A look at how infections can leap from animals to people and how public health officials prepare for the next possible pandemic.
Every couple of months, the Public Health Nerd Club gathers in Philadelphia to drink red wine out of plastic cups and to talk shop—for fun.
They geek out over vaccination rates, infectious diseases, health disparities, data and infographics.
Jennifer Chapman co-founded the group to share stories and strategies from the frontlines, and members include researchers, a sociologist, health communicators and HIV experts from across Philadelphia.
“Sometimes science is done and it sits on the shelf and it’s hard to get it out to the community,” said Chapman, who works at the Children’s Hospital of Philadelphia, where she helps people take their HIV medication the way it’s been prescribed.
“I think some of the best work comes from casual conversations, networking,” she said.
Chapman is also hoping to raise the public profile of public health, which she says is the invisible, important stuff, that many of us take for granted, such as seat belts, clean water and sewers.
In May, the book club read the book “Spillover: Animal Infections and the Next Human Pandemic.” In it, author David Quammen tracks zoonoses, infections that leap from animals to people.
The animal—or animals—that is the preferred habitat for a virus, is called the “reservoir host.” Scientists think the relationship between the virus and that species probably goes back millions of years. The virus likely lives inconspicuously—comfortably replicating–in the host animal without killing the reservoir, or even making it sick.
University of Pennsylvania infectious disease physician Stephen Gluckman led the book club discussion in May. He was expecting “Spillover” to be a sensational story–shoddily researched.
“On both counts I was wrong,” Gluckman said.
“I was impressed with the writer’s ability to explain science,” he said. “I think the description of R0 [R-naught]–that magic number that if it’s above one you have a sustainable epidemic and if it’s below one, you don’t. I think that was very well done, and that’s statistics. Nobody likes statistics.”
Quammen writes that zoonotic viruses are like predators that eat their prey from within:
“Although infectious disease can seem grisly and dreadful, under ordinary conditions it’s every bit as natural as what lions do to wildebeests and zebras, or what owls do to mice. But conditions aren’t always ordinary.”
Over time, some viruses change and are able to move out of their home in a bat, a mouse or a chimpanzee. Pathogens can adapt to cause havoc in humans.
Malaria, Lyme disease, Ebola and HIV are all zoonotic diseases.
“The concern there is not just that they make a person sick,” Gluckman said. “Do they have the ability to spread and make a lot of people sick?”
Anticipating the next potential pandemic
During book group, Carter Cowden, a researcher from The Children’s Hospital of Philadelphia, asks Gluckman the question that’s on everyone’s mind: “What illnesses are you worried most about causing the next pandemic?”
For Gluckman, it’s flu.
That’s not the exotic, scary answer you might expect, but it’s the kind of practical answer you get from public health people.
They wonder about the next bug that’s contagious enough and deadly enough to go global–not to worry, but to be prepared.
The group grouses that too few Americans get a flu shot, and Gluckman says too many doctors have downplayed the seriousness of influenza. Too often physicians use the term ‘flu’ when people really have a cold.
“People often don’t have an appreciation for how bad a disease it is,” Gluckman said. “Even if you don’t die, you are sick. It’s not a cold.”
Around the book-group circle, “Spillover” gets high praise for its sound science, plainly told. Nicole Johns, with the Philadelphia Office of HIV Planning, said she especially liked the chapters that tell the origin story for the Human Immunodeficiency Virus. Johns said the writing reminded her of the stigma-free depictions of HIV that she uses as education tools in her work.
“If this was the conversation we were having about HIV all along, thinking about it as a zoonosis, and looking at it as something that emerged in the beginning of the 1900s, and not 1981 with an airline attendant, where would we be in treatment and prevention?” Johns said.
Further along—perhaps—in the fight against the epidemic, she said.
Middle East Respiratory Syndrome
Middle East Respiratory Syndrome–or MERS–is the latest suspected zoonotic disease that’s grabbed the attention of those in the public health industry. There are no cases in Pennsylvania, but a few days after the illness reached the United States, there was a statewide conference call to talk about the science and to tamp down the hype.
Pennsylvania’s Physician General Carrie DeLone pleaded with doctors not to clog-up the state testing laboratory with specimens from patients who may have a fever or respiratory distress, but probably do not have MERS.
DeLone said doctor’s offices and emergency rooms should gather a travel history from patients to find out if they have traveled to the Middle East in the last 14 days—and then call the state health department if there’s a suspected case of MERS.
The Pennsylvania Medical Society hosted the call, and Michael Fraser, the group’s executive vice president, called for a measured response.
“It’s a little bit of change in practice,” Fraser said. “It’s not just another day at the office, you don’t usually ask someone if they’ve been to the Arabian Peninsula when they show up at the office.”
MERS has a 30 percent death rate—which is high–but seems to require very close contact to spread from one person to the next. It is a coronavirus and is distantly related to the SARS virus that sickened patients and health workers in 2003.
“Public health officials are watching it closely, they fear that it might have the potential to become more transmissible from human to human,” said science writer David Quammen.
At a briefing in mid-May, Centers for Disease Control and Prevention officials said there is no evidence, so far, that the MERS virus has changed in a way that would make it easier to spread person to person.
In his book “Spillover” Quammen walks with disease detectives in the field as they track different zoonoses.
When a new pathogen starts to make humans sick, Quammen says scientists try to answer certain questions quickly: “Where did it come from? What animal? Where is this thing lurking, why did it spill into humans now? How far is it going to go?”
“It turned out that the SARS virus was pretty good at riding airplanes,” Quammen said. “Eventually it infected about 8,000, and killed about 800.”
Another zoonosis, Ebola, had a high death rate and was devastating in the regions where the outbreaks surfaced, but it’s not “the next big one” that public health experts worry about.
“Ebola is the virus that people love to hate,” Quammen said. “They’ve heard lurid things about this horrific virus that comes off the central African forest living in some creature there. But it does not ride airplanes very well.”
To be a true threat as a global pandemic, a virus needs be both deadly serious and highly contagious.
Intrigue with zoonosis
Lots of people love a good disease-detective story, but zoonotic diseases are pretty common. So why has the search for zoonoses and their reservoir hosts captured our imagination, including the 2011 movie “Contagion” and the popular thriller “The Hot Zone”?
“It’s–in a way–more interesting and dramatic than diseases that circulate in water or sewage,” Quammen said.
The fact that a virus comes from bats or camels—for many, that’s mysterious.