The role of birds in the eco-epidemiology of tick-borne pathogens

In this review the authors summarize the epidemiological role of tick infestation of birds, in the context of the recent scientific results. Birds play an important role in the transportation of ticks and tick-borne pathogens, some of which may pose a risk to humans and domestic animals. Two host-generalist tick species, lxodes ricinus and Haemaphysalis concinna occur more often on birds in Central Europe, than ornitophilic tick species. The prevalence of tick infestation among birds may depend on several factors, such as migrating strategy (short or long distance migrants), feeding level (on the ground or above), climatic factors and also the pathogens living in ticks. It is known that during the spring migration birds arriving from the south may carry developmental stages of exotic ticks (e.g. Hyalomma species) and if these immature ticks are able to moult to adults, they can feed on domestic animals. Bird ticks may carry viruses (e.g. TBE virus), bacteria (mostly Borrelia spp., Anaplasma spp. and Rickettsia spp.) and parasites (Babesia spp.) which could represent potential threat to humans. Ticks of migratory songbirds could carry exotic pathogens, as well. The knowledge on tick-borne pathogens in bird tissues is limited, but Anaplasma phagocytophilum, Coxiella burnetii and Rickettsia spp. have been shown to be present in the blood of birds. In this way, it has been demonstrated, that avian hosts can be potential reservoirs of bacteria. Therefore it is important to monitor birds and their ticks, especially because birds are the most common representatives of wildlife near human communities and animal farms, so they can easily pose a risk to human and animal health.