The state government says 70 people have died of chikungunya in the last three weeks. Most of these deaths have occurred in the coastal district of Alappuzha, which is surrounded by backwaters, thus making many villages breeding grounds for the mosquitoes that are carriers of the fever.

Kerala's Health Minister P K Sreemathi, who is camping at Alappuzha to monitor the situation, said the state government has sought immediate help from WHO because "it is for the first time that we are hit by this kind of a disease."

"We want WHO experts to make a detailed survey of the villages and the people affected by the disease. We want to ensure that the disease does not spread further," she told rediff.com over the telephone.

Chikungunya is transmitted by infected mosquitoes. Typically, the Aedes aegypti mosquito (tiger mosquito) spreads the disease.

WHO says other mosquitos also infect the disease, which is usually prevalent in Africa, South-East Asia, southern India and Pakistan. It occurs principally during the monsoon.

Generally, health experts say, chikungunya is not fatal. In the last three months, there have been some 300 deaths across southern India -- in Tamil Nadu, Andhra Pradesh, Karnataka and Kerala -- mainly due to chikungunya.

In July, Tamil Nadu had the largest number of cases; these were centered around the southern districts of Madurai and Tirunelveli.

According to Dr K Velayudhan, chief medical officer, Alappuzha district, nearly 60,000 people who are showing symptoms of the disease have been admitted to various hospitals. "We have sent more doctors, nurses and field health workers to the hospitals," he said.

Dr Velyaudhan, however, does not think that all the cases of viral fever reported in the district are necessarily chikungunya cases. "We have sent blood samples for tests to ensure whether they test positive for the disease," he said.