Some fungi can
grow on your skin, causing several different conditions
including jock itch, athlete's foot and ringworm. These
fungi are known as dermatophytes.. There are about 40 species
in three genera.
Cutaneous
Infections
These fungi are not really parasitic in the sense of attacking
living tissue. They attack the dead cells of the epidermis,
and cause a kind of dermatitis. The irritation caused by
the fungus stimulates the skin cells to divide more rapidly.
This means that more flakes of skin containing infective
mycelium will be shed.
20 of the dermatophytes
grow only on people, causing diseases called ‘tineas' .
These occur on various parts of the body. They may affect
the scalp ‘tinea capitis' (ringworm of the scalp), the groin
‘tinea cruris' (jock itch) and the feet ‘tinea pedis' (athelete's
foot).
‘Tinea capitis'
is often caused by Microsporum audouinii or Trichophyton
tonsurans. Ringworm of the scalp is recognized as round,
spreading patches of irritation and/or baldness.
‘Tinea cruris'
- ‘Crotch Rot' and ‘tine pedis' athlete's foot is caused
by Epidermophyton
floccosum.This produces short-lived infections and
relies on shed skin for quick spread to other hosts.
Usually these
fungi are contracted in change rooms from small pieces of
shed skin, but spores can survive in carpets and upholstery
for up to 2 years.
Microsporum
canis
has its reservoir in the cat. It can cause ringworm of the
scalp or body. It can be transmitted to dogs or people but
will die out after one or two person to person transfers.
Trichophyton
rubrum
causes chronic infections of the foot and toenails and can
produce infective material for several years.
Treatment
Topical treatments for athlete's foot and ringworm are Tolnaftate
(Tinactine) Canesten (Clotrimazole), haloprogin, miconazole
nitrate. More persistent cases can be treated by oral doses
of Griseofulvin, an antifungal antibiotic derived from Penicillium
griseofulvum.
A much more detailed
account can be found in the book and CDROM.
