Chandrakant Lahariya | Nipah outbreak in Kerala: Why a One Health' strategy is vital

There is a fresh outbreak of the Nipah virus disease in Kerala. This is the fourth Nipah virus outbreak since 2018, when 23 cases and 21 deaths due to the virus were reported. Other than Kerala, the Nipah virus has been reported from and caused deaths in West Bengal in 2001 and 2007.

The Nipah virus was first identified from an outbreak in Malaysia in 1998-99 and has got its name from the Nipah river village locality where it was first isolated. Since then, there have been a few major outbreaks in nearby countries such as Singapore, Bangladesh and India. The virus has been detected in natural reservoirs of fruit bats from multiple countries such as Cambodia, Ghana, Indonesia, Madagascar, the Philippines and Thailand.

The Nipah virus disease is a zoonotic disease that spreads from the natural reservoir of Pteropus medius species of bats (commonly referred to as fruit bats) to humans through an intermediate host such as a pig or horse. The outbreak always starts from animal to human transmission, but then continues with human-to-human transmission. Moreover, considering the reservoir host bats are present everywhere, experts believe that once Nipah virus activities are reported from any setting, the virus may continue to be present and there might be repeated outbreaks.

The symptoms of the Nipah virus diseases are similar to other common viral illness. The affected person usually has fever, headache, sore throat, muscle pain and other respiratory difficulty, dizziness, drowsiness and in rare cases neurological symptoms. While infections are rare, the fatality rate is higher. Infection is suspected if there is an ongoing Nipah virus transmission in the area, travel history or contact history with a confirmed case. The laboratory confirmation is required to arrive at a diagnosis. There is no licensed vaccine to prevent the disease and no specific treatment available. The majority of cases are symptomatic.

In recent times, in India and other parts of the world, there have been many outbreaks of viruses, including the Zika virus and Norovirus, and a surge of a few zoonotic diseases. For India and every country, it clearly is time to step up and strengthen the disease surveillance system and health data recording and reporting systems. The laboratory capacity developed for Covid-19 should be optimally used to conduct testing for other emerging infections. It is also the time to ensure coordinated actions between the state governments and municipal corporations to develop joint action plans against zoonotic diseases and share the responsibility for public health actions.

In Covid-19, there was a lot of attention focused on past or ongoing lab research on bats. The fact is that research on bats is done because they are reservoirs of many known and unknown viruses, including the Nipah virus. It is known that once reported from a setting, the virus may recur from reservoir hosts in different settings. Epidemiologists over the last few years have flagged the need for ecological studies to understand the dynamics of the Nipah virus. 

Lately, Kerala and other states in South India have reported more new viruses than in most North Indian states. This is partly due to a robust and sensitive surveillance system which some states have, more than other states. The repeated emergence of viruses shows the need for nationwide ecological studies on these viruses and on the transmission dynamics of their spillover to humans.

The current Nipah outbreak in Kerala is not a reason for concern for citizens. We have experience in handling the Nipah outbreak and our systems are better prepared to respond to diseases after Covid-19. Yet, more important is that the government should be better prepared and take action to strengthen surveillance systems, invest in ecological and anthropological studies on emerging diseases and “One Health” should be an approach to intervene. The emergence of new viral illnesses in various parts of the country makes headlines. However, we forget that there are many other viral illnesses, which are common yet ignored. The dengue this year has witnessed a spike. Chikungunya is another common viral illness. In the last few months, there was a spike in respiratory illnesses by flu viruses, SARS CoV2 and most likely other respiratory viruses. The influenza-like illness and severe acute respiratory illnesses surveillance need to be strengthened.

This situation is also a reminder of a future in which climate change, deforestation, global warming, indiscriminate use of anti-microbials, etc mean that there would be more diseases which would keep troubling humanity. Anthropogenic activities such as expansion of human activity in natural habitats essentially mean exposure of human beings to the natural reservoirs of pathogens essentially mean we are at increased risk of zoonotic diseases.

It is in this backdrop that the concept of “One Health” should be given greater importance. In the last few years, there has been a lot of academic discussion in India on “One Health”. There is a background work going on for the launch of the National One Health Mission led by the office of the principal scientific adviser to the Government of India. These would be the right and timely steps. Yet, these discussions get momentum only when there is an outbreak. We need to roll out interventions with sufficient coordination amongst stakeholders and the activities should be well funded. To be effective, the “One Health” approach must be implemented through the primary healthcare network in the country to make a real difference. In a world full of viruses, preparedness and learning from the past is the best response.