Occurrence of Coxiella burnetii in Polish dairy cattle herds based on serological and PCR tests
Introduction
Coxiella (C.) burnetii is an obligate intracellular γ-proteobacterium and the etiological agent of zoonotic disease Q fever [1]. This pathogen was first described in 1930s [2,3] and currently is distributed almost worldwide, affecting a wide range of animal species [4]. Domestic ruminants (i.e. goats, sheep, cattle) are considered to be a major reservoir of C. burnetii, moreover, the wildlife fauna and ticks may also be an important sources of the pathogen. Taking into account that the clinical signs of coxiellosis in animals are non-specific and infection may be asymptomatic, especially in cattle, laboratory tests are crucial in Q fever diagnosis. Noteworthy is the fact that asymptomatic individuals and intermittent cattle shedders may remain negative in serological tests and unnoticeably shed the pathogen into the environment for several months or years [5,6]. The highest amounts of C. burnetii are shed during abortion and parturition in birth products (placenta, birth fluids), whereas lower levels are detected in milk, vaginal discharges, feaces, urine and semen [7]. In humans and animals inhalation of contaminated aerosols is the most common route of infection [8]. Sporadic cases of Q fever transmission by sexual contact, blood transfusion and transplantation were also reported [9,10]. The phenomenon of C. burnetti shedding in milk may pose a potential threat for public health, not only for occupationally exposed people but also for raw milk consumers [11,12].
Serological screenings of ruminant herds have been performed in many countries to assess exposure to the pathogen and the zoonotic risk [[13], [14], [15]]. The complement fixation test (CFT), indirect immunofluorescence assay (IFA) or enzyme-linked immunosorbent assay (ELISA) may be used, but the latter is thought to be the most robust and has good specificity and high sensitivity [[16], [17], [18]]. Moreover, the testing of BTM samples using ELISA allows a preliminary evaluation of the herd status, ease of sampling and reduces costs. In Poland Q fever is a notifiable disease, additionally serological monitoring survey of cattle and small ruminants has been implemented since 2010. The previous study showed that percentage of C. burnetii seropositive cattle herds in Poland is significant [19].
The objectives of this research were to estimate the prevalence of antibodies against C. burnetii in dairy cattle herds based on sera and bulk tank milk samples (BTM) analysis and to compare the results of real-time PCR and ELISA tests performed on BTM specimens.
Section snippets
Materials and methods
This study was a part of larger research project and was carried out between January 2014 and December 2017. Samples were collected specifically for this investigation from non-vaccinated dairy cattle by authorized veterinarians following standard procedures and with farmers’ consent. According to the Local Ethical Committee on Animal Testing at the University of Life Sciences in Lublin (Poland), formal ethical approval is not required for this kind of study.
Results
The presence of anti-C. burnetii antibodies was confirmed in serum samples obtained from 669 cows (25.39%) and seropositive animals were identified in 237 of 969 tested cattle herds. Seroprevalence at herd-level was calculated at 24.46%. Detailed data about the prevalence of seropositive herds and animals in Polish Voivodeships are summarized in Table 1. The percentages of seropositive herds in Voivodeships varied from 2.5% in Lesser Poland to 61.4% in Lubusz Voivodeship. The highest prevalence
Discussion
C. burnetii infections are noted in many animal species all over the world. In recent years number of reports about shedding of the pathogen in domestic ruminants, including dairy cattle, have been increased. Infected livestock may experience reproductive disorders including late abortion, stillbirth, premature delivery and delivery of weak offspring, reduction of conception rate or metritis [20], which can cause significant economic losses. Moreover, financial losses may also occur due to
Conclusion
This study was carried out to provide an insight into current epidemiological situation of C. burnetii in Polish dairy cattle. Analyses of BTM and serum samples revealed that the presence of specific immunoglobulins in tested dairy cattle herds is common and correlated with shedding of C. burnetii and recorded in different regions of the country. These findings underscore the importance of surveillance, application of adequate biosecurity measures and increasing the awareness of Q fever,
CRediT authorship contribution statement
Monika Szymańska-Czerwińska: Conceptualization, Methodology, Validation, Formal analysis, Writing - original draft, Writing - review & editing, Visualization, Project administration, Funding acquisition. Agnieszka Jodełko: Investigation, Writing - original draft, Writing - review & editing, Visualization. Krzysztof Niemczuk: Conceptualization, Writing - review & editing, Visualization, Supervision.
Declaration of Competing Interest
All authors declare no competing interests.
Acknowledgments
This work was funded by the National Science Centre, Poland (Grant No. 2015/17/D/NZ7/00816). The funder of the study had no role in study design, data collection, data analysis, data interpretation, or writing of the report.
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Prevalence of Coxiella burnetii in Central and Eastern European dairy herds
2020, Comparative Immunology, Microbiology and Infectious DiseasesCitation Excerpt :In the present study, detection of C. burnetii specific antibodies showed higher positivity than the PCR assays in all countries, ranging between 62.50–70.83% (Serbia, Slovenia) and 86.79–100.00% (Croatia, Czech Republic, Hungary, Slovakia). Previous publications reported lower ELISA positivity of bulk tank milk samples from Europe, ranging between 25–37.9% (Greece, Ireland, Portugal) and 45.5–78.6% (Belgium, Denmark, the Netherlands, Poland, Spain) [27,33,34,36–40]. Positive correlation was found between herd sizes and percentage of C. burnetii positive results (with PCR and/or ELISA tests), assuming that herds of 250 animals or more (with farm structures resulting in crowded herds) are at higher risk for Coxiella infection.
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