On July 12, a brand new lethal Nipah virus an infection was confirmed in a 52-year-old man within the Palakkad district of Kerala, marking the tenth occasion of Nipah virus spillover (transmission of the pathogen from animals to people) within the southern Indian state since 2018.
This yr alone, Kerala has reported 4 Nipah instances, together with two deaths, all inside a 50km (30-mile) radius, on the border of the Malappuram and Palakkad districts.
The state stays on excessive alert, with 675 folks underneath surveillance throughout 5 districts.
Here’s what we all know concerning the Nipah virus, its signs and the way authorities are containing it.
What’s the Nipah virus?
Nipah virus (NiV) is a extremely pathogenic zoonotic virus (a virus that may be transmitted from animals to people) which causes dying in 40 to 75 % of human contaminated instances. Alongside the Hendra virus, which is present in Australia, NiV is likely one of the most notable viruses from the henipavirus genus of the paramyxovirus household, answerable for a spread of neurological – typically respiratory – ailments in people and animals.
Fruit bats of the Pteropodidae household, ubiquitous throughout Oceania, South and Southeast Asia, and sub-Saharan Africa, are pure reservoirs of the virus, which means the virus naturally lives and reproduces in these mammals with out inflicting them any hurt.
The spillover of the virus to people can occur straight or by way of intermediate hosts comparable to pigs or horses, which come into contact with people.
What are the signs of the Nipah virus?
In keeping with the World Well being Group (WHO), human NiV infections vary from asymptomatic an infection to acute respiratory an infection, seizures and deadly encephalitis (irritation of the mind).
The medical presentation of NiV an infection is neurological, affecting the central nervous system and leading to acute encephalitis syndrome (AES), characterised by seizures, confusion and lack of consciousness. When the illness advances, it will probably trigger injury to the lungs and may result in life-threatening acute respiratory misery syndrome (ARDS).
The incubation interval of the virus is believed to be 4 to 14 days.
The place have there been Nipah virus outbreaks earlier than?
The primary human NiV an infection was recorded in 1998, when pig farmers and butchers from Malaysia and Singapore contracted the virus from contaminated pigs. The outbreak affected greater than 250 people and precipitated greater than 100 deaths.
There have been subsequent, nearly annual outbreaks in Bangladesh since 2001, with human an infection traced to the consumption of date palm sap contaminated with urine or saliva from contaminated fruit bats.
In 2014, NiV infections within the Philippines had been related to the slaughter of horses and consumption of contaminated horse meat.
India has reported two outbreaks in West Bengal in 2001 and 2007. In 2018, South India reported its first NiV outbreak in Kerala, when 19 confirmed instances led to 17 deaths. Since then, Kerala has reported NiV spillovers nearly yearly.
What has occurred in Kerala?
Though Kerala has recorded 10 cases of NiV spillover since 2018, solely two of them became outbreaks with cases of human-to-human unfold.
“We are actually reporting single instances of Nipah infections quite than a cluster or outbreak like in 2018,” Thekkumkara Surendran Anish, nodal officer on the Kerala One Well being Centre for Nipah Analysis and Resilience, stated.
The final six NiV infections within the state have been single-case spillovers with no human-to-human transmission. The latest uptick in recorded instances is all the way down to the strengthened surveillance system within the state, in line with Anish.
“Hundreds of individuals die in India yearly because of AES or ARDS, [where] we don’t know the trigger. NiV, in actual fact, shouldn’t be a typical trigger for respiratory and encephalitis syndromes,” he stated. “However in Kerala, as a result of all the well being system is prioritising Nipah, we’re detecting extra Nipah infections.”
On the identical time, it’s regarding that each one 4 NiV infections in 2025 had been reported in a small timeframe inside a small space, Anish added. “4 unbiased spillover occasions inside a few months in a 50km radius recommend a really excessive presence of contaminated bats and the virus within the space.
“What it tells us is that in sure geospatial areas in Kerala, there’s a excessive chance of Nipah spillovers, primarily as a result of the bats in these localities appear to be extremely infectious for a brief interval in the course of the yr.”
What’s inflicting the unfold of the Nipah virus in Kerala?
