Snakebites Are On the Rise As Snakes Migrate With Climate Change

May 24, 2019
Stat

Mwende, a smart 13-year-old girl who dreams of being an engineer, was picking tomatoes in her backyard in the outskirts of Nairobi when a venomous puff adder bit her on the right arm. Although her father rushed her to the hospital, it lacked antivenom medication and the only way to save her life was to amputate her arm.

This wasn’t an isolated incident. Mwende (not her real name) became part of an exploding global problem of snakebites.

As the climate changes, snakes are on the move and snakebites are becoming more common. Over the last decade, and estimated 30 million people worldwide have been bitten by snakes, with nearly 5.4 million bites in the last year alone. On average, one person dies every five minutes from the bite of a venomous snake. And these worrisome numbers are underestimates, since most bites are never reported, especially in poor rural areas.

Mwende must now learn how to cope with life as a disabled person, which comes with great stigma in Nairobi. She had to learn how to write with her left hand and her future livelihood is in jeopardy. Yet her suffering — like that of hundreds of thousands of snakebite victims worldwide — was avoidable. Her arm could have been saved if the hospital had the antivenom serum she needed.

This oversight reflects a bigger problem: the widespread failure of public health systems from Kenya to India to the United States to prepare for the threats posed by snakes on the move. To stem this rising tide of death and disability, health systems must begin preparing now.

Less than 2% of Africans currently have access to antivenom. This medication is expensive because major manufacturers have ceased production. Their market exit has created a supply vacuum that unscrupulous businesses have gleefully entered with fake antivenoms that are expensive, ineffectual, and sometimes toxic.

Human-driven climate change — including rising temperatures and an increase in severe events like drought, heat waves, floods, cold spells, and wildfires — are making snakes’ traditional territories uninhabitable. Snakes are left with three options: migrate, adapt, or die.

Serpents like the one that bit Mwende are today being seen hundreds of miles from their native habitats. Migratory patterns are changing, as different species move either north or south. New research suggest that snakes will have slithered their way to northern Canada by 2050, and could be sunning themselves in northwestern Alaska by 2100. Northward migration of snakes beyond their traditional limits has already been seen in China. These migrant snakes will intrude on human populations, leading to more snakebites. They may also disrupt fragile ecosystems by preying on endangered species.

Climate change is also driving snake evolution. Burmese pythons, which are native to Southeast Asia, have been living in Florida since the 1980s and are now well-established in the state. A record cold spell in Florida in 2010 induced genetic adaptation in the surviving Burmese pythons that made them more cold tolerant. Their population has since exploded to between 30,000 and 150,000 in the Everglades, an area roughly the size of Israel. In early April, a 17-foot-long python with 73 developing eggs was captured there, the largest yet seen in Florida. Other snakes are adapting their behaviors to cope with climate change. In India, shorter winters are making snakes come out of their form of hibernation (called brumation) earlier, leading to more human encounters with snakes.

Snakes that are unable to adapt or migrate are dying off. They will have become extinct in parts of South East Asia in 50 years if warming there continues unabated. Although their extinction may sound appealing, snakes have their benefits, from controlling rats in rice paddy fields to individually consuming thousands of ticks per year. The decline of rattlesnakes, for example, has been associated with a rise in tick-borne diseases like Lyme disease.

A few things should be done — and urgently. Countries need to update their maps of snake habitats and educate communities about new threats they may face from venomous snakes. Because different antivenoms are needed for different snakebites, this mapping will also help determine what antivenoms are needed where. Governments should consider providing manufacturers with incentives like tax breaks to resume production of antivenoms and to lower their prices for these drugs. Unscrupulous producers should be identified and prosecuted.

It is also important to begin funding research on promising universal antivenom candidates to treat bites from different snake species and on lifesaving antidotes like the antiparalytic drug neostigmine. The returns on such research investments will be immense.

To be sure, these actions should not distract from the root cause of the problem. Global efforts to mitigate and reverse climate change must accelerate. The implementation of public health actions now will save millions of lives over the next decade, and avoid crippling disabilities.

Policymakers in many countries tend to view snakes as a poor man’s problem and, as cynics sometimes point out, countries only pay attention to health problems when the affluent are threatened. As climate change brings hissing serpents to the leafy suburbs, it is time for governments to listen and act.