Common Cold Can Kill Healthy Chimpanzees

You don’t hear about many humans dying from the “common cold” anymore, but a healthy community of wild chimpanzees in Uganda’s Kibale National Park contracted the respiratory disease, which led to 5 deaths. The puzzling outbreak has left scientists working to find out why rhinovirus C was killing healthy chimps.

A research team from the University of Wisconsin-Madison’s (UW-Madison) School of Veterinary Medicine investigated the outbreak, which occurred in February 2013, and recently published their findings in the journal Emerging Infectious Diseases.

Rhinovirus C is 1 of 3 rhinovirus species that all cause respiratory disease in humans, and is more severe than rhinovirus A and rhinovirus B. Rhinovirus C seems to affect young children the most—it can become especially severe if left untreated. The virus also affects certain people who have a version of the receptor that makes them highly susceptible to the virus.

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"It was completely unknown that rhinovirus C could infect anything other than humans," said Tony Goldberg, DVM, PhD, a professor at the UW-Madison School of Veterinary Medicine and one of the authors of the study. "It was surprising to find it in chimpanzees, and it was equally surprising that it could kill healthy chimpanzees outright."

The Outbreak

The 2013 outbreak affected most of the 56 chimpanzees in the community, but only killed 5. One of the deceased was a 2-year-old chimp named Betty, while the others were adult chimpanzees up to 57 years old.

"Chimps seem to be genetically predisposed to have problems with this virus," said James Gern, MD, a professor of allergy and immunology at the UW-Madison School of Medicine and Public Health and another author of the study. "The virus found in Betty was one that looked like it came from a human, and the level of virus in the lung was comparable to what we see in children."

Research

After examining the DNA of the chimpanzees in the affected community, Goldberg discovered that every chimp had the specific receptor that makes cells highly sensitive to rhinovirus C. He went so far as to say that there’s a “species-wide susceptibility of chimps to this virus.”

According to Ann Palmenberg, PhD, a professor of biochemistry at UW-Madison and an author of the study, rhinovirus C is not a chimp-adapted virus. She also said there is about a remarkable 9% mortality rate of rhinovirus C.

“That’s why kids with the CDHR3 high-risk mutation are at increased risk for being hospitalized with severe respiratory illness,” she said.

Implications

For the most part, outbreaks of respiratory disease in wild chimpanzees go undiagnosed even though they are not uncommon. And even when outbreaks are investigated, Goldberg said other unrelated viruses have been in play.

"In most cases, we don't find out what it is,” he said. “We're thinking that rhinovirus C might be a major, missed cause of disease outbreaks in chimps in the wild.”

The authors of this study advocate for engineering interventions and prevention strategies for rhinovirus infection for both humans and the wild apes that are now known to be at potential risk of infection.