Asymptomatic dermatophyte scalp carriage: laboratory diagnosis, epidemiology and management

Abstract

Asymptomatic carrier is defined as an individual who has dermatophyte-positive scalp culture without signs or symptoms of tinea capitis. The prevalence of asymptomatic carriage differs from region to region with a rate of 0.1-49%. Anthropophilic dermatophytes, Trichophyton tonsurans and Trichophyton violaceum, have been generally associated with high rates of asymptomatic carriage. Hence, the presence of dermatophytes on healthy scalp hairs of children may be a potential source of infection for schoolmates, playmates and/or households. Although it was also reported in adults, most carriage has been observed in children especially among those between 4 and 8 years of age, while male to female ratios vary between studies. It is still unclear, whether carriers should be treated with topical antifungal shampoos or oral antifungals or both, as some studies indicate that some untreated cases become culture-negative after 2-12 months. This review provides details on related dermatophyte fungi, laboratory diagnosis, epidemiology, ways of spreading as well as treatment and follow-up results of asymptomatic carriage. An integration into the school health programs is proposed, which will render the possible dealing of the subject in a comprehensive and reasonable manner.

Comparison of the contamination rates of culture media used for isolation and identification of dermatophytes

“…In the 21st century, the medical relevance of dermatophytes has grown due to increased urbanization, traveling, immigration, communal life (such as sports and fitness facilities), and the prevalence of obesity and an aging population (2). The clinical importance of proper isolation of dermatophytes needed for reliable diagnosis is well recognized by many physicians and microbiologists; however, proper isolation is not routinely utilized in most laboratories (3,4). Although fungal culture is more time-consuming than molecular diagnosis, the former is readily available throughout the world and is currently the "gold-standard" method of diagnosing fungal infections and/or carrier states and for the direct identification of dermatophytic fungi on primary isolation media (1,(3)(4)(5)(6).…”

Fungal Infections From Human and Animal Contact

“…12 Similar shifts in predominance of etiologic dermatophytes have occurred in Canada and Europe. 12,18 Tinea capitis, the most contagious of dermatophyte infections, 19 may be more often transmitted from one human to another by sluffed epithelial cells and hair than by direct contact. Both T. tonsurans and M. audouinii may be found on clothing and bedding or furniture, the former on combs and brushes.…”

“…19 Scalp carriage predominately involves anthropophilic dermatophytes, is highest among early-school-age children and has variable gender ratios. 19 The relative risk of spread from asymptomatic scalp carriers versus those with active ringworm is unclear but likely related to spore load.…”

“…19 Scalp carriage predominately involves anthropophilic dermatophytes, is highest among early-school-age children and has variable gender ratios. 19 The relative risk of spread from asymptomatic scalp carriers versus those with active ringworm is unclear but likely related to spore load. 19 Tinea capitis infections may be passed from one generation to another within household families due to low-grade infections or asymptomatic carriers.…”

“…19 The relative risk of spread from asymptomatic scalp carriers versus those with active ringworm is unclear but likely related to spore load. 19 Tinea capitis infections may be passed from one generation to another within household families due to low-grade infections or asymptomatic carriers. 12 Recently, an outbreak of M. audouinii tinea capitis in elementary schools in Germany was reportedly related to a family returning from vacation in Africa.…”