Dr. Jeff Donovan is a Canadian and US board certified dermatologist specializing exclusively in hair loss. To schedule a consultation, please call the Vancouver office at 604.283.9299
As we've seen this week, "tinea capitis" refers to infection of the scalp by various types of fungi. Tinea capitis is common among children and rare in adults. People living in close contact and sharing combs and similar type material are at higher risk for acquiring tinea capitis.
A recent study from Thailand has some important lessons about tinea capitis. In this study, 60 young male Buddhist monks with tinea capitis were studied. Many different types of fungi were uncovered from scalps included the anthropophilic fungus Trichophyton violaceum (60 %) and Trichophyton mentagrophytes (43 %). Microsporum canus (common in Europe) was less commonly found (35 %) and Trichophyton tonsurans (common in North America) was found in only 13 % of cases.
Much to my surprise, 95 % of the monks had evidence of scarring alopecia - a feared complication of tinea capitis type infections. The authors proposed that educational efforts regarding avoiding sharing personal items and improvement in personal and environmental hygiene is needed to reduce infection.
Bunyaratavej et al. Clinical and Laboratory Characteristics of a Tinea Capitis Outbreak among Novice Buddhist Monks. Pediatric Dermatology 2017; 1-3.
Continuing with our theme this week of fungus, we will focus on seborrheic dermatitis and dandruff. These are extremely common scaly scalp conditions. A fungus known as "Malassezia" is now believed to play a key role in seborrheic dermatitis and dandruff.
Most human beings are covered in Malassezia. It's just part of being human and living on planet Earth. Only in a minority of people do these fungi cause any sort of health problems.
Malassezia were originally discovered by the French scientist Louis Charles Malassez in the late 1800's. There are now recognized to be 14 types of Malassezia. For trivia lovers, Malassezia globosa (mainly) and Malassezia restricta (less so) are the most common causes of seborrheic dermatitis.
Malassezia are difficult to culture so one can not simply send samples off to the lab. These fungi need fats and lipids to survive - so they live in areas of the body rich in sebaceous (oil) glands such as the scalp and face.
Anti-dandruff shampoos are generally quite effective in killing these fungi. Common ingredients in shampoos include ketoconazole, zinc pyrithione, selenium sulphide and ciclopirox.
Scalp fungal infections, also known as "tinea capitis", can be acquired from human to human transmission, or from animals or soil. In different areas of the world, the main agent causing tinea capitis differs.
The family pet is one potential source. Dogs, cats, and guinea pigs can transmit infection - mostly among children. Any child with suspected tinea capitis should have a skin scraping to determine the infective agent. Is the infection coming from another child? a pet? the soil? Treatments can be differ slightly depending on the cause.
A infective dermatophyte fungus known as Microsporum canis is the most common fungal agent transmitted by dogs. Even if the dog has no signs of skin or fur problems, transmission to humans can still take place.
In some areas of Europe, Microsporum canis is the number one cause of tinea capitis. In North America, tinea capitis in children is most often caused by another fungus known as Trichophyton tonsurans. Some Microsporum canis infections in children have the potential to be highly inflammatory and can cause discomfort and pain. Rapid treatment with oral antifungal agents is needed to prevent permanent scarring in children. Topical antifungals and topical antifungal shampoos are not effective. Oral agents are mandatory.