Original articleDetection of tick-borne pathogens in roe deer (Capreolus capreolus), in questing ticks (Ixodes ricinus), and in ticks infesting roe deer in southern Germany
Introduction
The hard tick Ixodes ricinus is the most common tick species in Germany and plays an important role as a vector of several pathogens in Europe. Amongst these pathogens are potentially human pathogenic protozoa and bacteria such as Babesia microti, B. venatorum (also named Babesia sp. EU1 in previous literature), Anaplasma phagocytophilum, and Rickettsia helvetica [reviewed in (Heyman et al., 2010)].
Roe deer serves as a host for B. capreoli (Malandrin et al., 2010) and B. venatorum (Bonnet et al., 2007, Duh et al., 2005). The latter has been reported associated with human disease (Häselbarth et al., 2007, Herwaldt et al., 2003). B. microti is mainly found in voles and mice (Duh et al., 2003), and a human case has also been reported in Europe (Hildebrandt et al., 2007). A. phagocytophilum causes human (Petrovec et al., 1997), equine (Silaghi et al., 2011e), canine (Kohn et al., 2011), and feline (Heikkilä et al., 2010) granulocytic anaplasmosis and tick borne fever in ruminants (Nieder et al., 2012). Wild ruminants such as roe deer show high infection rates with A. phagocytophilum and have been suggested as reservoir hosts (Liz et al., 2002, Oporto et al., 2003, Polin et al., 2004, Skarphédinsson et al., 2005, Stefanidesova et al., 2008). No clinical case of granulocytic anaplasmosis in humans has yet been documented in Germany, but serological evidence of previous infection was detected in persons at high risk for exposure to I. ricinus (Fingerle et al., 1997). Rickettsia spp. cause tick- or flea-borne rickettsioses in humans. R. slovaca (Silaghi et al., 2011c), R. helvetica (Silaghi et al., 2011c), R. felis (Dobler and Wölfel, 2009), R. monacensis (Silaghi et al., 2008b), R. massiliae (Dobler and Wölfel, 2009), and R. raoultii (Silaghi et al., 2011c) have been recorded in Germany. The vertebrate reservoirs of some Rickettsia spp. are unknown. However, rodents are presumed reservoirs of R. helvetica (Schex et al., 2011).
The aims of this study were:
- (i)
to determine the prevalence of Babesia spp., A. phagocytophilum, and Rickettsia spp. in roe deer and I. ricinus (engorged and questing ticks) with molecular methods
- (ii)
to identify the pathogen species by sequencing with special attention to coinfection
- (iii)
to analyze the differences in infection rates with the pathogens in roe deer, engorged, and questing ticks with statistical methods and thus
- (iv)
to analyze the role of roe deer as a potential reservoir host for Babesia spp., A. phagocytophilum, and Rickettsia spp.
Section snippets
Study site
The study site ‘Angelberger Forst’ is a 641-hectare-large forest area (48°06′36.42″ N, 10°34′33.40″ E) located 580–660 m above sea level near Tussenhausen (Bavaria, Germany). The climate is intermediate with 950–1000 mm rainfall/year. The average temperature balances between 6.5 and 7.5 °C. The vegetation is mixed forest with mainly beech-grove (Fagus sylvatica), in places fir (Abies), oak (Quercus), and spruce (Picea) on fine loam (Forstdirektion Oberbayern-Schwaben, 2004). More than 100
Results
A total of 95 roe deer of different gender (52 females, 43 males) and age [(individuals/age in years: 27/<1; 48/1–2; 20/>2) judged by the hunter] was screened for A. phagocytophilum, Babesia spp., and Rickettsia spp., and 95 spleen, 86 blood, and 56 skin samples were available (Table 2). A total of 557 adult ticks (426 females, 131 males) from 44 roe deer (range 1–20 ticks collected/individual) was collected from the animals. The numbers of immature ticks on these deer are unknown. The number
Discussion
Previous studies suggested that the tick density in forests and the occurrence of tick-borne pathogens are influenced by the abundance and distribution of potential reservoir hosts such as roe deer (Jensen et al., 2000, Rizzoli et al., 2009) which serves as one of the main feeding hosts for I. ricinus (Carpi et al., 2008). Roe deer inhabits several kinds of tick-infested habitats and is known to migrate more than 100 km carrying a highly variable tick burden. This extent of the migration area
Acknowledgments
The authors are most grateful to Claudia Thiel, Tim Tiedemann, Andrea Mihalkov, and Ute Maurer for excellent technical assistance. Thanks to Melanie Kauffmann for providing the roe deer samples of 2010. This study was partially funded by EU grant FP7-261504 EDENext and is catalogued by the EDENext Steering Committee as EDENext076 (http://www.edenext.eu/). The contents of this publication are the sole responsibility of the authors and do not necessarily reflect the views of the European
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2021, Ticks and Tick-borne DiseasesCitation Excerpt :The most prevalent I. ricinus is involved in the transmission cycles of B. divergens (e.g., Blaschitz et al., 2008; Skotarczak and Cichocka, 2001), B. microti (Gray et al., 2002), B. venatorum (formerly Babesia sp. EU1) (e.g., Overzier et al., 2013; Silaghi et al., 2012), and B. capreoli (Venclikova et al., 2015). The first three species are responsible for cases of human babesiosis (Gray et al., 2010).