MCQ of the Day: 28 October 2026

Answer: B. Domestic pigs. Acute encephalitis in a child from eastern Uttar Pradesh during the monsoon, with paddy fields, pig rearing and CSF IgM against a flavivirus, points to Japanese encephalitis virus, transmitted mainly by Culex tritaeniorhynchus, which breeds in rice fields. Pigs develop high, prolonged viraemia without serious illness, so many feeding mosquitoes become infected. This amplifies the virus near human dwellings, and rising infection in pigs often comes before human cases.
A. Herons, egrets and other wading birds are the maintenance (reservoir) hosts in the enzootic cycle, but pigs living close to people are the main amplifiers of human risk.
C. Humans are dead-end hosts: viraemia is low and brief, so they do not infect mosquitoes.
D. Horses can develop encephalitis but, like humans, are dead-end hosts.