It can affect anyone, although it is more common in people living in tropical areas with poor sanitation. Diagnosis can be difficult because other parasites look very similar to E. histolytica when viewed under a microscope. Affected individuals are not always ill. Medicines are available if your doctor determines that you are infected and need treatment. Amebiasis is an intestinal (intestinal) disease caused by a microscopic (tiny) parasite called Entamoeba histolytica, which is spread through human waste (poop). Often there are no symptoms, but, sometimes it causes diarrhea (loose stools/feces), nausea (feeling sick in the stomach), and weight loss. About 600 cases of the disease are reported in New York state each year.
How does it spread?
Amebiasis is contagious. People who have amoeba in their intestines can pass the infection to others through stool (poop) even if they have no symptoms. When infected feces contaminate the food or water supply, amoebiasis can spread rapidly to many people at once. This is especially true in developing countries, where drinking water can be contaminated.
Amebiasis can also spread between people through improper hand washing, sharing contaminated items, and sexual contact. Amebiasis usually occurs in areas where living conditions are crowded and unsanitary. The disease is common in Africa, Latin America, and parts of Asia. It is rare in the United States but is sometimes seen in people who have immigrated to or traveled to countries where amebiasis is more common.
Who is at risk for amebiasis?
Although anyone can get the disease, it is more common in people who live in tropical areas with poor sanitation. In the U.S, amebiasis is most common in:
- People who have traveled to tropical places with poor sanitation.
- Immigrants from tropical countries with poor hygiene conditions.
- People who live in institutions with poor hygiene conditions.
- Men who have sex with men.
How can I get infected with E. histolytica?
histolytica infection can occur when a person:
- Put anything that has touched the stool (poop) of a person infected with E. histolytica into their mouth.
- E. histolytica cysts (eggs) picked up from contaminated surfaces or fingers are swallowed.
Symptoms
Only 10% to 20% of people infected with E. histolytica become ill from the infection. Symptoms are often quite mild and may include loose stools (poop), abdominal pain, and cramping. An amoebic dysentery is a severe form of amebiasis that is associated with abdominal pain, bloody stools (feces), and fever. Rarely, E. histolytica invades the liver and forms an abscess (collection of pus). In rare instances, it has been shown to spread to other parts of the body, such as the lungs or brain, but this is very rare.
What is the cause of amebiasis?
E. histolytica is a unicellular protozoan that usually enters the human body when a person ingests cysts through food or water. It can also enter the body through direct contact with fecal material. The cyst is a relatively inactive form of the parasite that can survive for months in the soil or environment where it was deposited in the feces. Microscopic cysts are present in the soil, manure, or water contaminated with infected feces.
Food handlers can transmit cysts while preparing or handling food. Transmission is possible during anal sex, oral anal sex, and colonic irrigation. When cysts enter the body, they accumulate in the digestive tract. Parasites reproduce in the digestive system and migrate to the large intestine. There, they can penetrate the intestinal wall or colon.
How is amoebiasis diagnosed?
Your healthcare provider will ask you to submit a stool (poop) sample. Because E. histolytica is not always found in every stool sample, you may be asked to submit multiple stool samples from several different days.
Diagnosis of amebiasis can be very difficult. One problem is that other parasites and cells look very similar to E. histolytica when viewed under a microscope. Therefore, people are sometimes told they are infected with E. histolytica when they are not. Entamoeba histolytica and another ameba, Entamoeba dispar, which is about 10 times more common, look similar when viewed under a microscope. Unlike E. histolytica infection, which sometimes makes people sick, E. dispar infection does not make people sick and therefore does not require treatment.
If you’ve been told you’re infected with E. histolytica but feel fine, you may be infected with E. dispar instead. Unfortunately, most laboratories do not yet have tests that can tell whether a person is infected with E. histolytica or E. dispar. Until these tests become more widely available, it is generally best to assume that the parasite is E. histolytica.
A blood test is also available but is recommended only if your healthcare provider thinks your infection has spread outside of the intestine (gut) to another organ in your body, such as the liver. . However, this blood test may not be helpful in diagnosing your current illness because the test may be positive if you have had amoebiasis in the past, even if you are not currently infected.
How is amebiasis treated?
Several antibiotics are available to treat amebiasis. Treatment should be prescribed by a physician. You will only be treated with an antibiotic if your E. histolytica infection has not made you sick. If your infection has made you sick, you will probably be treated with two antibiotics (first one and then another).
How can I prevent amebiasis?
Proper sanitation is the key to avoiding amebiasis. As a general rule, wash your hands thoroughly with soap and water after using the bathroom and before handling food.
If you are traveling to places where the infection is common, follow these guidelines when preparing and eating food:
- Wash fruits and vegetables thoroughly before eating.
- Avoid eating fruits or vegetables unless you have washed and peeled them yourself.
- If you must drink tap water, boil it for at least 1 minute, or use a store-bought “absolute 1-micron” filter and disinfect the filtered water with chlorine, chlorine dioxide, or iodine. Add pills.
- Avoid ice cubes or fountain drinks.
- Avoid unpeeled fresh fruits or vegetables.
- Avoid milk, cheese, or other dairy products.
- Avoid food sold by street vendors.