Are infectious reproductive pathogens of large ruminants a threat to improving food security? An investigation from Cambodia.

In Cambodia, information on common pathogens causing reproductive losses in cattle and buffalo are lacking, despite there being a need to address livestock health to enhance food security. We analysed stored buffalo (n = 29) and cattle (n = 471) serum samples collected in 2016 using commercially available enzyme-linked immunosorbent assay kits. Antibodies to Neospora caninum, bovine viral diarrhoea virus (BVDV), Leptospira interrogans serovar Hardjo and Brucella abortus were detected in buffalo samples at 79.3% (95% CI 64.6-94.0), 3.4% (95% CI 0-10.0), 0% and 0%, respectively, and in cattle at 4.2% (95% CI 2.4-6.0), 6.4% (95% CI 4.2-8.6), 8.1% (95% CI 5.6-10.6) and 0%, respectively. The high N. caninum seroprevalence in buffalo was associated with increasing age, with buffalo having a 13.1% chance of being seropositive at birth, increasing to 99.4% by age 7 (p = 0.045). This suggests a predominance of horizontal transmission, possibly from exposure to faeces from free-roaming village dogs. Cattle L. interrogans serovar Hardjo seroprevalence was highest in Tbong Khmum province (20.4%) compared to other provinces (p < 0.001), and may be compromising bovine fertility and creating a zoonotic risk for smallholders who may contract leptospirosis from farm work. These high infection rates prompt further research to determine: to what extent these pathogens are linked to the low reproductive efficiency observed in large ruminants in Cambodia, the risk factors to pathogen exposure and appropriate strategies to reduce these risks. Low BVDV and B. abortus exposure is an important observation. Increasing large ruminant livestock trade into the country will require improved biosecurity and disease surveillance to prevent their emergence. An enhanced understanding of the status of infectious reproductive livestock pathogens in Cambodia can assist development projects to make evidence-based strategies to enhance cattle and buffalo health and improve food security.