21–30, 31–40, and >40 years) and gestational stages (first, second, and third trimesters).

2.3. Sample Collection and Processing

Under sterile medical conditions, 5 mL of venous blood was drawn via venipuncture from each participant into plain serum separator tubes. Samples were left to clot completely at room temperature and then centrifuged at 2,200×g (equivalent to 5,000 rpm in a standard laboratory benchtop centrifuge) for 10 minutes to isolate the serum. Serum aliquots were transferred to sterile microtubes and stored at −20∘C until serological profiling was performed.

2.4. Serological Testing

All serum samples were analyzed using a commercial Toxo IgG/IgM Combo Rapid Test Cassette (Biomed Diagnostics, Germany; Sensitivity: 98.2%, Specificity: 99.1%). The lateral flow immunochromatographic test (ICT) was performed at room temperature strictly according to the manufacturer’s protocols. The emergence of distinct colored bands in the test and control windows indicated positive results.

2.5. Questionnaire and Data Collection Variables

A pre-tested, structured interview questionnaire was administered to each participant to compile socio-demographic, dietary, and clinical profiles. Collected independent variables included maternal age, gestational trimester, number of children (parity), regular dietary habits (consumption of raw/undercooked meat such as raw lamb liver or umfitfit), history of prior miscarriages, historical record of prior diagnosed parasitic infections, and history of bearing children with congenital abnormalities.

2.6. Statistical Analysis

Data were cleaned, coded, and entered into the Statistical Package for the Social Sciences (SPSS) software version 26.0. Descriptive statistics were used to compute absolute frequencies and percentage values. To determine the associations between categorical independent risk factors and the binary outcome of T. gondii IgG seropositivity, the Pearson Chi-square (χ2) test was applied. A P-value of <0.05 was established as the threshold for statistical significance.

2.7. Ethical Considerations

Ethical approval for this study was formally granted by the Ethical Review Board of the Department of Medical Parasitology, Faculty of Medical Laboratory Sciences, Shendi University (Approval No: SU-FMLS-2025-042). Before enrollment, the clinical purpose, benefits, and voluntary nature of the study were explained to each participant, and written or verbal informed consent was obtained.

3. Results

Out of the 300 pregnant women screened, 140 tested positive for anti-T. gondii IgG antibodies, yielding an overall seroprevalence of 46.7% (140/300). No sample demonstrated positive results for anti-T. gondii IgM antibodies, indicating a lack of acute, active infections within this study group.

To evaluate epidemiological risk variables clearly, all socio-demographic, dietary, and clinical factors have been integrated into a comprehensive, single univariate analysis table (Table 1).

4. Discussion

Establishing localized seroprevalence profiles for Toxoplasma gondii is vital for shaping screening guidelines and maternal health policies. In this study, screening 300 pregnant women using an immunochromatographic lateral flow technique revealed an IgG seropositivity rate of 46.7%, with no corresponding IgM detection. This pattern mirrors chronic, latent maternal exposure rather than active, acute infection

The observed 46.7% seroprevalence rate highlights the endemic nature of the parasite within the River Nile State. This finding is higher than the 34.1% reported in Khartoum by Elnahas (14) and the 34.7% documented by Abd Elwahid et al. in the neighboring locality of Eldamar using ELISA-based assays (18). Variations in seroprevalence across these studies may stem from differences in diagnostic test sensitivities, local culinary habits, and environmental humidity levels that affect oocyst survival. However, our findings align closely with data from Gezira State, where rates between 68% and 73.3% emphasize the extensive distribution of T. gondii throughout central livestock-rearing regions of Sudan (15).

The immunochromatographic test (ICT) was chosen for its point-of-care utility, rapid results, and lack of requirement for specialized laboratory infrastructure. While ICT assays provide practical field utility, they are screening tools that lack the quantitative precision of enzyme-linked immunosorbent assays (ELISA) or the avidity testing required to determine exactly when an infection was acquired. This stands as a recognized limitation of this methodology.

Analysis of risk factors showed no statistically significant differences across maternal age groups (P=0.989), indicating that exposure risk is fairly uniform across a woman’s reproductive years. However, a strong correlation was identified between seropositivity and raw meat consumption (69.0%, P=0.000). In Sudanese communities, traditional culinary practices often include eating raw beef or sheep liver, or dishes like umfitfit (undercooked ruminant tripe seasoned with spices). Because livestock graze in areas accessible to stray felines, tissue cysts are common in local meat, making undercooked meat a major route for human transmission.

A clear statistical association was also observed between first-trimester screening and IgG positivity (85.7%, P=0.000). This pattern likely reflects early clinical selection, as women with a history of recurrent reproductive challenges are more likely to seek medical evaluation early in their first trimester.

Additionally, strong correlations were found between IgG seropositivity and poor obstetric history, including prior miscarriages (P=0.000) and children born with congenital abnormalities (P=0.000). While these findings suggest a clear link, caution is needed when interpreting causation from cross-sectional data. Because the study found only IgG antibodies, indicating past exposure, these historical reproductive complications cannot be definitively attributed to active toxoplasmosis during those specific pregnancies. Nonetheless, the high rate of chronic exposure among women with adverse obstetric histories suggests that toxoplasmosis may be a contributing factor to reproductive health issues in this region, pointing to a clear need for further prospective cohort studies.

5. Conclusion

This study confirms a high seroprevalence of latent Toxoplasma gondii exposure (46.7%) among pregnant women in Shendi, Sudan. Seropositivity is strongly linked to dietary habits, notably the consumption of raw or undercooked meat, as well as histories of miscarriage and congenital defects. These findings emphasize the need for public health initiatives, including educational campaigns on food hygiene and meat preparation, along with integrated prenatal screening to protect maternal and fetal health.