Infection rates, parasitemia levels, and genetic diversity of hematozoa in New World waterfowl

Abstract

Blood parasites can limit the productivity of birds and increase the vulnerability of isolated and naïve populations to extinction. I examined 804 blood samples collected from 11 species of South American waterfowl to assess infection by Haemoproteus, Plasmodium and/or Leucocytozoon parasites. In addition, I strove to develop a new molecular tool to quickly and accurately determine relative parasitemia rates of Leucocytozoon parasites in avian blood. I used samples collected from waterfowl in interior Alaska (n = 105) to develop and optimize a real-time, quantitative PCR methodology using TaqMan fluorogenic probes. Molecular screening produced an apparent prevalence rate of 3.1% for hematozoa infections in South American waterfowl samples, and analysis of hematozoa mitochondrial DNA produced 12 distinct hematozoa haplotypes, four of which were identical to hematozoa lineages previously found infecting waterfowl in North America. Phylogenetic analyses of hematozoa DNA revealed close relationships between parasite lineages infecting waterfowl on both continents. Our qPCR assay showed high levels of sensitivity (91%) and specificity (100%) in detecting Leucocytozoon DNA from host blood when compared to results from a well-used nested-PCR protocol. Additionally, statistical results of a linear regression supported correlation between relative parasitemia estimates from our qPCR assay and greater numbers of parasites observed on blood smears (R2 = 0.67, P = 0.003).