Clinical Presentation

Pediculosis is diagnosed by positive identification of the adult louse either with the naked eye or under the microscope, as well as by the positive identification of the oval-shaped nits on the hair shaft or clothes under the microscope. (See Figures 1-3 on main page).

Symptoms in Humans:
The symptoms of pediculosis are both superficial and mild. Ectoparasites (the lice) are found on the scalp, skin or clothes. Few adult parasites are usually found on the skin but nits are present in hundreds. For example, body lice are found on the body only when they are feeding, otherwise the are typically found on the inner seams fo clothes. Priuritus (or itching) is very common where lice and nits are on the skin. At the site of infestation on the skin itchy papules can develop in response to the saliva and fecal excretions of the louse where it bites the host. Occasionally these papules can lead to secondary bacterial infection, due to bacteria present in the saliva and feces of the louse, with symptoms similar to mange. Parasites such as those that cause louse-borne relapsing fever (B. recurrentis) and louse-borne typhus(R. prowazeki, R. quintana)can also be transmitted in this way. Typhus infection symptoms include fever and chills, agitation alternating with fatigue, and on the fifth or sixth day of the fever, macular eruption on the skin.


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