Q&A with Dr. Kenneth Katz: Severe, drug-resistant and sexually transmitted ringworm

Many people may be familiar with ringworm, a common, contagious fungal infection (having nothing to do with worms) that can infect the skin, hair, or nails. The infection can also be sexually transmitted, and in recent years, particularly severe types of ringworm infections (called “tinea” by the medical community) that are “drug resistant,” or difficult to treat with standard medications have been experienced by men who have sex with men and others.

Kenneth Katz, MD, a Kaiser Permanente San Francisco-based dermatologist who is also a member of SFAF’s Board of Directors, joins us to give additional information about this infection.

Thank you for answering our questions, Dr. Katz. Let’s start with what we know about how common this infection is. How widespread is it?

We are describing this as an emerging infection. Drug resistant ringworm cases have been seen in other parts of the world in the past 10 years, including parts of Asia and Europe, with a recent outbreak among men who have sex with men in Paris. We are now starting to recognize and see cases in the U.S. I’ve heard from a colleague in New York who has seen about 5 cases, and I have seen one case in my clinic. It was the worst case of ringworm I’ve seen in my nearly 20 years as a practicing dermatologist.

What made it the worst case you have seen? What are the symptoms of drug resistant ringworm?

I described the drug resistant case of ringworm I treated as the worst I have ever seen because of how miserable it made the patient. They were suffering so much from how itchy it was. It also took time to realize that the usual medications were not working and to do the necessary testing to determine it was drug resistant ringworm.

Compared with typical, non-drug resistant ringworm, drug resistant ringworm infections can be very severe–covering larger regions of the body–and extremely itchy. Infections show up as red and scaly sores, often round, that can be in the groin, on the butt, body, feet, and on the face. The sores can also be painful.

The cases reported in Paris were thought to be sexually transmitted because they appeared around the genitals and anus, on the butt, and on the face.

Can anyone get this type of drug resistant ringworm?

Yes. The infection is transmitted by skin-to-skin contact, so anyone coming into close contact with a sore on the skin of someone who has this type of ringworm might get it.

I will say that we don’t know exactly how much contact it takes to transmit it. Some cases have been among people who live in the same household who probably have a lot of contact with each other. And some of the infections have been described as happening during sex, which would mean quite a bit of skin-to-skin contact.

But people of any age, gender, sexual orientation, or HIV status can get ringworm or drug resistant ringworm.

What symptoms should people be aware of?

Keep an eye out for a rash on your skin, especially if it’s itchy, scaly, or widespread (or if it’s just around your genitals, anus, butt, or face).

How should people get tested and treated?

If you’re worried about a rash or other symptoms, get it checked out by a healthcare provider. You don’t necessarily have to see a dermatologist, and–depending on what the rash looks like–you might not need any testing at all. Testing involves taking and sending a sample to a lab, with specialized molecular testing for the type of fungus that causes drug resistant ringworm.

Many people, if they get an itchy rash, just grab hydrocortisone cream over the counter and start applying that. That can help for many rashes, but in the case of fungal infections, hydrocortisone and other topical steroid medicines are like fertilizer for fungus, and actually worsen the infection.

Treatment for drug resistant cases involves treatment with an oral antifungal medicine that’s not used for standard ringworm cases (it’s not a “first-line” treatment). It will typically require a longer course of treatment.

How worried should people be about this infection?

At this point, the infection is relatively uncommon, so I wouldn’t be overly concerned about it, but I think there’s a reasonable chance we might begin to see more of it in the U.S., including among gay men and other men who have sex with men.

As a clinician, I’m worried because we recently experienced an outbreak of another skin-to-skin infection in the U.S. among gay men–mpox–that was first noticed in Europe and then gained momentum in the U.S. during the summer season when people were out and about and having a lot of skin-to-skin contact.

It’s important that public health agencies and the medical community are ready to respond in case we see a similar trajectory with this infection. San Francisco AIDS Foundation has been in touch with local, state, and federal public health agencies, and we are pushing for preparation and for other agencies to take this seriously and be prepared to offer testing, treatment, and information.