Seroprevalence and Risk Factors of Brucella Infection in Dairy Animals in Urban and Rural Areas of Bihar and Assam, India

Abstract

This study assessed seropositivity of Brucella infection in dairy animals and risk factors associated with it. The cross-sectional study used multi-stage, random sampling in the states of Bihar and Assam in India. In total, 740 dairy animals belonging to 534 households of 52 villages were covered under this study. Serological testing was conducted by indirect enzyme-linked immunosorbent assay (iELISA). Animal-level Brucella seropositivity was found to be 15.9% in Assam and 0.3% in Bihar. Seropositivity in urban areas (18.7%) of Assam was found to be higher than in rural areas (12.4%). Bihar was excluded from the risk factor analysis, as only one Brucella seropositive sample was detected in the state. A total of 30 variables were studied for assessing risk factors, of which 15 were selected for multivariable regression analyses following a systematic process. Finally, only three risk factors were identified as statistically significant. It was found that animals belonging to districts having smaller-sized herds were less likely (p < 0.001) to be Brucella seropositive than animals belonging to districts having larger-sized herds. Furthermore, the chance of being Brucella seropositive increased (p = 0.007) with the increase in age of dairy animals, but decreased (p = 0.072) with the adoption of artificial insemination (AI) for breeding. We speculated that the identified risk factors in Assam likely explained the reason behind lower Brucella seropositivity in Bihar, and therefore any future brucellosis control program should focus on addressing these risk factors.

Estimates of the Economic Cost Caused by Five Major Reproductive Problems in Dairy Animals in Assam and Bihar, India

“…Demographic features of the sampled households and dairy animals are described elsewhere [ 14 , 15 ]. In brief, it was found that mean herd size of dairy farms in Assam (4.1) was significantly ( p < 0.01) higher than in Bihar (2.8), and higher in urban areas (5.5) than in rural areas (2.9).…”

“…Our study found that larger herd size (>10 dairy animals) was significantly associated with higher rates of the selected reproductive problems ( Table 1 ). Larger herds may have poorer sanitation and hygiene with large numbers of animals kept in small confined places where disease transmission might be easier [ 15 ]. Further, we found that households rearing animals under a fully stall-fed system (zero grazing) experienced higher rates of the selected reproductive problems than those who reared dairy animals under partly stall-fed conditions.…”

“…and Leptospira spp. infection in urban/peri-urban areas than rural areas in Bihar and Assam [ 29 , 30 , 31 ]; these infections are considered as the main cause of the five selected reproductive problems [ 15 , 32 , 33 , 34 ].…”

“…Different researchers have reported different rates of prevalence of reproductive problems in different parts of the world, but most agree that the prevalence of the reproductive problems we selected ranges widely from 0.2% to 25.0%. These differences might be because of location of the farms (urban or rural areas), rearing systems, herd size (small, medium or large), and breed of animals (indigenous or improved) as discussed above [ 15 ]. Regional differences in etiology also cannot be ruled out [ 15 , 34 ].…”

“…This analysis used data collected during a cross-sectional study conducted in two of the poorest Indian states, Assam and Bihar, during 2015–16. The detailed sampling methods for the study are explained elsewhere [ 14 , 15 ]. In short, a survey of 534 dairy farming households was conducted using multi-stage sampling where, at the first stage, three districts were purposefully selected in each state based on their importance in terms of dairy development (classified as high, medium, and low).…”