Emerging Viruses: 'Any Outbreak, Anywhere in the World, Can Be a Threat, Everywhere'
NEW ORLEANS, LA—“The germs are fighting back.” And, with international travel, “any outbreak, anywhere in the world can be a threat, everywhere.”
That's the reality of an increasingly connected world, said Malik Peiris, PhD, of the School of Public Health at the HKU-Pasteur Research Center, The University of Hong Kong, Pokfulam, Hong Kong.
Dr. Peiris, who spoke on emerging viruses as a result of “change” in a closing plenary presentation at IDWeek 2016, played a key role in the 2003 discovery that a novel coronavirus caused SARS. His work focuses on emerging viruses and diseases at the animal-human interface, including influenza, coronaviruses such as SARS and MERS, and others.
Factors or “changes” that predispose to infectious disease emergence and re-emergence include microbial adaption and change, ecological and environmental factors, urbanization, animal husbandry practices and trade, pet animal trade, international travel, international trade, human demographics and behavior, breakdown of public health and wars, and technology and change in health care.
The SARS virus most likely has existed for centuries. So, what happened that led to the emergence of SARS in 2002–2003?
Dr. Peiris pointed to “clear changes” that had occurred.
“In Guangdong Province, in southern China, it is a cultural practice to consume wild game animal meat in the winter months. But this has been a culture that has been going on for centuries. It's not new. But what was new, was to support the demand of an increasingly affluent population, a whole industry had grown up, with huge markets, with a huge diversity of species all housed together to serve this game animal trade. So that was new.
“And, of course, the other thing that was new was travel. If even 50 years ago, an outbreak like SARS occurred somewhere in China, there may have been cases, there may have been deaths in one village or another, but it probably would have died there,” Dr. Peiris said.
However, in 2003, patient AA, the index case, arrived in Hong Kong from Guangzhou, China, and stayed 1 day at “Hotel M” in Room 911. He infected 16 other hotel guests or visitors to the same floor of the hotel and was treated at Kwong Wah Hospital, causing additional clusters of 238 and 12 cases in Hong Kong.
Two visitors went to Canada, triggering a cluster of 136 cases; 3 went to Singapore, where 238 cases were recorded; and 1 went to Vietnam, where 63 cases were recorded. Two other visitors had gone to the Philippines and then the United Kingdom, 3 had gone to the United States, and 3 had gone to mainland China.
Ultimately, 8,000 cases of SARS was reported, causing 800 deaths worldwide at a cost of $40 billion.
Subsequently, it was shown that SARS-like coronavirus was present in the live game animals at the markets. The animals included Himalayan palm civets, which house P. larvate; raccoon dogs (N. procyonoides), and other small mammals. However, these animals were just the amplifiers. The natural reservoir was determined to be bats, “so a SARS-like coronavirus still exists right to this day in these bat populations, although it probably has to undergo a bit further adaptation before it can pose a human threat again,” he said.
Options for response to emerging infectious diseases include early detection; “getting ahead of the curve”; “control at source,” including improved infection control for human health and intervening to reduce risk at the animal/human interface; and “platform technologies/gap analysis,” he concluded.