Crabs and Scabies

What are crabs & scabies?

Crabs (Pthirus pubis) live on pubic & other coarse body hair. Similar to head and body live, crabs are also called pubic lice (pediculosis pubis). Although they live on blood, crabs can survive 24 hours off a human body. They can be seen by the naked eye or with a magnifying glass & look like their seaside namesake. Crabs have 3 stages: egg or nit, nymph, & adult.

Scabies (Sarcoptes scabiei) cannot be seen except with a microscope & can live nearly anywhere on the human body. The female scabies mite burrows under human skin & lays eggs. Ten days later the eggs become adult. The type of mites that infect dogs & other animals, known as mange, cannot reproduce on humans.

How are crabs & scabies transmitted?

Crabs are usually transmitted by sexual contact since the crabs can move from coarse hair (pubic area, eyelashes, eyebrows, facial hair, chest, or armpits–not usually head hair) of the infected person to coarse hair of another person. Nonsexual transmission is possible by sleeping in an infested bed, using infested towels, wearing infested clothing, or in theory, an infested toilet seat (highly unlikely).Scabies are transmitted through close physical contact. Sleeping together is more likely to spread scabies than a brief sexual encounter & in fact, sex is not needed to transmit scabies. Its also possible to pass scabies through prolonged contact with infested linens, furniture, or clothing. Its not likely scabies is passed on by casual contact (shaking hands or hugging) or contact with inanimate objects (toilet seats or park benches).How are crabs & scabies diagnosed?Crabs are noticed because of the intense itching/pruritus & can be diagnosed by seeing lice or nits on the coarse hair. Itching is caused by an allergic reaction to the bites, usually 5 days after getting crabs. You or the medical worker can see whitish-gray or rust colored individual crabs or nits with the naked eye or a magnifying glass. Nits/eggs are white ovals stuck near the root of the hair. Crab bites can cause “blue spots” which last for several days.Scabies also causes pruritus, but sensitization must occur before itching begins. The first time you have scabies, sensitization can take several weeks, but any future scabies can bring on itching in 24 hours. Scabies itching is often worse at night. These mites are usually found between & around fingers & toes, pubic & groin area, armpits, bend of the elbow & knee, wrist, navel, breast, low on the buttocks, waist & abdomen. In rare cases, scabies can be seen on the palm of the hand, sole of the foot & above the neck. Sometimes a zigzag or S pattern can be seen due to the burrowing made by the mite, or you can see sores/lesions that are like a rash or pimple & brown in color. Scrapings or shave biopsies from a lesion or needle extraction of a mite can be examined by microscope to decide if scabies are present. Burrow Test (BIT) or topical tetracycline solution can be used to look for the zigzag or S pattern of the mites burrow on your skin.

What is the treatment for crabs?

The U.S. Centers for Disease Control & Prevention (CDC) recommends:

– 1% permethrin creme rinse, available over the counter, applied to infested areas & washed off after 10 minutes

OR – 1% lindane shampoo (Kwell), available only by prescription, applied to infested areas & carefully washed off after 4 minutes. Lindane should not be used on broken skin & is NOT for pregnant or breastfeeding women, for children younger than 2 years, anyone with seizures, dermatitis or known allergies to ingredients in lindane.

OR – Pyrethrins with piperonyl butoxide, available over the counter, applied to the infested areas & washed off after 10 minutes.

Note – Do NOT use these treatments for the eyes. Crabs in eyelashes & eyebrows must be treated by prescription eye ointment twice a day for 10 days.

– After treatment, nits/eggs will be stuck to your hair, but can be removed by fingernails or fine-tooth comb.

– Even with successful treatment, itching can continue due to skin irritation or allergic reaction. Over the counter hydrocortisone cream can help.

– Bedding & clothing must be decontaminated by machine washing & drying with a hot cycle, or dry-cleaned or removed from body contact for at least 72 hours. Be sure to wear only clean clothing & sleep in clean sheets & blankets to avoid getting crabs again.

