Urban Japanese Encephalitis: Time for a Reality Check

Abstract

Expansion of JEV from its historical rural origin in the Oriental Realm has been evident. Apprehensions were raised by several investigators that the occurrence of Japanese Encephalitis (JE) in the urban areas is a possibility. Creating wetlands, rice farms, and piggeries close to the rural-urban periphery to support the increasing urban population facilitates the migration of mosquitoes, ardeid birds, and pigs in these areas. The presence of vectors (Culex vishnui complex), reservoirs (the ardeid birds), and the amplifying hosts (pigs) together in these urban and peri-urban areas creates highly conducive situations for the JE transmission thus, creating an urban ecotype for JE. Apart from the primary vectors, JEV has been isolated from several species of mosquitoes belonging to different genera. JE antibodies have also been detected in several birds and mammals other than the known reservoirs and amplifying hosts. Such mosquitoes, birds, and mammals might be acting as complementary or maintenance vectors and reservoirs, respectively, which likely can keep the virus circulating perennially in nature. The reported occurrence of JE in urban areas from different geographical locations is decidedly indicative of the reality of the urban JE. It is thus pertinent that an inclusive approach encompassing sustained epidemiological surveillance and monitoring be adopted to formulate season-wise and area-wise strategies to contain JE both in rural and urban areas.