Epidemiological Study of Toxoplasma infection in Humans and Sheep Using Molecular, Serological, and Traditional Techniques in Central Iraq

Background: The parasitic protozoan Toxoplasma gondii is the cause of serious diseases known as toxoplasmosis. All warm-blooded vertebrate animals are susceptible to infection. Despite its significance, recent data on the prevalence and genetic diversity of T. gondii in human and sheep populations in central Iraq are limited.Objectives: This study aimed to determine the prevalence of T. gondii infection in humans and sheep in Diyala and Baghdad provinces, Iraq, using serological and molecular techniques, and to genetically characterize circulating strains based on the regenerating gene (Reg). Methods: The one hundred placentas of sheep in Diyala and Baghdad (۵۰ samples from each province) were examined. An infected sheep placenta sample was digested with the pepsin enzyme. This was intended for performing the dyeing process with Giemsa stain and extracting the genomic DNA, using the tissue genomic DNA isolation kit (buffy coat) of seropositive individuals with Geneaid, Bioteccorp, Taiwan. Polymerase chain reaction (PCR) amplification targeted a ۵۲۹ bp fragment of the REGs gene in T. gondii. Human serum samples were collected from ۱۰۰ human blood samples (male and female) from Diyala and Baghdad (۵۰/۵۰). The enzyme-linked immunosorbent assay (ELISA) results were recorded according to the manufacturer’s instructions. The study period was from September ۲۰۲۴ to April ۲۰۲۵. Results: The overall infection rate in sheep was ۲۵% (۲۵/۱۰۰), with a higher rate in Diyala (۳۰.۳%) than in Baghdad (۲۰%). In ewes, the highest prevalence (۴۳.۳۳%) was observed at ۴ years of age. ELISA testing of human sera (n=۱۰۰) revealed an overall seroprevalence of ۲۳.۹۱%. The rate was significantly higher in Diyala (۳۰.۹۵%) than in Baghdad (۱۸%), and higher in females (۴۰%) than in males (۴.۷۶%). The highest infection rate (۳۳.۳۳%) was found in the ۲۵-۳۵-year age group. “Phylogenetic analysis of the Reg sequences showed that Iraqi isolates clustered most closely with strains from Iraq, Indonesia, China, Italy, Netherlands, Pakistan, Turkey, Iran, Chile, Myanmar, Nigeria, Saudi Arabia, and India. Phylogenetic analysis of the evolutionary distribution of REGs in ۲۰ local isolates detected in Diyala and Baghdad (the middle of Iraq), with ۳۶ global isolates of T. gondii deposited in GenBank, indicated a diverse evolutionary lineage.Conclusion: This study confirms that toxoplasmosis remains a highly endemic zoonosis in central Iraq, with a significant prevalence in both sheep and human populations. The high genetic diversity of T. gondii strains and the identified risk factors (location, gender, and age) highlight the need for targeted public health and veterinary control measures.

کلیدواژه ها:

Diyala ، Human ، Molecular ، serological ، sheep ، Toxoplasmosis