Aras Part Medical International Press International Journal of Medical Parasitology and Epidemiology Sciences 2766-6492 7 2 2026 06 29 Molecular and Histopathological Study of Sarcocystis spp. Parasites Infecting Selected Species of Local Birds in Al-Diwaniyah Governorate / Iraq 127 132 10.34172/ijmpes.6274 EN Hayder Akriem Muslim https://orcid.org/0009-0002-7566-7072 Khaled Thamer Alshaebani https://orcid.org/0000-0002-0056-3511 Journal Article 10.34172/ijmpes.6274 2026 04 16 2026 05 27 Introduction: Sarcocystis is a globally widespread parasite that has garnered increasing attention in recent years due to its health and economic impacts. It is a significant parasitic disease that contributes to neurological disorders in infected animals and causes substantial economic losses in livestock production. This study aimed to detect Sarcocystis infection in wild pigeons, domestic chickens, and ducks in Al-Diwaniyah Governorate using macroscopic, microscopic, and molecular examinations. The study also evaluated the influence of infection-related factors and the efficacy of different diagnostic methods. Methods: The study examined 150 birds between October 2025 - March 2026, 50 of each species. Diagnosis was based on comparisons of macroscopic and microscopic examinations using three methods (pepsin digestion, slide crushing, and garlic press), Nested-PCR targeting the 18S rRNA gene, and histological examinations. Results: Gross examination showed an overall infection rate of 6%, whereas microscopic examination revealed a higher rate of 32%, confirming its superior sensitivity and diagnostic efficiency. The pepsin digestion method was particularly effective compared to slide-crushing, crushing, and garlic-pressing methods. Wild pigeons exhibited the highest infection rates, with the esophagus being the most frequently affected organ. Statistically, the analyses did not show significant differences in infection rates by bird sex, time of year, or geographic region, despite higher infection rates in winter. Nested-PCR confirmed positive infections at 622 base pairs. Genetic analysis identified Sarcocystis columbae in wild pigeons, Sarcocystis wenzeli in domestic chickens, and Sarcocystis rileyi in ducks. Histological examinations revealed parasitic cysts within muscle fibers, accompanied by inflammatory changes and cellular infiltration. Conclusion: This study concludes that microscopic examination using pepsin digestion is the most efficient and reliable diagnostic tool in conventional laboratories. At the same time, molecular and genetic analysis remains the cornerstone for accurate qualitative classification of parasite isolates. These results highlight the critical importance of integrating microscopic, histological, and molecular examinations to ensure a comprehensive and accurate diagnosis of Sarcocystis in birds.