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Climate change impacts reportedly making cholera outbreaks worse

The bacteria behind one of history’s deadliest diseases is thriving again due, in-part, to the increased frequency of extreme weather. Outbreaks in 2022 were reportedly up 50% on yearly averages.

Last year, some 200,000 Malawians were displaced by two tropical storms in a single month and around 60 people died. 19 months on from the tragedy, cholera outbreaks have completely deviated from their usual patterns and experts are concerned.

As cholera is a diarrheal illness which spreads in regions without access to clean water and sanitation, it makes sense that floods would exacerbate an outbreak. What wasn’t expected is that the spread would be rampant throughout the dry season months after storms Ana and Gombe had subsided.

In a typical year, illness related to the bacteria rears its head from December to March with cases highly concentrated around Lake Malawi in the south. In August 2022, however, an outbreak permeated northern and central areas and by early February 2023, infections peaked at 700 per day – with a fatality rate thrice as high as the average.

A line chart showing that global cholera cases have increased roughly fourfold since 2000

Across the entire planet, cholera cases have risen roughly fourfold since the year 2000 and continue to do so. Following the alarming figures from Malawi, many are now seriously questioning whether the affects of climate change and intensifying weather are relevant factors in the disease’s yearly upsurge.

The World Health Organisation says that while poverty and conflict remain enduring drivers of the spread, climate change and worsening flash floods are surely ‘risk multipliers.’

‘Malawi’s water-sanitation indicators were already extremely bad,’ says UNICEF health emergency specialist Raoul Kamadje, ‘but the storms made a bad situation worse.’

There is little credence to the theory that warming temperatures turbocharge the outbreak of cholera directly, but ‘one of the big mechanisms by which extreme events will impact cholera risk is the destruction of water and sanitation infrastructure,’ explains Kamadje.

On that front, the World Bank estimated in 2022 that cyclone Ana collapsed 340 boreholes and destroyed 54,000 latrines, meaning those displaced will have utilised whatever water sources were available to them, including those contaminated with cholera. Crops inevitably also came into contact with the disease in sodden farmlands across the south.

Droughts as a result of extreme heat in places like Kenya, Ethiopia, and Somalia have all seen cholera proliferate over the past year too, as larger populations are forced to make use of the same water sources. Malnourishment in poverty stricken areas, meanwhile, further weakens the immunity of locals.

Not in anyway discrediting other factors, such as vaccine rates, access to aid, and the formation of landslides through deforestation, but myriad signs point to climate change and its secondary impacts as being significant in the growing number of cholera cases year-on-year.

Regardless of differing opinions on the matter, though, the worrying thing is that there will be plenty more opportunities to measure the correlation between extreme weather and the spread of disease in the near future… and therein lies the bigger problem.