Purpose Haemosporidian parasites of birds such as Plasmodium, Haemoproteus, and Leucocytozoon have complex life cycles involving two types of hosts: Vertebrates and invertebrates. The prevalence of these parasites is influenced by the interactions between these hosts and the environment. Birds infected with avian haemosporidians serve as a valuable model for studying the effects of environmental factors on the spread of endemic pathogens. Methods In our study in southern Iran, which is known for its mild winters and hot summers, 237 blood samples from 41 bird species were analyzed. Each sample was analyzed using nested PCR for the cytb gene associated with the genera Haemoproteus, Plasmodium, and Leucocytozoon. Result The results showed a high infection rate (55. 69%) of parasites, with the Passeridae family having the highest rate (43. 18%). Wind speed, latitude and altitude were the key factors for the prevalence of Haemoproteus, Plasmodium and Leucocytozoon, while longitude, annual precipitation, relative humidity, NDVI index and distance to water were other influencing factors. The migratory status of the host birds had no effect on the prevalence or diversity of the parasites. Conclusion The study identifies wind speed, latitude and altitude as key factors in the prevalence of Haemoproteus, Leucocytozoon and Plasmodium, but other diverse environmental factors also play a role. Further research on avian communities and dipteran vectors in southern Iran is needed to fully understand the environmental factors influencing parasite prevalence.

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