Outbreak of viral encephalitis in Bihar, India

An outbreak of viral encephalitis is ravaging the childrenof Magadh division in Bihar India. This is the second wave of encephalitis that has hit the state after the rainy season with 383 children affected and 82 lives lost. The local health authorities are ill equipped to handle such an epidemic and Bihar being one of the poorest states of India does not help much. Conveniently the local media has given it scant or no coverage.

Image courtesy: The Hindu

 Suspected causative agents

It appears that more than one microorganism is responsible for the outbreak with the Japanese encephalitis virus (JEV) being the prime suspect. It is estimated that at least one third of the cases are caused by JEV which is endemic in the region. JEV, a flavivirus, consists of eight virus species and two subtype viruses. Japanese encephalitis is a zoonotic disease with the zoonotic cycle affecting mosquitoes and pigs and/or water birds. Humans are dead end hosts and become infected accidentally. The major vector implicated in transmission to humans is the mosquito Culex tritaeniorhynchus, breeding mainly in rice paddies. Both rice paddies and pigs are abundant in rural Bihar, perpetuating the epidemic.

JEV has an incubation period of 5 to 15 days with the average incubation period being 6-8 days. There is usually a prodromal period at the onset characterized by nausea, vomiting, diarrhea, fever and headache. The prodromal period, which can last for several days, is followed by higher mental functional abnormalities ranging from mild confusion to coma. Seizures are common in children. Tremors and other movement disorders may occur. Acute flaccid paralysis resembling poliomyelitis may also occur. The fever generally disappears by the second week of the disease followed by the onset of extrapyramidal symptoms like chorea.

On examination, hypertonia and hyperreflexia may be present. There may be cranial nerve involvement like facial palsy etc. Parkinson like extrapyramidal features may be present. Mortality in resource poor settings is about 35%.

In ProMED-mail, an internet based outbreak reporting system of the International Society for Infectious Diseases, enterovirus infection has also been suggested as a plausible etiologic agent. However there is no evidence available at present for an enteroviral cause.

Failure of Policy?

Following an outbreak of JE in 2009 in the Bodh Gaya division of Bihar, a massive vaccination campaign was launched in that division and no further cases of JE were reported. Inexplicably such vaccination campaigns were not organized in other divisions of the state. Result – fresh outbreak in another division (Magadh).

The local hospital is also in shambles with water and power shortages and the only ventilator lying useless.

Mackenzie, J., Gubler, D., & Petersen, L. (2004). Emerging flaviviruses: the spread and resurgence of Japanese encephalitis, West Nile and dengue viruses Nature Medicine, 10 (12s) DOI: 10.1038/nm1144