The death of a 12-year-old boy from the virus rekindles fears of an outbreak of the Nipah virus in India.
The SARS-CoV-2 epidemic has raised concerns about the viruses circulating in foreign countries, and particularly in Asia. In India, it is the Nipah virus that has been of particular concern for several years. A virus present in South and South-East Asia, recalls the Institut Pasteur.
The death of a 12-year-old child in the province of Kerala, in the south of the country, on September 5 has aroused this concern. The region has since been placed on alert. Kerala State Health Minister Veena George explained that “at the moment there is no reason to panic”, adding that “we must be careful”.
Deceased within 48 hours
The 12-year-old boy first exhibited symptoms of encephalitis, a brain infection, and myocarditis, before being hospitalized on September 3. 48 hours later, the boy died in hospital. A sample, sent to the National Institute of Virology, reveals that the child is positive for the Nipah virus.
Two health workers are then identified as having symptoms of infection with the virus, among 20 high-risk contacts of the victim. In total, 188 people are considered as contact cases of the young boy, and therefore potentially infected.
A mortality rate of over 70%
If the young boy is the only victim identified, concern is keen because of the characteristics of this virus, for which there is no treatment. The Nipah virus is transmitted from animals to humans through the saliva of a fruit bat, the fruit bat. Pigs, dogs and horses can mediate between bats and humans. Between humans, the virus is spread via the secretions of patients, but above all, the mortality rate is over 70%, according to the Pasteur Institute.
What makes it even more difficult to stem an outbreak of the Nipah virus is that the incubation period can be long, up to 45 days in some cases, which means that the carrier of the virus, unaware that it is is infected, has many possibilities of spreading it.
The destruction of bat habitat involved
Detected for the first time in 1998 in Malaysia with the pig as an intermediate host between the bat and the human, the Nipah virus then causes more than 300 infections including more than a hundred deaths.
Researchers then determine that forest fires and local drought dislodged bats from their natural habitat and forced them to head for fruit trees, which grow on the same farms as pigs.
Under stress, bats have been shown to spread more viruses. Forcing them to move around and be in close contact with a species they don’t normally interact with has allowed the virus to pass from bats to pigs to farmers.
Contamination by ingesting palm juice
According to the Pasteur Institute, the virus is transmitted to humans mainly by ingesting palm juice contaminated by bats, which in particular fly over markets and can infect via their droppings.
The BBC reported on the situation of a market in Cambodia, where a team of researchers identified bats carrying the virus. At night, bats fly to the date palm plantations and drink the juice that drains from the tree. From the tree, their urine ends up in the containers left by the traders to collect the palm juice. During the day, this juice is sold in the market, thus infecting buyers.
The fear of a virus mutation
An example of proximity between humans and the virus which makes researchers fear the worst. “This type of exposure could allow the virus to mutate, which could cause a pandemic”, explains Veasna Duong, head of the virology unit of the scientific research laboratory of the Institut Pasteur in Phnom Penh at the BBC, in last january.
Between 2001 and 2011, 11 different epidemics of Nipah in Bangladesh were detected in 196 people, of which 150 died. In 2019, the province of Kerala where the victim has just been registered recorded 17 victims in 2019.
Each year, the World Health Organization (WHO) lists the pathogens likely to cause a public health emergency in order to decide the priority of its research and development funds, and focuses on those that present the greatest risk to human health, those with epidemic potential and those for whom there is no vaccine. The Nipah virus is in the top 10.
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