Viruses can be expected to increase with global warming as humans and wild animals are forced into closer contact, a leading Israeli epidemiologist said Monday, as the world battled a pandemic that seemed potentially more dangerous than any other infectious disease in a century.
“Many emerging infectious diseases are the result of animal-human contact,” Prof. Manfred Green of Haifa University’s Department of Epidemiology, a former head of the university’s School of Public Health, told The Times of Israel.
“Global warming, along with population growth, is a factor that is likely to increase that contact. Animals that lose their natural habitats through climate-related phenomena such as fire, or that migrate as temperatures get higher, will probably move increasingly into the human space in search of food. People will continue to move into wildlife spaces such as forests to farm. Either way, the contact is likely to increase.”
AIDS originated with chimpanzees and Ebola is suspected to have come from African fruit bats, for example. Bats are also suspected in the current coronavirus outbreak, in light of the genetic similarity between bat viruses and human coronaviruses, including the SARS-CoV (Severe Acute Respiratory Syndrome virus) and MERS-CoV (Middle East Respiratory Syndrome virus). The latter, which began in Saudi Arabia, has been found in several countries in camels.
In 2009, the US Agency for International Development (USAID) launched PREDICT to strengthen the world’s ability to detect and act to limit the potential for zoonotic viruses — those passing from animals to humans — with pandemic potential.
Researchers found that “nearly 75 percent of all new, emerging, or re-emerging diseases affecting humans at the beginning of the 21st century are zoonotic.”
During its first decade, PREDICT discovered 1,100 unique viruses, provided aid to 60 disease detection laboratories, and trained 6,200 people in 30 countries.
According to The New York Times, it had the support of former US presidents George W. Bush and Barack Obama. Now, however, “the federal government is quietly shutting” the program down.
The paper quoted Dr. Gro Harlem Brundtland, the former director-general of the World Health Organization, as saying that the end of PREDICT’s activities was “really unfortunate, and the opposite of what we’d like to see happening.”
The WHO has warned categorically that climate change, along with other demographic, social, and technological changes, will affect infectious disease occurrence.
That includes vector-borne diseases, responsible for more than 17% of all infectious illnesses and more than 700,000 deaths annually.
Scientists already know that the ranges of mosquitoes — carriers of malaria — are expanding as the world warms.
Do viruses just disappear?
Asked what makes viruses disappear, Green said, “Part of the answer is that we don’t know.”
The H2N2 Asian, or avian, flu pandemic of 1957, which also originated in China, and killed an estimated one to two million people, disappeared before it could be fully understood, he said.
The SARS outbreak of 2003 — which infected more than 8,000 people worldwide, killed nearly 800 and also had its origins in animals — was so lethal that people died quickly, limiting the virus’s ability to spread.
But (H1N1)pdm09, a strain of flue that surged across the US and then onto the wider world in 2009 and caused 12,500 deaths in the US and anything from 151,700 to 575,400 globally, continues to kill, although in much smaller numbers. Unlike the coronavirus, it mainly affects children and young and middle-aged adults.
Most viruses stayed around, Green said, but tended to use up most of their available hosts and get weaker as they spread. If they were unable to adapt to the immunity of people who had already gotten over the disease, they died out.
“The likely assumption is that coronavirus will be with us for years and that most people will become immune, but that it will continue to affect particular populations such as newborns, where it will be very mild.”
Green, a former head of the Health Ministry’s National Center for Disease Control, went on, “If the epidemic continues and we don’t manage to control it, then according to data from Italy, China and South Korea, 1% of corona cases could die. Even half a percent could mean 10,000 to 15,000 deaths in the country, mainly among the elderly.”
The government, however, was “pretty much taking the advice of the medical establishment” on the coronavirus, he continued, saying that he did not see any political calculation in the decision-making despite claims to the contrary. “Health Minister [Yaakov] Litzman has some good professional people around him. I think we will pull through this, but it could take a year.”