The Indian Council of Medical Research has confirmed that fruit bats were the source of Nipah virus, Hindustan Times reported on Tuesday. The outbreak in May killed 17 people in Kozhikode and Malappuram.

“Scientists have found conclusive evidence of Nipah virus infection in the fruit bats found in the area,” the newspaper quoted Union Health Minister JP Nadda was quoted as saying.

Nipah is a virus that can be transferred from animals to humans. It causes fever and cold-like symptoms in its patients that quickly advances to encephalitis, which is inflammation of the brain, and myocarditis, or inflammation of the heart. There is no vaccine or cure for Nipah infections at present.

In May, the National Institute of High Security Animal Diseases found that body fluid samples collected from insectivorous bats in Changaroth gram panchayat in Kozhikode district did not have the Nipah virus. Researchers then suspected the role of fruit bats in spreading the infection, and have now confirmed it.

The infections were first reported in Changaroth panchayat.

“The 21 bats trapped and tested [in May] were insectivores that do not carry the Nipah virus, [but] 55 bats trapped in the second round included fruit bats, which tested positive for the Nipah virus,” an unidentified scientist at Indian Council of Medical Research told Hindustan Times.

The Kerala government this week declared Kozhikode and Malappuram free of the Nipah virus.