The Nipah Virus/NiV
The Nipah virus was first identified in 1999 due to an outbreak of a Nipah virus infection in pigs and pig farmers in Malaysia in 1998. 265 people were infected and 105 died. Nearly one million pigs were culled by the Malaysian authorities to stop the spread of the disease. Reports of goats, horses, sheep and even cats and dogs being infected with the Nipah virus were recorded in the same outbreak in 1999.
The Nipah virus therefore takes its name after a Malaysian village, Sungai Nipah in which the first outbreak was recorded.
The subsequent outbreaks were reported in Bangladesh, Malaysia, Singapore and India in 2001, 2003, 2004, 2005 and also in the following years.
The mortality rate of the Nipah virus infection is 50 to 75% with the most recent outbreak of the disease in May 2018 in the south of India, Kerala, with 21 deaths recorded. However, the most recent case of the Nipah virus infection was recorded in May 2019 in Kerala, the south of India, with the infected recovering completely.
The total number of people who died of the Nipah virus infection since 1998 is thought to be around 700.
Origin and Spread
Fruit bats also known as “flying foxes” have been found to be a natural reservoir of the Nipah virus as well as a source of various coronaviruses.
The Nipah virus is a zoonotic virus as the SARS-CoV-2 virus causing COVID-19.
Zoonotic means that the virus spreads from animals to humans. The Nipah virus can spread to humans directly from bats as in the case of being bitten by the bat or having consumed the bat and from infected pigs. Those who have close contact to infected pigs and those living in the areas close to fruit bats are at a risk of catching the Nipah virus.
How are pigs related to fruit bats that are the source of the Nipah virus?
Pig farms are usually closely located to the fruit trees which are frequented by fruit bats for food.
Unfortunately, fruit bats have no etiquette when it comes to eating and the nibbled pieces of fruit, their urine and other excrete during their fruit eating lands on pigs and on the pig farm land. Pigs are then infected and the Nipah virus enters the humans via the food chain.
Other sources of infection with the Nipah virus include:
Using water from the wells inhabited by bats
Eating unwashed or poorly washed fruit and veg that have bat excrete on them
Consuming contaminated food
Consuming palm toddy/raw date palm sap used to make palm jaggery which in turn is used as an alcoholic beverage- palm wine. Watch the video below to see what sap collection involves.
Why is drinking palm toddy/raw palm sap can be a risk factor of contracting the Nipah virus?
Palm toddy is collected in open containers and bats easily get to them to drink toddy occasionally urinating in it. This contaminates the palm toddy with the virus.
The Nipah virus is then passed on from an infected human to a healthy human by direct contact.
Symptoms of the Nipah virus infection usually appear within 5 to 14 days after initial exposure and include:
Shortness of breath
These symptoms can worsen into a coma within 48 hours and the complications include brain inflammation(encephalitis) and seizures.
Those who are suspected of having Nipah virus should be isolated for the supportive treatment as there is no specific treatment as of 2020 and no vaccine against the Nipah virus.
Recent outbreak of the Nipah virus infection in Kerala
In May 2018 an outbreak of the Nipah virus infection was reported in Kozhikode district of the south Indian state of Kerala. 23 cases were recorded out of which 21 people died including a nurse who got infected with the Nipah virus from her patient before his initial diagnosis. The outbreak ended in June 2018.
There was another case of a person being infected with the Nipah virus in Kerala, Ernakulam district in May 2019; however, he survived and left the hospital in July 2019.
The previous outbreaks of the Nipah virus in India occurred in 2001 with 45 deaths and in 2007, 5 deaths reported. The majority of the Nipah virus outbreaks take place in Bangladesh though.
Minimising the Risk of Nipah Virus Infection
Certain measures can be taken to minimise the risk of catching the Nipah virus.
It is always wise to seek medical help if you have been bitten by a bat as they are reservoirs of numerous viruses including the Nipah virus with a high mortality rate.
Fruit and veg should be properly washed and peeled to avoid bat excrete being consumed.
Water from wells that are visited by bats is also a risk.
Food should not be left without being covered so as to avoid the possibility of the bat’s excrete contamination.
Raw palm toddy collected in open containers is very risky as it may contain bat excrete and therefore be contaminated with the virus. Closed containers should be used to prevent bats from accessing the palm toddy in them.
Pig farms ideally should not be in close proximity to the places where bats are abundant.
Local communities should be made aware of the signs, symptoms of the Nipah virus and the ways to minimise the risk of catching and spreading the Nipah virus.
Next Potential Pandemic?
The Nipah virus has been around since 1998 and it has reappeared on numerous occasions and annually in Bangladesh taking the lives of people.
It is easily transmissible among wildlife, livestock and people and it has a high mortality rate. This makes it one of the dangerous viruses that has pandemic potential.
The Nipah virus has been identified as a priority for the WHO Research and Development Blueprint.