Central Idea

The reappearance of Nipah infection in Kerala, with two confirmed deaths and two individuals under treatment, has raised concerns about this lethal viral disease.
Nipah, while not as contagious as COVID-19, is significantly more deadly, with a case fatality rate ranging from 40% to 75%.

What is Nipah Virus Infection?

Nipah is a zoonotic disease, meaning it is transmitted to humans through infected animals or contaminated food.
Direct person-to-person transmission through close contact with an infected individual is also possible.
Symptoms include fever, headache, cough, sore throat, difficulty in breathing, and vomiting.
In severe cases, Nipah infection can progress to disorientation, drowsiness, seizures, and encephalitis (brain swelling), ultimately leading to coma and death.

Historical Outbreaks: The Nipah virus was first reported in Malaysia (1998) and Singapore (1999), deriving its name from a Malaysian village where it was first isolated. The primary mode of transmission from animals to humans is through the consumption of contaminated food. This can occur via the consumption of raw date palm sap or fruit contaminated with saliva or urine from infected bats.
Animal Host Reservoir: Fruit bats, commonly known as flying foxes, are the known hosts of the virus. They transmit it to other animals like pigs, dogs, cats, goats, horses, and sheep. Human infection usually occurs through direct contact with these animals or the consumption of food contaminated by their saliva or urine. Human-to-human transmission is also documented, particularly in families and healthcare settings.

Slow Spread: Unlike the rapid transmission of SARS-CoV-2, the Nipah virus spreads more slowly. However, its high mortality rate is a significant concern.
High Mortality: During outbreaks, Nipah has shown a mortality rate as high as 68-75%. For example, in the 2001 Siliguri outbreak, 45 of the 66 infected individuals succumbed to the virus. Similarly, during the 2018 Kerala outbreak, 17 of the 18 confirmed patients died.
Localized Outbreaks: Notably, Nipah outbreaks have remained localized and were contained relatively quickly. The virus’s limited infectiousness and low human-to-human transmission contribute to this containment.
Reproductive Number (R0): Studies indicate an R0 of about 0.48 for Nipah outbreaks, signifying a slow rate of transmission within the population. An R0 value below one suggests that an infected person does not infect more than one other individual, leading to a relatively rapid end to the outbreak.
High Death Rates Limit Transmission: The virus’s high death rates also play a role in restricting its transmission.