Pathogenesis (development of disease)
The head louse (Pediculus humanus capitis) belongs to the ectoparasites of humans, that are parasites that live on the body surface. They stay exclusively in the body heat. They belong to the bloodsuckers. All stages of development take place on the host. Freshly hatched nymphs (young lice) are 1-2 mm, adult lice are about 3 mm long.
Larvae hatch from the eggs attached to the hair after about seven to ten days. After another ten days, the larvae are sexually mature. The life span is about four weeks.
Empty, whitish egg cases (nits) remain attached to the hair after the nymphs hatch.
Head lice require blood every two to three hours. They survive for a maximum of three days separated from the host.
Head lice cannot jump. Pets are not carriers.
Etiology (causes)
Behavioral causes
- Transmission through close physical contact (“hair-to-hair contact”).
- Less common is transmission through objects that come into contact with the hair
