Nipah Outbreak in Kerala

Syllabus: GS2/ Health, Government Policies & Interventions, Issues Arising out of their Design & Implementation

In News 

• There have been frequent outbreaks of Nipah in Kerala in recent years.

More About the News

• Three of the four Nipah outbreaks in Kerala in 2018, 2021 and 2023 have been in Kozhikode district; the 2019 outbreak was in Ernakulam district.
• Recent survey: An ongoing nationwide survey in 14 States by the National Institute of Virology (NIV) Pune has found Nipah virus antibodies in fruit bats (Pteropus medius) in nine States, including Kerala, and the Union Territory of Pondicherry.

About Nipah 

• About: Nipah is a zoonotic disease, which means it is transmitted to humans through infected animals or contaminated food. 
• History:  The first outbreaks of the Nipah virus among humans was reported from Malaysia (1998) and Singapore (1999). The virus takes its name from the village in Malaysia where the person in whom the virus was first isolated died of the disease.
• Host reservoir: The animal host reservoir of the virus is the fruit bat, commonly known as flying fox. Fruit bats are known to transmit this virus to other animals like pigs, and also dogs, cats, goats, horses and sheep.
• Symptoms: Fever, headache, cough, sore throat, difficulty in breathing, and vomiting.In severe cases, disorientation, drowsiness, seizures, and encephalitis (swelling of the brain) can occur, progressing to coma and death.
  • Usually, people with Nipah virus infection present with encephalitic symptoms. But in the latest outbreak, patients presented with pure respiratory symptoms, not reported anywhere in the world before.
• Transmission: The disease spreads through fruit bats or ‘flying foxes,’ of the genus Pteropus, who are natural reservoir hosts of the Nipah and Hendra viruses.
  • The virus is present in bat urine and potentially, bat faeces, saliva, and birthing fluids. 
  • The virus is transmitted to people from animals and can also be passed on through contaminated food or directly from person to person. 
  • Human-to-human transmission of the Nipah virus has also been reported among family and caregivers of infected patients.
  • Some cases of infection have also been reported among people who climb trees where bats often roost.
• Infectivity: The Nipah virus has low infectivity (R0 of 0.2-0.3 compared with R0 of over 1.5 in the case of SARS-CoV-2 virus).
• Fatality: According to the World Health Organization (WHO), Nipah has a relatively high case fatality ratio. The case fatality rate is estimated at 40% to 75%.  The very high death rates contribute to low transmission.
• Treatment: There are currently no drugs or vaccines specific for Nipah virus infection although WHO has identified Nipah as a priority disease for the WHO Research and Development Blueprint.
  • Intensive supportive care is recommended to treat severe respiratory and neurologic complications.
• Preventive Measures: Raising awareness about its spread & transmission.
  • Reducing the risk of bat-to-human transmission
  • Reducing the risk of animal-to-human transmission by using Gloves and other protective clothing.

Challenges

• Unestablished transmission route: While date palm sap was linked to Nipah virus outbreaks in Bangladesh, and pigs acting as intermediate hosts were responsible for Nipah outbreaks in Malaysia, the route of virus transmission from bats to humans has not been clearly established in Kerala.
• Possible reasons: The four outbreaks in five years may be because the virus has either become endemic in bats in Kerala or is a reflection of Kerala’s superior healthcare system that thoroughly investigates undiagnosed fever cases for possible Nipah virus infection or both. 
• Undetected deaths: With fruit bats positive for Nipah virus antibodies being found in other States, it is likely that Nipah virus infection and deaths may be going undetected in other States while they get picked up in Kerala, especially in Kozhikode district. 
• Single Nipah testing facility: There is no Nipah testing facility anywhere in India except NIV Pune.

Way Ahead

• Outbreaks are rare but Nipah has been listed by the WHO as one of several diseases deserving of priority research for their potential to cause a global epidemic, alongside Ebola, Zika and Covid-19.
• Scientists fear a mutated, highly transmissible strain will emerge from bats.
• Scientists have also warned that the climate crisis is increasing the risk of “zoonotic spillover” events, with 15,000 instances of viruses jumping between species predicted over the next 50 years.

Source: TH