At least two people have died in the southern Indian state of Kerala from a rare bat virus, also known as Nipah virus, the government said.
Nipah can be transmitted from animals to human beings. It is believed that the virus originated in bats of the family Pteropodidae.
Symptoms in an infected person include fever, vomiting, headache and respiratory problems, with a fatality rate of up to 75 per cent.
The federal National Institute of Virology on Tuesday confirmed the death of two men.
Mangalatt Haris, 40, died on Monday and Kallat Mohammedali, 49, died on August 30.
Mr Mohammedali’s nine-year-old son and 25-year-old brother-in-law have also tested positive for the virus, making him the index case of the outbreak, the government said.
Kerala Health Minister Veena George warned citizens to “be vigilant in the situation of Nipah virus being confirmed again in the state”.
Ms George said that the government has prepared a list of 75 primary contacts of the suspected Nipah victims and who are assumed to be in the high-risk category.
Preventive and disease management measures have been activated In Kerala and contact tracing and surveillance measures are under way.
Authorities have issued an alert in the neighbouring districts of Kannur, Wayanad and Malappuram.
“Because two relatives of the first deceased person have tested positive, it can be surmised that he was also positive for Nipah and he can be considered as the index case,” Ms George said.
“Sixteen teams have been selected for Nipah defensive activities. After the meeting, a special meeting of doctors was called ... [and a] control room set up to co-ordinate activities,” she said.
Mr Mohammedali died with fever and pneumonia-like symptoms at a private hospital. His samples were not collected at the time because he had liver cirrhosis and other comorbidities. It was assumed he died from the health complications.
The samples were sent to the National Institute of Virology in Pune in the western state of Maharashtra to test for the presence of the deadly virus after four members of his family were admitted to hospital on September 9 and 10 with symptoms atypical of fever and pneumonia, media reports said.
What is Nipah virus?
Nipah virus, or NiV, is a zoonotic virus, meaning it can be transmitted from animals to people. Fruit bats of the Pteropodidae family are the natural host of Nipah virus, according to the World Health Organisation.
The virus can also be transmitted to people from contaminated foods and from human-to-human contact with an infected person.
What are the symptoms?
Infections in humans range from asymptomatic to acute respiratory infections and fatal encephalitis – inflammation of the brain.
Infected patients initially develop fever, headaches, myalgia or muscle pain, vomiting and sore throat, according to the World Health Organisation.
This can be followed by dizziness, drowsiness, altered consciousness, and neurological signs that indicate acute encephalitis, progressing to coma within 24 to 48 hours.
Some people can also experience atypical pneumonia and severe respiratory problems, including acute respiratory distress.
The incubation period – the interval between infection and the onset of symptoms – ranges from four to 14 days.
The case fatality rate is estimated at between 40 per cent and 75 per cent, but the WHO says that the rate varies depending on the outbreak and local capabilities for epidemiological surveillance and clinical management.
When was the first outbreak?
The first outbreak of the virus was reported in Malaysia among pig farmers in 1989, according to the EU's European Centre for Disease Prevention and Control.
There was another outbreak a year later in Singapore including 11 abattoir workers linked to infected pigs imported from a farm in Malaysia.
In total, 246 cases were reported from these two outbreaks.
The transmission is thought to have occurred via unprotected exposure to secretions from the pigs, or unprotected contact with the tissue of a sick animal.
An outbreak was recognised in Bangladesh in 2001, and outbreaks have occurred in that country almost every year since. In India, the first outbreak was reported in Kerala in 2018 when 17 people died from the virus. In 2021, a 12-year-old boy from Chathamangalam died.
Diagnosis and treatment
The initial signs and symptoms of the virus infection are nonspecific, which can hinder the accurate diagnosis and detection.
There are no drugs or vaccines available to treat the virus infection but patients are put under intensive support care to treat respiratory and neurologic complications.
