Birds as reservoirs for Borrelia burgdorferi s.l. in Western Europe: circulation of B. turdi and other genospecies in bird–tick cycles in Portugal

Abstract

Summary Birds are important in the ecology of Borrelia burgdorferi sensu lato (s.l.) because they are important hosts for vector tick immature stages and are known reservoirs for some Borrelia genospecies. The aim of our study was to assess the role of common passerine bird species as reservoirs for B. burgdorferi s.l. in Western Europe. We surveyed birds in enzootic areas in Portugal, where no information is available for birds as reservoirs for this aetiologic agent and where B. lusitaniae, for which few reservoirs have been identified, is the dominant genospecies. Twenty‐three birds (2.9%), including Turdus merula, T. philomelos, Parus major and Fringilla coelebs harboured infected ticks, but only Turdus sp. harboured infected tick larvae. In one study area, although B. lusitaniae was dominant in questing Ixodes ricinus, no ticks feeding on birds were infected with this genospecies, and B. valaisiana was the dominant genospecies in I. ricinus larvae feeding on birds. In the other area ticks collected from birds were mainly I. frontalis which were infected with B. turdi. Two skin biopsies (4.2%) from two T. merula were positive, one for B. valaisiana and the other for B. turdi. This is the first report for B. turdi in Western Europe.

Ticks (Acari: Ixodidae) as ectoparasites of Brazilian wild birds and their association with rickettsial diseases

“…Birds were shown to be important mobile hosts responsible for the spread of one or more stages of ticks and tick-borne pathogens such as Rickettsia, Borrelia, Anaplasma and Ehrlichia (ANDERSON et al, 1896;PARKER et al, 1933;HOOGSTRAAL, 1961;1963;SOMOV;SOLDATOV, 1964apud HUBÁLEK 2004OLSEN et al, 1993;GERN et al, 1998;HUMAIR et al, 1998;ALEKSEEV et al, 2001;BJÖERSDORFF et al, 2001;DANIELS et al, 2002;SANTOS-SILVA et al, 2006;SMITH et al, 2006;OGDEN et al, 2008;HAMER et al, 2011;GELLER et al, 2013;NORTE et al, 2013;LITERAK et al, 2015).…”

Characterization Through Multilocus Sequence Analysis of Borrelia turdi Isolates from Portugal

“…Turdus sp., in particular T. merula (see also xenodiagnostic experiment in [14]) and T. philomelos, and P. major [12,10] have been suggested as the main bird species responsible for the maintenance of enzootic cycles of B. turdi with their endophilic ticks (I. frontalis). In this study, 15 out of the 17 B. turdi-positive cultures and five out of the six B. turdi isolates were obtained from ticks feeding on these bird species, supporting their prominent role in the maintenance of B. turdi in circulation.…”

“…Culture tubes were incubated at 34°C and monitored regularly for Borrelia growth by observation under a dark field microscope. After 25±10 days (mean ± SD), DNA was extracted from cultures by thermolization as described previously [12]. A nested PCR targeting the flaB gene [18] was performed on the extracted DNA.…”

“…These detections derived mostly from ornithophilic ticks such as I. frontalis, feeding on thrushes (Turdus sp.) and Parus major, and B. turdi prevalence varied between 7 and 56 % in I. frontalis feeding on birds [10][11][12][13]. B. turdi has also been detected in Ixodes ricinus [9,12] although with lower prevalence and in T. merula skin biopsies [12].…”

“…Borrelia turdi is a genospecies first detected in Japan in 1996 [6], in an endophilic tick (Ixodes turdus) feeding on a passerine bird (Emberiza spodocephala [7]). Recently, B. turdi was reported from the Republic of Korea [8] and has been increasingly detected in Europe, including in Norway [9], Belgium [10], Spain [11] and Portugal [12,13]. These detections derived mostly from ornithophilic ticks such as I. frontalis, feeding on thrushes (Turdus sp.)…”