Not like in Bangladesh, the place there was a devoted channel for the virus to spill over to people (contaminated date palm sap), there isn’t any apparent supply in Kerala – or, no less than, the “spillover mechanism” to this point stays unclear.
“We don’t know the precise spillover mechanism, however it appears to be extremely sporadic in Kerala. For instance, you unknowingly are available in contact with an contaminated bat or its droppings,” Anish stated.
The generally accepted trigger is spillover from the human consumption of fruits contaminated by bat saliva or urine. Nevertheless, virological examination of bat-bitten fruits has yielded unfavourable outcomes to this point.
A brand new paper by the Indian Council of Medical Analysis suggests the virus could also be airborne.
“Illness-causing microbes have totally different routes of transmission to achieve and infect human hosts,” Thekkekara Jacob John, one of many authors of the paper, and an emeritus professor on the Christian Medical School, Vellore, stated. “Certainly one of them is airborne transmission, like in Tuberculosis, whereby microbes float within the air for longer distances and are inhaled distant from the supply.”
The authors of the paper consider their speculation “accommodates the uncommon however recurrent spillovers of NiV in Kerala”, the place there are not any mechanical vectors for the virus, comparable to in Bangladesh or Malaysia.
What are the authorities doing to comprise the Nipah virus in Kerala?
To this point, Kerala has been profitable in containing the unfold of the virus utilizing trace-and-test procedures. Throughout 10 “spillover occasions”, the case depend stands at simply 37 contaminated people.
The important thing to this can be a robust surveillance system, stated Anish. “When a Nipah case is established, all main contacts of the affected person are instantly traced and monitored underneath home quarantine. In the event that they take a look at constructive for the virus, we instantly begin antiviral therapy,” he stated.
The prophylactic therapy of “main contacts” with broad-spectrum antiviral medicine has helped cut back mortality. “In our expertise, if we are able to deal with Nipah early, it will probably undoubtedly be cured,” Anish stated.
“Syndromic surveillance is one other essential facet, whereby, in hospitals throughout the state, any affected person presenting with AES or ARDS is examined for Nipah,” Anish stated.
Kerala has been steadily enhancing its well being system. The state now has 4 labs able to conducting RT-PCR (Reverse Transcription Polymerase Chain Response) exams for detecting energetic NiV infections.
“All of it comes all the way down to political dedication,” Anish stated. “The state ensures that efforts of all the well being system stay centered on Nipah outbreaks.”
What’s the therapy for Nipah virus? Is there a vaccine in improvement?
The WHO has recognized Nipah as a precedence illness for its Analysis and Growth Blueprint – a world technique and preparedness plan for epidemics.
The College of Oxford’s NiV vaccine, which started in-human trials in January, was granted assist from the Precedence Medicines (PRIME) scheme of the European Medicines Company (EMA) in June.
Nevertheless, there are not any medicine but accessible that particularly goal NiV an infection.
Since there are not any accredited therapy protocols for NiV, and as a result of excessive threat of mortality, docs have used broad-spectrum antivirals. Ribavirin is the antiviral of alternative, because it has been discovered to be efficient towards NiV infections in people on a number of events.
Throughout a 2023 outbreak in Kerala, early utility of the antiviral Remdesivir resulted in an improved case fatality fee. Monoclonal antibodies (copies of antibodies, created in a laboratory) have additionally been used to forestall extreme illness manifestations in high-risk people.
How can we keep away from zoonotic viruses just like the Nipah virus?
In keeping with Anish, NiV is a mannequin case examine for a “one well being” method to combating high-threat pathogens. The one well being method recognises the truth that human well being is interlinked with the well being of animals and the setting.
“[One health] is a mix of three issues – human well being, animal well being and setting well being,” Anish stated. “You need to deal with all these items to scale back the probabilities of zoonotic spillovers comparable to Nipah.”
Roughly 60 % of rising human pathogens are zoonoses, transmitted from animals to people. Ecological disruption and the unfold of human populations into wildlife habitats are main causes for the emergence of those zoonotic viruses.
Local weather change is one other rising concern, with rising temperatures attributed to influencing infections, viral load and human-animal interactions.