My next book, due out this summer from Enslow Publishers, is entitled Disease-Hunting Scientist: Careers Hunting Deadly Diseases. Each of its chapters focuses on one particular scientist whose work is related to hunting disease.
The chapters are much longer than these science columns, but I thought in honour of the book’s release, I’d try over the next little while to boil down some of those chapters into columns.
Call it the Reader’s Digest Condensed Books Version—not just condensed, but extremely condensed!
One chapter focuses on Jonathan Epstein, a veterinarian epidemiologist with the Consortium for Conservation Medicine. In 2005, he led the first of five expeditions into China that eventually determined that bats were the “natural reservoir” of the virus that emerged into humans in 2003 as Sudden Acute Respiratory Syndrome (SARS).
The SARS outbreak began on November 16, 2002, when the first case of an unusual form of pneumonia was reported in Guangdong province in southern China. It soon spread to countries around the world, including Canada. A vigorous containment effort paid off, but by the time SARS burned itself out, 8,098 people had become ill and 774 had died.
Scientists soon realized that SARS was caused by a new strain of coronavirus, the same kind of virus that causes many other upper respiratory infections, including the common cold.
They suspected it had emerged in the live animal markets of Guangdong.
According to Epstein, those marketplaces are “a complete menagerie. There are animals of all species, of all types, alive and dead, being kept together in very unhygienic conditions. As soon as someone picks one out, they butcher it with bare hands right there on site, so there is plenty of opportunity for cross-infection to occur among different animals.”
A WHO team tentatively concluded that the virus had jumped to humans from civets. But had it originated with civets, or did it circulate naturally in some other species?
Epstein became involved when he contacted Hume Field, a veterinarian epidemiologist in Australia, in search of research partners interested in testing bats in China for Nipah virus, which he’d been researching in Malaysia, where it emerged in 1998, killing 100 people.
Field wondered if the SARS virus might also be circulating in bats, and that eventually gave rise to the expedition led by Epstein, and the four that followed.
“There were bat biologists with expertise on a lot of things related to bats, but no one had a lot of experience collecting diagnostic samples from wild animals,” Epstein explains.
The expedition worked in extensive cave systems as much as two kilometers long, with some caverns as large as airplane hangars. To catch bats, they strung “mist nets,” similar to a volleyball net but with a much finer mesh, between two twenty-foot-tall bamboo poles.
Viruses can be transmitted by bats in their feces. To minimize that risk, the researchers wore long clothes, face masks with filters, safety glasses–and, of course gloves, made of a tough material stronger than latex that allows good movement but is puncture-resistant; bats “have pretty sharp teeth,” Epstein notes.
As each bat was untangled, it was put into a small cloth bag in which the bats could hang. That calmed them. Then the scientists began collecting samples of blood, saliva and feces.
The lab results revealed four or five different viruses within the bats, all within the SARS coronavirus family.
Putting all the pieces together, scientists now presume that bats infected with a SARS-like coronavirus were brought into the marketplace, where they came in contact with civets. In the civets, the virus mutated. It then jumped from civets to people.
“What happened with SARS is what everyone fears might happen with avian influenza,” Epstein says. Part of the mandate of Epstein’s employer, the Consortium for Conservation Medicine, is to point out that problems such as the emergence of the SARS virus arise from human behavior, not from anything the animals have done.
“The knee-jerk reaction from the public may be, well, if these bats are carrying a disease that kills people, why not just get rid of the bats. Our job is to say, no, these animals serve a very important function ecologically.
“We need to recognize that human activities are what are causing these diseases to emerge. It’s not the fault of the animals.”