Prevalence of Neospora caninum Antibodies and Associated Risk Factors in Dairy Herds in Bangladesh

Introduction: Neospora caninum is a major cause of bovine abortion and reproductive failure worldwide, but epidemiological evidence from Bangladesh dairy systems remains limited. This study estimated N. caninum antibody prevalence and associated herd- and cow-level risk factors.

Methods: A cross-sectional study was conducted in 14 districts of Bangladesh from January 2023 to December 2024. Bulk milk samples from 113 dairy herds and individual cow milk samples (n = 873) were tested using the ID Screen® Neospora caninum Indirect ELISA (Innovative Diagnostics, Grabels, France). Herd-level risk factors were assessed using univariable logistic regression followed by multivariable and stepwise logistic regression. Cow-level risk factors were assessed using univariable and multivariable mixed-effects logistic regression, with farm included as a random intercept.

Results: Herd-level and cow-level antibody prevalences were 8.8% (95% CI: 4.6–16.1%) and 6.5% (95% CI: 5.0–8.4%), respectively. At the herd level, univariable analysis identified herd size greater than 120 animals (OR: 9.33; 95% CI: 1.07–81.77), more than four calves (OR: 5.16; 95% CI: 1.04–25.48), and more than three repeat breeding cases (OR: 4.16; 95% CI: 1.02–17.07) as significantly associated factors. In the final stepwise herd-level model, only herds with more than four calves were retained (OR: 5.16; 95% CI: 1.04–25.48; P = 0.044). At the cow level, mastitis was the only significant factor in univariable analysis (OR: 0.316; 95% CI: 0.100–0.997; P = 0.049); no factor reached significance in the final multivariable model.

Conclusions: These findings demonstrate N. caninum exposure in Bangladesh dairy herds. The association with calf number may reflect herd structure and possible vertical transmission dynamics. Routine surveillance, improved reproductive health monitoring, and strengthened biosecurity practices are recommended.