Britain's increasingly severe drought conditions could elevate the risk of infectious disease outbreaks, according to scientists who have reviewed nearly 100 previous studies. The research indicates that prolonged dry spells can facilitate the spread of potentially deadly diseases.
As water sources like rivers and ponds diminish, animals and disease-carrying insects are forced into smaller, concentrated areas. This increases the likelihood of pathogens circulating and potentially infecting humans. The review, conducted by researchers at the University of Colorado at Boulder, highlights that climate change is contributing to more frequent, extreme, and unpredictable droughts, presenting a significant challenge for disease control.
While the specific threats to the UK may differ from those in other regions, scientists have identified several concerns. Leptospirosis, also known as Weil's disease, is a bacterial infection already present in the UK. It is spread through the urine of infected animals, such as rats and livestock, which can contaminate water bodies. Human infection can occur when contaminated water enters cuts or is ingested, with symptoms ranging from flu-like aches to severe organ failure.
Another concern is cryptosporidium, a parasite that can spread through contaminated drinking or recreational water, leading to symptoms like stomach cramps, severe diarrhea, vomiting, and dehydration.
Researchers noted that in parts of the US and Europe, dry spells have been linked to an increase in diseases like West Nile virus and cholera. Although West Nile virus is not currently circulating in British mosquitoes, experts are monitoring the situation. In 2023, the UK Health Security Agency detected fragments of West Nile virus genetic material in British mosquitoes, though no ongoing transmission has been confirmed.
The review, published in the journal Trends in Ecology & Evolution, suggests a global shift in disease patterns as the world becomes drier. "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."
Historical data indicates that July was the driest on record for England and Wales, with the UK experiencing its third driest July. This has led to increased pressure on water supplies, with hosepipe restrictions affecting millions of people.
The study also draws parallels from observations in other regions. In North America, mosquito-borne illnesses like West Nile virus and St. Louis encephalitis virus have become more prevalent during certain drought conditions. Drier conditions can also increase airborne pathogens, potentially aiding the spread of diseases such as Valley fever.
Professor Pieter Johnson, one of the study's authors, previously observed these effects while researching frogs in California. During a severe drought in 2014, shrinking ponds led to higher infection rates and more severe cases of a waterborne parasite among the amphibians. With over three-quarters of the world's land experiencing drier conditions in recent decades, understanding these shifts is considered crucial for predicting future disease outbreaks.