Blood parasites (Trypanosoma, Leucocytozoon, Haemoproteus) in the Eurasian sparrowhawk (Accipiter nisus): diversity, incidence and persistence of infection at the individual level

BACKGROUND

A high prevalence of parasites may result from life-long persistence of infection or from high reinfection rates. We have studied blood parasites in a breeding population of the accipitrid raptor, Eurasian sparrowhawk (Accipiter nisus), to determine parasite diversity and turnover.

METHODS

During this 7-year study, 210 adult Eurasian sparrowhawks breeding in the city of Prague were checked for parasites using several diagnostic methods.

RESULTS

In both female and male raptors, parasites of the genus Leucocytozoon were the most prevalent (92% and 85%, respectively) followed in decreasing order of prevalence by those of genus Trypanosoma (74% and 68%, respectively) and genus Haemoproteus (46% and 16%, respectively). The prevalence of all parasites increased with age in both sexes, with the females at each respective age having the higher prevalence. There was a positive association between Haemoproteus and Leucocytozoon infections. Persistence at the individual level was higher than incidence for Trypanosoma and Haemoproteus. In the case of Leucocytozoon and Trypanosoma, most individuals probably become infected in their first year of life or even before dispersal from the nest. The detected parasites belonged to Trypanosoma avium sensu stricto, Leucocytozoon sp. (haplotypes ACNI1 and ACNI3) and Leucocytozoon mathisi (haplotype ACNI4) and two new lineages of the Haemoproteus elani complex (ACCNIS6 and ACCNIS7). Detailed analysis of parasite lineages in individuals that were repeatedly sampled revealed lineage turnover that would otherwise remain hidden. Phylogenetic analysis revealed that the detected Haemoproteus belongs to a phylogenetically distant group whose taxonomic position requires further analysis.

CONCLUSIONS

All three genera of blood parasites persist in infected individuals, thus enabling sustainability of vector transmission cycles. Prevalence increases with age; however, there is a high turnover of Leucocytozoon lineages. No clear evidence of parasite-induced mortality was found, and most of the individuals were infected early in life, particularly in the case of Leucocytozoon.

Biting midges (Ceratopogonidae) as vectors of avian trypanosomes

Background

Although avian trypanosomes are widespread parasites, the knowledge of their vectors is still incomplete. Despite biting midges (Diptera: Ceratopogonidae) are considered as potential vectors of avian trypanosomes, their role in transmission has not been satisfactorily elucidated. Our aim was to clarify the potential of biting midges to sustain the development of avian trypanosomes by testing their susceptibility to different strains of avian trypanosomes experimentally. Moreover, we screened biting midges for natural infections in the wild.

Results

Laboratory-bred biting midges Culicoides nubeculosus were highly susceptible to trypanosomes from the Trypanosoma bennetti and T. avium clades. Infection rates reached 100%, heavy infections developed in 55–87% of blood-fed females. Parasite stages from the insect gut were infective for birds. Moreover, midges could be infected after feeding on a trypanosome-positive bird. Avian trypanosomes can thus complete their cycle in birds and biting midges. Furthermore, we succeeded to find infected blood meal-free biting midges in the wild.

Conclusions

Biting midges are probable vectors of avian trypanosomes belonging to T. bennetti group. Midges are highly susceptible to artificial infections, can be infected after feeding on birds, and T. bennetti-infected biting midges (Culicoides spp.) have been found in nature. Moreover, midges can be used as model hosts producing metacyclic avian trypanosome stages infective for avian hosts.