Causes and risk factors
E histolytica is present as two forms in the lumen and mucosal crypts of the large bowel- identical-appearing cysts and motile trophozoites. In the absence of diarrhoea, trophozoites encyst in the large bowel. Trophozoites passed into the environment die rapidly, but cysts remain viable in soil and water for several weeks at appropriate temperature and humidity. Humans are the only host and are susceptible. Only cysts are infectious, since after ingestion they survive gastric acidity which destroys trophozoites. Transmission occurs through ingestion of cysts from fecally contaminated food or water. Flies and other arthropods also serve as mechanical vectors; transmission also results from contamination of food by the hands of food handlers. Where human excreta is used as fertilizer, it is often a source of food and water contamination. Person-to-person contact is also important in transmission of the disease; it can affect any one but the infection is more common in young and middle aged adults. Risk factors for severe amoebiasis include alcoholism, cancer, malnutrition, old age, pregnancy, recent travel to a tropical region, use of corticosteroid medication to suppress the immune system. Predisposing conditions for amoebiasis include crowding, poor sanitation, and poor nutrition
Clinical presentation
Person infected with E histolytica can remain asymptomatic or may produce signs and symptoms. It may take 2-4 weeks for the infection to manifest itself. Sign and symptoms of acute amoebiasis include mild diarrhoea to severe dysentery. Stools contain blood and mucus. There are stomach cramps, fever associated with loose stools. Ulcerations in the colon can occur. Symptoms of Chronic amoebiasis include gastrointestinal symptoms accompanied with fatigue, weight loss and occasional fever the infection will spread to other parts of the body through the bloodstream. Liver is the most common extra intestinal site affected by the E histolytica where it causes amoebic liver abscess. Other extra intestinal sites are lungs, brain, genitalia.
Investigation
Medical history by the patient and Clinical examination by the doctor helps in diagnosis. Stool examination is necessary. Microscope examination of 3 stool specimens several days apart to see the presence of cyst. Routine haemogram; Serological blood test to detect the presence of antibodies is recommended. Ultrasound of the abdomen is advised. Colonoscopy is indicated when there is bloody diarrhoea.
Treatment
Medicines include antibiotics especially anti protozoal and anti parasitic drugs, anti spasmodic, NSAIDs. Amoebiasis can cause dehydration. Fluid replacement therapy to replace the fluid loss is required by oral or intravenous fluid administration. Probiotics may be tried to help the growth of healthy bacteria. As per the guidelines given by WHO, the infection diagnosed by microscopy alone should not be treated, if the patient is asymptomatic and has no other indications suggestive of E histolytica infection.
Other Modes of treatment
The other modes of treatment can also be effective in treating amoebiasis. Homoeopathy is a science which deals with individualization considers a person in a holistic way. This science can be helpful in combating the symptoms. Similarly the ayurvedic system of medicine which uses herbal medicines and synthetic derivates are also found to be effective in treating
Facts and figures
The infections are present worldwide but are most prevalent and severe in subtropical and tropical areas under conditions of crowding, poor sanitation, and poor nutrition. About 500 million persons worldwide are infected with entamoeba. Invasive E histolytica may constitute 5 million cases, with mortality in the range of 100,000 per year.
