Bat coronaviruses silently infect tens of thousands of people every year, posing pandemic risk, study warns – The Independent

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There may be more than 65,000 cases of bat-borne coronaviruses silently infecting people in Southeast Asia, according to a new study that could lead to new tools to improve preparedness against future pandemics .

The flying mammals are known to host coronaviruses that can be transmitted to humans, including SARS-related coronaviruses.

Previous studies have suggested that transmission of these viruses to humans may be relatively common in some parts of the world.

However, human-bat interactions are also known to vary across regions, influenced by a variety of social, ecological and economic factors at individual and community scales.

The research, published on Tuesday in the journal Nature communicationused a new framework to estimate and map the risk of potential SARS-related coronaviruses spreading from bats to humans in Southeast Asia.

Researchers, including those from EcoHealth Alliance in the US, developed a method to assess the distribution and frequency of bat SARS-related corona virus risk in Southeast Asia.

They built predictive models for 26 bat species known to host SARS-related coronaviruses in the region, allowing them to map where human populations overlap with these bats.

Then scientists used disease prevalence and demographic data as well as risk assessments to calculate the number of people infected each year with SARS-related coronaviruses (SARSr-CoV) of bat origin in Southeast Asia.

Researchers estimate using the framework that a median of approximately 66,000 cases of SARS-related coronaviruses spill over to humans annually.

“Our estimate that a median of ~66,000 people are infected with SARSr-CoVs each year in Southeast Asia suggests that bat-to-human SARSr-CoV spillover is common in the region, and is undetected by surveillance programs and clinical studies in the majority of cases,” scientists wrote in the study.

Evidence of such silent, undetected infections has also been shown for other viral infections of bat origin.

For example, researchers say that targeted surveillance of encephalitis patients in a small number of clinics in Bangladesh showed that the deadly Nipah virus causes annual outbreaks with an overall mortality rate of about 70 percent, despite only recently being reported in the country”.

“Our calculation of undetected spillover represents the first published effort, to our knowledge, to identify the spillover risk of SARSr-CoVs from bats to humans,” say researchers.

Regions in southern China, northeastern Myanmar, northern Vietnam, and the “populated regions of Indonesia” have the highest diversity of SARSr-CoV host species, the study noted.

Scientists say many of these cases go undetected because of limited surveillance, or because they can resemble other diseases.

While more data are needed to validate these findings and predict transmission risk through intermediate hosts, scientists say the research can help design surveillance and prevention programs in regions where these disease spillover events are more likely to occur.

They say their spillover risk assessment strategy of diseases jumping from animals to humans could be used as a tool to improve preparedness for emerging diseases of bat origin.

“These data on the geography and scale of spillover can be used to target surveillance and prevention programs for potential future bat-CoV emergence,” they wrote in the study.

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