What to know about rare fungal infection

A cluster of rare fungal infections was discovered in two pet cats and a veterinarian who treated them, the Centers for Disease Control and Prevention announced Wednesday in a report published in the journal Emerging Infectious Diseases.

All three cases – occurring in late 2022 and early 2023 – were caused by a fungus called Sporothrix schenckii..

The report comes as the CDC monitors the spread of a similar fungal infection, also in cats, in South America. This infection is spread by a related fungus called Sporothrix brasiliensis and has not been detected in the United States.

Sporotrichosis – the disease caused by Sporothrix infection – is rare in the United States, but it is not unheard of. It is generally contracted through contact with sharp plants that can pierce the skin like rose thorns, giving it the nickname “rose bush disease.” Sporotrichosis tends to cause a skin infection that is very slow to heal, but it is not contagious, according to the CDC.

However, when cats are infected, they carry a very high fungal load, meaning their wounds pose a higher risk of spreading the infection to other cats, dogs and people, said Ian Hennessee, an officer with the service. of epidemic intelligence at the CDC and lead author. of the report.

“They have these horrible wounds on their faces and in their nasal passages and on their paws, and those lesions are full of these fungi,” Hennessee said.

Infections do not usually cause concern among public health officials.

“The only reason this particular case came to the attention of the Department of Health was human involvement,” Dr. Erin Petro, a public health veterinarian with the Kansas Department of Health and Environment, said in Topeka. “That piqued our interest.”

The first case involved an indoor-outdoor cat who had a paw injury that did not heal with antibiotics. She transmitted the infection to a veterinary technician through a scratch, puncturing the technician’s glove and the skin underneath. A few months later, a second cat from the same household also became ill.

Neither the first cat nor the veterinary technician were immediately diagnosed with the fungal infection, delaying how quickly they received antifungal medication. The vet tech was put on antifungal medication for eight months and his infection cleared up. The first cat was also given antifungal medication, but it eventually became sicker and its owners had it euthanized. The second cat was treated much more quickly and recovered.

“The good news is that this fungal infection is treatable and cats can be cured if diagnosed early,” said Dr. Arturo Casadevall, a microbiologist and chair of molecular microbiology and immunology at the school. of Johns Hopkins Bloomberg Public Health in Baltimore. , who was not involved in the report.

However, he added, “these infections take a long time to get better.”

The Kansas Department of Health and Environment suspects there was at least one other infected cat on the property, a stray cat with facial lesions that died on the property but was not tested.

Sporothrix in Brazil

Most infections in cats, and sometimes in dogs, end like the second cat’s story, Petro said: “They get treated and it goes away.” »

Additionally, S. schenckii infections are rarely transmitted by cats.

This is not the case in South America, where the S. The brasiliensis species is much more contagious.

This species spreads rapidly among cats and has been known to infect people who are simply near infected cats, but do not come into contact with any wounds. Hennessee said these cases could be due to the fungus being on surfaces and a person touching those surfaces and then their eyes or nose, but it’s not clear.

The fungus was discovered in southeastern Brazil, but has since spread to other South American countries. From 1998 to 2016, more than 4,500 human cases contracted from cats were reported, according to the CDC.

The cases in Kansas raised concerns that S. braziliensis might be the culprit, but testing revealed it was the other species.

“We’re not sounding the alarm that Sporothrix schenckii is almost as much of a concern as Sporothrix brasiliensis,” Hennessee said.

“We know it’s possible that one day we could see cases of Sporothrix brasiliensis in the United States,” he said. “We want to raise awareness without alarming them too much. »

Petro expects that many more S. schenckii infections occur each year and do not get attention, either because the fungal infection goes unreported or goes undiagnosed in first place.

Most fungal infections in the United States go unreported, meaning the CDC doesn’t track the number of cases. Sporotrichosis is one of them.

“There is a big problem with fungal diseases, but they tend to go unnoticed,” Casadevall said.

Hennessee said the report aims to raise awareness among veterinarians and pet owners so that cases of sporotrichosis can be detected before they spread between cats or pass to humans. But infections are still considered rare and not serious in the United States.

“If you have an outdoor cat that has a lesion that hasn’t healed, you should at least ask their veterinarian if it could be a fungus,” Casadevall said. “You have to think about it.”

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