Sero-positivity of Japanese Encephalitis Virus in Equine Population of India Using IgG ELISA: Unraveling the Need for Vaccination.

The research addresses the prevalence of mosquito-borne Japanese Encephalitis (JE) in the equine population in India, demonstrating a need for vaccination due to a high percentage of horses carrying the virus.

Objective and Methodology

• The primary goal of this study was to assess the presence of the Japanese Encephalitis virus in the equine population of India using an indirect IgG ELISA method. This was important as, unlike in other countries, horses in India are not vaccinated against JE, making them more susceptible to the disease.
• The research developed an indigenous ELISA (Enzyme-Linked Immunosorbent Assay), as earlier surveillance was restricted due to the lack of locally developed ELISA and the high cost of imported kits.
• Using the developed ELISA, a total of 2,069 horse serum samples were screened for IgG against the JEV.

Findings

• The ELISA developed for the study demonstrated a diagnostic sensitivity and specificity of 84.73% and 86.70%, respectively, confirming its reliability.
• The validation studies also revealed good reproducibility of the ELISA, with kappa values ranging between 0.75 to 1 across different laboratories. This result suggests a high level of consistency of the test’s results across different settings.
• Out of the total 2,069 horse serum samples tested, 401 samples tested positive for IgG against JEV. This translates to an overall sero-positivity rate of 19.38% in the equine population of India, pointing to a significant presence of the virus in these animals.
• Interestingly, a sero-positivity of 25.90% and 12.22% was discovered in Himachal Pradesh and Jammu-Kashmir, both hill states of the North zone of India. This finding indicates the possible spread of the virus to even the non-endemic parts of the country.

Implications

• The study’s findings highlight the high prevalence of the JE virus in the equine population in India and signals a major health concern for both horses and humans, given the zoonotic nature of the virus.
• Given the study’s results, it recommends and underlines the need to initiate vaccination of horses against JE in India to prevent the disease’s morbidity and mortality.