Amoebic Liver Abscess Flashcards
What organism is responsible for Amoebic Liver Abscess (ALA)?
The organism responsible for Amoebic Liver Abscess (ALA) is Entamoeba histolytica, a protozoan parasite.
How common is Amoebic Liver Abscess (ALA) globally?
Amoebic Liver Abscess (ALA) is an uncommon but potentially life-threatening complication of Entamoeba histolytica infection, causing up to 40 million infections annually and leading to 100,000 to 400,000 deaths from intestinal and extra-intestinal amoebiasis.
Is South Africa considered an endemic area for Amoebic Liver Abscess (ALA)?
South Africa is not considered an endemic area for Amoebic Liver Abscess (ALA), but cases have been treated at local hospitals, such as the “Red Cross Children’s Hospital.”
How is Entamoeba histolytica transmitted?
Entamoeba histolytica is transmitted via the fecal-oral route.
Where does Entamoeba histolytica typically establish itself in the body?
Entamoeba histolytica typically establishes itself in the colon, where it invades the mucosa, causing ulceration and colitis. It can then spread to distant extra-intestinal sites, with the liver being the most common site.
How common is Amoebic Liver Abscess (ALA) in patients with amoebic infection?
Amoebic Liver Abscess (ALA) occurs in approximately 5-7% of patients who develop amoebic infestation of the intestinal tract.
Which age group is most affected by Amoebic Liver Abscess (ALA)?
Amoebic Liver Abscess (ALA) is more common in adults, but it also occurs in children, although reports on pediatric cases are sporadic.
What is the second most common form of invasive amoebiasis?
After amoebic dysentery, amoebic liver abscess is the second most common form of invasive amoebiasis caused by Entamoeba histolytica.
What percentage of children and adults with invasive intestinal amoebiasis develop Amoebic Liver Abscess (ALA)?
Amoebic Liver Abscess (ALA) occurs in 1-5% of children and 10-50% of adults with invasive intestinal amoebiasis.
How does Entamoeba histolytica begin its life cycle?
The life cycle of Entamoeba histolytica begins when a person ingests cysts from contaminated food or water, typically through the fecal-oral route
What happens to the cysts once they are ingested by a host?
Once ingested, the cysts pass through the stomach and into the small intestine, where they excyst (break open) and release trophozoites (the active form of the parasite).
What do trophozoites do after excysting in the intestine?
After excysting, trophozoites travel to the large intestine, where they adhere to the mucosal lining and can invade the intestinal wall, leading to ulceration and amoebic colitis. Some trophozoites also disseminate to other organs, such as the liver, causing an abscess.
How are cysts formed in the life cycle of Entamoeba histolytica
Trophozoites in the large intestine can encyst, forming cysts that are excreted in the host’s stool. These cysts are the infectious form of the parasite.
How do cysts of Entamoeba histolytica spread the infection?
Cysts excreted in the stool contaminate the environment, including food, water, or surfaces, and can be ingested by a new host, thus completing the life cycle of Entamoeba histolytica.
What is the role of the liver in the life cycle of Entamoeba histolytica?
The liver can be a site for extra-intestinal infection. Trophozoites that invade the intestinal wall may spread through the bloodstream to the liver, where they can form abscesses, leading to Amoebic Liver Abscess (ALA).
How does Entamoeba histolytica cause systemic infection?
Entamoeba histolytica causes systemic infection when trophozoites break away from the intestine and enter the bloodstream, spreading to other organs such as the liver, lungs, and brain.
What is the relevance of understanding the life cycle of Entamoeba histolytica in the diagnosis of Amoebic Liver Abscess (ALA)?
What is the relevance of understanding the life cycle of Entamoeba histolytica in the diagnosis of Amoebic Liver Abscess (ALA)?
How is amoebiasis diagnosed in South Africa?
Since amoebiasis is not endemic in South Africa, the diagnosis is often made after excluding other causes of dysentery, abdominal pain, and fever. Amoebiasis should still be kept in the differential diagnosis for all children with diarrhoeal illness, dysentery, and abdominal pain.
What are the most common symptoms of Amoebic Liver Abscess (ALA)?
The most common symptoms of ALA include:
Right upper quadrant pain
High fever (virtually present in all cases)
What symptoms are less common in Amoebic Liver Abscess (ALA)?
Less common symptoms include:
-Anorexia and vomiting (present in less than 30% of cases)
- A history of dysentery, which is also uncommon
What signs are typically observed in the clinical examination of a patient with Amoebic Liver Abscess (ALA)?
Signs often observed include:
- Right upper quadrant pain and point tenderness over the liver
- Abdominal distension
- Hepatomegaly (enlarged liver)
- Oedema of the anterior abdominal wall, particularly in the right upper quadrant
What is a key finding during the clinical examination of the liver in ALA?
On careful examination, the liver is often exquisitely tender, and the point of most tenderness is very specific, helping to localize the infection.
How does a travel history assist in the diagnosis of Amoebic Liver Abscess (ALA)?
If a patient presents with a very high fever, right upper quadrant pain, specific tenderness, and a relevant travel history (to endemic areas), the diagnosis of ALA is almost certain.
What are the main complications of Amoebic Liver Abscess (ALA)?
As the abscess enlarges, it can rupture into:
- The peritoneal cavity
- The pleural space
- The pericardium
In each case, symptoms will be related to the body cavity or organ involved.
