Crabs is the vernacular for
pubicPubic lice liceBody lice
Crab lice
Head lice
Lice, body with stool (pediculus humanus)
Lice, head - nits in the hair with close-up
Pubic lice, scientific name Phthirus pubis. They are small bugs, only a millimeter across, that live in the
pubicPubic lice area. "Crabs" comes from the fact that indeed they look a lot like crabs when
enlargedEnlarged adenoids
Enlarged prostate under a microscope, including marked enlargement of the front claws, with which it clings to
pubicPubic lice hairs. They move very slowly and are often noted as "
spotsBirthmarks - pigmented
Liver spots
Measles, koplik spots - close-up
Mongolian blue spots"; the infected person often doesn't realize the spots are living things. The nits (eggs) they lay, which are found attached to the base of the pubic hairs, are whitish and more visible than the lice themselves, so they may be more easily noticed. Itching is the most common symptom. Because lice live only in and around the pubic area, they usually are sexually transmitted--but some exceptions occur, e.g. in persons who share a bed without sex.
Happily, crabs are almost never serious, much more a nuisance than a real health threat. But the condition is seen mostly in people at risk for other STDs, so anybody with a new infection should be tested for other common STDs, like chlamyidia, gonorrhea, etc.
The most common treatments are shampoos or creams that contain the drug permethrin (e.g., Elimite) or pyrethrins (e.g., Rid).
I hope that helps. HHH, MD