Ringworm (also known as tinea, jock itch, or athlete’s foot) is a common infection caused by dermatophyte fungi, known to affect skin, hair, or nails. It causes skin infections that are typically mild and are often treated with topical antifungals.
However, in recent years, newly emerging dermatophyte strains have been causing more severe and harder-to-treat ringworm. Notably, one emerging strain, Trichophyton mentagrophytes genotype VII(TMVII), is associated with sexual contact. In recent years, TMVII infections linked to sexual contact have been reported among men who have sex with men in Europe and in travelers returning from Southeast Asia. The first US case of TMVII was reported in June 2024, after which public health authorities were alerted to additional cases; all were associated with recent sexual contact. Other dermatophyte species have also been reported to cause ringworm transmitted through sexual contact.
Here are some key points to know about sexually transmitted ringworm.
Tell me more about sexually transmitted ringworm: What is causing it?
Skin-to-skin contact is a common mode of ringworm transmission. In recent years, transmission of ringworm via intimate or sexual contact has been increasingly recognized. However, clinicians may not immediately consider ringworm when evaluating genital, facial, or perianal lesions. Infections with sexually transmitted TMVII commonly cause lesions on anatomical sites that may be exposed during intimate or sexual contact, such as the face, genitals, and perianal region. Sexual transmission of TMVII has been reported in Europe, predominantly among men who have sex with men, for several years. Other dermatophyte strains have been reported in association with sexual contact, including the emerging strain Trichophyton indotineae. However, sexual transmission is not the main mode of transmission for T indotineae and other dermatophyte strains.
When should clinicians suspect a potential case of sexually transmitted ringworm?
Providers should consider sexually transmitted ringworm when seeing ringworm in locations associated with intimate contact (for example, a rash on or around the genitals, perianal area, or mouth).
The typical appearance of ringworm is a raised, ring-like, erythematous rash with a scaly border that grows over time. The rash may appear pink, brown, or gray on different types of skin. Patients may note itching and flaking of the rash. In areas with hair such as the beard area, ringworm can present as pustules and be associated with hair loss.
Emerging ringworm infections can present in atypical or more severe ways, including a highly inflammatory (painful, scarring, or otherwise severe) rash, a rash affecting a large area or multiple sites, nodules, and pustules.
Sexually transmitted ringworm may be considered based on sexual history and recent sexual contact with someone with known TMVII. Recent history of travel to a region with reported sexually transmitted ringworm may increase suspicion of TMVII. In patients with a travel history to South Asia, T indotineae should be considered, especially if the rash does not improve with oral terbinafine.
How can testing help guide the diagnosis of sexually transmitted ringworm infection?
When evaluating a rash that may represent ringworm, providers should use a confirmatory test such as potassium hydroxide (KOH) preparation when possible. KOH prep can confirm the presence of a fungus that causes ringworm, but it does not identify the species or type of ringworm. Testing such as fungal culture and molecular testing can help identify specific types of ringworm, but these tests are not often performed and may take a long time to yield results.
Routine fungal cultures cannot identify TMVII and T indotineae; these tests may identify the genus Trichophyton, but only advanced molecular testing, which is available at selected US laboratories, can identify TMVII and T indotineae.
We recommend confirmatory testing because ringworm can easily be misdiagnosed as skin conditions such as psoriasis or eczema. The use of topical steroids can worsen a ringworm infection, so clinicians should be cautious about treating a rash with topical steroids if the etiology is unclear. Treatment should not be delayed if testing is not available.
Clinicians who suspect a case of TMVII infection or infection with another emerging type of severe or antifungal-resistant ringworm can contact the CDC at fungaloutbreaks@cdc.gov. More details on how clinicians can pursue testing to identify emerging strains of ringworm can be found on the American Academy of Dermatology (AAD) emerging diseases task force website.
How should clinicians treat and manage sexually transmitted ringworm?
If TMVII infection is suspected, providers can consider starting empirical treatment with oral terbinafine. Although data are limited, experience from case series suggests that TMVII may require oral antifungal treatment because it can cause severe skin infections and often does not improve with topical antifungals. Clinicians should advise patients that they may need prolonged treatment courses until the rash resolves, with possible need for treatment courses of 6-8 weeks or longer.
Any diagnosis of a sexually transmitted infection is an opportunity to engage patients in comprehensive sexual health services. Patients with suspected sexually transmitted ringworm should be evaluated for HIV and other sexually transmitted infections, including syphilis, chlamydia, and gonorrhea; clinicians should discuss and facilitate access to other preventive services, such as HIV preexposure prophylaxis if the patient is HIV negative and at risk for HIV. Patients should also notify their partner(s) about the diagnosis.
Is sexually transmitted ringworm a public health concern?
It is important to know that very few cases of TMVII have been reported in the US thus far. CDC continues to monitor emerging dermatophyte strains because these types of ringworm can cause more severe or difficult-to-treat infections. Clinicians should be aware of the potential severity of sexually transmitted ringworm infections and of how diagnosis and treatment of these infections may differ from typical management of ringworm.
