Nipah is known to kill approximately nine out of 10 people infected. In its first outbreak in India in 2018, 89 per cent patients of the 23 infected died.
However, in much relief, no death has been reported after the two casualties. According to a top virologist, privy to the developments, it looks like the end of the outbreak.
“Going by past experience, it is over now,” the virologist working in a top government lab told News18. However, the official statements are on hold due to the ongoing incubation period of samples and people isolated.
As per the World Health Organisation, the incubation period is in range from 4-14 days.
On September 13, Kerala Health Minister Veena George announced that the Nipah cases detected in the state were of the Bangladesh strain.
This strain is known to cause respiratory distress syndrome, which makes patients feel breathless during the initial symptoms and pushes them onto ventilators.
This was the fourth time the Nipah outbreak took place in Kerala. In the first Indian outbreak in 2018, fruit bats were found causing the infection. Fruit bats are natural reservoir hosts of the Nipah viruses. The virus is present in bat urine along with bat faeces, saliva, and birthing fluids.
In May 2018, the investigation found that the index patient was in direct contact with fruit bats while cleaning the well of his house in a village in Kerala. Next year also, the outbreak took place in the month of May, indicating the linkages between bats and mango harvesting season.
In 2021, the third outbreak of Nipah took place in the month of September followed by the latest outbreak, again in September — defying the trend of the first two years in mango season.
The findings of the latest investigations have still not been made public.
With no vaccines or antiviral drugs available to save the lives of infected patients, it is clear that India needs to put a system in place to prevent reported or non-reported outbreaks. This could be somewhat similar to the efforts made by Bangladesh where bats were found infecting the palm sap. The country was able to control Nipah cases for more than seven years but unusual deaths were reported once again in 2023.
The Bangladesh Story
Nipah virus (NiV) was first discovered in 1999 following an outbreak of the disease in pigs and people in Malaysia and Singapore. However, at present, sporadic episodes are reported only from India and Bangladesh.
In Bangladesh, the Nipah virus was discovered in April-May of 2001. Bat saliva and excreta were found to be the reasons behind the infection, which was brought on by consuming raw date palm sap.
Since then, the virus has affected around 330 people out of which 231 died. Currently, the Bangladeshi government warns against drinking raw date palm sap during outbreak seasons, usually between November and May.
The palm trees — which are known habitats of bats — are protected by covering them with bamboo skirts during collection season.
The Bangladesh government also promoted public awareness in vulnerable areas with habitats of bats. These programmes are run especially from November to May in newspapers, regional TV and radio.
According to a paper written by Bangladeshi authors on the need for developing prevention strategies against Nipah, “any fume or specific chemical can be developed so that the bats or birds would remain out of the range of the fruit or date plants at least during the harvesting seasons especially in the winter”.
“Taking bitten fruits by bats should be avoided; any structure like iron frame can be employed around the date sapping area.”
They wrote that as a preventive measure, a greenhouse can be developed for the fruits or date sap. They also suggested producing artificial frequencies of ultrasound that may cause disturbance in bats’ location precision and cause distraction.
“…animals like bats and some birds make sounds to overcome the obstacles. They produce echolocation which is a sound system that bats make to find the location of insects…”
Need to Strengthen Animal Health Surveillance
Nipah virus infection is generally described as an emerging bat-borne zoonotic disease transmitted to humans through infected animals or contaminated food.
The repeated comeback of Nipah reflects a need for strengthening the animal health surveillance system to detect new cases and provide early warning for veterinary and human public health authorities.
Many experts believe that the reason behind the scare in Kerala for the fourth time has nothing to do with the geography of the state but the strength of its surveillance that it catches the outbreak then and there.
Kerala – A Unique State With Strong Surveillance?
In July, the Indian Council of Medical Research (ICMR) found evidence of the Nipah virus circulation in the bat population across nine states and one Union Territory in India.
“So far, the survey has been completed in 14 states and two Union Territories. The presence of Nipah viral antibodies has been found in bats in the states of Kerala, Tamil Nadu, Karnataka, Goa, Maharashtra, Bihar, West Bengal, Assam and Meghalaya and the Union Territory of Pondicherry,” Dr Pragya Yadav, scientist ‘F’ and group leader, Maximum Containment Laboratory, ICMR-NIV, told The Indian Express.
Does this mean that the virus could be in circulation in other states too but Kerala ended up detecting it? More scrutiny is required to understand the findings of the government survey along with putting stronger surveillance mechanisms across India and working on vaccines and other treatment options against the disease.
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