Britain's worsening drought could trigger outbreaks of infectious diseases, scientists have warned. Researchers say prolonged dry spells can make potentially deadly diseases spread more easily.
As rivers and ponds dry up, animals and disease-carrying insects can be forced into ever-smaller pockets of water, creating potential hotspots for infection. A new review has examined almost 100 previous studies to investigate how increasingly dry conditions could reshape the spread of infectious diseases.
The review was carried out by researchers at the University of Colorado at Boulder and published in the journal Trends in Ecology & Evolution.
Britain is not immune to the disease risks created by drought, although the threats here would be different from those seen in other parts of the world.
Leptospirosis risk in the UK
One of the biggest concerns is leptospirosis, also known as Weil's disease, a bacterial infection already found in the UK. It is spread by bacteria carried in the urine of infected animals, particularly rats and livestock, which can contaminate rivers, lakes and other waterways.
People can become infected when contaminated water gets into cuts or through the eyes, nose or mouth. Symptoms range from mild flu-like aches to severe, life-threatening organ failure.
A similar concern applies to cryptosporidium, a parasite that can spread through contaminated drinking or recreational water. It can trigger stomach cramps, severe diarrhoea, vomiting and dehydration.
West Nile virus and cholera
The researchers warn that climate change is making droughts more frequent, extreme and unpredictable, creating a new challenge for controlling disease. They said that in the US and parts of Europe, West Nile virus and cholera could become more common because of increased dry spells.
West Nile virus is not currently circulating in British mosquitoes, but experts are already monitoring the possibility of it becoming established as the climate changes. The UK Health Security Agency detected fragments of West Nile virus genetic material in British mosquitoes for the first time in 2023, although officials stressed there is currently no evidence of ongoing transmission in the UK.
"We are expecting to see shifts in the types of parasites and diseases that predominate in a drying world," the researchers wrote. "Some infections will disappear in certain places, but under different conditions, transmission can become so intense that it offsets the loss of infection elsewhere."
They said that as drought shrinks water sources, animals may become concentrated around the remaining pools and rivers, potentially increasing opportunities for pathogens to circulate.
Frogs, dust and diseases elsewhere
In North America, mosquito-borne illnesses such as West Nile virus and St Louis encephalitis virus have become more prevalent under some drought conditions. Drier conditions can also increase the amount of contaminated dust in the air, potentially helping diseases such as Valley fever to spread.
Professor Pieter Johnson first witnessed the effect while studying frogs in California infected with a waterborne parasite that causes them to develop extra limbs. When a severe drought struck in 2014, the shrinking ponds forced the amphibians into fewer remaining bodies of water, and the result was more severe infections and higher infection rates among the frogs.
With more than three-quarters of the world's land experiencing drier conditions in recent decades, the researchers say understanding these changes could be crucial for predicting future outbreaks.
Driest July on record
It was the driest July on record for England and Wales, with the Met Office describing the month as an extraordinary period of heat, sunshine and almost complete lack of rain. The UK as a whole had its third driest July on record with 28.9mm of rainfall, while England recorded 6.5mm and Wales 9.3mm, both their driest Julys on record. Northern Ireland had its eighth driest July with 26.9mm, while Scotland was not close to breaking records with 72.0mm.
Canals have been left running dry across England and Wales as Britain continues to bake in what could become its hottest summer ever. Water supplies are coming under increasing pressure, with hosepipe restrictions now affecting millions of people and further restrictions being considered in some areas.