So far, TMVII, the dermatophyte strain most associated with spread through sexual contact, has not been documented to have antifungal resistance. More rarely, sexually transmitted ringworm may be caused by other emerging dermatophyte strains that are antifungal-resistant, such as T indotineae. Itraconazole is the recommended first-line treatment for T indotineae infections.
How can clinicians counsel patients with sexually transmitted ringworm?
Ringworm can spread with skin-to-skin contact, so patients should avoid such contact with others while they have a rash. They should also avoid sharing personal items (such as razors or towels) and clothing, and launder their clothing, towels, and bedding in a high heat cycle.
People can reduce their risk of getting all types of ringworm infection by keeping their skin clean and dry, changing their socks and underwear daily, and wearing sandals in public locker rooms and other public spaces. People should avoid skin-to-skin contact with anyone with ringworm or an unexplained rash. Before having sex, people can check in with their partners and be aware of unexplained rashes on their partners’ bodies.
Where can clinicians go to learn more about sexually transmitted and other emerging types of ringworm?
CDC has partnered with the AAD to create set of online resources for clinicians for diagnosing and managing emerging dermatophyte infections. Clinicians who suspect or confirm antimicrobial resistant ringworm infection are also encouraged to submit cases to the AAD’s Emerging Diseases Registry. Clinicians wanting further guidance on how to manage suspected or confirmed ringworm infection with an emerging dermatophyte strain can also contact the CDC at fungaloutbreaks@cdc.gov. Useful information on emerging dermatophyte infections for providers and patients is also available on CDC’s website.
Relevant Reading
Zucker J, Caplan AS, Gunaratne SH, et al. Notes from the Field: Trichophyton mentagrophytes genotype VII — New York City, April-July 2024. MMWR Morb Mortal Wkly Rep 2024;73:985-988. Source
Spivack S, Gold J, Lockhart SR, et al. Potential sexual transmission of antifungal-resistant Trichophyton indotineae. Emerg Infect Dis. 2024;30:807-809. Source
Jabet A, Dellière S, Seang S, et al. Sexually transmitted Trichophyton mentagrophytes genotype vii infection among men who have sex with men. Emerg Infect Dis. 2023;29:1411-1414. Source
COMMENTARY
What to Know About Sexually Transmitted Ringworm
Priyanka Anand, MD; Jeremy A.W. Gold, MD, MS; Laura A.S. Quilter, MD, MPH
DISCLOSURES
| December 13, 2024Editorial Collaboration
&
Ringworm (also known as tinea, jock itch, or athlete’s foot) is a common infection caused by dermatophyte fungi, known to affect skin, hair, or nails. It causes skin infections that are typically mild and are often treated with topical antifungals.
However, in recent years, newly emerging dermatophyte strains have been causing more severe and harder-to-treat ringworm. Notably, one emerging strain, Trichophyton mentagrophytes genotype VII(TMVII), is associated with sexual contact. In recent years, TMVII infections linked to sexual contact have been reported among men who have sex with men in Europe and in travelers returning from Southeast Asia. The first US case of TMVII was reported in June 2024, after which public health authorities were alerted to additional cases; all were associated with recent sexual contact. Other dermatophyte species have also been reported to cause ringworm transmitted through sexual contact.
Here are some key points to know about sexually transmitted ringworm.
Tell me more about sexually transmitted ringworm: What is causing it?
Skin-to-skin contact is a common mode of ringworm transmission. In recent years, transmission of ringworm via intimate or sexual contact has been increasingly recognized. However, clinicians may not immediately consider ringworm when evaluating genital, facial, or perianal lesions. Infections with sexually transmitted TMVII commonly cause lesions on anatomical sites that may be exposed during intimate or sexual contact, such as the face, genitals, and perianal region. Sexual transmission of TMVII has been reported in Europe, predominantly among men who have sex with men, for several years. Other dermatophyte strains have been reported in association with sexual contact, including the emerging strain Trichophyton indotineae. However, sexual transmission is not the main mode of transmission for T indotineae and other dermatophyte strains.
When should clinicians suspect a potential case of sexually transmitted ringworm?
Providers should consider sexually transmitted ringworm when seeing ringworm in locations associated with intimate contact (for example, a rash on or around the genitals, perianal area, or mouth).
The typical appearance of ringworm is a raised, ring-like, erythematous rash with a scaly border that grows over time. The rash may appear pink, brown, or gray on different types of skin. Patients may note itching and flaking of the rash. In areas with hair such as the beard area, ringworm can present as pustules and be associated with hair loss.
Emerging ringworm infections can present in atypical or more severe ways, including a highly inflammatory (painful, scarring, or otherwise severe) rash, a rash affecting a large area or multiple sites, nodules, and pustules.
