The role of Palaearctic-African migratory birds in the distribution of exotic tick (Hyalomma) species and the possibilities of spreading tick-borne diseases

Abstract

Background: Migratory birds are able to carry ticks, but their role in disseminating exotic ticks and tick-borne pathogens over great distances has not been determined in the Netherlands.

Methods: In total 1888 ticks from 607 tick-infested birds in the Netherlands and 9 ticks derived from 7 birds in Greece were removed and examined. Ground-feeder, non-ground feeder, sedentary, short- and long-distance migratory birds were all carrying ticks. More ticks were found on ground-feeder and short-distance migratory birds. The highest tick-infestation (n=24) was found on a Dunnock, which is a non-ground feeder.

Results: The predominant tick species was I. ricinus 96,0%. Other species that were found were respectively Ixodes frontalis 1,4%, I. arboricola 0,27%, I. lividus 0,21% and I. hexagonus 0,05%. No exotic tick species were found. Most ticks were nymphs (83,6%), followed by larvae (14,7%) and a few adults (0,69%). A selection of the collected ticks was made to investigate if the ticks carry any pathogens. A percentage of 11,8% of these selected ticks, all Ixodes ricinus nymphs, were found positive for different pathogens. Neoehrlichia mikurensis was found, Babesia venatorum and only one Borrelia species, the Borrelia garinii, was found with RLB.

Conclusions: Migratory birds do play a role in the dispersal of tick-borne diseases like Neoehrlichia mikurensis and Babesia venatorum to regions where these pathogens were not really common. Further research needs to be done to investigate the ability of exotic tick species can be distributed by migratory birds.