Agent factors :- * Caused by group B arbovirus (flavivirus) * The main reservoirs are Ardeid birds and pigs * Pigs are amplifiers of the virus and they do not manifest ove symptoms but circulates the virus Host factors :- * Most common in the age group of <15 years of age * Man - incidental dead end host * Affects other animals also and horse is the only animal which does not shows symptoms of encephalitis Vector:- * Transmitted by culex tritaeniorrhynchus - most impoant vector, others are C.Vishnuii and c. Gelidus * Incubation period is 5-15 days * Case fatality rate - 20-40% Ref:- K Park, 24th ed; pg num:- 302-303