Original article
Detection of tick-borne pathogens in roe deer (Capreolus capreolus), in questing ticks (Ixodes ricinus), and in ticks infesting roe deer in southern Germany

https://doi.org/10.1016/j.ttbdis.2013.01.004Get rights and content

Abstract

The hard tick Ixodes ricinus is the most common tick in Central Europe and plays an important role as a vector of several pathogens. In the complex life cycles of these pathogens, the role of wild animals as natural reservoirs has been discussed. The aims of this study were to investigate the role of roe deer (Capreolus capreolus) as a potential reservoir host for Babesia spp., Anaplasma phagocytophilum, and Rickettsia spp. Therefore, we explored the differences in the infection rates of roe deer and engorged and questing ticks with these pathogens from a single forest site with special attention to coinfection.

Blood, spleen, and skin samples of a total of 95 roe deer individuals were screened by molecular methods for these pathogens from September 2010 to January 2012 in the ‘Angelberger Forst’ (Bavaria, Germany). Moreover, 331 engorged ticks from 44 roe deer individuals and 199 host-seeking ticks from the same area were screened.

Altogether, the following prevalence rates and a high diversity of species were detected for the respective pathogens in individual animals and ticks: (i) Babesia spp.: roe deer, 89.5%; engorged ticks, 7.3%; questing ticks: adults, 2.5%, nymphs, 3.3%. Sequencing revealed B. venatorum, B. capreoli, and B. microti. (ii) A. phagocytophilum: roe deer 98.9%; engorged ticks, 86.1%; questing ticks: adults, 8.9%, nymphs, 0.8%. (iii) Rickettsia spp.: roe deer, 0%; engorged ticks, 16.6%; questing ticks: adults, 13.9%, nymphs, 17.5%. Sequencing revealed R. helvetica. Furthermore, several coinfections were detected in both roe deer and ticks. The high prevalence rates of B. capreoli and A. phagocytophilum in roe deer support their role as reservoir hosts for these pathogens, but no evidence for a role of roe deer in the life cycle of R. helvetica could be provided.

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

References (70)

  • L. Bertolotti et al.

    Borrelia lusitaniae and spotted fever group rickettsiae in Ixodes ricinus (Acari: Ixodidae) in Tuscany, central Italy

    J. Med. Entomol.

    (2006)
  • E. Bezzel et al.

    Brutvögel in Bayern. Verbreitung 1996 bis 1999

    (2005)
  • S. Bonnet et al.

    Babesia sp. EU1 from roe deer and transmission within Ixodes ricinus

    Emerg. Infect. Dis.

    (2007)
  • J.A. Carlyon et al.

    Invasion and survival strategies of Anaplasma phagocytophilum

    Cell. Microbiol.

    (2003)
  • G. Carpi et al.

    Tick infestation on roe deer in relation to geographic and remotely sensed climatic variables in a tick-borne encephalitis endemic area

    Epidemiol. Infect.

    (2008)
  • S. Casati et al.

    Presence of potentially pathogenic Babesia sp. for human in Ixodes ricinus in Switzerland

    Ann. Agric. Environ. Med.

    (2006)
  • S.M. Chen et al.

    Identification of a granulocytotropic Ehrlichia species as the etiologic agent of human disease

    J. Clin. Microbiol.

    (1994)
  • C.J. Clopper et al.

    The use of confidence or fiducial limits illustrated in the case of the binomial

    Biometrika

    (1934)
  • J.W. Courtney et al.

    Multiplex real-time PCR for detection of Anaplasma phagocytophilum and Borrelia burgdorferi

    J. Clin. Microbiol.

    (2004)
  • G. Dobler et al.

    Typhus and other rickettsioses: emerging infections in Germany

    Dtsch. Ärztebl. Int.

    (2009)
  • D. Duh et al.

    Cervids as babesiae hosts, Slovenia

    Emerg. Infect. Dis.

    (2005)
  • D. Duh et al.

    The molecular evidence of Babesia microti infection in small mammals collected in Slovenia

    Parasitology

    (2003)
  • V. Fingerle et al.

    Human granulocytic ehrlichiosis in southern Germany: increased seroprevalence in high-risk groups

    J. Clin. Microbiol.

    (1997)
  • R.A. Fisher

    The logic of inductive inference

    J. Roy. Stat. Soc. Series A

    (1935)
  • Forstdirektion Oberbayern-Schwaben, 2004. Managementplan zum FFH-Gebiet 7829-301 “Angelberger...
  • J. Franke et al.

    Coexistence of pathogens in host-seeking and feeding ticks within a single natural habitat in Central Germany

    Appl. Environ. Microbiol.

    (2010)
  • L. Gern et al.

    Efficient transmission of Borrelia burgdorferi between cofeeding Ixodes ricinus ticks (Acari: Ixodidae)

    J. Med. Entomol.

    (1996)
  • E.G. Granquist et al.

    A morphological and molecular study of Anaplasma phagocytophilum transmission events at the time of Ixodes ricinus tick bite

    Acta Vet. Scand.

    (2010)
  • H.M. Heikkilä et al.

    Anaplasma phagocytophilum infection in a domestic cat in Finland: case report

    Acta Vet. Scand.

    (2010)
  • M.J. Herron et al.

    The interactions of Anaplasma phagocytophilum, endothelial cells, and human neutrophils

    Ann. N.Y. Acad. Sci.

    (2005)
  • B.L. Herwaldt et al.

    Molecular characterization of a non-Babesia divergens organism causing zoonotic babesiosis in Europe

    Emerg. Infect. Dis.

    (2003)
  • P. Heyman et al.

    A clear and present danger: tick-borne diseases in Europe

    Expert Rev. Anti Infect. Ther.

    (2010)
  • A. Hildebrandt et al.

    Diversity and coexistence of tick-borne pathogens in central Germany

    J. Med. Entomol.

    (2011)
  • A. Hildebrandt et al.

    First confirmed autochthonous case of human Babesia microti infection in Europe

    Eur. J. Clin. Microbiol. Infect. Dis.

    (2007)
  • P.D. Hillyard

    Ticks of North-West Europe Synopses of the British Fauna No. 52

    (1996)
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