The Infection Rate of Bird-Feeding Ticks with and Varies with Host Haemosporidian Infection Status.

BACKGROUND

Birds are known to maintain and spread human pathogenic borreliae, but they are common hosts of diverse parasite communities, notably haemosporidians. Only a few studies examined whether tick infestation and/or prevalences vary with hosts' haemosporidian infection status.

METHODS

Here, we study whether infestation rates and infection rates in bird-feeding ticks vary according to haemosporidian infection status in a community of free-living avian tick hosts.

RESULTS

Birds of six avian species harbored the majority of ticks. Both the tick infestation prevalence and the intensity peaked during spring and summer, but while bird-feeding nymphs prevailed in spring, bird-feeding larvae dominated in summer. Almost half of the bird-feeding ticks were found to be positive for s.l. Although the majority of infections involved bird-associated and , appears to be the dominant strain circulating in locally breeding avian species. We detected a negative link between the hosts' haemosporidian infection status and the infection rate of bird-feeding ticks, but the association was dependent on the host's age.

CONCLUSIONS

Our results on tick infestation intensity support the idea that more immunologically vulnerable hosts harbor more ticks but suggest that different mechanisms may be responsible for tick infestation rates among immunologically naïve and experienced avian hosts. The results on infection rates in bird-feeding ticks are consistent with studies revealing that intracellular parasites, such as haemosporidians, can benefit from the host immune system prioritizing immune responses against extracellular parasites at the expense of immune responses against intracellular parasites. The findings of our study urge for a more robust design of parasitological studies to understand the ecology of interactions among hosts and their parasites.