Cross Sectional Analysis of Major Viral Diseases in Shrimp Farms of Kerala, India

Effective disease surveillance is crucial to predict, identify, and manage disease outbreaks in the shrimp aquaculture. A cross-sectional study was conducted to identify the major viral diseases occurrence in shrimp farms of Kerala. A two-stage random sampling was employed involving the selection of 31 shrimp farms in the first stage and 23 individual shrimp in the second stage. The surveillance was carried out from October 2023–2024, targeting major DNA viruses: WSSV, HPV, MBV, IHHNV and RNA viruses: IMNV, CMNV, TSV, DIV, LSNV, YHV-1 by using PCR and histopathological analysis. Among the 31 shrimp farms surveyed, WSSV was detected in 7 farms, while all other viral pathogen tested negative. The histopathological examination revealed characteristic Cowdry type A and basophilic inclusion bodies in the stomach, gill and pleopods consistent with WSSV infection. The overall prevalence of WSSV was observed as 22.6%. The relatively low prevalence is attributed due to the reduction in shrimp farming activity in Kerala as most farms operated only one production cycle per year. The risk factors analysis indicated that WSSV infection was significantly associated with specific variables including a culture duration exceeding 35 days, ammonia concentration > 0.5mg/L, stocking densities > 25 shrimps/m ² , L. vannamei as the cultured species. This surveillance study provides valuable insights into the present status of shrimp viral diseases in Kerala and offers a foundation for improved prevention and control strategies in shrimp aquaculture.