Monday, Feb 06, 2023

Nipah in Kerala: last year, this year, what next

Nipah virus: As of now, scientists feel the current outbreak is likely localised, like last year’s. People who have had close contact with a patient are considered to be at potential risk.

Explained: Nipah makes a comeback in Kerala; all you need to know The natural host of the Nipah virus is fruit bats of the Pteropodidae family and Pteropous genus. (Express File Photo: Javed Raja)

A youth from Ernakulam district in Kerala has tested positive for the Nipah virus infection, a year after a similar outbreak in the state had claimed 17 lives. The infected patient this year has survived for more than 10 days now, and health authorities are hopeful that this latest outbreak would be contained soon. The infected patient has been isolated, and everyone he had potential contact with in the last few days is being screened.

The virus

Nipah virus causes a so far incurable infection in human beings, which can sometimes be fatal. The infection is generally transmitted from animals to human beings, mainly from bats and pigs. Human-to-human transmission is also possible, and so is transmission from contaminated food.

The natural host of the virus are fruit bats of the Pteropodidae family and Pteropous genus, widely found in South and South East Asia. However, the actual source of the current infection is not yet known, said Dr D T Mourya, director of Pune-based National Institute of Virology (NIV), which is at the forefront of efforts to contain the virus. Scientists are currently working on finding the epidemiological link of the outbreak.

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First identified in 1999 in Malaysia, Nipah virus infections have been detected quite frequently in Bangladesh. There have been a few incidents of infection in India earlier, apart from last year’s outbreak in Kerala.

Patients either show no symptoms of the infection, thereby making it difficult to detect, or develop acute respiratory problems, or encephalitis that often becomes fatal.

The World Health Organization (WHO) says the infection has been found to be fatal in 40% to 75% of the infected patients. There is no treatment available as of now, either for humans or animals, nor any vaccine.

The previous outbreak

Last year’s outbreak was confined to two districts, Kozhikode and Malappuram. Studies by NIV have revealed that a particular kind of fruit bat, Pteropus spp, was most likely the source of human infection in 2018. Research led by NIV scientist Pragya Yadav suggested that this particular strain might have been circulating in the local bat population.


The newly detected case in Kerala, authorities believe, could actually be a result of intensified preventive and containment efforts after last year’s outbreak. There has been an increased awareness and vigilance in the community. According to Dr Mourya, this helped in early detection this time.

Not just in Kerala

Nipah virus has been found in other parts of India earlier. The first outbreak was in 2001 in Siliguri, where more than 30 people were hospitalised with suspected infection. Another outbreak happened in 2007 in Nadia of West Bengal. Again, over 30 cases of fever with acute respiratory distress and/or neurological symptoms were reported, five of which turned out to be fatal. Last year, after the outbreak in Kerala, doctors tested samples from suspected cases in Karnataka, Telangana and Maharashtra. All of them tested negative.

Can it spread?

As of now, scientists feel the current outbreak is likely localised, like last year’s. So far only one suspected sample has tested positive. More people showing symptoms are being screened and so are people in physical contact with them.


A study by NIV, published last month in the journal Emerging Infectious Diseases, reported that the risk for asymptomatic infections (in which the infected person does not show overt symptoms) was higher among people with a history of exposure to body fluids of infected patients as compared to those who only had physical contact with the patient. After the study, the NIV advised extreme care for healthcare workers and caregivers — double gloves, fluid-resistant gown, goggles, face shields, closed shoes and similar other protective gear — and a limited number of visitors to the patient.

People who have had close contact with a patient are considered to be at potential risk. These include people who have slept in the same household , have had direct physical contact either with the patient or a deceased who had an infection, or have touched the blood or other body fluids (saliva, urine, sputum) of the patient during illness.

First published on: 05-06-2019 at 00:06 IST
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