The death toll due to Nipah rose to 12 in Kerala, with one more person succumbing to the deadly virus in Kozhikode today.

The deceased, 75-year-old Kalyani, was undergoing treatment at the Medical college in Kozhikode since May 16, official sources said.

Two days ago, 61-year-old V Moosa had died of the virus infection.

Two members of his family had died earlier of the virus.

His eldest son had also died, but his samples were not tested.

Lini Puthussery, a nurse who had initially treated members of Moosa's affected family members at Perambra Taluk hospital in the district, also died after being infected by the virus.

About 160 samples were sent for tests to the National Virology Institute (NVI) Pune and 15 cases tested positive, health department sources said.   

Of the 15 confirmed cases, 12 people have died so far.

With samples of insectivores bats testing negative forthe virus, samples of fruit-eating bats are being collected from nearby Perambra, the epicenter of the Nipah virus, to besent for tests at the National Institute of High Security Animal Diseases in Bhopal.

Experts from NIV and departments of Animal Husbandry and Forest have begun collecting samples which would be sent to NIHSAD, to test for presence of the virus in the fruit-eatingbats, Dr N N Sasi, the Director Animal Husbandry, told PTI.

Earlier, samples of three insectivorous bats caught froman unused well of the Moosa family, which lost three members to the virus, were sent to the Bhopal laboratory along withsamples of pigs, goats and cattle in the five km radius of theaffected area and all of them tested negative, he said.

"We are trying to catch fruit-eating bats from thePerambra region now," Sasi said.

According to an official, the droppings, urine andsecretions of the bats would also be sent for testing.

A Union Health Ministry advisory has said that the virus,which commonly affects animals such as bats, pigs, dogs, andhorses, can spread to humans, causing serious illness.

Spread of the virus to humans may occur after close contact with other Nipah infected people, infected bats, or infected pigs.

Meanwhile, the Kerala government has said travellers need to avoid only Kozhikode and Malappuram districts from wherethe deaths have been reported.

Earlier, the government had issued an advisory, stating that travelling to any part of Kerala was safe.

However, if travellers wished to be extra cautious, theymay avoid the four districts -- Kozhikode, Malappuram, Wynadand Kannur, it said.

The outbreak of the virus infection, which is a newlyemerging zoonosis that causes severe disease in both animalsand humans, is suspected to be from an unused well which wasinfested with bats.

The natural host of the virus is believed to be fruitbats of the Pteropodidae family, Pteropus genus.  -- PTI