Amebiasis

What is Amebiasis?

Amebiasis is an infection caused by a parasite. The parasite belongs to the protozoan family Entamoeba histolytica. It infects the intestines. Symptoms associated with this infection include abdominal cramping, loose stool, and abdominal pain. Not everyone with amebiasis experiences significant symptoms.

Who is at risk for Amebiasis?

Amebiasis is prevalent in tropical nations with poor sanitation. It is very common in the Subcontinent of India, parts of Africa, and parts of South and Central America. It is very rare in the United States.

The factors that constitute a high risk for amebiasis include:

  • Immigrants from tropical countries with poor sanitation
  • Traveling to tropical countries with high unsanitary conditions
  • People who reside in areas that are not healthy or hygienic such as prisons.
  • Homosexuality
  • A compromised immune system and other health conditions

Causes of amebiasis

The disease is caused by E. histolytica, a protozoan that gets into the human body when the concerned person ingests cysts via water or food. The protozoan can also enter the body directly when you get in contact with fecal matter.

The cysts have the ability to survive for months in an inactive state in the soil or environment where they are deposited in feces. The cysts are microscopic and are present in fertilizer, soil, or water that has been polluted with infected feces. The cysts may be transmitted by food handlers while in the process of preparing or handling the food. Transmission can also take place during anal sex, colonic irrigation, or oral-anal sex. The cysts lodge in the gastrointestinal tract upon getting into the body. Once they get into the body, they release a trophozoite, an active form of the parasite. The parasites multiply in the gastrointestinal tract, from where they migrate to the colon. The result of this is colitis, tissue destruction, and bloody diarrhea. The person who has been infected can then spread the disease via the release of new cysts into the environment. Cysts get into the environment through infected feces.

Symptoms of amebiasis

Symptoms appear 1-4 weeks after contact with cysts. Studies by the Centers for Disease Control and Prevention has it that only 20 percent of amebiasis patients fall ill from the infection. Symptoms occurring at this stage are usually not serious and include abdominal cramping and loose stools.

The trophozoites after reaching the intestinal walls, get into the general circulation from where they travel to the internal organs. They can then have access to the heart, lungs, brain, liver, and other vital organs. Once they invade an internal organ, they have the potential to cause:

If the lining of your intestine is attacked by the parasite, it results in amebic dysentery. An amebic dysentery is a bad form of amebiasis. It involves severe stomach cramping and frequent bloody and watery stools. The parasite frequently invades the liver. Symptoms of amebic liver disease include abdominal tenderness and fever.

Diagnosis of amebiasis

The doctor will first inquire about your recent travel and health history. You may be tested for E. histolytica. You will be asked to submit samples of your stool for several days to check for the presence of cysts. You may also be asked to do lab tests to verify your liver function. This will help determine whether or not your liver has been affected.

After the parasite leaves the intestine, they may no longer show up in the stool. Your doctor may order a CT scan or an ultrasound to check for lesions in your liver. If the lesions are seen, then a needle aspiration will be done to see whether or not the liver has any abscesses. The presence of abscesses indicates the severity of the infection. Finally, there may be the need for a colonoscopy to check for the presence of the parasite in your colon (the large intestine).

Treatment for amebiasis

At the initial stage (the uncomplicated stage), treatment usually consists of a 10-day course of metronidazole, also known as Flagyl. This is present in the form of a capsule. You may also be given some medication to control nausea (if necessary). If the parasite has gotten into the intestine, then you will be given treatment to arrest the parasite and also to treat the infected organs. Perforations in the peritoneal tissues or colon will require surgery.

What is the prognosis for people with amebiasis?

The condition is very responsive to treatment and usually clears up in two weeks. Prognosis is also good in serious conditions provided the patient gets the appropriate medical treatment. If the condition is not treated, then it can be fatal.

Preventing amebiasis

The best way to prevent amebiasis is to sanitize your environment. Wash your hands thoroughly with soap and water after using the restroom, and before touching food.

If you are traveling to locations where the infection is common, then be sure to do the following:

  • Wash all foods properly before eating
  • Stick to soft drinks and bottled water
  • Boil your water or treat it with iodine before drinking
  • Avoid fountain drinks or ice cubes
  • Avoid cheese, milk or any other unpasteurized dairy product
  • Do not eat food sold by vendors.