India has documented cases of hantavirus, but the variant circulating here caused far less severe disease than the lethal strain spotted at luxury cruise ship, MV Hondius, India’s top epidemiologist Dr Raman Gangakhedkar told News18.
With mortality rates expected to be around 40 per cent in Andes virus infection, India’s indigenous strain kills a fraction of those infected — a crucial distinction as global concern mounts.
“Hantavirus has been reported in India. There have been stray reports of hantavirus affecting our side, even in Asia and also in India,” said Gangakhedkar, former head, division of epidemiology and communicable diseases at India’s apex health surveillance body, Indian Council of Medical Research (ICMR).
The difference between
the two strains is stark. The Andes hantavirus spreading through Chile and Argentina causes a pulmonary syndrome — attacking the lungs — with mortality rates reaching 40 per cent. India’s endemic variant presents entirely differently.
“There is a difference between them. We do not get pulmonary syndrome (in the one that impacted India). What we get is one that affects our kidneys.”
When the disease manifests in India, patients develop a haemorrhagic fever associated with renal syndrome. They bleed and their kidney function deteriorates, but mortality is substantially lower. “The one in Andes causes 40% mortality. The one in India is pretty small, it is only up to one, two, we do not know, it could be up to 10%.”
According to Gangakhedkar, now a distinguished professor at Symbiosis International, Pune, while our exposure may be more, “the occurrence of severe disease is lower”.
The epidemiological data reveals a striking picture: hantavirus exposure in India is far more common than clinical cases would suggest. The former scientist explained that antibody studies — evidence of past infection — have found exposure in up to 10 per cent of high-risk populations, meaning people get exposed to these rodents and therefore the virus, but it rarely causes severe illness.
“They have found that we have antibodies against hantavirus because of our exposure to up to even 10% of people in high-risk situations, they have been found to have antibodies against it.”
The reason clinical cases remain rare despite this widespread exposure is perhaps a reflection of the milder nature of India’s strain. “It could be a milder infection more often, whatever is occurring in the Indian population. No case of human-to-human transmission has been reported in India so far.”
On risk from the lethal Andes strain, he said: “There is no evidence to suggest that the fatal kind of a strain which has high mortality which is associated with Andes has come to India.”
According to a study conducted at Christian Medical College, Vellore and published in 2008, while there has been no documented case of hantavirus disease from India, serological evidence exists – meaning that researchers confirmed the presence of anti-hantavirus antibodies in 28 (74%) of the 38 sera tested. “This study confirms the presence of hantaviruses in India and warrants increasing awareness of the problems of emerging pathogens and the threats they may pose to the public health system,” said the authors of the study published as “Seroepidemiological study on hantavirus infections in India”.
Why viruses keep emerging
The parade of novel viral outbreaks — COVID, bird flu, monkeypox — isn’t random. Two factors are driving increased detection of emerging viruses globally.
The first is improved diagnostic capability. “If you look at the newer viruses that are emerging, there are two reasons why they are emerging or at least getting reported. One thing is that our ability to diagnose has improved. You have molecular tests that are available, immunological tests that are available.”
But improved detectionalone doesn’t explain the pattern. Climate change is fundamentally reshaping how humans and wildlife interact. “One of the reasons is climate change. These new organisms that are coming are essentially from largely veterinary or those wild animals that are there in the jungle. Today, because of climate change, the interaction that tends to occur between human beings and animals has increased.”
The mechanism is straightforward. When extreme weather strikes—heatwaves, droughts, floods—animals abandon their natural habitats in search of resources. “There is a heatwave all around, what would those animals do in the forest? If they do not have access to water, they are going to come to the human-inhabited areas because they want to have water. You have droughts, you have floods, you have all kinds of emergencies. So, this is going to keep on increasing so that new infections are likely to come.”
Yet not every spillover from animals to humans results in a pandemic threat. Viruses face biological constraints. “All animals tend to have their own set of organisms which can cause infection within their body. Now, not all organisms can infect a human. There could be some which mutate so much that they are able to enter into the human body and only those may, if at all, cause disease,” Dr Gangakhedkar explained.
The implication is clear: while emerging infections will continue, the majority won’t pose existential threats. “It is something which we should not be excessively or become neurotic about.”
India’s surveillance system
India has built infrastructure to detect and respond to novel threats. “We have successfully established one health programme today in India. We have a strong IDSP programme, where people can report mysterious deaths that occur, whether a few deaths that occur, a single mysterious death that has occurred, you can report and the government investigates the same.”
This integrated approach—connecting human health surveillance with veterinary monitoring—represents a critical advance. “Coordination has improved in one health programming that has been implemented recently, where surveillance is conducted in human beings as well, and in animals also, and there is sharing of information that tends to occur about newer kinds of disease episodes or infections that are happening, are being reported.”
For ordinary citizens, the takeaway is straightforward: “What you should follow even as an ordinary citizen, what I would say is follow the hygienic procedures, hygienic principles.”
Basic preventive measures — handwashing, avoid handling animal excreta, food safety, pest control — remain the most powerful tools against zoonotic diseases.
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