Comparative performance of microscopy, nested PCR, and real-time PCR for screening avian haemosporidian parasites in Afrotropical starlings (family Sturnidae).

Prevalence studies of avian haemosporidian parasites frequently use microscopy and the nested polymerase chain reaction (PCR) protocols for detecting infections. Newer PCR protocols to detect parasites are being developed, with the distinct advantage of reducing screening cost and time, as well as increasing efficiency and sensitivity. The detection ability of microscopy and nested PCR was compared against a real-time PCR (qPCR) protocol using genomic DNA extracted from 240 bird blood samples collected from three starling species (Cape Starling, the Greater Blue-eared Starling, and the Wattled Starling; family Sturnidae) in the Kruger national park, South Africa. All three protocols successfully detected avian haemosporidian parasites with the qPCR having a considerable edge against the other two methods. Fifteen unique cytochrome b lineages were identified of which seven were new lineages. Microscopy and nested PCR recorded similar prevalence (32.92% and 35.42% respectively). The qPCR protocol used here, although more sensitive (52.92% prevalence), is not able to differentiate between parasite genera but provides the opportunity to screen a large number of samples in large-scale studies within a specific region. This study recommends the development and adoption of new molecular protocols with increased sensitivity and accuracy in prevalence studies. Nevertheless, microscopy remains essential for the morphological description of parasites and for distinguishing between abortive and successful chronic infections. The PCR-based method displays the detection of the parasitic genome but does not reveal whether parasites have or will develop into a successful infection.

Avian haemosporidia in native and invasive sparrows at an Afrotropical region.

Bio-invasions are a major threat to biodiversity and ecosystems globally and may contribute to the proliferation of emerging infectious diseases. We examined the prevalence and phylogenetic diversity of avian haemosporidian parasites infecting the non-native house sparrows (Passer domesticus) and the native southern grey-headed sparrows (Passer diffusus). Blood samples from 104 sparrows (74 house sparrows and 30 southern grey-headed sparrows) mist-netted inside and around the Kruger National Park were used. Genomic DNA was extracted from each blood sample and subjected to nested PCR analyses, Sanger sequencing and phylogenetic analyses. Overall, 35.57% (37/104) of the birds sampled were infected with at least one haemosporidian parasites. Southern grey-headed sparrows had a higher parasite prevalence (60%) than house sparrows (24.3%). A total of 16 parasite lineages were identified, of which eight were novel lineages. Whereas Haemoproteus spp. showed the highest lineage diversity, Leucocytozoon spp. were the most prevalent parasites, albeit with significant differences between sparrow species. A single Plasmodium sp. infection was recorded in a southern grey-headed sparrow. In support of the enemy release hypothesis, we found that prevalence on non-native house sparrows was lower than prevalence recorded in their region of origin and also that they were infected only by indigenous parasites lineages.