Blackbirds and Song Thrushes Constitute a Key Reservoir of Borrelia garinii , the Causative Agent of Borreliosis in Central Europe

Abstract

Blackbirds (Turdus merula) and song thrushes (Turdus philomelos) were found to carry 95% of all spirocheteinfected tick larvae among 40 bird species captured in Central Europe. More than 90% of the infections were typed as Borrelia garinii and Borrelia valaisiana. We conclude that thrushes are key players in the maintenance of these spirochete species in this region of Central Europe.Lyme borreliosis is a tick-transmitted zoonosis caused by spirochete bacteria from the genus Borrelia. This genus comprises 13 named species, and at least 4 of these cause disease in humans, namely, Borrelia burgdorferi, Borrelia spielmanii, Borrelia afzelii, and Borrelia garinii (1,14). All known strains of Lyme borreliosis spirochetes are maintained in nature by vertebrate hosts and ixodid ticks, with humans being ecological dead-end hosts.For Europe, pheasants (Phasianus colchicus), a few seabird species, and some passerine bird species have been shown to be reservoir competent for B. garinii and B. valaisiana but not for B. afzelii, a rodent specialist (4,5,6,7,13). However, little is known about the roles of the numerous European woodland bird species in the ecology of Lyme borreliosis spirochetes (2, 13). Therefore, we captured birds of a wide range of species, many of which are migratory, and determined their importance as hosts to ticks and as reservoirs for Lyme borreliosis spirochetes in selected sites of Central Europe.Ticks were collected from birds captured in four woodlands in Slovakia (16) during 2001 and 2002 and, in 2003, at one woodland in the southeastern Czech Republic. Questing adult and nymphal Ixodes ricinus ticks were collected from Slovak sites. Extracted DNA (3) was subjected to nested PCR targeting the 5S-23S intergenic spacer and also, in some cases, the flaB gene of Lyme borreliosis spirochetes (8, 15). Spirochete infections determined in ticks were assigned to species by the reverse line blot assay (5,8,15) or by DNA sequencing.Risk factors for tick infestation and infection with B. burgdorferi genospecies were investigated in negative binomial and logistic regression models, respectively. Explanatory variables were month, year, site, and bird species. Data from the Czech Republic were excluded because of differences in collection year and bird species range. The level of significance was set at a P value of Ͻ0.05. Because of the poor fit of Poisson regression models, the negative binomial models were used. For detailed statistical methods and results, see the supplemental material.Tick infestations of birds. Of 529 birds captured (345 and 184 at sites in Slovakia and the Czech Republic, respectively, comprising 40 species of 17 families), 187 (145 in Slovakia and 42 in the Czech Republic) carried I. ricinus (463 and 157 larvae and 375 and 495 nymphs in Slovakia and the Czech Republic, respectively) (Table 1). In Slovakia, blackbirds (Turdus merula), song thrushes (Turdus philomelos), and European robins (Erithacus rubecula) carried 55.6% of all collected I. ricinus ticks. In the Czech Republic, Europea...

Tick-Borne Pathogens in Ticks Feeding on Migratory Passerines in Western Part of Estonia

“…Common blackbirds and thrushes serve as main reservoirs for B. garinii and B. valaisiana in Europe (Humair et al 1998, Hanincova et al 2003b, Taragel'ova et al 2008. The results of our study also support the notion that birds of Turdus spp.…”

“…There are several studies reporting the presence of B. afzelii in bird-feeding ticks (Humair et al 1998, Comstedt et al 2006, Kipp et al 2006, Poupon et al 2006, Taragel'ova et al 2008, Franke et al 2010b), although B. afzelii is regarded to be a rodent-associated genospecies in Europe (Humair et al 1999, Hanincova et al 2003a). It has been previously shown that birds do not serve as adequate reservoirs for B. afzelii, and furthermore, that the uptake of avian blood initiates the elimination of B. afzelii in the tick (Kurtenbach et al 2002).…”

Low Haemosporidian Diversity and One Key-Host Species in a Bird Malaria Community on a Mid-Atlantic Island (São Miguel, Azores)

“…In Europe, the Eurasian Blackbird carries high parasite loads, not only for avian malaria, but also for other parasites such as Borrelia spp. (Hatchwell et al, 2000;Taragelova et al, 2008). (Fig.…”

Borrelia bavariensis sp. nov. is widely distributed in Europe and Asia

“…RFLP analysis revealed that strains of this subtype were genetically highly homogeneous (Marconi et al, 1999). Furthermore, ospA type 4 strains form a distinct ecotype within B. garinii and utilize rodents as reservoir hosts (Hu et al, 1997;Huegli et al, 2002), while other subtypes of B. garinii are transmitted by birds (Dubska et al, 2009;Hanincová et al, 2003b;Taragel'ová et al, 2008). In Asia, NT29 and related strains also comprise a rodent-associated ecotype within B. garinii, but their relationship to ospA type 4 strains from Europe remained unclear as European and Asian B. garinii not only differed in their ospA pattern, but also showed differences in the RFLP pattern of the 5S-23S intergenic spacer (reviewed by Miyamoto & Masuzawa, 2002).…”