{
  "id": 2340050,
  "title": "In a drier world, some infectious diseases are unexpectedly thriving",
  "url": "https://urgent.news/2026/08/21/in-a-drier-world-some-infectious-diseases-are-unexpectedly-thriving",
  "topic": "science",
  "section": "Science",
  "published": "2026-08-21T08:30:00.000Z",
  "source": {
    "name": "Grist",
    "slug": "grist",
    "url": "https://grist.org/drought/even-in-droughts-these-waterborne-diseases-can-boom/"
  },
  "original_language": "en",
  "account": "As droughts become more widespread, certain infectious diseases are thriving in unexpected ways. A new study published in Trends in Ecology and Evolution reveals how a drier world may contribute to the spread of deadly infections and parasites. Tara Stewart Merrill, an aquatic disease ecologist at the Cary Institute of Ecosystem Studies and coauthor of the paper, explains that while water-borne diseases typically flourish when there is plenty of water, some actually proliferate during droughts. This phenomenon, known as the \"drought-disease paradox,\" is the focus of the research.\n\nThe study, coauthored by Pieter Johnson from the University of Colorado Boulder, examined nearly 100 scientific studies of diseases across the animal kingdom, from humans to insects. The researchers found that the majority of human parasites and many pathogens require water to survive. Contrary to expectations, some diseases, including cholera, West Nile virus, and dengue, actually increase in prevalence when drought conditions prevail.\n\nMerrill and Johnson became interested in the drought-disease paradox while studying parasites in pond ecosystems in California. They observed that more than half of their study sites dried up, leading them to investigate how drought might influence disease transmission across ecosystems worldwide. As the planet warms and fossil fuels contribute to climate change, the atmosphere draws more water from the landscape, causing more intense and prolonged droughts. According to a United Nations report, the world is now 77% drier than it was three decades ago.\n\nThe consequences of these droughts have already been felt. California's droughts led to thousands of excess valley fever cases, and the 2014 superdrought contributed to the state's second-highest West Nile virus cases. In Somalia, a superdrought resulted in nearly 80,000 cholera cases, causing over a thousand deaths. In Brazil, where millions suffer from dengue each year, droughts have been shown to increase the risk of infection by several months.\n\nDisease transmission is closely tied to the movement of animals seeking water. As water distribution changes due to drought, animals must travel farther to access it, which can lead to new transmission opportunities. For instance, during droughts in the African savannah, some watering holes dry up, forcing animals like zebras, elephants, rhinos, and giraffes to congregate around the remaining pools. The increased crowding also results in higher fecal matter concentrations, facilitating the spread of parasites that lay their eggs in animal waste. Georgia Titcomb, a wildlife disease ecologist at Colorado State University, notes that after periods of reduced rainfall, parasites are more likely to thrive, with up to 100,000 eggs per kilogram of dung. Similar patterns have been observed in other regions, such as bird populations carrying West Nile virus, which can come closer to mosquitos during droughts, leading to higher mosquito populations capable of infecting humans.\n\nMoreover, drought-induced reductions in bodies of water can force birds carrying West Nile virus into closer proximity with mosquitos, resulting in more infected mosquitos that can transmit the disease to humans. Droughts can also heat up bodies of water, creating conditions that allow some dangerous mold, algae, and bacteria to flourish. In certain cases, the diminished availability of water can be detrimental to pathogens, bacteria, fungi, and parasites, as extreme conditions can render them uninhabitable. The severity of the drought plays a crucial role, as bacteria like Vibrio vulnificus, responsible for 80,000 cases of food poisoning annually in the United States, can initially spread during droughts but are eliminated if the drought persists. Additionally, heavy rainfall during an extended drought can exacerbate outbreaks, a phenomenon known as \"weather whiplash,\" which is becoming increasingly common due to global warming.",
  "summary": "Researchers are beginning to untangle how the “drought-disease paradox” works.",
  "key_points": [
    "Droughts cause rise of cholera, West Nile, dengue cases",
    "Drought-disease paradox: water-borne diseases thrive in droughts",
    "Droughts force wildlife closer to mosquitos, increasing infection risk"
  ],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}