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Spike in dengue fever cases due to global warming, warns WHO
Global warming that is marked by higher average temperatures, precipitation and longer periods of drought could prompt a record number of dengue fever infections worldwide, the World Health Organization (WHO) warned on Friday.
“About half of the world's population is at risk of dengue, and dengue affects approximately 129 countries,” said Dr Raman Velayudhan, WHO’s Head of the Global Programme on control of Neglected Tropical Diseases. “We estimate that about 100 to 400 million cases are reported every year. This is basically an estimate and the American region alone, for example, has reported about 2.8 million cases and 101,280 deaths.”
Dengue, also called breakbone fever, is the most common viral infection that spreads from mosquitoes to people. Most people with dengue do not have symptoms and recover in one to two weeks. But some people develop severe dengue and need hospital care.
“In some cases, especially when you get the infection for the second time, which we call a secondary infection, this can lead to severe dengue and it can be fatal too,” explained Dr. Velayudhan, briefing journalists at the United Nations in Geneva.
Dengue is spread by the Aedes species of mosquito. The disease is more common in tropical and subtropical climates. Its incidence has grown dramatically worldwide in recent decades, Dr. Velayudhan explained.
“In 2000, we had about half a million cases and today in 2022 we recorded over 4.2 million cases, which really shows an eight-fold increase. And, this can be much higher as we get more and more accurate figures.”
Asia represents around 70 per cent of the global disease burden and the future outlook is bleak, according to the WHO expert. In Europe, the Aedes mosquito is established and dengue and chikungunya infections have been reported for more than a decade.
“European countries are also on alert because Europe had recorded an Aedes transmission of either dengue or chikungunya since 2010,” said Dr. Velayudhan. “We have had more outbreaks since then and it is estimated that the mosquito is present in about 22 European countries.”
Numerous factors in addition to climate change have driven the spread of dengue fever, such as the increased movement of people and goods, urbanization and pressure on water and sanitation.
“The mosquito manages to survive even when there is water scarcity,” said the WHO expert. “So, both during a flood situation as well as a drought situation, dengue can increase. The virus and the vector multiply faster at a higher temperature. This is a well-known fact.”
Dengue fever does not have a specific treatment and there is no direct drug intervention available. Usually, the disease is treated with medicines to treat fever and pain.
A dengue test takes two to three days to receive a reliable result.
Several new tools are under development that provide greater hope in preventing and controlling dengue, such as better diagnostics. A few antivirals are undergoing clinical trials.
“Two or three of these candidates are going through Phase Two trials and will move on to Phase Three, which is very promising,” Dr. Velayudhan said. “There is also one dengue vaccine in the market, which has got certain limitations, and two other candidates are actually in the pipeline and are under review.”
The UN health agency stresses that prevention is key. Because the mosquito bites during the day, it is important that people protect themselves at home, in schools and at work by spraying repellent around buildings.
Other protective measures include mosquito coils and sleeping under nets.
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- Exterior medium shot: UN Palais with flags
- Wide shot: moderator behind podium and attendees at the press conference, screens with speakers on both sides of the podium
- SOUNDBITE (English) – Dr Raman Velayudhan, WHO Unit Head Global Program on control of Neglected Tropical Diseases coordinating dengue and arbovirus initiative: “About half of the world's population is at risk of dengue, and dengue affects approximately 129 countries. We estimate that about 100 to 400 million cases are reported every year. This is basically an estimate. And the American region alone, for example, has reported about 2.8 million cases and 101’280 deaths.”
- Wide shot: moderator behind podium and attendees at the press conference, screen with speakers on the side
- SOUNDBITE (English) – Dr Raman Velayudhan, WHO Unit Head Global Program on control of Neglected Tropical Diseases coordinating dengue and arbovirus initiative: “In some cases, especially when you get the infection for the second time, which we call a secondary infection, this can lead to severe dengue and it can be fatal too.”
- Medium shot: attendees in the foreground, screen with speakers in the background
- SOUNDBITE (English) – Dr Raman Velayudhan, WHO Unit Head Global Program on control of Neglected Tropical Diseases coordinating dengue and arbovirus initiative: “In 2000 we had about half a million cases and today in 2022 we recorded over 4.2 million cases, which really shows an eight fold increase. And actually this can be much higher as we get more and more accurate figures.”
- Medium shot: moderator behind podium and attendee at the press conference, screen with speakers on the side
- SOUNDBITE (English) – Dr Raman Velayudhan, WHO Unit Head Global Program on control of Neglected Tropical Diseases coordinating dengue and arbovirus initiative: “The European countries are also on alert because Europe had recorded an Aedes transmission of either dengue or chikungunya since 2010. We have had more outbreaks since then and it is estimated that the mosquito is present in about 22 European countries.”
