PCR Detection of Granulocytic Ehrlichiae in Ixodes ricinus Ticks and Wild Small Mammals in Western Switzerland

Abstract

The presence of granulocytic ehrlichiae was demonstrated by PCR inIxodes ricinus ticks and wild small mammals in Switzerland in two areas of endemicity for bovine ehrlichiosis. Six ticks (three females and three nymphs) (1.4%) of 417 I. ricinus ticks collected by flagging vegetation contained ehrlichial DNA. A total of 201 small mammals from five species, wood mouse (Apodemus sylvaticus), yellow-necked mouse (Apodemus flavicollis), earth vole (Pitymys subterraneus), bank vole (Clethrionomys glareolus), and common shrew (Sorex araneus), were trapped. The analysis of I. ricinus mammals collected on 116 small mammals showed that nine C. glareolus voles and two A. sylvaticus mice hosted infected tick larvae. In these rodents, granulocytic ehrlichia infection was also detected in blood, spleen, liver, and ear samples. Further examinations of 190 small mammals without ticks or with noninfected ticks showed the presence of ehrlichial DNA in spleen and other tissues from six additional C. glareolus, three A. flavicollis, and one S. araneus mammals. This study suggests thatA. sylvaticus, A. flavicollis, S. araneus, and particularly C. glareolus are likely to be natural reservoirs for granulocytic ehrlichiae. Partial 16S rRNA gene sequences of granulocytic ehrlichiae from ticks and rodents showed a high degree of homology (99 to 100%) with granulocytic ehrlichiae isolated from humans. In contrast, groESL heat shock operon sequence analysis showed a strong divergence (approximately 5%) between the sequences in samples derived from rodents and those derived from samples from questing ticks or from other published ehrlichia sequences. Dual infections with granulocytic ehrlichia andBorrelia burgdorferi were found in ticks and small mammals.

Retracted: Established and emerging pathogens inIxodes ricinusticks collected from birds on a conservation island in the Baltic Sea

“…The infection of two nymphs, parasitizing the same bird, may be a result of co-feeding transmission. As infection prevalences of host-seeking ticks with A. phagocytophilum can reach up to 23.6% (Skarphedinsson et al, 2007) and some mammal species show high infection rates, these pathogens may have a reservoir in mammalian tick hosts, such as sheep, deer or rodents, rather than in birds (Liz et al, 2000;Ladbury et al, 2008).…”

“…Few data exist on the role of birds in transmitting other zoonotic agents to ticks. The obligate intracellular Gram-negative bacterium Anaplasma phagocytophilum (Proteobacteria: Rickettsiales: Anaplasmataceae) is the causative agent of human granulocytic anaplasmosis (HGA), a febrile illness of man and several domestic animals which is widespread in Europe (Skotarczak et al, 2006;Špitalská et al, 2008;Torina et al, 2008) and is mainly transmitted by I. ricinus and I. trianguliceps (Liz et al, 2000). Transovarial transmission of A. phagocytophilum in Ixodes ticks could not be demonstrated and therefore reservoir hosts are thought to be necessary to the maintenance of the lifecycle (Dumler et al, 2001).…”

“…Transovarial transmission of A. phagocytophilum in Ixodes ticks could not be demonstrated and therefore reservoir hosts are thought to be necessary to the maintenance of the lifecycle (Dumler et al, 2001). Previous studies have discussed a multitude of different reservoir species for A. phagocytophilum, including sheep, deer and small mammals (Liz et al, 2000;de la Fuente et al, 2008;Ladbury et al, 2008). As they can carry infected ticks over long distances, migrating birds are considered important vehicles for Anaplasma spp., but their role as reservoir hosts remains unclear (Bjoersdorff et al, 2001;Skotarczak et al, 2006;Ioannou et al, 2009).…”

Anaplasma phagocytophilum in Ruminants in Europe

“…30 Until the recent recognition that free-living rodents do harbor variants of A. phagocytophilum, it has been largely thought that TBF variants were maintained in a tick-ruminant cycle, with persistent infections of domestic and free-living ruminants serving as the source of continuous transmission, as no transovarian transmission has been demonstrated. 31 However, the recent demonstration that wood mice (Apodemus sylvaticus), yellow-necked shrew (Apodemus flavicollis), field voles (Microtus agrestis), and bank voles (Clethrinomyces glareolus) are competent hosts of A. phagocytophilum [32][33][34] suggests that rodents may also be important reservoirs of infection. However, compared to ruminants, the latter appear to develop low levels of bacteremia and have shorter life cycles.…”

Composition and Function of Haemolymphatic Tissues in the European Common Shrew

“…S. araneus has an unusually diverse parasite fauna, which includes ectoparasites [20][21][22], Bartonella and trypanosome infections [23][24][25][26][27], Anaplasma phagocytophilum [27,28], and Pneumocystis carinii [29], as well as over 20 helminth species [30]. The extent to which shrews are able to mount immune responses to these parasites is unknown: commons shrews have a fast metabolic rate even for their small body size [31] but store very little energy as fat [32].…”