Abstract
BackgroundMigratory birds can cross geographical and environmental barriers and are thereby able to facilitate transmission of tick-borne pathogens both as carriers of infected ticks and as reservoirs of pathogenic microorganisms. Ixodes ricinus is one of the most abundant tick species in the Northern Hemisphere and a main vector of several Babesia species, some which pose a potential threat to human and animal health. At present only two cases of overt babesiosis in humans have so far been reported in Sweden. To better understand the potential role of birds as disseminators of zoonotic Babesia protozoan parasites, we investigated the presence of Babesia species in ticks removed from migratory birds.MethodsTicks were collected from birds captured at Ottenby Bird Observatory, south-eastern Sweden, from March to November 2009. Ticks were molecularly identified to species, and morphologically to developmental stage, and the presence of Babesia protozoan parasites was determined by real-time PCR.ResultsIn total, 4601 migratory birds of 65 species were examined for tick infestation. Ticks removed from these birds have previously been investigated for the presence of Borrelia bacteria and the tick-borne encephalitis virus. In the present study, a total of 1102 ticks were available for molecular analysis of Babesia protozoan parasites. We found that 2.4% of the ticks examined, all I. ricinus, were positive for mammal-associated Babesia species. Out of all Babesia-positive samples, Babesia venatorum was the most prevalent (58%) species, followed by Babesia microti (38%) and Babesia capreoli (4.0%). B. venatorum and B. capreoli were detected in I. ricinus larvae, whereas B. microti was only present in I. ricinus nymphs. This supports the view that the two first-mentioned species are vertically (transovarially) transmitted in the tick population, in contrast to B. microti. The largest number of Babesia-infected ticks was removed from the common redstart (Phoenicurus phoenicurus) and European robin (Erithacus rubecula).ConclusionsThis study reveals that Babesia protozoan parasites are present in ticks infesting migratory birds in south-eastern Sweden, which could potentially lead to the dissemination of these tick-borne microorganisms into new areas, thus posing a threat to humans and other mammals.Graphical
Highlights
Migratory birds can cross geographical and environmental barriers and are thereby able to facilitate transmission of tick-borne pathogens both as carriers of infected ticks and as reservoirs of pathogenic microorgan‐ isms
Several studies in the Scandinavian countries have shown the presence of ticks and tick-borne infections in returning migratory birds, especially well-studied pathogens such as Borrelia burgdorferi sensu lato (s.l.) [2], Rickettsia spp. [3], and tick-borne encephalitis (TBE) virus [4]
The total nucleic acids were reverse-transcribed to cDNA using the illustraTM Ready-to-Go RT-PCR Beads kit (GE Healthcare, Amersham Place, UK), which served as template in all the polymerase chain reaction (PCR) assays
Summary
Migratory birds can cross geographical and environmental barriers and are thereby able to facilitate transmission of tick-borne pathogens both as carriers of infected ticks and as reservoirs of pathogenic microorgan‐ isms. Europe, where a large part of the avifauna migrate, either to milder regions in western Europe or the Mediterranean region, or long distances to sub-Saharan Africa or even Asia This means that birds returning in spring could carry ticks from regions that better sustain yearround transmission of tick-borne pathogens, and possibly contribute to reseeding foci of infections in temperate and boreal areas. The potential for less-studied, rarer, or unknown pathogens in bird-borne ticks to be detected in birds has come into focus recently, for instance with the bacterium Neoehrlichia mikurensis, which once identified has been shown to be fairly abundant in ticks [5] Another pathogen of concern is Babesia spp., a protozoan parasite causing babesiosis—an emerging tick-borne human disease in the Holarctic region
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
