Page content: Victorian statutory requirement | Infectious agent | Identification | Incubation period | Public health significance & occurrence | Reservoir | Mode of transmission | Period of communicability | Susceptibility & resistance | Control measures | Outbreak measures

Victorian statutory requirement

Notification is not required.

School exclusion: readmit the day after appropriate treatment has commenced.

Infectious agent

Microsporum spp. includes Microsporum canis as the primary causative agent in Australia of tinea capitis and corporis. Trichophyton spp. also cause disease for example T. rubrum, T.mentagrophytes and Epidermophyton floccosum.

Identification

Clinical features
The clinical features of tinea infections are those of superficial fungal infection of the skin, nails or hair:

• tinea capitis results in a small papule that spreads peripherally leaving fine, scaly patches of temporary baldness. Infected hairs become brittle and break off easily.
• tinea corporis appears as a flat, red, ring-shaped lesion of the skin. It is usually dry and scaly or moist and crusted but sometimes contains fluid or pus. The lesion tends to heal centrally.
• tinea pedis is commonly known as ‘athlete’s foot’. It occurs as itchy, scaling, cracking of the skin or blisters containing a thin watery fluid. This occurs commonly between the toes.
• tinea unguium is a chronic fungal disease involving one or more nails of the hands or feet. The nail gradually thickens and becomes discoloured and brittle. Caseous-looking material forms beneath the nail or the nail becomes chalky and disintegrates.

Method of diagnosis
Diagnosis can be made by microscopic examination of material from the affected area or by fungal culture.

Incubation period

The incubation period differs:

• tinea corporis has an incubation period of four to ten days
• tinea capitis has an incubation period of 10–14 days
• the incubation period of tinea pedis and tinea unguium is probably weeks but exact limits are unknown.

Public health significance & occurrence

Tinea capitis mainly affects children.

M. canis is usually contracted from infected kittens or puppies.

The highly contagious M. audouinii spreads from person to person and does not occur in Australia.

Tinea capitis may extend to tinea corporis. It occurs worldwide.

Tinea corporis occurs worldwide and relatively frequent. Males are infected more than females. Infection can occur from direct or indirect contact with skin and scalp lesions of infected persons or animals.

Tinea pedis occurs in children and adults and is spread by using communal facilities such as showers at swimming pools. Adults are affected more often than children and males more than females. Infection is more frequent and severe in hot weather.

Tinea unguium occurs commonly but there are low rates of transmission, even to close family associates. It is spread by direct contact with skin or nail lesions of infected persons or indirectly through contact with contaminated floors or showers.

Reservoir

Reservoirs for tinea are:

• tinea capitis: humans and animals including dogs, cats and cattle
• tinea corporis: humans, soil and animals including cattle, kittens, puppies, guinea pigs, mice and horses
• tinea pedis: humans
• tinea unguium: humans and rarely animals or soil.

Mode of transmission

Direct transmission occurs through human to human contact, for example T. rubrum and T.mentagrophytes. Animal-to-human contact also occurs, for example M. canis and T. verrucosum. Tinea can be transmitted indirectly through contaminated soil, for example M. gypseum.

Period of communicability

The fungus persists on contaminated materials as long as lesions or animal hair harbour viable spores.

Susceptibility & resistance

Young children are particularly susceptible to tinea capitis (Microsporum canis). All ages are susceptible to infections particularly those caused by Trichophyton spp.

Susceptibility to tinea corporis is widespread. It is aggravated by friction and excessive perspiration in axillary and inguinal regions, and when environmental temperatures and humidity are high.

Susceptibility is variable for tinea pedis and infection may be inapparent. Repeated attacks are frequent.

An injury to the nail predisposes to tinea unguium infection. Reinfection is frequent.

Control measures

Preventive measures
Measures differ according to cause:

• for tinea capitis parents should be educated about modes of spread from infected children and animals
• for tinea corporis shower bases, mats and floors adjacent to showers should be disinfected. Infected animals should be avoided
• for tinea pedis gymnasiums, showers and similar sources of infection should be thoroughly cleaned and washed. Shower areas should be frequently hosed and rapidly drained. Users of such areas should be encouraged to carefully dry (and perhaps powder) between their toes.

Control of case
Control depends on the cause:

• for tinea corporis infected children should be excluded from schools and swimming pools until at least 24 hours following the commencement of appropriate treatment. It can be treated effectively with topical medications
• for tinea capitis oral griseofulvin is the treatment of choice for resistant infection, for example T. tonsurans. Topical anti-fungal medication may be used concurrently
• for tinea pedis topical fungicides are recommended but oral griseofulvin may be indicated in severe protracted disease. Feet should be kept dry as possible and exposed to air by wearing sandals. Socks of heavily infected individuals should be boiled or discarded to prevent reinfection
• for tinea unguium oral terbinafine should be given daily for six weeks for finger nails and twelve weeks for toe nails.

Consult the current version of Therapeutic guidelines: antibiotic (Therapeutic Guidelines Limited).

Note: M. canis infection is self-limiting in children before puberty and griseofulvin may not be necessary. Consult a specialist about treatment.

Control of contacts
Investigate household contacts, pets and farm animals for evidence of infection. Treat infected contacts, human or animal.

Control of environment
See Preventative measures, above.

Outbreak measures

Children and parents should be educated about modes of spread, prevention and the necessity of maintaining a high standard of personal hygiene. In case of epidemics, consider examination of all children to identify cases. Disinfect contaminated articles.