Nipah, which was first identified during an outbreak in Kampung Sungai Nipah, Malaysia in 1998, is primarily carried by fruit bats of the Pteropodidae family.

"Sajietta am almost on the way. I don’t think so we can meet. Sorry. Take care of our children. Please try to take them to Gulf. They should not be left alone like our father. Lots of love…" was the last message 28-year-old nurse Lini Sajeev wrote to her husband before reportedly succumbing to the deadly Nipah virus that has put Kerala on high alert.

According to the district collector’s office, the death toll due to Nipah stood at six, with at least 20 other suspected cases. The case initially came into light after three members of a family from Panthirikkara Sooppikkada in Changaroth grama panchayat, Kozhikode district, died of viral encephalitis with myocarditis. While 26-year-old Mohammed Sadik and his brother 28-year-old Mohammed Salih died on 5 May and 18 May respectively, their aunt Mariyam passed away on 19 May.

The Kerala government has taken up several precautionary measures in order to contain the virus from spreading elsewhere. Sooppikkada has been locked down, and advisories have been set up on food and hygiene habits; besides families staying close to the affected dwellings have been evacuated to safer places and domestic animals are being kept under observation.

The state health department said it will be setting up isolation wards in government and private hospitals to contain the deadly virus that has a fatality rate of 70 percent.

"It is now a local epidemic. It may become a local epidemic in other nearby areas; (but) we are trying our best to contain it from spreading," said Rajeev Sadanandan, additional chief secretary at the Department of Health and Family Welfare.

"Now, the disease is being spread by people to people contact. All suspected cases are being treated for Nipah," he said.

But despite precautionary measures, authorities concerned are yet to identify reasons on how the disease that was hitherto identified only in the eastern and northeastern parts of the country, spread to Kerala.

"Nobody knows how the virus has spread to Kerala. What we are hearing is that wells in the infected area (Sooppikkada) was contaminated with the virus. However, we must probe all angles," said George Varghese, Virology in-charge at the Pushpagiri Research Centre.

The possibility that infected bats migrated all the way to Kerala and are intermediate receptors spreading the disease is an unlikely scenario as fruit bats are not known to migrate long distances.

But Sadanandan said, "We have to believe that bats migrate long distances. If not then how did it spread to Thailand from Malaysia and then to Bangladesh and West Bengal?"

According to the World Health Organisation (WHO), Nipah is capable of infecting pigs and other domestic animals and there are no vaccines available for the disease; the primary treatment for infected humans is through intensive supportive care.

Nipah, which was first identified during an outbreak in Kampung Sungai Nipah, Malaysia in 1998, is primarily carried by fruit bats of the Pteropodidae family. The virus can spread through other mediums including human to human contact as well.

In Malaysia, pigs were the intermediate hosts; in subsequent Nipah outbreaks, no intermediate hosts were identified.

Several people had lost their lives to Nipah in Bangladesh in 2004 after consuming date palm saps contaminated by fruit bats and there were a few other outbreaks in and around the region. In 2006, the virus had raised concerns in Siliguri, West Bengal, a state where the first case had been detected as early as 2001. But most of these cases were said to have resulted from human to human contact.

"We don’t want to take any chances. However, we can only confirm on all cases being Nipah or not after we get reports from the National Institute of Virology in Pune," said Sadanandan, and confirmed that three of four persons who died of fever in Kozhikode district, were infected by the Nipah virus.

The Centre has sent a team of experts to coordinate with state authorities and monitor the situation. "Reviewed the situation of deaths related to nipah virus in Kerala with Secretary Health. I have directed Director NCDC to visit the district and initiate required steps as warranted by the protocol for the disease in consultation with state government (sic)," Union Health Minister JP Nadda had tweeted on Sunday.

The Central team includes Surjit Singh, director for the National Centre for Disease Control, SK Jain, head of epidemiology, NCDC, P Ravindran, director, Emergency Medical Relief, and Naveen Gupta, head of Zoonosis, NCDC. They are accompanied by two clinicians and an expert from the Ministry of Animal Husbandry.

George said experts are still in the dark in finding the exact reason behind the virus spreading in the state and added that the government should take an initiative to start a study led by virologists.

Sajeesh, who is survived by her husband and two children, was hospitalised for a week before finally succumbing to her ailment on Monday morning. She was reportedly treating two men suspected to have been infected by Nipah. Though her death is yet to be confirmed as a Nipah casualty, her body was immediately cremated at the electric crematorium as a precautionary measure.

"Lini used to work at a private hospital. She left her job to take care of a small child. She had joined the government taluk hospital as a temporary staff during the last dengue fever outbreak there. She was a workaholic and always committed to her work," a person close to Lini said, adding that Lini fell ill after treating two infected persons.

Following the outbreak in Kozikhode, speculations of the excessive use of antibiotics was being attributed to Keralites being affected. But Philip Mathew, a public health consultant for ReAct Asia Pacific, rubbished this theory and said, "This is a viral disease. This has nothing to do with the excess usage of antibiotic drugs. Excess usage of antibiotic drugs plays a role only in bacteria infected diseases."

The author is a member of The NewsCart, a Bengaluru-based media startup.