After a three-year gap, a case of the zoonotic Nipah virus infection (NiV) has rung the bells in Kerala's Kozhikode district when a 12-year-old boy succumbed to death.
NiV outbreak was detected in the same region previously on 19 May 2018. This was South India's first NiV outbreak.
However, the Nipah outbreak reported in May 2018 was the third outbreak in overall India.
The prior cases were reported in 2001 and 2007, both in West Bengal. There were a total of 23 cases detected, including the index case, which included 18 laboratory-confirmed cases. The way this outbreak was controlled by state and central government agencies has been recognised as a success story.
Past Global Outbreaks:
The Nipah virus was originally identified in 1999 after an outbreak among Malaysian pig farmers. Since 1999, no new outbreaks have been recorded in Malaysia.
It was also identified in Bangladesh in 2001, and nearly annual outbreaks have occurred there since then.
Evidence of the virus has been identified in the known natural reservoir (Pteropus bat species) as well as many other bat species in a number of countries, including Cambodia, Ghana, Indonesia, Madagascar, the Philippines, and Thailand.
Signs and symptoms:
For Nipah, according to WHO, "Infected people initially develop symptoms that include fever, headaches, myalgia, vomiting and sore throat. This can be followed by dizziness, drowsiness, altered consciousness, and neurological signs that indicate acute encephalitis."
Infection with Nipah virus can result in mild to severe disease, including swelling of the brain (encephalitis) and potentially death.
Source and transmission of NiV:
During Malaysia's first recognised outbreak, which also affected Singapore, most of the human infections were caused due to direct contact with sick pigs or their infected tissues. Unprotected contact with pig fluids or any diseased animal tissue leads to the transmission.
In Bangladesh and India, the source of infection was the consumption of fruits or fruit products (such as raw date palm juice) contaminated with urine or saliva from infected fruit bats.
Health experts at the Centre suspect Rambutan fruit to be the likely source of the Nipah virus that has claimed one life in Kozhikode
Human-to-human transmission of Nipah virus has also been reported among family and care givers of infected patients.
In Siliguri (West Bengal), India in 2001, the virus was transmitted within a health-care setting, where 75% of cases occurred among hospital staff or visitors.
In Bangladesh from 2001 to 2008 about half of all reported cases were caused by human-to-human transmission while giving treatment to sick patients.
NiV in domestic animals and prevention:
In Malaysia (1999), outbreaks of the Nipah virus in pigs and other domestic animals such as horses, goats, sheep, cats, and dogs were initially recorded.
Based on the experience from the 1999 Nipah outbreak involving pig farms, frequent and thorough cleaning and disinfection of pig farms using proper detergents may be beneficial in avoiding infection.
If an outbreak is detected, the animal premises should be immediately quarantined.
There are presently no medicines or vaccines specifically designed to treat Nipah virus infection, despite the fact that WHO has classified Nipah as a priority disease for the WHO Research and Development Blueprint.
Severe respiratory and neurologic problems should be treated with intensive supportive treatment.
When Nipah was first discovered in 1999 in Malaysia and Singapore, it resulted in nearly 300 human cases and more than 100 deaths and caused massive economic impact as more than 1 million pigs were killed to help control the outbreak.