Extraintestinal amebiasis

Alternative names
Hepatic amebiasis; Amebic liver abscess; Abscess - amebic liver

Definition
Amebic liver abscess is a collection of pus in the liver caused by the intestinal parasite Entamoeba histolytica.

Causes, incidence, and risk factors

Amebic liver abscess is caused by the same organism, Entamoeba histolytica, that causes amebiasis, an intestinal infection. The organism is carried through the blood to the liver where the abscess is formed. Patients may or may not have symptoms of intestinal infection concurrently with liver abscess.

The infection is present worldwide, but is most common in tropical areas where crowded living conditions and poor sanitation exist. Africa, Latin America, Southeast Asia, and India have significant health problems associated with this disease. Transmission occurs through ingestion of cysts in fecally contaminated food or water, use of human excrement as fertilizer, and person-to-person contact.

Risk factors for Amebic liver abscess include malnutrition, old age, pregnancy, steroid use, malignancy, immunosuppression and alcoholism. Recent travel to a tropical region is a risk factor. In the U.S., institutionalized people and male homosexuals are known high-risk groups.

Symptoms

     
  • Fever  
  • Abdominal pain       o In the right, upper quadrant (from the enlarged, tender liver)       o May be intense, continuous, stabbing  
  • General discomfort, uneasiness, or ill feeling (malaise)  
  • Sweating  
  • Chills  
  • Loss of appetite  
  • Weight loss  
  • Diarrhea  
  • Jaundice  
  • Joint pain (may occur)

Signs and tests
These tests detect abscess in the liver:

     
  • Abdominal ultrasound  
  • Abdominal CT scan or MRI  
  • Liver biopsy - rarely done due to high risk of complications  
  • Liver scan  
  • Liver function tests may show abnormalities  
  • A CBC shows elevated white blood cell count, indicating infection.  
  • A serology for amebiasis is positive  
  • Indirect hemagglutination test (see Coombs’ test - indirect) shows abnormalities

Treatment
Antimicrobial therapy with metronidazole is the usual treatment for liver abscess. The abscess may rarely be drained to help relieve some of the abdominal pain associated with the abscess. Medication such as paromomycin must also be taken to eliminate intestinal amebiasis to prevent recurrence of the disease.

Expectations (prognosis)
Without treatment, the abscess may rupture and spread into other organs, and death may occur as a result. With treatment, the chance of complete cure or only only minor problems is high, at least 80-90%.

Complications
The abscess may rupture into the abdominal cavity, the lining of the lungs, the lungs, or the sac around the heart. The infection can also spread to the brain.

Calling your health care provider
Call your health care provider if symptoms develop after travel to an area where the disease is known to occur.

Prevention
When traveling in tropical countries where poor sanitation exists, drink purified water and do not eat uncooked vegetables or unpeeled fruit. Public health measures include improved water purification and waste treatment for underdeveloped countries.

Johns Hopkins patient information

Last revised: December 7, 2012
by Sharon M. Smith, M.D.

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