All the sera used for this study were diagnosed as serologically negative for brucellosis by Rose Bengal Plate Test as well as ELISA. So, the current study was further designed to know about the status of other abortifacient agents in these animals, other than
Brucella organisms.
Neospora caninum is considered one of the most frequent infectious organisms causing abortion in bovines worldwide. In our study, out of 165 serum samples, 33.94% samples were seropositive for neosporosis by this monoscreen antibody ELISA. Among these, 21 samples were from cattle and 35 samples were from buffaloes with a seropositivity of 53.85% and 21%, respectively (Table 1). The presence of
Neospora caninum antibodies in the bovines indicates the existence of infection in these animals. Seroprevalence of
N.
caninum in dairy cattle has been reported in different regions of world. The reported seroprevalence of
N.
caninum exposure in cattle ranges between 7.6 and 41% in the Americas, 10.7 and 19.6% in Africa, 4.1 and 43% in Asia, 0.5 and 27.7% in Europe and 10.2% in Oceania
(Semango et al., 2019). Seroprevalence of neosporosis in buffalo were reported upto 88.3% worldwide, while that from India was 9.97%-50% (
de Barrows et al., 2020). Mahajan et al., (2019) reported seropositivity of 10.5% in cattle and 21.6% in buffaloes from Punjab, while
Abdeltif et al., (2022) reported seroprevalence of 36.2% in cows from Northeast Algeria. In our study, a significantly higher seropositivity was found among buffaloes than cows, having an Odds ratio of 4.38.
Mahajan et al., (2019) also found higher seropositivity and abortion rate among buffaloes when compared to cows from Punjab.
It was found that 32 (37.21%) animals from the age group 3-5 years were seropositive for neosporosis. A seropositivity of 36.21% and 14.295 were observed from age groups of >5 years and <3 years, respectively. The results obtained were statistically analyzed and found that the seropositivity of
N.
caninum antibodies in different age groups were statistically non-significant. This result is in accordance with the findings of
Yadav et al., (2016). Llano et al., (2018) and
Serrano-Martinez et al., (2019) also reported that 3-5 age groups of animals were at more risk to the infection when compared to other age groups. However there have been reports that seroprevalence of
N.
caninum decreased significantly with the increase in age of cows
(Noori et al., 2019), while some researchers couldn’t find any relationship of the disease and the role of age
(Darijani et al., 2021).
It was found that, all the seropositive animals in our study were associated with abortion or reproductive problems like infertility with seropositivity of 36.36%. None of the male animals were positive for neosporosis in this study. The animals which had abortion at third trimester of pregnancy were more seropositive (43.05%) for neosporosis, when compared to first (18.75%) and second trimester (38%). This may be due to the immune system of pregnant animals which is more exposed to
N.
caninum during middle and last trimester of pregnancy rather than first trimester
(Abdeltif et al., 2022). Several other studies also reported association of abortion history with seroprevalence of
N.
caninum (Sengupta et al., 2013; Yadav et al., 2016; Noori et al., 2019; Llano et al., (2018; Miroud et al., 2019; Changoluisa et al., 2019; Mahajan et al., (2019). The multiparous animals exhibited higher seropositivity (41.07%) for neosporosis in comparison to primiparous (23.81%) bovines.
Llano et al., (2018), Miroud et al., (2019) and
Serrano-Martinez et al., (2019) also found a significantly higher proportion of
N.
caninum antibodies in multiparous dairy cattle.
The rural areas of the State where the bovine herds are reared have easy and constant access to the definitive host like dogs. The presence of definitive host in the premises of bovine farms may aggravate the transmission of the parasite by horizontal route. The lacunae in hygienic managemental farm practices can aggravate the infection level in bovines because of the ingestion of oocysts through contaminated food, fodder and water. Since this infection has significant impact on economy of the livestock industry, the awareness among farmers is required to prevent the neosporosis and biosecure the bovine population of the State. The presence of
Neospora caninum antibodies in these bovines indicates the exposure of the animals for this organism. This indicates neosporosis may have been associated with abortion in these animals, giving a second thought on other abortifacient agents, which should be studied in future elaborately, involving the entire livestock population of the State.
