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Abstract

Neospora caninum has been detected only sporadically in cases of ovine abortion, and it has therefore traditionally been considered as an unimportant parasite in small ruminants. This study was carried out with the aim of identifying the pathogen causing serious reproductive problems on a commercial sheep farm. Sera from all rams and ewes tested negative for antibodies against Border disease virus, Schmallenberg virus and Coxiella burnetii, and infections by these agents were therefore ruled out. Nevertheless, seropositivity to N. caninum and/or Toxoplasma gondii was detected, although the seroprevalence was higher in the case of N. caninum. The percentage of lambings and the number of lambs per dam were significantly lower in ewes that were seropositive to N. caninum while no effect on these parameters was detected in ewes that were seropositive to T. gondii. There was also no evidence of infection by T. gondii in the foetal/lamb tissues analyzed by PCR and/or immunohistopathological techniques. On the contrary, the DNA of N. caninum was detected in 13 out of 14 foetuses/lambs descendant from dams seropositive to this parasite. Characteristic lesions caused by N. caninum and/or its antigen were also detected. Genotyping of the N. caninum DNA revealed only two closely related microsatellite multilocus genotypes. The results clearly demonstrate that infection by N. caninum was the cause of the low reproductive performance of this sheep flock.

Influence of the gestational stage on the clinical course, lesional development and parasite distribution in experimental ovine neosporosis

“…However recent studies in small ruminants suggest that neosporosis may be a more important cause of reproductive disorders than it has traditionally been considered, at least in certain scenarios. Recent serological surveys have shown high prevalences in asymptomatic sheep and goats from some flocks [ 1 ] and evidence has accumulated that points towards N. caninum as a cause of natural abortion and reproductive failure in sheep and goats [ 6 - 8 , 27 ].…”

“…In sheep, naturally occurring N. caninum transmission was first described in a congenitally infected lamb [ 4 ]. Subsequently N. caninum infections in sheep have been reported worldwide [ 5 - 8 ]. Nevertheless, Toxoplasma gondii is regarded as the primary parasite cause for both sheep and goat abortion [ 1 , 6 , 8 ], and the epidemiological, clinical and economic importance of neosporosis in small ruminants has been traditionally considered to be much less relevant compared to cattle [ 9 , 10 ].…”

“…Nevertheless, Toxoplasma gondii is regarded as the primary parasite cause for both sheep and goat abortion [ 1 , 6 , 8 ], and the epidemiological, clinical and economic importance of neosporosis in small ruminants has been traditionally considered to be much less relevant compared to cattle [ 9 , 10 ]. However, recently acquired evidence suggests that N. caninum is an important abortifacient in small ruminants [ 6 ], or even the main cause of reproductive losses in some flocks [ 7 , 8 ]. Despite the obvious significance of ruminant neosporosis, there are still many aspects that require further studies, such as host-pathogen interactions, pathogenicity and immunological control.…”

Extended-spectrum antiprotozoal bumped kinase inhibitors: A review

“…The parasite owes its economic importance primarily to the fact that it causes abortion in cattle, and stillbirth and/or birth of weak calves, with estimated annual losses of around 1.3 billion US dollars in the 10 countries where data is available (Reichel, et al, 2013). Natural N. caninum infection in sheep and concomitant Neospora -induced abortion problems have also been reported (Gonzalez-Warleta, et al, 2014, Moreno, et al, 2012). In addition, N. caninum infection can result in birth of clinically healthy, but persistently infected calves, which in turn then vertically transmit the parasite to the next generation.…”

Systemic and local immune responses in sheep after Neospora caninum experimental infection at early, mid and late gestation

“…On the other hand, although cattle represent the most relevant and economically important target host, recent studies consider N. caninum as an important abortifacient also in small ruminants [ 9 ], and even the main cause of reproductive losses in some flocks [ 10 , 11 ]. Moreover, it would be desirable to have a well-established in vivo model for ruminant neosporosis in order to improve the knowledge of the disease, as well as to carry out vaccine or drugs efficacy assays [ 12 ].…”