Serological and molecular epidemiology of leptospirosis and the role of dogs as sentinel for human infection in Nigeria.

OBJECTIVE

Prospective cross-sectional study of dogs in Nigeria to study leptospirosis, inferred to be endemic in all regions of the country by researchers. Aim is to generate empirical updated evidence of leptospiral infection and delineate serovars involved.

METHODS

Study determined the sero-prevalence and infection rate in 342 dogs using sero-assays, culture isolation and novel qPCR. In-house designed primers targeting conserved regions were used to amplify genes in quantitative Real-Time PCR (qRT-PCR) for leptospiral detection to serogroups. Molecular analysis of the leptospiral 16S rRNA and LipL32 genes were used for identification of pathogenic Leptospira species. Primers targeting the O-antigen (rfb) region of the Leptospira lipopolysaccharide (LPS) were used for differentiating serovars based on comparative melting temperature (Tm) analysis against reference serogroups.

RESULTS

Overall serological and bacteriological prevalence of 56 (16.4%) and 40 (11.7%) respectively was recorded. Vaccination, ages and season(s) were the strongest determinants of infection. Unvaccinated animals, stray dogs and symptomatic dogs presented statistically significant (P < 0.05) higher risk of infection: OR 25.531 (6.108, 106.712; 95% CI).

DISCUSSION: The evidence suggests 1 of every 10 dogs is infected and could be symptomatic for the disease or a carrier of leptospires in the studied region in Nigeria with attendant public health risks.