West Nile virus: the Indian scenario

Area of Science:

• * Veterinary Virology
• * Medical Entomology
• * Arbovirology

Background:

• * West Nile virus (WNV) is a significant flavivirus transmitted by arthropods, typically causing mild West Nile fever (WNF) in humans and horses.
• * Mosquitoes, particularly Culex species, are the primary vectors, maintaining the virus in a bird-mosquito cycle.
• * In India, WNV is present, with various mosquito species implicated as potential vectors, and ardeid birds possibly playing a role in its enzootic maintenance.

Purpose of the Study:

• * To describe the current status of West Nile virus in India.
• * To review WNV vectors, transmission dynamics, and diagnostic approaches in the Indian context.
• * To discuss control strategies and the challenges in WNV management.

Main Methods:

• * Literature review of existing studies on WNV in India.
• * Analysis of experimental data on potential vectors and transmission.
• * Summary of diagnostic techniques and genetic characterization of Indian WNV isolates.

Main Results:

• * Several Culex species (e.g., Cx. tritaeniorhynchus, Cx. vishnui) and Aedes albopictus are identified as potential WNV vectors in India.
• * Transovarial transmission has been demonstrated in Culex mosquitoes.
• * Indian WNV isolates belong to genetic lineage-I; diagnosis relies on serological and RT-PCR methods.
• * Japanese encephalitis virus (JEV) is more prevalent in South India, with cross-protective immunity observed between WNV and JEV in experimental models.

Conclusions:

• * Integrated vector control strategies are crucial for managing WNV, primarily targeting Culex mosquito populations.
• * While WNV infection is generally mild, supportive therapy is recommended for encephalitis cases.
• * Currently, no commercial vaccines are available for WNV in humans or animals, necessitating ongoing research and surveillance.