Snakebite burdens the health systems of most tropical countries, with thousands of deaths and disabilities every year. Our knowledge of where venomous snakes live and their impact on human populations is currently insufficient. Climate change will only exacerbate the issue by affecting where, when, and how snakes share space with people. This is because snakes will shift their distributions as temperatures rise and extreme events become more common. They will become either more or less abundant and change their activity patterns. Humans will change farming practices, and there will be greater pressures to migrate or be displaced. As a result, human–snake contact and conflict are expected to become more pronounced or frequent in some regions.
Given the substantial investment required to supply resources such as antivenom to communities in need, any mitigation strategies that are planned to control this neglected tropical disease (NTD) need to be ‘future-proofed’ and potential crisis situations anticipated.
The World Health Organization (WHO) is using geographic information systems (GIS) and state-of- the-art modelling techniques to map snake distributions and snakebite incidence to predict the future changes in snake–human conflict expected because of climate change.
Snake distribution mapping
The WHO NTD team, in collaboration with the Division of Data, Analytics and Delivery for Impact, has collaborated with snake experts to define the distribution of hundreds of medically relevant snake species and created species distribution models showing the suitability of habitat at 1 km resolution for all these snakes under current and future climate conditions (2050 and 2090). The team overlayed these models with human population data and snakebite risk factors to find areas where humans and snakes have the most contact and how these contact zones will likely change.
Headline results
Many deadly snake species are predicted to increase in abundance and come into contact with more people.
Many snake species will shift their ranges, meaning people will encounter new kinds of snakes in many areas.
Key messages and calls to actions
Climate change will impact both snakes and people. Negative impacts on snakes can lead to negative impacts on people by displacing snakes and forcing them into new environments where they will come into contact with people previously unexposed to them.
Action: Focus on educating people who are exposed to snakes already or will be in the future and ensure they have the skills to coexist with snakes without being bitten. Plan conservation areas of good habitat for snakes to use as refuge from extreme events to reduce snake–human contact resulting from displacement.
There is substantial overlap of where people and venomous snake species live across many regions of the world. Especially in agricultural areas, complete avoidance of contact with snakes is impossible and may become worse with climate change.
Action: Provide antivenom stockpiles in the most appropriate health centres where snakebites are endemic and frequent. Change the positions of stockpiles so they will still be effective when snakes shift their distributions. Provide protective equipment to effected farmers to reduce risk of being bitten by snakes.
Many areas are under-surveyed for snake distributions and snakebite cases.
Action: Engage with local authorities, scientists and the general public to collect and provide data to WHO to improve maps and models of snake distributions and snakebite incidence.
Health facilities capable of treating snakebite are sparsely distributed in many developing countries.
Action: Provide funds, medication, training, and equipment to increase the number of health facilities that can treat snakebite, especially in snakebite-prone rural areas. Provide transport support for remote patients.
Many available antivenoms lack efficacy.
Action: Conduct product reviews and testing and give manufacturers guidelines to improve antivenom quality. Inform health services and patients about trusted products to seek out.
Antivenom availability, affordability, and geographical placement has been insufficient for decades and improvements have been slow. Considering the potential increase in human–snake conflict in many areas with climate change, mitigation strategies require urgent improvements and future-proofing.
Immediate actions need to be taken to resolve a neglected tropical disease that affects millions annually and reach the WHO target of reducing snakebite-related deaths and injuries by 50% by 2030.