HKU Bulletin November 2021 (Vol. 23 No. 1)

THE ‘ONE HEALTH’ CHALLENGE Health threats from animal and environmental sources are on the rise – not just from COVID-19, but antimicrobial resistance and other infectious diseases such as Middle East Respiratory Syndrome (MERS). HKU academics have been at the forefront producing collaborative, multidisciplinary research to identify and control these threats. What does One Health mean in practice? Professor Malik Peiris, TamWah-Ching Professor in Medical Science, of the School of Public Health, one of the most highly cited scholars in the world on emerging infectious diseases and recent joint recipient of the prestigious 2021 John Dirks Canada Gairdner Global Health Award with colleague Professor Guan Yi, Daniel C K Yu Professor in Virology, provides a telling example based on his work as a virologist in Sri Lanka in the 1980s. He specialised back then in mosquito-borne diseases, and Japanese encephalitis was on the rise in a region of the country. After much investigation, the cause was found to be a well-intentioned policy: the government decided to help poverty-stricken rice farmers by giving them pigs to raise. The combination of mosquitoes and pigs – which are often a vector of viruses between humans and other animals – “just lit the spark to the dynamite,” he said. “I’m sure the health department wouldn’t have thought of this happening either. It just shows how these ecological balances can be upset by some of the most well- meaning gestures.” Such interplay between humans, animals and the environment is at the heart of the One Health concept, which started to consolidate after outbreaks of H5N1 bird flu and SARS (both centred in Hong Kong) and was formally endorsed by the World Health Organization (WHO), Food and Agriculture Organization and World Organisation for Animal Health in 2010. It has leapt up the agenda in the wake of COVID-19, which has been the latest and worst of recent viruses that threaten human health. “For the last two decades, we have had a major, novel infectious disease threat almost every two or three years – SARS, swine flu, avian flus H5N1 and H7N9, MERS, Zika, Ebola and now COVID-19,” Professor Peiris said. All have been traced to animal sources – birds, bats, pigs, camels and primates – but human interactions with these animals have created conditions that allow viruses to jump species. “Previously, livestock was raised in a backyard. People had a few pigs or chickens and if a virus got into those animals and jumped to humans, it was a localised effect,” he said. “Now, livestock animals are raised in the tens of thousands and shipped thousands of miles to market. You also have these game animal markets, which have become a huge trade because of greater affluence in China and parts of Asia, and you can have thousands of animals in the larger markets. That is, of course, how SARS managed to develop. “COVID-19 really should be a wake-up call to the global community that humans are not superhuman. The forces of nature are much more powerful than us and we tamper with this at our peril.” Viruses not the only threats Professor Peiris and other scholars at HKU are at the frontlines trying to assess the threats emerging from the human-animal- environment interface and propose ways to manage them. The concern is not confined to viruses but also antimicrobial resistance (AMR), which is developing more slowly than new viruses but has the potential to be very damaging to health. AMR was identified by the United Nations Environment Programme (UNEP) in 2017 as one of the top six emerging issues of global environmental concern. Currently, about 700,000 people die each year because AMR has made antibiotics less effective against bacterial infections. By 2050, the number could be 10 million (twice as many as died of COVID-19 in its first 18 months) if nothing is done, according to a UK-commissioned report. A 2019 report by the UN’s Interagency Coordination Group on Antimicrobial Resistance, titled ‘No Time to Wait’, also warned of the growing impact of AMR on the environment and ecological systems. Professor Zhang Tong of the Department of Civil Engineering leads an ongoing theme-based research project to investigate AMR flows from pollution hotspots to the environment, with a focus on sewage. He works in collaboration with HKU’s School of Public Health and the Hong Kong Government and is also a member of an expert panel preparing a special report on the environmental impact of AMR for a special session next year of the UNEP. “It is impossible to completely remove antibiotics from wastewater so some inevitably escapes into the environment,” he said – whether from human or animal farm sewage or the effluents of the pharmaceutical industry. The residual antibiotics may apply selective pressure on bacteria, some of which will develop resistance to these antibiotics. “Eventually, there will be more and more superbugs.” He is in the process of collecting water and soil samples from multiple sites, such as hospitals, water treatment plants, farms, beaches and sewage treatment plants, with the aim of developing a local map of the current baseline conditions that can be used to monitor AMR progress in Hong Kong’s environment and develop control strategies. The baseline will also be compared to other territories to see how Hong Kong fares globally. Professor Malik Peiris (second from right) and his team found that novel coronavirus can infect the human respiratory tract even better than SARS-CoV. An electronmicroscope picture shows that the cells fromhuman bronchial tissue can be infected byMERS-CoV and theMERS-CoV can replicate in human respiratory tissues. COVID-19 really should be a wake-up call to the global community that humans are not superhuman. The forces of nature are much more powerful than us and we tamper with this at our peril. PROFESSOR MALIK PEIRIS 04 The University of Hong Kong Bulletin | November 2021 05 COVER STORY

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