New Delhi: India accounts for the highest number of snakebite cases and deaths in the world. A snakebite can kill, and survivors can be disabled. Yet, publicly available government data for snakebites are patchy--different data sets giving widely different numbers.

There's also a class dimension to who is worst affected by snakebites: most victims live in rural, forested or agricultural areas, as snakes live and move more freely there.

"There is no single registry for this data. It exists with the government and with the police and is collected by hospitals. This has created different data on snakebites across data sets," said Deepti Beri, a researcher at the India office of the George Institute for Global Health, Australia. Beri has been studying snakebite data in India and has found big differences in how data are recorded and that the numbers vary across data sets.

Take, for instance, two government data sets which provide data on snakebites: The National Health Profile (NHP) and the National Crime Records Bureau (NCRB). For at least three years (2018, 2017, 2016), the number of snakebite cases recorded by the NHP is 18 to 22 times the number recorded by the NCRB.

In the case of snakebite deaths, however, the NHP recorded only 10% to 13% of the number recorded by the NCRB.

Furthermore, the NCRB recorded nearly the same number of snakebite cases as deaths. In other words, according to the NCRB data, nearly all the people who were bitten by snakes in these three years also died.

But the NHP shows that the percentage of snakebite deaths is only between 0.5% and 0.7% of the total cases of snakebites.

One possible reason for the nearly same number of snakebite cases and resultant deaths in the NCRB data could be the way they are collected for the NCRB. The police would collect data when there is a police case--in the event of a death--needing police investigation; not necessarily when people are just admitted to hospitals, said Soumyadeep Bhaumik, a medical doctor and health-policy researcher at the George Institute for Global Health. "These issues are all research questions for us to explore further in public health."

"How we design data capture mechanisms matters," said Bhaumik whose current doctoral research is on snakebites. "If we design data collection in such a way that it only records cases of snakebites of people who come to a hospital, then it will not pick up cases within rural and tribal communities, especially where people do not go to a hospital, perhaps because there is no hospital nearby. They may instead be going to local faith-healers, for example."

Snakebite morbidity could not be likened to, say, a disease such as hypertension that occurs widely and all around India, explained Bhaumik. Snakebites are highly localised in terms of the areas and environments in which they occur, and are impacted by snake-human conflict, and environmental and occupational factors. Hence the data collection for it also has to address these differences.

Snakebites affect people with much less of a "political voice" and so, the urgency to address it is also less, he said.

Having better data, which are also localised, will help researchers and government officers identify where to make interventions and what kind of interventions, said Beri. "For example, if we see a high number of snakebites being reported from a particular area, which may be where a lot of people are involved in agriculture, then distributing rubber boots to people who work in fields can minimise their risk of being bitten by snakes."

"It is not just the deaths from snakebites which should concern us; a large number of people are also left with disability, mental health issues and social stigma [as a result of snakebite]. Better data and research into snakebites will help us address this," said Bhaumik.

Snakebite death numbers in India

In 2011, researchers published a paper on snakebite numbers in India, which aimed to clear up the confusion, as part of The Million Deaths Study (MDS).

The MDS project looked at various causes of death in India, such as maternal and child health, cancer, malaria, alcohol, injuries and suicide. The study was conducted in collaboration with the Registrar General of India and it monitored nearly 14 million people across 2.4 million households. The researchers studied any and all deaths in these families.

A key paper on snakebite deaths as part of the MDS--'Snakebite Mortality in India: A Nationally Representative Mortality Survey'--was published, as we said, in 2011. Four of the authors followed up on this research with another publication in 2020--'Trends in snakebite deaths in India from 2000 to 2019 in a nationally representative mortality study.'

The 2011 paper estimated that 46,000 snakebite deaths took place in India in 2005. The 2020 paper estimated the annual deaths from snakebites to be an average of 58,000 (1.2 million snakebite deaths between 2000 and 2019). The World Health Organization (WHO) acknowledged this in 2019, saying that the 2011 study showed that the estimate of snakebite deaths in India is 30 times higher than the Indian government's figure for the same period.

In 2019, the WHO said that 81,000-138,000 people die annually from snakebites globally. Seeing this in light of the 2020 study would mean that the Indian deaths from snakebites occupy the bulk of the global toll.

On the increased number of annual snakebite deaths between the 2011 and 2020 studies, Prabhat Jha, one of the authors in both the papers, puts it down to population growth in India. "Snakebite deaths rose due to population growth. These rates per population fell at younger ages, less so in middle ages but with more people, the total number of snakebite deaths rose modestly," said Jha, an epidemiologist at the University of Toronto.

Why are snakebites under-counted

The under-counting of snakebite cases in India may impact the numbers globally as the researchers of the 2011 paper described: "Because a large proportion of global totals of snakebites arise from India, global snakebite totals might also be underestimated."

The researchers said that one of the main reasons for this under-counting is cases or deaths of only those people are recorded who come to a hospital setting, whereas many people die at home and do not report to a health facility.

Only 23% of snakebite deaths in the MDS survey had happened in a hospital, according to this survey. This means that hospital data itself are incomplete and yet these are the main source of data on snakebites in India.

The researchers suggest that community tracking of snakebite deaths may be vital to fill in the gap created by recording only hospitals' data. Community surveillance will pick up cases of deaths at home.

Furthermore, there might be more deaths taking place in private hospitals, which are not picked up by the government, which only collects data from public hospitals, according to the 2020 study. As many as 154,000 snakebite deaths came from public and private hospitals over a 13-year period, but only 15,500 deaths were reported in government data in the same period, the study said. This means the "routine reporting system captured only 10% of the expected hospital-based deaths".

How to plug the gap

The researchers of the 2020 study recommended that the government of India could designate snakebites as a notifiable disease, such that doctors will have to notify the government of every case. These data would be updated in India's Integrated Disease Surveillance Programme.

In 2017, the WHO listed disease developed from snakebites in the first category of its list of neglected tropical diseases. In 2019, the WHO
proposed
that all countries work together to reduce mortality and disability from snakebites by 50% before 2030. Given India's outsized contribution to global numbers on snakebite deaths, a better estimation of the extent of snakebite deaths and disability in India will be key to tackling national as well as global numbers.

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