I don't really believe "Crabs" should be classified as an STD, because it is not really a disease, and for certain individuals is often non-sexually transmitted. It is an insect infestation on the hair outside the body, and is usually treated not with medication, but with insecticidal shampoo or cream (Pyrethrins/piperonyl shampoo over the counter; Kwell, etc. by prescription). (There are, however, some internally-taken compounds which will kill them, but these are not commonly used.) If your dog has fleas, you don't usually say he has a disease, but rather needs a flea bath. Similarly, if a human has crabs, I'm not sure it should be considered a disease in the same class as infectious STD's, or other parasitic infestations, which do internal things in the body. Someone mentioned "jock-itch," which is a fungal infection. Given the choice, I'd personally feel better about crabs, but not much. The lice are not killed by washing, etc, so hygene or lack thereof is not a factor. Crabs are the smallest of the several forms of lice which infest human hair. They prefer softer hair in dark, moist locations, and therefore will not usually migrate to the scalp, although they sometimes do lodge in eyebrows and beards. The lice grab onto a hair shaft at the point where it meets the skin, and periodically bite at the base of the hair to obtain nourishment. On many people, this causes intense itching, and the major medical complication of crabs is self-inflicted injury from excessive scratching. They then lay their eggs glued to the hair shaft in a little ball called a nit. Note that the whole of this is external to the body, except for the biting. From what I've read, the nature of the lice's fluids present when biting make it unlikely that infection will occur at the bite site.
On most people, only the genital region has enough suitable hair to support them, so the infestation, if transmitted by sexual contact, generally stays in the crotch. However, for men with lots of fine body hair, they tend to migrate all over the body. (Crab lice are much smaller than typical body lice, look different, and can be easily differentiated from a normal body lice infestation.) The chest is a prime target, but men with very hairy arms or sometimes legs can support them there as well. As such, very hairy men can spread crabs by upper body contact. My observation is that the little things actually prefer the chest/arm region over the crotch if the host is very shaggy.
Getting rid of Crabs is simple, but you need to follow certain procedures carefully, particularly if using over the counter products and if you are very hairly. The OTC products kill the live lice, but do not kill the eggs. The instructions often talk about mechanically removing the eggs by combing, but this is more or less impossible if your body is very hairly all over. Therefore, you have to treat yourself once, then retreat after waiting a period of time longer than the gestation period of the eggs, but shorter than it takes the hatchlings to reach sexual maturity, so that the next batch hatches, but are not yet able to lay more eggs. This period is about 3 days, but the most effective course is to use two follow-up treatments after the initial one, each spaced two days. Becasue the eggs can lodge in clothing and bedding, it is important to change and wash these items with each treatment. It takes very hot water to destroy the eggs in washing, so the safest bet is just to not reuse a potentially contaminated item for about 10 days. Kwell and certain other prescription remedies will destroy the eggs, so they work in one treatment, but the precautions in handling clothing and bedding are still necessary to avoid reinfestation. In either case, if you are furry, you must treat your entire body, not just the groin, even if that is where the problem seems to be limited to. If you have a partner, you should synchronize treatments. The OTC shampoos, when sold in the USA, say to apply them for not more than 10 minutes, in accordance with FDA guidelines. However, I note that the exact same formulations, when sold in certain other countries, have instructions saying to leave them on for 30 to 60 minutes. You can guess which is more effective.
By this time, you've probably guessed that I've had them, and more than once. The first time, it horrified me, and I felt really dirty. Then I came to learn more about it, and found that men with a similar degree of fur, particularly those who assoicate with other such men, run into this from time to time. I remember once being really embarassed to tell a boyfriend that I discovered I was infested (from a third party), and to my relief, he just laughed-- of all the things I could have picked up, he was happy it was just lice, and remarked that he was so smooth he didn't think he was at any risk. I have only had it once in the pubic region. (That was the first time, and since then I've declined blowjobs from men with extreme beards.) The other times, it has spread between upper bodies, and even in cases where we never had actual sex, but just a furry cuddle with our pants still buttoned.
