Nipah virus — a deadly condition spread by fruit bats — has killed more people in the southern Indian state of Kerala overnight.
Today the death toll of the virus — which has no vaccine — rose to 11, with almost 100 people being treated as potential cases.
There are worries the brain-damaging virus has spread to a second state after two suspected cases were reported in neighbouring Karnataka.
A 20-year-old woman and a 75-year-old man are being treated for symptoms of the disease in the city of Mangalore after they travelled to Kerala and had contact with infected patients.
Samples of their blood have been taken for screening, with results expected tomorrow.
Mortality rates for Nipah — which starts with flu-like symptoms — are around 70%.
The first death from the disease was reported on Friday, with health officials traced back to a well infested with diseased bats.
Local officials have warned those coming to Kerala — which is popular with tourists — to avoid infected areas.
State official Rajeev Sadanandan said the districts of Kannur, Kozhikode, Malappuram and Wayanad should be avoided at all costs.
"Since there are many foreigners who travel to Kerala, we are advising they can avoid these district for abundant caution," he said.
But he insisted Kerala was otherwise safe for tourists, as the infection "remains highly localised".
All of the current cases are believed to be linked to one family.
A nurse who treated some of the victims died after becoming infected herself.
Health Minister KK Shailaja told a news briefing at least 17 patients were currently confirmed as having Nipah — which was first discovered in 1998.
"All steps to prevent the spread of the virus have been taken," she said.
She urged people not to destroy fruit bat colonies, believed to be the cause of the animals coming into contact with humans.
The World Health Organisation has named Nipah as one of the 10 most dangerous viruses in the world — because of how quickly it spreads and how hard it is to contain.
It comes as fears grow of an Ebola epidemic in the Democratic Republic of the Congo after patients escaped from a quarantine zone.
Earlier this week a nurse became the latest victim of the fatal disease.
