The third week of May 2018 started with a panic across the entire Kerala state because of the Nipah virus (NiV) outbreak which claimed 11 lives including a nurse who was attending one of the possible NiV infected patients at the local hospital. The family of the nurse decided to cremate her body instead of burying despite being a Christian to stop the spread of the deadly virus. Since then the state government is trying to make all the necessary arrangements to tackle the panic which is widespread across the state. The state government has also released emergency funds to restrict the virus outbreak and a team from National Centre for Disease Control (NCDS) is closely monitoring the outspread of the disease.
According to the World Health Organization (WHO), NiV infection is a newly emerging zoonosis with 70% mortality rate. Fruit bats are the natural host of NiV which belongs to Pteropodidae family, Pteropus genus. There are also intermediate hosts such as plants and animals consumption of which spreads the disease among humans. The virus can be transmitted by consuming fruits eaten by infected bats and birds. Direct contact with infected bats, pigs and humans also lead to transmission of NiV.
The first cases of NiV infections were reported from the state of Perak in West Malaysia in September 1998 which had a major industry of pig farming. This lead to the culling of around 1.1 million pigs to control the outbreak. Later, the outbreak was reported in Bangladesh in almost every year from 2001 to 2013. In India, two outbreaks were reported in the eastern state of West Bengal, in 2001 and 2007 where the disease was contracted by consuming raw date palm sap contaminated by infected fruit bats urine or saliva. Initial studies have shown that NiV was reacting to the antibodies against the Hendra virus, however, later the viral genome was sequenced and showed around 20% difference from the Hendra virus.
The incubation time of NiV is 5-14 days and symptoms usually appear 3-14 days of exposure. The major symptoms of the infection are fever, dizziness, headache, and vomiting that often leads to encephalitis (inflammation of the brain) and coma. NiV also causes infection in pigs and other domestic animals. As of now, there is no vaccine available to treat NiV infection. Patients are generally treated by intensive supportive care.
Various environmentalists have claimed that the NiV was present in the bats for centuries, however, the major concern is that how the infection has been spread only recently. The rapid urbanization, as well as intervention of humans into the bat-inhabited regions, could possibly be one of the reasons of the NiV emergence. During the 2007 outbreak in West Bengal, it was reported by the healthcare workers that the horde of bats was found to be hanging from the trees around the patient’s residence which suggested the transmission of the virus from bats to humans.
Since there are limited treatment options, the focus should be on the prevention of NiV infection. People should be cautioned about not to consume the fruits that have fallen on to the fields especially in those areas which are inhabited by bats. Drinking of toddy brewed in open containers near palm trees should be avoided. Domestic animals which can also be carriers of NiV should be kept indoors since they can consume the partially eaten fruits often dropped by fruit bats. Maintain a distance from the patients so as to avoid ingestion of droplets when they cough or sneeze and also avoid sharing of food, bed, and clothes. The recent source of an outbreak in Kerala could be attributed to the bats which had taken shelter in a well of one of the diseased patient. So one should avoid drinking water contaminated by the excrements of pigs and bats. And more importantly, healthcare workers who are in close proximity should wear proper gloves and masks while treating patients with NiV infections.
Saketh Kapoor is a Graduate student at Stem Cells and Regenerative Medicine Centre, Yenepoya (Deemed to be University).