Sexually transmitted ringworm may be considered based on sexual history and recent sexual contact with someone with known TMVII. Recent history of travel to a region with reported sexually transmitted ringworm may increase suspicion of TMVII. In patients with a travel history to South Asia, T indotineae should be considered, especially if the rash does not improve with oral terbinafine.
How can testing help guide the diagnosis of sexually transmitted ringworm infection?
When evaluating a rash that may represent ringworm, providers should use a confirmatory test such as potassium hydroxide (KOH) preparation when possible. KOH prep can confirm the presence of a fungus that causes ringworm, but it does not identify the species or type of ringworm. Testing such as fungal culture and molecular testing can help identify specific types of ringworm, but these tests are not often performed and may take a long time to yield results.
Routine fungal cultures cannot identify TMVII and T indotineae; these tests may identify the genus Trichophyton, but only advanced molecular testing, which is available at selected US laboratories, can identify TMVII and T indotineae.
We recommend confirmatory testing because ringworm can easily be misdiagnosed as skin conditions such as psoriasis or eczema. The use of topical steroids can worsen a ringworm infection, so clinicians should be cautious about treating a rash with topical steroids if the etiology is unclear. Treatment should not be delayed if testing is not available.
Clinicians who suspect a case of TMVII infection or infection with another emerging type of severe or antifungal-resistant ringworm can contact the CDC at fungaloutbreaks@cdc.gov. More details on how clinicians can pursue testing to identify emerging strains of ringworm can be found on the American Academy of Dermatology (AAD) emerging diseases task force website.
How should clinicians treat and manage sexually transmitted ringworm?
If TMVII infection is suspected, providers can consider starting empirical treatment with oral terbinafine. Although data are limited, experience from case series suggests that TMVII may require oral antifungal treatment because it can cause severe skin infections and often does not improve with topical antifungals. Clinicians should advise patients that they may need prolonged treatment courses until the rash resolves, with possible need for treatment courses of 6-8 weeks or longer.
Any diagnosis of a sexually transmitted infection is an opportunity to engage patients in comprehensive sexual health services. Patients with suspected sexually transmitted ringworm should be evaluated for HIV and other sexually transmitted infections, including syphilis, chlamydia, and gonorrhea; clinicians should discuss and facilitate access to other preventive services, such as HIV preexposure prophylaxis if the patient is HIV negative and at risk for HIV. Patients should also notify their partner(s) about the diagnosis.
Is sexually transmitted ringworm a public health concern?
It is important to know that very few cases of TMVII have been reported in the US thus far. CDC continues to monitor emerging dermatophyte strains because these types of ringworm can cause more severe or difficult-to-treat infections. Clinicians should be aware of the potential severity of sexually transmitted ringworm infections and of how diagnosis and treatment of these infections may differ from typical management of ringworm.
So far, TMVII, the dermatophyte strain most associated with spread through sexual contact, has not been documented to have antifungal resistance. More rarely, sexually transmitted ringworm may be caused by other emerging dermatophyte strains that are antifungal-resistant, such as T indotineae. Itraconazole is the recommended first-line treatment for T indotineae infections.
How can clinicians counsel patients with sexually transmitted ringworm?
Ringworm can spread with skin-to-skin contact, so patients should avoid such contact with others while they have a rash. They should also avoid sharing personal items (such as razors or towels) and clothing, and launder their clothing, towels, and bedding in a high heat cycle.
People can reduce their risk of getting all types of ringworm infection by keeping their skin clean and dry, changing their socks and underwear daily, and wearing sandals in public locker rooms and other public spaces. People should avoid skin-to-skin contact with anyone with ringworm or an unexplained rash. Before having sex, people can check in with their partners and be aware of unexplained rashes on their partners’ bodies.
Where can clinicians go to learn more about sexually transmitted and other emerging types of ringworm?
CDC has partnered with the AAD to create set of online resources for clinicians for diagnosing and managing emerging dermatophyte infections. Clinicians who suspect or confirm antimicrobial resistant ringworm infection are also encouraged to submit cases to the AAD’s Emerging Diseases Registry. Clinicians wanting further guidance on how to manage suspected or confirmed ringworm infection with an emerging dermatophyte strain can also contact the CDC at fungaloutbreaks@cdc.gov. Useful information on emerging dermatophyte infections for providers and patients is also available on CDC’s website.
Relevant Reading
Zucker J, Caplan AS, Gunaratne SH, et al. Notes from the Field: Trichophyton mentagrophytes genotype VII — New York City, April-July 2024. MMWR Morb Mortal Wkly Rep 2024;73:985-988. Source
Spivack S, Gold J, Lockhart SR, et al. Potential sexual transmission of antifungal-resistant Trichophyton indotineae. Emerg Infect Dis. 2024;30:807-809. Source
Jabet A, Dellière S, Seang S, et al. Sexually transmitted Trichophyton mentagrophytes genotype vii infection among men who have sex with men. Emerg Infect Dis. 2023;29:1411-1414. Source
Public Information from the CDC and Medscape
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