A new study by Swiss scientists has found that global warming may further threaten the human population by facilitating diseases caused by viruses that are increasingly difficult to kill. The work, which has been published in the journal Environmental Science & Technology, suggests that waterborne viruses that are forced to adapt to warmer climates due to climate change are infectious for longer periods of time. They also become more resistant to disinfectants like chlorine.
This implies that the quality of microbial water could be worse in hot regions, and the health risks from viruses much greater.
While it is true that sunlight, high temperatures, and other microbes can inactivate viruses found in surface waters, thus reducing their ability to spread disease, scientists seem to hope that the way viruses react its environment evolves in response to climate change . In a way that the human being will have a harder time coping.
As the Earth continues to warm, many scientists expect to see changes in the timing, geography, and intensity of disease outbreaks around the world. And some experts believe that climate change, along with other environmental shocks, could help facilitate the emergence of more new diseases, such as COVID-19 in this case.
Enteroviruses and other pathogenic viruses can cause infections as benign as a cold or as dangerous as polio. They are found in feces and are released into the environment from sewage and other sources. Its survival depends on its ability to withstand the environmental conditions it encounters. Hence the researchers wanted to find out how viruses might adapt to these kinds of changes and how this would affect their resistance to disinfection.
The team created four different populations of a human enterovirus by incubating samples in flasks of lake water at 10 ° C and 30 ° C, with and without exposure to sunlight. They then exposed the samples to heat and disinfectant (chlorine). They found that viruses adapted to warm water were more resistant to heat inactivation than those adapted to cold water . They also observed little or no difference between the four strains in terms of inactivation when exposed to sunlight or other microbes. In cold water, warm water adapted viruses also remained active longer than cold water strains. In addition, they withstood chlorine exposure better.
The findings suggest that viruses in warmer waters “will persist in an infectious state for longer and will also be more resistant to disinfection,” said Tamar Kohn, co-author of the work, although she also cautioned that the laboratory study had not yet been validated. over field.
Still, adaptation to hot conditions shows that viruses in the tropics or in regions affected by global warming could become much more difficult to eliminate by chlorination or heating, according to the researchers. They also state that this increased resistance could increase the time that viruses take to infect and make someone sick when they come into contact with contaminated water.
Referencia: Anna Carratalà, Virginie Bachmann, Timothy R. Julian, Tamar Kohn. Adaptation of Human Enterovirus to Warm Environments Leads to Resistance against Chlorine Disinfection. Environmental Science & Technology, 2020; DOI: 10.1021/acs.est.0c03199
