As Kerala grapples with Nipah virus, a look back at all six outbreaks since 2001

About 153 health workers are estimated to be in the contact list of the confirmed cases in Kerala. Nine panchayats in Kozhikode district have been declared as containment zones and 800 people have been brought under observation. A state-level control room has been opened and neighbouring Wayanad district has set up 15 core committees to tackle emergency situations and ramp up surveillance activities.

The zoonotic virus transmitted to humans through infected animals or contaminated food, has been reported in other parts of the world over the years. The first Nipah virus case was detected in 1999. The virus spread to pigs and people in Malaysia's village Kampung Sungai Nipah. About 300 human cases and over 100 deaths were reported and more than 1 million pigs were killed to curb the spread of the virus, according to Centres for Disease Control and Prevention.

The name Nipah has been attributed to a village in Malaysia, Kampung Sungai Nipah, where the first patient was isolated and later succumbed. While Malaysia did not report Nipah cases afterwards, India and Bangladesh have witnessed multiple outbreaks since then. In Bangladesh, the virus appeared in 2001, 2003, 2004, 2005, 2007, 2008, 2010, and 2011. Nipah outbreaks have been limited to West Bengal and Kerala in India.

In India, the first outbreak was reported in West Bengal's Siliguri in January-February 2001. Out of the 66 cases reported, 45 fatalities occurred. Back then, India lacked containment facilities to prevent the spread of the virus and the country sought aid from USA’s Centers for Disease Control for diagnosis during the second outbreak.

The second outbreak reported in 2007 killed around five people and 50 people were infected in West Bengal's Nadia district bordering Bangladesh. Since the Indian Council of Medical Research's National Institute of Virology was set up in Pune in 2005, the virus was detected in a timely manner then.

Kerala reported 18 Nipah virus cases claiming 16 lives in May 2018. With no prior experience in handling a diseases with such high fatality rate, the state government followed the protocol for Ebola virus disease then. Those who came under the contact of infected people were put under isolation for 21 days, their contacts traced and secondary contacts identified.

The third outbreak led to the development of a point-of-care test for the Nipah virus. In June 2019, Ernakulam district reported one case of Nipah virus. The infected person reported fever and encephalitis-like symptoms. The person survived with supportive care and no other contact persons exhibited symptoms.

While Kerala grappled with Covid pandemic, a 12-year-old boy succumbed to Nipah virus in Kozhikode. About 188 persons were traced to have had contact with the infected boy and were isolated. A point-of-care-testing facility was set up in Government Medical College in the district.