Detection of ovine leptospirosis in various agro-climatic zones of Odisha in the aftermath of cyclone Hudhud using a multi-faceted approach

Abstract

Leptospirosis is an important emerging zoonotic disease responsible for hampering the productivity of ovine husbandry worldwide. A total of 1,877 ovine serum samples were collected from five agro-climatic zones of Odisha following the aftermath of cyclone Hudhud. A multifaceted approach for detection of anti-Leptospira antibodies using Microscopic Agglutination Test (MAT), in-house developed rapid spot tests such as recombinant Loa22 antigen-based Latex Agglutination Test (rLoa22 LAT) and rLoa22-based IgG Dot ELISA Dipstick Test (rLoa22 IgG DEDT) were developed. Further, nucleic acid detection of leptospirosis employing Polymerase Chain Reaction (PCR) utilizing LigBF/LigBR and G1/G2 were performed. Additionally, renal histopathology of kidneys from MAT positive sheep was also used for investigating leptospirosis in sheep. MAT results for ovine sera revealed a seropositivity of 16.62% (312/1877) with maximum agglutinins detected against serovar Pomona. Among agro-climatic zones, South Eastern Ghat recorded the highest seroprevalence while Western Central Table Land recorded the lowest seroprevalence for ovine leptospirosis. A total of 296 and 345 sera tested positive by rLoa22 LAT and rLoa22 IgG DEDT respectively. PCR performed on kidneys of MAT positive sheep revealed amplicons for LigBF/ LigBR and G1/G2 primers in 104 and 93 sheep respectively. The histopathological evidence such as tubular atrophy, severe tubular degeneration and necrosis with interstitial and periglomerular fibrosis suggestive of chronic leptospirosis was present in 78 sheep. This multi-pronged approach of employing a battery of diagnostic tests would allow the execution of mediation strategies to curb ovine leptospirosis following natural calamities such as cyclones.