Diagnosis by PCR of Coxiella burnetii in aborted fetuses of domestic ruminants in Portugal

Abstract

Coxiella burnetii is a non-motile, obligate intracellular, Gram-negative microorganism that is the causative agent of Q fever, a widespread zoonosis. Cattle, sheep and goats are considered to be the primary sources of human infection (McQuiston and Childs 2002), although occasional zoonotic infections have been linked to pets, birds, ticks and other arthropods (Buhariwalla and others 1996, Maurin and Raoult 1999). Human beings are infected by the inhalation of contaminated aerosols or the ingestion of infected fresh milk and dairy products. The disease in human beings is usually asymptomatic or characterised by a febrile syndrome with spontaneous recovery. In the acute form, pneumonia and granulomatous hepatitis may occur; endocarditis is the predominant clinical manifestation of chronic cases (Maurin and Raoult 1999). In animals the infection is generally subclinical, although abortions at the end of pregnancy, stillbirths and the delivery of weak offspring, and cases of retained placenta, endometritis, infertility and low birth rates may occur (McQuiston and Childs 2002, Arricau-Bouvery and Rodolakis 2005). Q fever is rarely reported and infections in livestock often go unnoticed; if sporadic abortions occur, they may not prompt an investigation. Infection is usually identified when human beings are affected through zoonotic exposure. Little is known about the occurrence and significance of C burnetii infection in domestic ruminants in Portugal. The infection has been reported sporadically in human beings, domestic ruminants, zoo animals (Clemente and others 2008) and companion animals (Bacellar and others 1995). The aim of the present study was to detect C burnetii DNA in fetal tissues, placentas and vaginal discharges from livestock that aborted naturally, and to gain evidence of its role in the occurrence of abortions. Between October 2006 and March 2008, 91 samples, from 29 cattle, 25 sheep and 37 goats with a history of abortion, were submitted to the authors' laboratory to investigate whether they were infected with C burnetii. The farms of origin were located in the northeastern and eastern mountainous regions, and in the south and southeast of Portugal. The samples were four vaginal swabs, 10 placentas and 77 pools of organs (brain, liver, spleen and lung) collected from the aborted fetuses (Table 1). The diagnosis of C burnetii was confirmed by PCR.

Prevalence of Coxiella burnetii in clinically healthy German sheep flocks

“…Recent PCR-based studies identified C. burnetii in 9% of tested sheep flocks in northern Spain [21] and in 18.6% of farms with small ruminants in southern Italy [22]. Two further studies on samples obtained from either ovine abortions in Sardinia [23] or ovine foetal organ samples and placentae in Portugal [24] discovered C. burnetii in 10.9% and in 36% of the cases, respectively. A Turkish study assessing milk samples collected from 22 flocks determined 6.5% C. burnetii positive animals in 12 flocks with a history of abortion and no positives in flocks without a history of abortion [25].…”

Coxiella burnetii associated reproductive disorders in domestic animals-a critical review

“…PCR analysis of multiple tissues from aborted lambs with PCR positive placenta, but without a histopathologically confirmed cause of abortion, have revealed C. burnetii DNA in multiple tissues. [27,30,31,35,64,74-80]. These findings indicate that C. burnetii may infect the fetus itself by the aminotic-oral route and haematogenously (Figure 1).…”

“…Parisi et al [24] and Clemente et al [27] found 17.2% and 11.6% PCR positive animals among cattle that had aborted, respectively. Real time PCR has been claimed to be a reliable tool in diagnosing Q fever abortion.…”

cute Q fever in Portugal. Epidemiological and clinical features of 32 hospitalized patients

“…4,28,29 Studies of cattle have also shown a high seroprevalence of C burnetii infection suggesting that Q fever is far from being a negligible disease in Portugal. 30,31 Despite several clinical cases of Q fever reported in the Portuguese literature, [32][33][34] only two studies have investigated the clinical and epidemiological situation of the disease in the country. 27,35 Q fever is a notifiable disease in Portugal since January 1, 1999 and an average of 0.1 cases per 10 5 inhabitants per year have been reported.…”