Biomedical Engineering Reference
In-Depth Information
Three species of lice (Class Pediculus and Class Phthirus) have adapted to
infect humans: Pediculus humanus capitus, the head louse, Pediculus huma-
nus corporis, the body louse, and Phthirus pubis (crab louse or pubic louse).
These lice are all hematophagus (blood-sucking), and can produce an inflam-
matory skin reaction at the site of infection. The eggs of lice are called nits.
The nits of head lice and pubic lice are deposited on hairs. The nits of body
lice are deposited on skin and clothing.
Hexapoda
Insecta
Diptera
Calliphoridae
*Cochliomyia
Oestroidea
*Calliphoridae
*Sarcophagidae
*Dermatobia
Myiasis is an infection of the larvae (maggots) of flies (Class Diptera). The
screw-worm (Cochliomyia hominivorax), despite its vivid name, is a type of
fly.
Because insect larva are small and squishy, they are often mistaken for
worms. The disease caused by Cochliomyia hominivorax is manifested by
worm-like larvae growing in skin. Whereas myiasis caused by most other
species of fly is an infection of dead animals, or necrotic parts of living ani-
mals (e.g., blowfly, flesh-fly), the screw-worm lays its larvae in living flesh
(human or animal). Fortunately, the screw-worm has been eradicated in the
USA Human and animal screw-worm infections occur in Central and South
America.
Another fly that can infect living human skin is the human botfly
(Dermatoba hominis). The botfly larvae attach to the skin, sometimes using
a passive vector, such as a mosquito, to arrive at a convenient entry point, at
which they burrow downwards. The botfly is found in Central and South
America.
When the larvae of flies are accidentally ingested, they can be found any-
where in the intestinal tract. If they are actively growing, the condition is
referred to as intestinal myiasis. If they are simply passing through, without
larval growth, the condition is called intestinal pseudomyiasis. Both conditions
are rare [100].
Hexapoda
Insecta
Siphonaptera
Hectopsyllidae
*Tunga
