Summary about Disease
Entamoeba histolytica infection, also known as amebiasis, is an intestinal illness caused by the parasitic protozoan Entamoeba histolytica. It can range from asymptomatic infection to severe dysentery and extraintestinal abscesses, primarily in the liver. The parasite is acquired through ingestion of contaminated food or water containing cysts of the parasite.
Symptoms
Symptoms vary widely. Many infected individuals are asymptomatic. When symptoms do occur, they can include:
Diarrhea (possibly bloody)
Abdominal pain and cramping
Nausea and vomiting
Fever (less common)
Fatigue
Weight loss
Liver abscess (if the infection spreads to the liver, causing right upper quadrant pain, fever, and tenderness)
Causes
The primary cause is the ingestion of Entamoeba histolytica cysts found in:
Contaminated food (often by infected food handlers)
Contaminated water (especially in areas with poor sanitation)
Fecal-oral contact (direct or indirect, e.g., poor hygiene)
Medicine Used
Treatment typically involves medication to eradicate the parasite. Common medications include:
Metronidazole (Flagyl): A nitroimidazole antibiotic used to kill the trophozoites in the tissues.
Tinidazole (Tindamax): Another nitroimidazole with a similar mechanism of action to metronidazole.
Paromomycin (Humatin): An aminoglycoside antibiotic used to eliminate cysts from the intestine after treatment with metronidazole or tinidazole.
Diloxanide furoate: An alternative luminal amebicide to paromomycin.
Chloroquine: Used in conjunction with metronidazole for liver abscesses.
Is Communicable
Yes, amebiasis is communicable. It spreads through the fecal-oral route, meaning the cysts of the parasite are shed in the stool of infected individuals and can infect others if ingested. Transmission is more likely in areas with poor sanitation and hygiene.
Precautions
Preventive measures include:
Proper hygiene: Frequent handwashing, especially after using the toilet and before preparing or eating food.
Safe water practices: Boiling water, using water filters, or drinking bottled water, especially in areas where water sources may be contaminated.
Safe food handling: Thoroughly washing fruits and vegetables, especially those grown in areas where human waste is used as fertilizer. Avoid eating raw or undercooked food in high-risk areas.
Sanitation: Improving sanitation systems to prevent fecal contamination of water and food supplies.
Travel precautions: Being cautious about food and water consumption when traveling to areas where amebiasis is common.
How long does an outbreak last?
The duration of an amebiasis outbreak can vary depending on the source of contamination and the effectiveness of control measures. Outbreaks can last for weeks or even months if the source of contamination is not identified and eliminated. Sporadic cases may continue to occur even after the initial outbreak is controlled.
How is it diagnosed?
Diagnosis typically involves:
Stool examination: Microscopic examination of stool samples to identify cysts or trophozoites of E. histolytica. Multiple stool samples may be needed, as parasite shedding can be intermittent.
Stool antigen testing: Detecting E. histolytica antigens in stool samples using enzyme-linked immunosorbent assay (ELISA) or other immunologic methods. These tests are more sensitive and specific than stool microscopy.
PCR (Polymerase Chain Reaction): PCR tests can detect the parasite's DNA in stool samples. This method is highly sensitive and specific but may not be widely available.
Serology: Blood tests to detect antibodies against E. histolytica. These tests can indicate past or present infection but cannot distinguish between the two.
Imaging: For suspected liver abscesses, imaging techniques such as ultrasound, CT scan, or MRI may be used.
Timeline of Symptoms
The incubation period (time from ingestion of cysts to the onset of symptoms) can vary from a few days to several weeks.
Asymptomatic: Many people carry the parasite without showing any symptoms.
Mild Symptoms (2-4 weeks after ingestion): Diarrhea, abdominal pain, and cramping may develop gradually.
Severe Symptoms (can develop later or in untreated cases): Dysentery (bloody diarrhea), high fever, and liver abscess formation can occur weeks or months after the initial infection. Symptoms can persist for weeks, months, or even years if left untreated.
Important Considerations
Asymptomatic Carriers: Individuals who carry the parasite but have no symptoms can still transmit the infection. They should be treated to prevent further spread.
Differentiation from Other Infections: Amebiasis symptoms can resemble other gastrointestinal infections. Accurate diagnosis is crucial for appropriate treatment.
Liver Abscess Complications: Untreated liver abscesses can rupture, leading to serious complications like peritonitis.
Travel History: A detailed travel history is important for diagnosis, as amebiasis is more common in certain regions.
Public Health Importance: Amebiasis is a significant public health problem in many developing countries, highlighting the need for improved sanitation and hygiene practices.