Amoebiasis

Amoebiasis is an inflammation of the intestines caused by a parasite (biological agent) – a special microorganism called Entamoeba histolytica. This microscopic parasite enters the body through contaminated food or water and infects the bowel casing. It is a kind of gastroenteritis infection and generally occurs in young to middle aged adults but can happen to anyone in areas with poor sanitation or living conditions. It is a common cause of diarrhea. This parasite is only found in humans and can thrive well in the intestine even without causing symptoms, or it can show some severe symptoms. It is a very common problem in tropics and subtropics. However, it has a very high rate in tropical countries like India, Mexico, Central and South America.

This parasite afflicts about 10% of the world\’s population. It is the third most common cause of death from parasitic infections after Schistosomiasis and Malaria. Thus Amoebiasis causes about 70,000 deaths per year throughout the world. About 90% of infections are asymptomatic which do not produce any symptoms and the remaining 10% produces a range varying from dysentery to amoebic liver abscess.

Causes

Amoebiasis occurs solely due to an infection caused by protozoa called Entamoeba histolytica. It commonly spreads by water infected by faeces or stools or from food served by contaminated hands. Even vegetables grown in soil contaminated by faeces can transmit the disease. Amoebiasis is thus a transmitted condition. The infection can also occur because of congested, unhygienic living condition. It can also be spread through the blood to the liver, brain or other important internal organs. If it affects the liver, it causes development of the typical anchovy paste like pus. Asymptomatic carriers transfer cysts in the faeces.

When the cyst of Entamoeba histolytica enters the small intestine, active amoebic parasites (trophozoites) become free to attack the epithelial cells of the large intestines, resulting in flask-shaped ulcers.

Symptoms and Signs

It can either occur as intestinal or extra-intestinal amoebiasis:

Intestinal amoebiasis
Intestinal amoebiasis can be divided into several categories:

Categories	Symptoms
Asymptomic infection	Most persons with this infection may not show any noticeable symptoms but may infect others. It is the most common type of amoebic infection.
Chronic non – dysenteric infection	Recurrence of diarrhea for 1 to 4 weeks, abdominal cramps, fatigue and weight loss.
Amebic dysentery	Sores, Bloody diarrhea, severe abdominal cramps, vomiting, chills, high fever etc. Acute amebic dysentery may cause inflammation of the appendix.
Ameboma	A mass of tissue in the bowel that may produce symptoms similar to cancer or other intestinal diseases.
Perianal ulcers	It may cause skin infections surrounding the patient’s anus. The ulcerated areas have a “punched-out” appearance and are painful.

Extra-intestinal amoebiasis

Patients of extra-intestinal amoebiasis show symptoms of fever and right upper abdominal pain. The case of Jaundice is rare. Amoebic liver abscesses can be noticed as pyrexia of unknown source. The abscess can sometimes burst into the pleural, perisoneal or pericardial cavities.

How is it diagnosed?

The doctor will study the symptoms, and recommend a stool test after examining the patient. The parasite can be found by a microscopic inspection of freshly passed stool. Rarely, the diagnosis seems difficult in cases with symptoms for a long time. Sometimes sigmoidoscopy (a lighted, flexible tube is used to look inside the lower part of the colon or large intestine) is adapted. Ultrasound, CT and MRI scans of the abdomen can help diagnose hepatic amoebiasis.

How is it treated?

The doctor will prescribe medication that includes metronidazole, diloxanide furoate, dehydroemetine, emetine, or paromomycin. The doctor also may prescribe more than one drug. If medication is stopped on the symptoms being gone but before the parasite is eliminated from the body, the infection may recur. An anti-diarrhoeal medication may also be prescribed. On the other hand Metronidazole can produce a metallic taste in the mouth and may also cause nausea. You must avoid Alcoholic drinks while taking metronidazole.

The symptom of diarrhoea usually lasts from 3 to 14 days but can last up to 4 weeks too depending upon the severity. Chance of recurrences cannot be negated completely.
Vaccines are not available to prevent nausea.

How can care be taken at home?

Give rest to the bowel by the intake of only clear liquids including water, juice, tea and oral rehydrating or electrolyte solutions. Drink frequently in order to avoid dehydration. Drinking small amounts at frequent intervals is helpful in nausea. Avoid solids that can cause cramps. Light soups, toast, rice and eggs are suggested to eat during recovery.

Is hospitalization necessary for amoebiasis?

Usually amoebiasis can be controlled on an out-patient basis. However, in serious cases, involving the liver or other organs, the patient requires hospitalization. Other cases for hospitalization include:

Treatment failure
Cases of chronic dysentery
Cases of liver abscess or any other extra intestinal infection

How can amoebiasis be prevented?

First ensure a safe drinking water supply by boiling or filtering drinking water. Remember, Chlorine is not effective in killing the parasite.
Avoid unsanitary water supplies.
Wash your hands well with soap and hot running water after going to the toilet and before eating or preparing food. This will help you eliminate the amoebiasis parasite that you may pick up from contaminated surfaces or from other sources including animals and animal wastes.
Proper food storage and preventing its contamination with faeces, flies, and contaminated water is also vital.
Infected homosexuals should avoid intimate contact and people touring overseas must take additional care.
Bathrooms and toilets must be cleaned frequently to prevent the spread of this disease.
Clean your hands after smoking or using a tissue handkerchief.
Avoid uncooked food.
Cook raw foods thoroughly.
Wash raw vegetables and fruits prior to cooking or eating directly.
Avoid unpacked drinks and ice.