Short communication
Coxiella burnetii and Francisella tularensis in wild small mammals from the Czech Republic

https://doi.org/10.1016/j.ttbdis.2019.101350Get rights and content

Abstract

Wild rodents are an important source of the tick-borne pathogens Coxiella burnetii and Francisella tularensis. The aim of our study was to assess the prevalence of antibodies and possible coexistence of these pathogens in wild small mammals from three localities in the Czech Republic. A total of 614 wild small mammals (324 Apodemus flavicollis, 145 Myodes glareolus, 50 Sorex araneus, 48 A. sylvaticus, 40 A. agrarius, six Microtus arvalis and one Talpa europaea) were trapped between 2012 and 2015. Their sera or heart extracts were examined by modified indirect enzyme-linked immunosorbent assay, with the detection of antibodies against C. burnetii and F. tularensis in 12 % and 7 % of animals, respectively; coinfection was identified in 4.4 % of animals. The prevalence of C. burnetii and F. tularensis antibodies statistically differed according to animal species and sex (p < 0.05); the seroprevalence of C. burnetii (p < 0.05) also differed in the sampling period. The highest prevalence of antibodies against C. burnetii and F. tularensis was detected in the case of M. glareolus (24 % and 14 %, respectively).

Introduction

Q fever is a widespread zoonotic disease caused by Coxiella burnetii, a ubiquitous intracellular bacterium infecting humans and a wide variety of animals. Transmission of the infection is primarily but not exclusively airborne, and ticks are usually thought to act as vectors (Duron et al., 2015). Pilloux et al. (2018) claimed that Ixodes ricinus plays a very minor role as a vector and reservoir of C. burnetii in Switzerland, thus supporting previous reports demonstrating the significant role of sheep and goats in the epidemiology of Q fever (Szymańska-Czerwińska et al., 2015; Gache et al., 2017). Farmers belong to a group with an increased risk of C. burnetii infection, presumably because of their contact with infected livestock (Szymańska-Czerwińska et al., 2015).

Francisella tularensis is a highly virulent intracellular bacterium that may infect a wide range of hosts, including invertebrates, mammals and birds, causing a zoonotic disease called tularemia. Humans can be infected through direct contact with infected animals, a contaminated environment or bites of infected arthropod vectors (Hestvik et al., 2015). Although F. tularensis infects several mammal species, antibodies against F. tularensis were also detected in wild animals, e.g. in 7 % of foxes and 1 % of wild boar (Otto et al., 2014). Nevertheless, only lagomorphs and rodents seem to have importance in the transmission of the infection (Rossow et al., 2014). Peak densities of rodent populations may trigger tularemia outbreaks. It is nevertheless unclear which small mammals are the main source of F. tularensis in Central Europe.

The aim of the study was therefore to assess the prevalence of antibodies against C. burnetii and F. tularensis in wild small mammals.

Section snippets

Material and methods

Sampling was performed using spring-loaded and live mouse traps in three Moravian localities (Poodří Protected Landscape Area, the Moravian Karst and the Mohelno National Natural Monument) from May to November in the years 2012 – 2015. Poodří is situated in northern Moravia (GPS: 49°69′98.23″N, 18°09′00.50″E), and trapping was carried out within an area of 10 ha in the Bažantula forest area, characterised by an oak Ficario-Ulmetum alnetosum association forest alternating with meadows. The

Results

Antibodies against C. burnetii and F. tularensis were detected in 74 (12 %) and in 41 (7 %) animals, respectively. Results according to animal species, sex, locality and year of trapping, are summarized in Table 1. The prevalence of antibodies against C. burnetii and F. tularensis depended on animal species and sex (p < 0.05); in the case of C. burnetii there was also a dependence on the year of collection. The prevalence of antibodies against both C. burnetii and F. tularensis differed in M.

Discussion

Blood serum is a standard type of sample to determine the presence of specific antibodies in humans and animals. In the case of dead rodents, heart extract was used as an adequate replacement for missing serum, since heart has been proved as a tissue with frequent occurrence of pathogens such as B. burgdorferi s.l. Heart extracts were adequately diluted to match the serum protein value (Grzesik et al., 2004). Before ELISA was used on wild rodents, the sensitivity of the commercial IgM and IgG

Conclusion

Q fever and tularemia are mandatory reportable diseases in the Czech Republic. In the last ten years, there have only been five cases of Q fever, while the average number of tularemia cases in this period reached 59 (www.szu.cz). Due to the high prevalence of C. burnetii and F. tularensis in captured animals, risk to humans cannot be excluded.

Ethical statement

The trapping of animals and the sampling were done according to the approved experimental projects (Poodří 39/2012, 45/2013, 78/2013, 41/2015, Moravian Karst 38/2012, 6/2013, 77/2013, 42/2015) approved by the Administration of the Poodří Protected Landscape Area, by the Administration of the Moravian Karst, and by the Ministry of the Environment of the Czech Republic.

Acknowledgements

This research was supported partly by EurNegVec COST Action TD1303 and the Specific Research Programme at Masaryk University, Czech Republic.

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