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Virus hunters continue search for animal link to COVID-19 infections in people
The key work of tracing the animal transmission source of the COVID-19 coronavirus infection in humans is ongoing and must be carried out to prevent future health emergencies, a top UN health agency scientist said on Friday, after the World Health Organization (WHO) confirmed more than 3.5 million cases of infection and 250,000 deaths globally.
Since the respiratory disease emerged in central China in late December, health officials have raced to locate where and how the virus was first transmitted from its animal host to humans.
It is believed that a now-closed Wuhan city wholesale market “played a role” in the outbreak, said Dr Peter Embarek, Food Safety and Zoonosis Expert at WHO, but it is not clear if it was the source.
“All these preliminary studies and interviews and collection of data and so on will help pinpoint both in time and in geographic terms where to look for the source; and it could be again, in this case, it could be again around the markets in Wuhan, but it could also be outside or further out, and therefore, there is no point jumping and starting to testing animals all over the place before having done this groundwork.”
In a videoconference with journalists, Dr Embarek highlighted the fact that many people showed few or no symptoms of infection with COVID-19, likely contributing to the outbreak’s rapid spread.
“We’ve learned a lot about the disease and we know that the vast majority of cases have no or mild symptoms, so it would not be surprising if at that time there were a lot of mild cases that were undetected because we didn’t even know they were mild cases at that time. And that could explain how some of the people who had no link with the market could have been infected.”
In previous coronavirus outbreaks, such as the MERS episode in 2012, finding the missing animal-human link has been far from easy, even though “everybody was looking for the source”, Dr Embarek explained.
In the end, it took months of epidemiological detective work and a slice of “luck” before the transmission link to camels was found, after health officials in Qatar reported two suspect cases linked to a farm, which were followed to confirm the link to the dromedaries.
“It’s not too late, and as I said for the MERS virus, it took about a year before we found the source,” Dr Embarek said. “So it’s never too late but it’s important that we try to find the source and understand what happened at the start of the event to avoid a repeat of this event and to avoid another spillover event in coming years with other different viruses.”
He added: “What would be of great help is if we could get hold of the virus before it adapted to humans, before the version we have now, because then we would better understand how it adapted to humans, how it evolved and what are the changes in the make-up of the virus that most likely did this adaptation. Because now we can see different structures of the virus, we can see mutations sometimes, but we don’t really understand which mutation is critical and which one is less critical; because they are mutating all the time and in 99 per cent of the case this mutation means nothing and we have to understand the critical ones.”
Echoing calls for stronger health controls on wet markets - a common feature of daily life throughout Asia - Dr Embarek noted that the “vast majority can be fixed, can be better organized, because it’s often a question of waste management”.
He added: “It’s a question of people movement and goods movement, it’s a question of separating live animals from animal products and from products that are fresh and cooked products, it’s a question of separating fresh fruits and vegetables from meat products or from live animals. It’s a question of separating the public from the live animals and the people vending and slaughtering these animals; so it’s more about management than regulations and inspections and cleaning and disinfections.”
Concerning the transmissibility of infection to various animals that regularly come into contact with humans, the WHO official noted that “cats and (these) felines are susceptible to the virus; studies with cats have also shown that cats can also transmit the disease to other cats, so this is a group of animals that is interesting to look at, because they are susceptible to the virus. Ferrets have also been shown to be susceptible to the virus, dogs to some extent, but not as efficiently and other species, like domestic species, like pigs, like poultry, chicken and turkey and the like do not seem to be susceptible to the disease, which is good news because we are producing and raising these animals on a very large scale.”
He also said that the new coronavirus could not be transmitted by mosquitos and parasites.
“There has been discussion about mosquitos and whether other animals could transmit the virus and that’s not the case,” Dr Embarek said. “These viruses have very specific affinities to certain animal species and again to their ability to attach and infect specific cells of different species. They cannot at all invade and infect particular animal species so it’s not like can invade whatever they touch or move into.”
Asked about the level of WHO collaboration with Chinese health authorities into tackling COVID-19, he responded that “China has most probably and most likely all the expertise needed to do the investigations; they have a lot of very qualified researchers to do that.”
