Red Circles Appear After Petting Cats? Hurry, Both You and Your Pet Need...

Learn about ringworm (tinea) transmitted between cats and humans - symptoms, diagnosis through fungal microscopy, and treatment with topical and oral antifungal medications.

Red Circles Appear After Petting Cats? Hurry, Both You and Your Pet Need...

During the Spring Festival, while visiting a friend's house, I noticed she was unconsciously scratching her arm. Lifting her sleeve, a circular red patch was clearly imprinted on the forearm, with a slightly raised edge and some peeling. Meanwhile, her British Shorthair cat was also scratching incessantly. This is ringworm — a skin disease that can be transmitted between humans and cats in both directions.

What is Ringworm, and Why Do Humans Get It from Cats?

Ringworm is caused by fungal infections. Once a cat is infected, their skin may exhibit red patches, scaling, hair loss, and itching. When humans are infected, the symptoms are similar. Some fungi (such as Microsporum and Trichophyton) can be transmitted between cats and humans through close contact.

Ringworm usually appears in the form of red patches or red circles, with scales on the edges. If the fungus infects the face, it causes 'tinea faciei'; if it lands on the body, it causes 'tinea corporis'. The most concerning scenario is when the fungus invades the scalp, resulting in 'tinea capitis' with hair loss.

This fungus can also be transmitted through dogs, rabbits, and other pets.

What Tests Should Be Done?

Experienced dermatologists can often diagnose ringworm by observing the morphology and inquiring about medical history. The key confirmatory test is 'fungal microscopy' — gently scraping skin scales from the affected area, preparing a potassium hydroxide (KOH) smear, and examining under a microscope for the presence of fungi.