Hundreds of children in Nepal and India have died since July.

Indian health officials' lack of preparedness has directly contributed to a spiraling outbreak of Japanese encephalitis in the country, public health experts charge.

Since July, the disease has claimed the lives of more than 764 children in the northern state of Uttar Pradesh, and sickened 3,551. Neighboring Nepal has reported another 259 deaths.

The disease, characterized by fever, loss of consciousness and seizures, is not new to India. Between 1998 and 2004, the country each year saw as many as 3,400 cases and up to 700 deaths from infections, according to India's National Vector Borne Disease Control Programme.

Everyone is ill prepared, with noequipment, no diagnostic reagents, no medicines or vaccines. Kamal Krishna Datta,, National Institute of Communicable Diseases in Delhi

Water-logged paddy fields in the monsoon months between July and September offer ideal breeding grounds for mosquitoes that transmit the virus from pigs—the main reservoirs—to humans. Children are particularly vulnerable.

Despite these factors, the government did not have preventive strategies in place, experts note. “There are no attempts to forecast, anticipate and understand the epidemiology of diseases and pass on the information to relevant districts,” says Kamal Krishna Datta, former director of the National Institute of Communicable Diseases in Delhi. “Everyone is ill prepared, with no equipment, no diagnostic reagents, no medicines or vaccines.”

Reality bites: Japanese encephalitis, transmitted by mosquitoes, has claimed 764 lives in India. Credit: Narendra Shrestha

Insecticide spraying for mosquito control is impractical because of the wide geographic area of the rice fields and accompanying environment problems. But the health ministry also did not opt for preventive vaccines for children, citing the lack of adequate production facilities and high cost—about $2 per dose—of producing the vaccine.

The Uttar Pradesh state government placed orders for the vaccine only in August after the outbreak was already in full swing. A vaccine would have been of little use then, as it takes a month to develop antibodies, notes Datta. “Vaccination should be done well before, and not during an epidemic,” he says.

In the southern state of Andhra Pradesh, where the disease is also endemic, the government in 2001 began buying doses of the vaccine from Vietnam. Incidence in the state has dropped from 343 in 2000 to none this year.

The most widely used vaccine for the disease is produced from the Japanese Nakayama strain of the virus grown in mouse brains, and given in three doses over 30 days. India's Central Research Institute in Kasauli can produce 500,000 doses and plans to double that number by 2006. But to cover Uttar Pradesh alone, 15 million doses would be required.

“Millions of baby mice are needed, and there is no infrastructure for such large-scale production,” says Sudhanshu Vrati, chief of virology at Delhi's National Institute of Immunology. Vrati and his colleagues are developing alternate vaccines using peptides and DNA fragments.

Chinese scientists have since 1989 successfully used a vaccine based on a weakened virus that shows 99% efficacy after a single dose (Lancet 358, 791–795; 2001). The World Health Organization (WHO) is expected to approve that vaccine “in the near future” according to Salim Habayeb, the WHO's representative in India.

In the meantime, some countries such as Korea and Nepal are conducting their own studies on the Chinese vaccine and licensing it for use. India should follow their example, some experts say.

As the toll mounted, Indian health minister Anbumani Ramadoss in September asked researchers to conduct safety trials on the Chinese vaccine. His ministry plans to launch a preventive vaccination program in all 60 endemic districts of India next year and increase vaccine manufacturing capacity.