WASHINGTON DC – The Pasteur Institute in Cambodia said it is researching wildlife trade and consumption in the country’s north in order to better understand the health risk posed by pathogen transmission from wild animals to humans.
The research comes amid growing scientific attention for pathogens in wildlife species in Southeast Asia as the possible source of the SARS-CoV-2 virus, which has caused a devastating global pandemic.
The Pasteur Institute told VOA Khmer that a team of scientists has been conducting an 18-month study since April 2020 on wildlife trade and consumption in Mondulkiri and Stung Treng provinces.
The main purpose of the research is to provide knowledge on the trade in and health of wildlife in order to identify possible pathogen transmission from animals to humans that can pose a threat to public health, the institute said.
SARS-CoV-2 first spread to humans on a large scale in eastern China in late 2019 and has since caused a COVID-19 pandemic that has killed about 3.38 million people worldwide.
While Cambodia was largely spared during the first year of the pandemic, it has experienced a rapidly worsening outbreak in recent months. Health authorities together with the Pasteur Institute have been battling the spread, which had infected 22,889 people and killed 156 by May 18.
Southeast Asian origins?
The precise origins of SARS-CoV-2 and how the deadly pathogen was transmitted from animal to human remain unknown. Virologists deem wild bats the main suspects, as they are known reservoirs for coronaviruses and could have passed on the SARS-CoV-2 to humans with traded wildlife as an intermediary.
Scientists have been on the hunt for species that could carry the SARS-CoV-2 and have focused on bats in China and, more recently, Southeast Asia. The closest match so far has been a virus found in bats in China’s Yunnan Province last year that was about 96 percent similar genetically. Dozens of other corona-viruses were found in bats in China in the past.
In late January, researchers working with the Pasteur Institute announced that tests on decade-old, frozen samples of horseshoe bats from Stung Treng Province had found a coronavirus about 93 percent similar genetically to SARS-CoV-2.
The researchers said the finding “indicates that SARS-CoV-2-related viruses have a much wider geographic distribution than previously understood and suggests that Southeast Asia represents a key area to consider in the ongoing search for the origins of SARS-CoV-2.”
In February, researchers in Thailand also found viruses closely matching SARS-CoV-2 in bats near Bangkok, while other research revealed that a trafficked pangolin in southern Thailand had developed antibodies effective against SARS-CoV-2.
Researchers and Cambodian health officials stressed that the ‘cousin’ of SARS-CoV-2 found in Cambodian bats is noninfectious, and that the chances of dangerous transmission of a virus from animal to human are generally very small.
Zoonotic diseases in Cambodian bats
Zoonotic diseases, nonetheless, represent a major threat to humans and attention to managing and monitoring health risks at the human-environment interface has become part of the ‘One Health’ approach promoted by the World Health Organization in recent years.
A 2016 Pasteur Institute study reviewed by VOA Khmer provides some details about the variety of viruses found in Cambodia’s bat population and their proximity to humans.
The study, which also collected the horseshoe bat sample that later revealed the cousin of SARS-CoV-2 in 2021, sampled 1,965 bats in northern Cambodia and southern Laos in 2010-2013. Many of the bats were found in fresh-food markets, wild meat restaurants, bat-guano farms, or caught by hunters in rural communities.
The 2016 study focused on then-known coronaviruses that can cause Severe Acute Respiratory Syndrome (SARS) in humans and found 4.7 percent from 17 genera of bats carried dozens of coronaviruses belonging to a group of viruses that can be highly pathogenic to humans.
This occurrence of SARS-related viruses was relatively low compared to, for example, bat populations in the Philippines (29.6 percent) and Hong Kong (12 percent), the study noted.
Understanding risk of future outbreak
Laurence Baril, the Pasteur Institute’s director, told VOA Khmer, “This [2016] finding rather highlighted the importance of continuous and sustainable ‘One Health’ research and that mechanisms of spillover and emergence of zoonotic diseases are complex to address.”
Baril said such research by the institute was important and required funding and time, while scientists were also at the forefront of testing and combating the current outbreak.
“The working balance is a challenge between daily contribution to the public health effort to combat COVID-19 under the coordination of the Ministry of Health and conducting the necessary research to better understand spillover and mechanism of emergence of new pathogens and risk of future outbreak,” she said.