Fungal Hair Infections (Tinea Capitis)
The vast majority of hair infections occur in children. Look for a mild scaling of the scalp(dandruff) or a very inflammatory looking (bacterial) abscess. Hair loss is common and may be permanent.
The degree of inflammation will depend in part on the response of the immune system, but it will also depend on whether the fungus evolved to be anthropophilic (on humans) or zoophilic (on animals).
Hair fungus invasion occurs on the hair shaft that the fungus grows. Common organisms in this type of infection are T. tonsurans, M. canis and M. audouinii
- Typical of T tonsurans is the Endothrix pattern of fungal growth, which is when the fungal spores grow inside the hair shaft.
- A 'black dot' pattern evolves, in which the hairs are broken off at the scalp, leaving bald patches.
- However, there may not be much reaction and will show as a very light scale.
- If the immune reaction is strong it will appear as a 'Kerion', which is an inflamed mass similar to an abscess.
- The person's lymph nodes may be enlarged in the neck. Watch for persistent inflammation, which can cause permanent scarring of the scalp, preventing further hair growth.
- M. canis produces the Ectothrix pattern (when fungus grows on the outer surface of the hair) and results in scaly patches with hair loss. Again, the area can either be localized or generalized on the scalp. As the name, M canis suggests, this organism normally grows on dogs but also cats and kittens. This fungus will produce immunofluorecence when examined with a Woods light. (Immunofluorescence is a laboratory technique to identify specific antibodies or antigens)
- Favus, also termed Tinea favosa, is one of the three primary patterns of hair infection (ectothrix, endothrix, favus) and is a term to describe the most aggressive type of scalp hair infection. It is caused by the fungus Trichophyton schoenleinii. It exists inside the hair shaft and produces air bubbles within the hair. Yellow thick crusts produce scarring because of the inflammation that develops.
- It is very important to diagnose scalp hair fungal infection in children as well as those in close contact to clear the infection as well as to prevent permanent bald patches.