- Medium shot: moderator behind podium at the press conference
- SOUNDBITE (English) – Dr Raman Velayudhan, WHO Unit Head Global Program on control of Neglected Tropical Diseases coordinating dengue and arbovirus initiative: “Also the high precipitation, increased temperature and even the mosquito manages to survive even when there is water scarcity. So both during a flood situation as well as a drought situation, dengue can increase. The virus and the vector multiplies faster at a higher temperature. This is a well-known fact.”
- Medium shot: attendee in the foreground, screen with speakers in the background
- SOUNDBITE (English) – Dr Raman Velayudhan, WHO Unit Head Global Program on control of Neglected Tropical Diseases coordinating dengue and arbovirus initiative: “There are very few antiviral research working on, and actually two or three of these candidates are going through phase 2 trials and will move on to phase 3, which is very promising. There is also one dengue vaccine in the market, which has got certain limitations, and two other candidates are actually in the pipeline and are under review.”
- Close shot: attendee taking a picture of the press conference
- Close shot: attendee typing
- Medium shot: moderator
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As world’s water reserves change, countries must prepare for a new reality: WMO
New data showing that rivers were at their lowest level for decades last year provides further evidence that the climate crisis is real and countries must act immediately to protect themselves from the increasing threat to communities and livelihoods, the UN World Meteorological Organization (WMO) said on Thursday.
The key findings from WMO’s State of Global Water Resources 2025 report covering the hydrological cycle and extreme events in the five-year period to last year:
- 2025 was one of driest years for river discharge in 35 years
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- Water storage on Earth’s land surface has decreased in past decade
- Widespread glacier loss across all regions for fourth consecutive year
- Asia and Africa are regions most affected by water-related disasters
- Water data availability has improved, but gaps remain in hard-hit areas
Highlighting the long-term decline in the Earth’s freshwater storage and glacier melt, WMO Secretary-General Celeste Saulo explained that the planet’s water reserves used to act as a planetary “savings account” that absorbed the occasional dry season, avoiding a water crisis. “One of the central stories of the 2025 report is what is happening to that savings account? And the simple answer is that we are depleting it,” she told journalists in Geneva.
Groundwater reserves are equally stretched and have been in decline since 2014, WMO’s report states, with nearly two-thirds of monitored wells worldwide showing levels lower than the historical norm and indicating a shift “further toward deficit…not recovery”.
“At the same time, we are seeing more water-related disasters,” Ms. Saulo said, while also stressing that the currently strengthening El Niño “will increase the risk of drought in some areas, and flooding in others”.
Glaciers disappearing
In 2025, for the fourth consecutive year, every major glaciated region on Earth lost ice mass, leading to short-term hazards including floods and long-term water insecurity, according to WMO.
Responding to a question about whether the changing global water cycle might have contributed to the deadly Nepal-China flooding disaster, Ms. Saulo explained that melting ice and rock was just one factor in the chain of events that ultimately sent a massive and deadly wall of water and debris downstream on 26 August, killing at least 1,367 people.
“You asked if it could happen again? Absolutely; the problem in this region is that there’s 63,700 glaciers at the last count,” she told a Press Conference in Geneva. “Even if you’re looking with remote sensing with satellites at these glaciers, you might see some faults, you might see some slight shifting, that does not mean necessarily catastrophic collapse. So, in order to plan for this, it’s very, very difficult. But the international community is looking very hard at ways in which we can bring people together to solve some of these monitoring issues.”
Data indicates that glaciers shrank between 2023 and 2025 with cumulative losses of 1,400 gigatonnes of water – or about one third of annual fresh water needs.
Every major glacier region on Earth lost ice for the fourth consecutive year.
“All 19 glacier regions around the globe lost ice; in Central Asia, Iceland, the Russian Arctic and western Canada and the United States, it was among the three worst years on record,” said Wayne Jenkinson, WMO’s Director of Hydrology and Cryosphere.
Some regions with smaller glaciers such as Central Europe, the Caucasus, the western Canada and the United States may already have reached “peak water”, Mr. Jenkinson warned.
“After this point, the glacier gives less meltwater each year simply because there is less ice left to melt. That matters for every community downstream that relies on water during hot, dry summers,” he explained.
Narelle van der Wel, WMO’s Head of Cryosphere Monitoring, Predictions and Services, stressed that while some further glacier loss is unavoidable, the eventual scale of the decline is not predetermined.
“Some glacier loss is inevitable, but total loss of glaciers is not yet inevitable,” she said, pointing to emissions reductions as central to limiting future losses.
Preparing for moving baselines
The report does not attribute every observed change to climate change alone. WMO says pressure on water resources and natural variability also contribute.
Mr. Jenkinson said governments need to prepare for “moving baselines” as historical patterns become less reliable.
“The situation 30 years ago is not where we are today,” he said. Countries, he added, need to prepare “for those changes that have really already arrived”.
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