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BMJ. 2007 November 10; 335(7627): 961.
PMCID: PMC2072010

Indian researchers look into vaccine's effectiveness as 300 die in encephalitis outbreak

Health authorities in India are trying to determine the cause of an outbreak of paediatric encephalitis in the northern state of Uttar Pradesh, where the government vaccinated susceptible children last year with a Chinese made vaccine against Japanese encephalitis.

The outbreak this year has affected several thousand children and killed at least 300 over the past few weeks. Doctors have said that only about 15% of the cases have been confirmed as Japanese encephalitis and that the illness in the rest of the children seems to be another form of viral encephalitis.

But the Indian Council of Medical Research is probing the circumstances under which Japanese encephalitis has resurfaced in a region where state authorities had claimed to have vaccinated nearly nine million children below the age of 15 years—99% of susceptible children.

Komal Prasad Kushwaha, a professor of paediatrics at the Baba Raghav Das Medical College in Gorakhpur, a town at the centre of the outbreak, said, “This virus appears to affect multiple organs. There is involvement of the heart, the liver, the kidney, and the brain.”

The college has itself recorded 1580 cases, of which just 187 have been diagnosed as Japanese encephalitis. “We suspect this is enterovirus associated encephalitis again,” Dr Kushwaha said.

Last year this mainly rural region experienced an outbreak of Japanese encephalitis that affected more than 3000 children. At the time India's National Institute of Virology detected enterovirus associated encephalitis in several cases. The institute is currently trying to culture and identify the virus this year.

But the return of Japanese encephalitis this year “raises questions,” said Gajinder Pal Singh Dhillon, director of the national vectorborne disease control programme in New Delhi. Either the vaccine coverage last year was overestimated or the vaccine didn't work as well as it should have, he said.

Last year medical experts expressed concern that the Chinese vaccine was used in India without standard tests of efficacy that precede the introduction of a new vaccine.

Critics pointed out that studies of the vaccine's ability to generate antibodies in Indian children were not done before it was used in regions with malnutrition and unsanitary conditions. Proponents of the vaccine had argued that the vaccine had been used in more than 200 million children in China over the past 18 years with “excellent efficacy.”

“We're now trying to determine what proportion of vaccinated children seroconverted,” said Nirmal Kumar Ganguly, director general of the Indian Council of Medical Research.

Biologists have long complained that investigations of outbreaks in India have been hampered by the absence of a facility for research into human infections that can operate at biosafety level 4, the highest biosafety level.

“When we don't know the identity of a lethal organism, we need to ideally study it in a level 4 facility,” said Gopal Pande, coordinator of India's first such facility, which is not likely to start operating before 2010.


Articles from The BMJ are provided here courtesy of BMJ Publishing Group