– Clothing in any special way is not needed in living areas, but some people prefer to vacuum or treat with a bug spray containing one of the active ingredients against crabs.

– Dont have sex until treatment is successful for you & all partners.

– If after about a week you still see crabs, do the treatment again, making sure that all bedding & clothing has been washed & dried on a hot cycle, dry-cleaned or kept isolated in a plastic bag for 2 weeks. Also make sure that all sex partners have been successfully treated. If treatment still doesnt work, contact your doctor.

What is the treatment for scabies?

– 5% permethrin cream applied to all areas of the body from the neck down & washed off after 8 to 14 hours

OR – 1% lindane lotion (1 oz.) or cream (30 grams) applied in a thin layer to all areas of the body from the neck down & carefully washed off after 8 hoursOR- Ivermectin, by mouth as ordered by your doctor, repeated in 2 weeks

Note – Both sexual & close personal contacts within the preceding month should be treated.

– Lindane should NOT be used immediately after a bath/shower, by those with dermatitis, pregnant or breastfeeding women, or children under 2 years.

– Scabies has developed resistance to lindane in some areas of the world & parts of the USA.

– Bedding & clothing should be decontaminated by machine washing, machine drying on hot cycle, or dry-cleaning OR removed from body contact for at least 72 hours. Fumigation of living areas is unnecessary.

– Crusted scabies (Norwegian scabies) is an aggressive infestation that usually occurs in people who have a weak immune system, are debilitated, or malnourished. These people should consult with a specialist when treating scabies.

– Crusted scabies are easier to transmit than scabies. There is no standard treatment, but some specialists recommend combining an external skin medicine & ivermectin or repeating doses of ivermectin. Lindane should be avoided for this type of scabies because of a risk of deadly results.

– The rash and itch of scabies may last for 2 weeks after treatment. Symptoms that last longer can be due to resistance to medicine or incorrect use of external skin medicine. Even with successful treatment, symptoms may continue or worsen due to skin allergy or other types of household mites.

– Specialists disagree about what to do if you still have symptoms after 2 weeks: some think treating again is best while others believe treatment should be repeated only if live scabies are found & then with a different medicine.

SPECIAL NOTES – Cabies epidemics often occur in nursing homes, hospitals, residential facilities, & communities. The entire population must be treated in these situations, with a specialist consulted. Ivermectin will be needed if external medicines fail.

How do I prevent crabs & scabies?

As with all STDs, the best prevention for crabs is not having sex or having sex with only one uninfected partner. Assuming you know scabies are in a household, have no contact with infested bed linens, clothing & furniture. Abstain from physical closeness, including sex, until treatment is successful. The only way to break the cycle of getting & passing on scabies is to follow treatment guidelines closely. Although latex condoms do not provide protection against crabs or scabies, correct, consistent latex condom use is effective in preventing other STDs.

What are possible complications?

Crabs are mostly uncomfortable & inconvenient, but bacterial infections can happen if you scratch too forcefully. Scabies are also mostly discomfort & annoyance, but like crabs, skin infections can happen from scratching too long & too hard. Crusted or Norwegian scabies should be watched for in elderly or very sick people, especially those with a weak immune system.

Who should I contact?

Having crabs means you may be at risk for another STD. Talk to your health care worker to decide about testing for other STDs. You are able to pass on crabs or scabies to others until treatment is complete. Bed linens & clothing can pass on either pest until treated or 2 weeks after the last time someone with crabs or scabies had contact with them. Remember that you can get either parasite back again by close contact with infested items or people. This means that any sexual partners or those in close contact with household linens (like sleeping for a night) within the last month should be treated. Telling a sex partner or household visitor can be embarrassing. Some feel that crabs and scabies are a sign of being unclean (not true!), so hesitate to contact those who might have gotten them. However, since it’s possible to pass crabs or scabies back and forth unless everyone is cured, it is important that you talk to them as soon as possible so they can be treated. Such discussions may be difficult, but concern for their health demonstrates maturity & can be an important step in personal growth & relationship building.

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