India began a fresh round of tests to trace the origin of a rare brain-damaging virus that has killed 13 people, a health official said on Monday, as initial tests on animals suspected of carrying the Nipah virus showed no sign of the disease.
All animal samples, including those from bats, cattle, goats and pigs from the southern state of Kerala, sent to the National Institute of High Security Animal Diseases, in Bhopal, Madhya Pradesh, were negative for Nipah, said animal husbandry officer A. Mohandas.
The department was now collecting samples of fruit bats from Perambra, the suspected epicenter of the infection and nearby areas, Mohandas said.