No new cases of Nipah virus have been reported since September 15 as part of the latest outbreak reported from Kozhikode, Kerala, this year (2023) — the third one in the district and the fourth in the state.
Dr Anoop Kumar A S, director – Aster North Kerala (Cluster) of Critical Care Medicine, who was extensively involved in the diagnosis, treatment and containment of cases during the 2018 and 2023 Nipah outbreaks in Kerala, says, “It is unlikely that a new case will crop up now. The outbreak is almost contained.”
Public health departments in Kerala — specifically Kozhikode, which has seen three Nipah outbreaks as of now — were more prepared this time due to their previous experience in controlling the infection.
Nipah virus outbreak: Measures taken by the health department
In coordination with the ICMR (Indian Council of Medical Research), NIV (National Institute of Virology), Pune and NIE (National Institute of Epidemiology), Chennai, the state health department mobilized 19 core committees, which were tasked with several public health response measures. This included surveillance, sample testing, contact tracing, patient transportation, case management, logistics and supplies, training and capacity building, risk communication, community engagement, psychosocial support and animal husbandry.
More than 53,000 houses were surveyed as of September 27, and 1,288 contacts, including high-risk individuals and healthcare workers, were identified, tested and quarantined. Nine villages in Kozhikode were declared as containment zones, and public events were restricted until October 1. A control room with a call center was also set up.
In addition, samples of bats, animal droppings, half-eaten fruits, etc. were collected from the village where the first infected individual lived, which is a 300-acre forest that is home to several species of bats. All these samples, however, tested negative for Nipah virus.
The state government also started training the healthcare workers on infection prevention and control (IPC), while also stocking up on personal protective equipment (PPE), drugs, etc.
In a press briefing shortly after the confirmation of the first case of Nipah virus infection in Kerala in September 2023, Veena George, Kerala’s minister for health, women and child development, said, “The public must try to avoid hospital visits, and there should only be one bystander for an admitted patient.” She also emphasized the need for wearing masks in public places as part of the Nipah control protocol. High-risk contacts are currently in isolation wards, which have been set up in hospitals across the district of Kozhikode.
Dr Kumar says that this time around, Nipah was suspected immediately after spotting the signs of a cluster of infected people, and samples were shipped the same day to the NIV. Isolation and containment protocols were initiated, and the officials of the state health department were informed of the same.
“We also took ample precautions while handling subsequent patients. There was no in-hospital spread happening through second-degree patients. The spread only happened from the index [first] patient. In 2018, we were sending samples to Manipal for screening. However, this time around, the Kerala government made arrangements to screen for Nipah at an ICMR facility in Kozhikode itself. All suspected patients with severe respiratory infections and encephalitis were screened there,” informs Dr Kumar.
NIV has said that the virus causing the current outbreak belongs to the Indian genotype or I-genotype, similar to the Nipah virus strain in Bangladesh. According to numbers available to the World Health Organization (WHO) about the 2023 Kerala Nipah outbreak, the case fatality rate (CFR) is at 33.3%.
The CFRs of all six outbreaks in India were different. In the first outbreak that occurred in Siliguri, West Bengal, in 2001, the CFR stood at 68%. The subsequent outbreaks occurring in Nadia, West Bengal, as well as Kozhikode and Malappuram, Kerala, in 2018 had CFRs of 100% and 91%, respectively. In 2019, a single case was reported in Ernakulam, Kerala, where the individual survived. Additionally, another individual in Kozhikode who had tested positive for the virus in 2021 did not survive.
The first case of the outbreak
The manner of exposure to the virus for the first individual during the current outbreak is unknown. The man was a relatively young adult without any previous comorbidities. He presented with severe symptoms of pneumonia and, within two days, developed multi-organ failure and died at a private hospital in Kozhikode on August 30.
While the cause of death was thought to be viral pneumonia, routine tests for common respiratory viruses like influenza, COVID and RSV (respiratory syncytial virus) were negative. The five other confirmed cases were all linked to this case, including two family members and close contacts who were present at the same hospital. The second person — a bystander in that hospital — succumbed to the virus after developing symptoms of pneumonia as well. “The first death was attributed to a secondary bacterial infection. Nothing unusual was noticed at that point in time. The case wasn’t investigated further, and no precautions were taken while handling the dead body. However, a cluster developed within the same family, and that’s when we suspected it could be Nipah,” says Dr Kumar.
With the last case of Nipah virus reported on September 15, doctors say the recent outbreak in Kozhikode, Kerala, has almost been contained. Due to prior experience in handling such cases, the diagnosis, identification and containment process was quicker this time around.