At the same time, he noted that it was “often useful sometimes to have discussions and to have collaborations with groups and with researchers and with people from all over the world who have had - gone through - similar events and similar studies and have things to share, have experience to share and that has always enriched and improved the speed and quality and likelihood of success of these very complex studies.”
EDITED STORY SHOTLIST
- SOUNDBITE (EN) - Dr Peter Embarek, Food Safety and Zoonosis Expert, WHO: “All these preliminary studies and interviews and collection of data and so on will help pinpoint both in time and in geographic terms where to look for the source; and it could be again, in this case, it could be again around the markets in Wuhan, but it could also be outside or further out, and therefore, there is no point jumping and starting to testing animals all over the place before having done this groundwork.”
- SOUNDBITE (EN) - Dr Peter Embarek, Food Safety and Zoonosis Expert, WHO: “We’ve learned a lot about the disease and we know that the vast majority of cases have no or mild symptoms so it would not be surprising if at that time there were a lot of mild cases that were undetected because we didn’t even know they were mild cases at that time. And that could explain how some of the people who had no link with the market could have been infected…”
- SOUNDBITE (EN) - Dr Peter Embarek, Food Safety and Zoonosis Expert, WHO: “What would be of great help is if we could get hold of the virus before it adapted to humans, before the version we have now, because then we would better understand how it adapted to humans, how it evolved and what are the changes in the make-up of the virus that most likely did this adaptation. Because now we can see different structures of the virus, we can see mutations sometimes, but we don’t really understand which mutation is critical and which one is less critical; because they are mutating all the time and in 99 per cent of the case this mutation means nothing and we have to understand the critical ones.”.”
- SOUNDBITE (EN) - Dr Peter Embarek, Food Safety and Zoonosis Expert, WHO: “It’s not too late, and as I said for the MERS virus, it took about a year before we found the source. So it’s never too late but it’s important that we try to find the source and understand what happened at the start of the event to avoid a repeat of this event and to avoid another spillover event in coming years with other different viruses.”
- SOUNDBITE (EN) - Dr Peter Embarek, Food Safety and Zoonosis Expert, WHO: “But the vast majority can be fixed, can be better organized, because it’s often a question of waste management, it’s a question of people movement and goods movement, it’s a question of separating live animals from animal products and from products that are fresh and cooked products, it’s a question of separating fresh fruits and vegetables from meat products or from live animals. It’s a question of separating the public from the live animals and the people vending and slaughtering these animals; so it’s more about management than regulations and inspections and cleaning and disinfections.”
- SOUNDBITE (EN) - Dr Peter Embarek, Food Safety and Zoonosis Expert, WHO: “Cats and these felines are susceptible to the virus; studies with cats have also shown that cats can also transmit the disease to other cats, so this is a group of animals that is interesting to look at, because they are susceptible to the virus. Ferrets have also been shown to be susceptible to the virus, dogs to some extent, but not as efficiently and other species, like domestic species, like pigs, like poultry, chicken and turkey and the like do not seem to be susceptible to the disease, which is good news because we are producing and raising these animals on a very large scale.”
- SOUNDBITE (EN) - Dr Peter K. Ben Embarek, Food Safety and Zoonosis Expert, WHO: “There has been discussion about mosquitos and whether other animals could transmit the virus and that’s not the case. These viruses have very specific affinities to certain animal species and again to their ability to attach and infect specific cells of different species. They cannot at all invade and infect particular animal species so it’s not like can invade whatever they touch or move into.”
- SOUNDBITE (EN) - Dr Peter Embarek, Food Safety and Zoonosis Expert, WHO: “China has most probably and most likely all the expertise needed to do the investigations; they have a lot of very qualified researchers to do that, but as I said, it is often useful sometimes to have discussions and collaborations with groups and with researchers and with people from all over the world who have had, gone through similar events and similar studies and have things to share, have experience to share and that has always enriched and improve the speed and quality and likelihood of success of these very complex studies.”
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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
- Past seven years have seen abnorfmal river flows
- 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”.
ends
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