Haemosporidian parasites in Kansas birds: molecular and histological evidence implicating Culicoides haematopotus (Diptera: Ceratopogonidae) in transmission.

Abstract

Haemosporidian parasites of birds are maintained through complex interactions among vertebrate hosts, arthropod vectors, and the parasites themselves, yet their vector-parasite relationships remain poorly resolved under natural conditions in North America. Haemoproteus species are among the most prevalent avian blood parasites and have been implicated in reduced host fitness and malaria-like disease. Here, we combined molecular and histological approaches to investigate Haemoproteus prevalence in wild birds and to identify potential Culicoides biting midge vectors in Kansas. Blood meals from field-collected Culicoides and hunter-collected turkey blood samples were screened using nested PCR targeting the Haemoproteus cytochrome b gene, followed by Sanger sequencing. We additionally dissected and microscopically examined salivary glands as well as turkey blood smears. Nearly all turkey blood samples (95.7%) were positive for Haemoproteus, revealing 2 distinct parasite clades and frequent coinfections. In contrast, Culicoides-based surveillance may have underestimated parasite prevalence in turkeys. Only Culicoides haematopotus consistently tested positive by PCR, and this species was the only one in which Haemoproteus sporozoites were detected in salivary glands. Sequencing of PCR amplicons from unfed C. haematopotus revealed amplification of a Culicoides-specific noncoding genomic region, highlighting limitations of molecular detection alone for vector incrimination. Together, these findings provide field-based evidence that C. haematopotus may serve as a vector of Haemoproteus in wild turkeys in Kansas, emphasizing the importance of integrating molecular and histological data when evaluating vector competence and potential population-level effects.