Illness in Utah and Colorado pet owners sheds light on rare, diphtheria-like infection
Add Axios as your preferred source to
see more of our stories on Google.
Illustration: Maura Losch/Axios
A diphtheria-like illness detected in Utah and Colorado is shedding light on how humans and pets exchange the bacterial infection, and how to treat it.
The big picture: In a report last week, the CDC announced that two cases, found in 2022 and 2023, were the first in the U.S. where pets and humans appear to have infected each other with C. ulcerans, a potentially harmful bacteria that hasn't been widely studied in humans.
- Corynebacterium ulcerans are more commonly found among animals — and can cause danger to wildlife and livestock, researchers in Japan wrote last year.
Zoom in: A northern Utah resident in 2022 complained of a leg wound that wouldn't heal. That patient, as well as their spouse, dog and three cats all eventually tested positive for the bacteria.
- A year later, a Colorado resident reported persistent upper respiratory problems. That patient as well as the dog of a visiting relative were infected.
The intrigue: The people and pets in the two states were given different antibiotics — and some turned out to be more effective than others.
- Erythromycin was the big winner, clearing up infections in the humans and animals alike.
How it works: C. ulcerans is similar to the bacteria that normally causes diphtheria — a highly contagious and often-serious disease that has been controlled in the U.S. by a vaccine. Diphtheria is spread through respiratory droplets or contact with sores.
- C. ulcerans also can lead to diphtheria, which includes symptoms like fever, sore throat, swelling and a gray coating in the nose or mouth, formed by dead tissue that was killed by a toxin that the bacteria produces.
- Infections of C. ulcerans are frequently asymptomatic but can become deadly if a sick patient goes untreated.
Zoom out: C. ulcerans, while uncommon, is considered an "emerging pathogen," researchers wrote in 2019.
- Cases have gradually risen in recent decades in several countries — in people and animals.
Threat level: "We do know it is very rare and therefore not a major threat to humans," Mary Hill, epidemiology manager for the Salt Lake County Health Department, wrote in a statement to Axios.
The big picture: The two U.S. cases amount to a small data set, but they provide some clues to health officials as to how best to treat C. ulcerans: antibiotics, disinfecting surfaces and limited contact with others.
- "Prompt identification, treatment, and control" are needed to avoid potentially serious complications, researchers wrote.