Survey of Infectious Etiologies of Bovine Abortion during Mid- to Late Gestation in Dairy Herds

Abstract

Bovine abortion of unknown infectious etiology still remains a major economic problem. Thus, we investigated whether Brucella spp., Listeria monocytogenes, Salmonella spp., Campylobacter spp. and Coxiella burnetii are associated with abortion and/or stillbirth in Tunisian dairy cattle. Using a pan-Chlamydiales PCR, we also investigated the role of Chlamydiaceae, Waddlia chondrophila, Parachlamydia acanthamoebae and other members of the Chlamydiales order in this setting. Veterinary samples taken from mid to late-term abortions from twenty dairy herds were tested. From a total of 150 abortion cases collected, infectious agents were detected by PCR in 73 (48.66%) cases, 13 (8.66%) of which represented co-infections with two infectious agents. Detected pathogens include Brucella spp (31.3%), Chlamydiaceae (4.66%), Waddlia chondrophila (8%), Parachlamydia acanthamoebae (5.33%), Listeria monocytogenes (4.66%) and Salmonella spp. (3.33%). In contrast, Campylobacter spp. and Coxiella burnetii DNA were not detected among the investigated veterinary samples. This demonstrates that different bacterial agents may cause bovine abortion in Tunisia. This is the first report suggesting the role of Parachlamydia acanthamoebae in bovine abortion in Africa. Further studies with a larger number of samples are necessary to confirm whether this emerging pathogen is directly linked to abortion in cattle.

Culture‐independent genomics of a novel chlamydial pathogen of fish provides new insight into host‐specific adaptations utilized by these intracellular bacteria

“…the Chlamydiaceae family. Molecular and sero-epidemiological surveys have detected CRBs in association with respiratory disease in humans (Kahane et al, 1998;Friedman et al, 1999) and livestock (Wheelhouse et al, 2013) and reproductive disease in both humans and animals (Borel et al, 2007;Baud et al, 2011;Barkallah et al, 2014). Further, murine respiratory disease models have recently been established for Waddlia chondrophila (Pilloux et al, 2016) and Parachlamydia acanthamoebae (Casson et al, 2008), as has a bovine model of P. acanthamoebae respiratory disease (Lohr et al, 2014) and a murine model of W. chondrophila genital infection (Vasilevsky et al, 2015), confirming Koch's postulates for these causative agents of disease.…”

Experimental challenge of pregnant cattle with the putative abortifacient Waddlia chondrophila

“…Several other studies have provided indirect evidence for a role for W. chondrophila in reproductive disease in cattle, with serological studies providing limited evidence of an association between W. chondrophila antibody titres and pregnancy failure5. More recently, studies in North Africa have identified the presence of W. chondrophila DNA in vaginal swabs from the dams of aborted bovine fetuses67.…”

Molecular prevalence of Chlamydia and Chlamydia-like bacteria in Tunisian domestic ruminant farms and their influencing risk factors

“…To know the responsible species of infection, PCR products were sequenced and analysed using the BLAST web interface (http://blast.ncbi.nlm.nih.gov/Blast.cgi). Among the 16S rRNA sequences of these 27 test‐positive samples, 12, 8 and 7 sequences with hits in the BLAST analysis belonged to Waddliaceae , Parachlamydiaceae and Chlamydiaceae families, respectively (Barkallah et al., ). No chlamydial DNA was detected in milk and blood samples.…”

“…Thus, it is not surprising that 17 of the 41 positive PCRs performed on vaginal swab samples were positive for Chlamydiaceae . The high prevalence of positivity (60%) for Parachlamydiaceae is important to investigate in our case as P. acanthamoebae , a species of this chlamydial family, is well known to cause reproductive disorders, especially in cattle (Barkallah et al., ; Borel et al., ). In our study, 12 samples from five ruminant herds were positive for P. acanthamoebae .…”

“…Similarly, the observed relationships between chlamydial infection and abortive and digestive disorders were consistent with what has generally been observed (Longbottom et al., ; Merdja et al., ; Wheelhouse et al., ). Under these conditions, the infection finds favourable ground for transmission through placental and foetal membranes, faeces and urines (Barkallah et al., ). In addition, conjunctivitis was found to be a major risk factor significantly associated with chlamydial infection in sheep.…”