What is gastrointestinal amebiasis?

Gastrointestinal amebiasis is an inflammation of the colon caused by a parasite that enters the body through contaminated food or drinking water. This infection is rare in developed countries and more common in areas with poor sanitation or living conditions.

The parasite Entamoeba histolytica causes this infection. This single-celled parasite can live in your intestine without causing symptoms, or you can have severe symptoms. Rarely, the organisms enter the liver, lungs, brain, or other organs through the blood.

How does it occur?

You may become infected when you eat food or drink water contaminated with feces that contain Entamoeba histolytica. Another source of the infection is food that has been handled by someone who has the parasites.

Another way the infection may be spread is through oral-anal sexual activity. The infection is common in male homosexuals and in institutions such as schools where there is close contact among people.

What are the symptoms?

The symptoms of gastrointestinal amebiasis include:

• diarrhea, sometimes alternating with relatively normal bowel movements

• abdominal cramps or tenderness

• bowel movements streaked with blood or mucus

• occasionally fever

• vomiting or nausea

• dehydration.

The time between the parasite's entry into your body and the appearance of the first symptoms can range from a few days to a few months.

How is it diagnosed?

To diagnose gastrointestinal amebiasis, your doctor will review your symptoms, examine you, and order a lab analysis of a sample of your bowel movement.

Occasionally, making the diagnosis is difficult if you have had the symptoms for a long time. Sometimes sigmoidoscopy is done. This is a procedure in which the doctor uses a lighted, flexible tube to look inside at part of your colon.

How is it treated?

Your doctor will prescribe medication such as iodoquinol, metronidazole, diloxanide furoate, dehydroemetine, emetine, or paromomycin. Your doctor may prescribe more than one drug; take them together or one after another, according to your doctor's directions. Take all of the medication your doctor prescribes. If you stop taking the medication when your symptoms are gone but before the parasite is eliminated from your body, your infection may return.

Your doctor may also prescribe antidiarrheal medication.

How long will the effects last?

The symptoms of diarrhea usually last 3 to 14 days but can last up to 4 weeks. Recurrences are possible.

How can I take care of myself?

If you have diarrhea, let your bowel rest by drinking only clear liquids such as water, juice, tea, bouillon, and oral rehydrating or electrolyte solutions. It is important to drink often so that you do not become dehydrated. Drink small amounts at frequent intervals if you feel too nauseated to drink fluids. Do not eat solid foods because they can cause cramps.

When your symptoms improve, eat small frequent meals or snacks. Do not fast. Avoid milk products and caffeine for a few days. Good foods to eat during this time of recovery are light soups, gelatin, crackers, toast, rice, eggs, and applesauce. Return to your normal diet gradually but avoid fresh fruit and vegetables, alcohol, and highly seasoned or spicy foods for several days.

If you have cramps or abdominal pain, it may help to put a hot water bottle or electric heating pad (set on low) on your abdomen.

If your symptoms persist or if you develop new symptoms, tell your doctor.

How can I help prevent gastrointestinal amebiasis?

• Avoid unsanitary water supplies.

• Wash your hands with soap and very warm water after going to the bathroom and before eating or preparing food.

• Avoid food that can't be cooked or peeled.

• Protect food from feces, flies, and contaminated water.

• When camping, boil water or treat it with iodine.

• Chlorine is not effective in killing the parasite. Globaline tablets are effective, as is iodine.

• Practice safe sex.