Scabies is a superficial skin infestation caused by Sarcoptes scabiei, a parasitic mite, and is most common in children younger than 2 years of age. The mite, which needs contact with human skin to survive, burrows into the stratum corneum, especially near the wrists, ankles, finger webs, areolas, anterior axillary folds, genitalia, or the face in infants. This widespread contagious condition is transmitted by close personal contact with an infected person or by contact with infected bedding and clothing.

Infestation with the human louse, a blood-sucking parasite, occurs in all age and socioeconomic groups. It causes severe itching, especially at night, which in turns leads to excoriated papules, pustules, and secondary infections. Itching is caused by a reaction to louse saliva deposited into the skin as they feed several times a day. The higher the number of lice present and subsequent bites, the more severe the itching. The lesions produced at the feeding sites are flat, pinpoint, and red. Excoriations and bloody crusts are caused by scratching. The louse may be seen in clothing seams, on scalp hair presenting as gelatinous nits, in the pubic area, and on the eyelashes of newborns born to a mother with pediculoses. The female louse produces hundreds of nits every 14 days. Body lice (Pediculus corporis) live mainly in clothing, moving to the body to feed, whereas head and pubic lice live attached to the hair shaft.

Head lice (Pediculus capitis) and body lice can live up to 72 hours on clothing, combs, and so forth; are most common in school-aged children; and are highly contagious if the child comes into contact with personal
items such as pillows and combs used by an actively infested person. Transmission may also occur via sharing headphones, hair clips, clothing, or blankets. The lice may look like common dandruff flakes but are not easily brushed away. Using a Wood lamp (ultraviolet light) allows the nits to be seen as a fluorescent spot. The occipital region, nape of the neck, and above the ears are common sites of infestation. The oval hair shaft shape of African-Americans makes it difficult for the parasite to cling, thus African-Americans have a lower incidence of head lice than do other ethnic groups.

Pubic lice (Phthirus pubis) resemble a crab, and therefore the infection is commonly called “crabs.” Common sites of infestation in addition to pubic hairs include eyelashes, mustache, beard, and axillary hair. Young children should be screened for infestations on their eyelashes and eyebrows. These lice are easily detected by using a magnifying glass and looking for reddish-brown specks in the pubic area. They can only live 24 hours without a blood supply and are easily spread.