Eleven contacts of the 12-year-old boy who died due to Nipah virus have shown symptoms of the disease, Kerala Health Minister Veena George said on Monday, according to NDTV.

Nipah is a virus that can be transferred from animals to humans. It causes fever and cold-like symptoms in patients before quickly advancing to encephalitis, which is inflammation of the brain, and myocarditis, or inflammation of the heart.

The parents of the 12-year-old boy and two of their relatives are among those found symptomatic. “Their condition is stable,” the health minister said. “The boy’s mother had fever on Sunday night, but it has subsided now.”

George said said the government has identified 251 people who came in contact with the boy and 129 of them are healthcare workers. Thirty of these healthcare workers have been quarantined, reported The Hindu. They are reportedly in a stable condition.

“The boy was taken to at least four healthcare institutions, including the MCH [Medical College and Hospital], Kozhikode, before being admitted to the private hospital where he died,” George said. “That is why a majority of the contacts are healthcare workers.”

On Tuesday, the health minister said that 24 samples of eight persons that had been sent to the National Institute of Virology in Pune have tested negative for the virus, ANI reported.

“We are testing more samples,” George said. “We have started field surveillance and will begin house-to-house surveillance in containment zones today [Tuesday].”

She added that a laboratory at the Government Medical College in Kozhikode will also begin testing samples on Tuesday. “We can do testing of almost all the people who are in isolation at the hospital today itself,” she said.

The Kerala government has put Kannur, Malappuram and Wayanad districts on high alert. All of these districts share their border with Kozhikode where the deceased boy lived.

The government has also collected the blood and swab samples of two goats from the house of the deceased. The goats had been unwell. Their samples have been sent to National Institute of High Security Animal Diseases in Bhopal.

On Sunday, a team of the National Centre for Diseases Control had collected samples of a fruit to identify the source of the infection.

Centre asks Kerala to boost surveillance

Meanwhile, the Centre has recommended a five-pronged strategy to the Kerala government to tackle the Nipah outbreak, reported The Indian Express. The recommendations were based on a report submitted by a central expert team that visited the state.

In a letter to Kerala Chief Secretary VP Joy, Union Health Secretary Rajesh Bhushan advised boosting hospital and community-based surveillance. Bhushan also said that district authorities should conduct contact-tracing, quarantine those who are found symptomatic and observe them for symptoms.

“Awareness needs to be created among the field formations for early detections of cases of acute cncephalitis syndrome and respiratory distress and [the] risk communicated to the public,” Bhushan said.

The health secretary also advised identifying adequate number of single occupancy rooms and intensive care units at the Government Medical College in Kozhikode for Nipah patients.

“A referral system be established along with earmarked ambulances and trained staff,” the letter said. “Adequate stock of Ribaverin [anti-viral medication] and personal protective equipment need to be maintained at the district level.”

The Centre also recommended setting up a control room for daily reporting of cases. “Coordination with animal health and wildlife department and other field officers may be initiated to trap and collect samples from fruit bats for virological studies and other associated measures,” the letter said.