American Medical Association Family Medical Guide - American Medical Association [647]
Because the human body has only limited natural defenses against parasites, it is almost impossible to eliminate them without treatment. Most types of dangerous infestations are rare in the United States, and the parasite-destroying drugs that are available are highly effective.
Tapeworm
Tapeworms are parasites that sometimes infest pigs, cattle, and fish. A tapeworm can be transmitted to a person who eats infested pork, beef, or fish that has not been adequately cooked. Under poor sanitary conditions, tapeworm eggs can be transmitted in the stool of infested people or animals. Once inside the intestines, a tapeworm anchors itself by embedding its head in the intestinal wall. The tapeworm then absorbs food and may grow to more than 30 feet long. A pork tapeworm can cause brain damage (cysticercosis) and liver damage; a fish tapeworm can cause anemia (see page 610). Despite strict government regulations for meat-packing procedures, meat that contains tapeworms occasionally gets on the market. However, thorough cooking will kill any worms in the meat.
Symptoms
Segments of the tapeworm break off and are eliminated in stool. In the stool, the worm segments look like short pieces of narrow white ribbon. If the worm remains in the intestines, it often causes symptoms such as weight loss, occasional abdominal pain, loss of appetite, and irritation around the anus.
Diagnosis and Treatment
If your doctor thinks you may have a tapeworm, he or she will examine a stool sample and prescribe medication to kill the parasite. The treatment can take several days. You may need to have samples of your stool examined during this time until you pass the tapeworm’s head (which indicates an end to the infestation) and follow-up stool tests after 1 month and again 3 months later to make sure the worm has been eliminated.
Scabies
Scabies (see page 126) is an infestation with tiny arachnids called mites that burrow under the skin and lay eggs. The mites can be spread through close physical contact such as sexual intercourse or from contact with infested clothes or bedding. Scabies most often affects the hands, wrists, armpits, buttocks, or genital area, rarely the head or face. The mites that cause scabies do not live long once they are removed from the skin.
Symptoms
The symptoms of a scabies infestation are caused by an allergic reaction to the insect’s excrement and usually develop within 2 to 6 weeks in people who have never been exposed to scabies before, and within 1 to 4 days in people who have previously been exposed. Symptoms include intense itching (usually at night) and red, raised bumps on the skin. Constant scratching can cause sores and scabs to form.
Diagnosis
To diagnose scabies, a doctor may apply a blue or black felt-tipped pen to an affected area of the body (usually the area between the fingers). If you have scabies, the ink will seep into the burrows in the skin caused by the mites. The doctor will wash the ink off the surface of the skin to expose the burrows, apply a drop of mineral oil, and scrape the area to get a sample. The sample will be examined under a microscope to check for eggs, mites, and mite feces.
Treatment
To treat a scabies infestation, your doctor will prescribe a cream or lotion containing the insecticide permethrin or lindane for you to apply to your entire body below the neck. Follow the directions on the label or your doctor’s instructions for application. Wash all infested areas of your body thoroughly before applying the cream or lotion. Do not apply lindane after a hot bath, which can increase the risk that it will be absorbed into the bloodstream, where it can be toxic. Immediately after beginning treatment, wash all contaminated clothing, bedding, and towels in very hot water and dry them in a hot dryer. Ironing everything can also help kill the mites. Spraying your furniture with gamma benzene hexachloride spray can help destroy