Q fever abortions in ruminants and associated on-farm risk factors in northern Cyprus

Background Q fever is caused by the obligate intracellular bacterium, Coxiella burnetii [1,2]. This disease is regarded as endemic worldwide, with the exception of New Zealand [3-6]. Cattle, sheep and goats are considered to be the primary source of transmission for humans [7,8]. Humans are infected mainly by inhalation of contaminated aerosols or by the ingestion of infected milk and/or fresh dairy products. In animals, Q fever is mainly subclinical but has especially been associated with reproductive disorders such as late abortions, stillbirths, weak off springs, metritis and infertility in ruminants [8-11]. Abortions during Q fever epizootics have been described in goats and sheep, but rarely documented in dairy cows [7,12]. Domestic pets, such as cats, dogs and wild-domestic birds such as rock doves (Columba livia) and geese (Anser anser) are known to be an additional source of infection [8,12-14]. Previous studies have reported occurrences of C. burnetii in migratory wild birds, rodents and ticks in southern Cyprus [15-17]. More than 40 species of ticks are naturally infected with C. burnetii. However, besides the aerosol route, the significance of ticks in transmitting the disease in ruminants and humans has previously been documented [8,9]. On the other hand, recent studies showed that ticks seem to play a major role in the circulation of C. burnetii in cycles of nature especially in wild life cycles. Ticks are also believed to probably play another crucial role in the transmission of the agent from infected wild vertebrates to domestic animals [5,18,19]. In humans, Q fever is mostly asymptomatic, the acute disease form is mainly limited flu-like illness, pneumonia or hepatitis while the chronic disease manifests with chronic fatigue syndrome or endocarditis [4,5,20]. On the reproductive health point of view, C. burnetii infections are known to cause abortions, stillbirth and premature deliveries in pregnant women. In the past, a series of Q fever outbreaks in both human and animal populations resulting in abortions on the island of Cyprus have been reported [10,21]. Studies done on the islands as far back as the 1970’s showed that Q fever has been an ongoing public health problem. Recently, the prevalence of IgG antibodies against C. burnetii phase II antigens was estimated to be at 52.7% for humans, 48.2% for goats, 18.9% for sheep, and 24% for cows. In this context, control of C. burnetii infection in ruminants is a vital component of public health [19]. There is no known record of humans contracting Q fever in northern Cyprus, which might be linked with lack of routine screenings and/or insufficient diagnostic units for C. burnetii [Northern Cyprus Ministry of Health, 2008]. The diagnostic enigma is that C. burnetii is difficult to culture, and detection in Cyprus was first done by complement fixation of antibodies [22,23]. Lately detection and diagnosis of C. burnetii, has been more effectively done by PCR based techniques, targeting the isocitrate dehydrogenase, superoxide dismutase gene and a transposon-like repetitive region [15,24-28]. The current technological advancement in these techniques has made them the most useful diagnostic tools for detection of C. burnetii in bovine aborted foetuses and ovine genital swabs [29-31]. Since the division of Cyprus in 1974, there has not been any research work on this disease in the northern region. Therefore, the aim of this study was to determine the occurrence of Q fever abortion using a PCR based method on DNA isolated from aborted foetal abomasal contents and placental tissues from ruminants in northern Cyprus. In addition, to determine the on-farm risk factors associated with the disease.