Transmission, Control and Prevalence of Pubic lice or “crabs”

It is estimated by sales figures on pediculicides that more than 3 million cases of pediculosis are treated each year in the United States. Most cases are due to head and public lice infestations. Infestations by body lice seems to be less common in this country. Infestations with pubic lice are more common in people of low socioeconomic status. Epidemics of louse-borne relapsing fever and epidemics typhus are now rare since the body louse is the only species implicated as their vector. Mass epidemics of these diseases have resulted when large populations have lived in unsanitary conditions as in times of famine, disaster, and war.

“Vagabond’s disease” is a diagnosis made in persons who continually harbor these lice and whose skin becomes hardened and darkly pigmented as a result of frequent louse bites and patient response. P. pubis infestation is frequently associated with the presence of other sexually transmitted infections, and patients presenting with public should should be examined for such infections.

Human lice are transmitted from one person to another primarily by intimate contact. Although all types of human lice are relatively host-specific, crab lice occasionally have been reported to infest dogs. Both head and body lice are transmitted by sharing personal articles such as hairbrushes, combs, towels, or clothing. Pubic lice do not seem to spread as rapidly as other human lice when off the host. They have a shorter life spam (24 hours compared with several days for other lice) and their movements are more lethargic. Sexual transmission is considered the most important means of pubic lice transmission. However, there are documented cases of transmission from toilet seats, beds, and egg-infested loose hairs dropped by infested persons on shared objects.

The population with the highest incidence of pubic lice is similar to that of gonorrhea and syphilis: single persons, ages 15-25 years. Prevalence of pubic lice infestation declines gradually to age 35 and is rare in persons older than age 35. Head lice is most common in children up to 6 years of age.

(Back to background and history of pubic lice or crabs from 
“transmission, control and prevalence of pubic lice”)