Sexually Transmitted Diseases (STDs In Men) (cont.)
Ectoparasitic Infections
What are ectoparasitic infections?
Ectoparasitic infections are diseases that are caused by
tiny parasitic bugs, such as lice or scabies. They are transmitted by close physical contact,
including sexual contact. The parasites affect the skin or hair and cause
itching.
What are pubic lice (pediculosis
pubis)?
Pubic lice, also called nits, are small bugs that
actually are visible to the naked eye. That is, they can be seen without the aid
of a magnifying glass or
microscope. The scientific term for the responsible organism, the crab louse, is
Phthirus pubis. These parasites live within pubic or other hair and are
associated with itching.
The treatment for pubic lice is usually with a 1% cream rinse of permethrin
that is applied to the affected area and washed off after 10 minutes.
Alternative treatments include a 1% shampoo of lindane applied for 4
minutes before washing off or pyrethrins with piperonyl butoxide applied for 10
minutes before washing off. None of these treatments should be used for
involvement near the eyes because they can be very irritating. The patient's
bedding and clothing should be machine-washed with hot water. All sexual
partners within the preceding month should be treated for pubic lice and
evaluated for other STD's.
Picture of pubic louse (crab)

What is scabies?
Scabies is an ectoparasitic infection caused by a small bug that is not
visible with the naked eye, but can be seen with a magnifying glass or
microscope. The bug is a mite known as
Sarcoptes scabiei. The parasites live on the skin and cause itching over the
hands, arms, trunk, legs, and buttocks. The
itching usually starts several weeks after exposure and is often associated with
small bumps over the area of itching. The itching of scabies is usually worse at
night.
The standard treatment for scabies is with a 5% cream of
permethrin, which is applied to the entire body from the neck down and then
washed off after 8 to 14 hours. An alternative treatment is one ounce of a 1%
lotion or 30 grams of cream of lindane, applied from the neck down and washed
off after approximately 8 hours. Since lindane can cause seizures, it should not
be used after a bath or in patients with extensive skin disease or rash. This is
because the lindane might be absorbed into the blood stream through the wet or
diseased skin. As an additional precaution, this medication should not be used
in pregnant or nursing
women or children younger than 2 years old.
Ivermectin is a drug taken by mouth that has also been
successfully used to treat scabies. The CDC recommends taking this drug at a
dosage of 200 micrograms per kilogram body weight as a single dose, followed by
a repeat dose two weeks later. Although taking a drug by mouth is more
convenient than applying the cream, ivermectin has a greater risk of toxic side
effects than permethrin and
has not been shown to be superior to permethrin in eradicating scabies.
Bedding and clothing should be machine washed in hot water (as with the
treatment of pubic lice). Finally, all sexual and close personal and household
contacts within the month before the infection should be examined and treated.
- Sexually transmitted diseases (STDs) can be spread
(transmitted) by intercourse, kissing, oral-genital contact, and sharing
sexual devices.
- Aside from abstinence, the use of latex barriers,
such as condoms, during intercourse and oral-genital contact (although not
100% effective) is the best means of preventing the spread of STDs.
- Genital or oral ulcers are most often caused by
herpes simplex, chancroid, syphilis, and lymphogranuloma venereum.
- Syphilis infection can either produce no symptoms or can cause oral or
genital ulcers, rash, fever, or a variety of neurological
illnesses ranging from forgetfulness to strokes.
- Chlamydia and gonorrhea can be transmitted alone or
together and cause inflammation of the urethra (urethritis), which the patient
experiences as burning on urination and a penile discharge (dripping).
- The human immunodeficiency virus (HIV), which causes
the acquired immunodeficiency syndrome (AIDS), is spread by infected blood or
sexual secretions and is often associated with one or more of the other STDs.
- Human papillomavirus (HPV) causes genital warts and
is associated with the development of anogenital carcinomas such as cervical
carcinoma in women and anal or penile cancers in men.
- Hepatitis B is transmitted primarily through sexual
contact while hepatitis C is transmitted more commonly by contact with
infected blood.
- Human herpes virus 8 (HHV-8) is a recently identified
virus that may be transmitted sexually and has been associated with Kaposi's
sarcoma (an unusual skin tumor), and possibly certain lymphomas (tumors of the
lymph tissue).
- Pubic lice and scabies are tiny parasitic bugs that can be spread by
skin-to-skin contact.
For more information please read the
Sexually Transmitted Diseases (STDs)
in Women article.
Last Editorial Review: 6/26/2006
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