Question

Write about the causes, symptoms, and modes of transmission of Amoebiasis.

Answer 1

Hint: This is a parasitic infection that occurs in the intestine. Amoebiasis is a common infection of the gastrointestinal tract in humans. It is more closely associated with poor sanitation and socio-economic status than with climate.

Complete answer:
Causes: Amoebiasis is caused by the protozoan Histolytica Entamoeba, or E. histolytica. Several protozoan species in the Entamoeba genus colonize humans but they are not all associated with a disease. It is present in two forms- Vegetative (trophozoite) and Cystic (cyst). Trophozoites multiply in the colon and encyst. The cysts are excreted in stools and are human-infective. In the presence of humidity and low temperature, cysts remain viable and infective for several days in feces, water, sewage, and soil.

Symptoms: The clinical spectrum includes asymptomatic infection, diarrhea, and dysentery, fulminant colitis and peritonitis, as well as extra-intestinal amoebiasis. It includes a loose stool, cramping in the abdomen, and pain in the stomach. Acute amoebiasis with frequent, small, and often bloody stools can present as diarrhea or dysentery. Chronic amoebiasis may present with symptoms of the gastrointestinal tract plus fatigue, weight loss, and occasionally fever. Extra-intestinal amoebiasis may occur when the parasite spreads to other organs, most commonly to the liver where it causes an abscess of the amoebic liver. The amoebic liver abscess causes fever and abdominal pain in the upper right quadrant.

Mode of transmission: A fecal-oral route, either directly through contact person-to-person or indirectly through the eating or drinking of fecally contaminated food or water. Transmission during anal sex, oral-anal sex, and colonic irrigation are also possible. The infection can also be transmitted by vectors such as flies, cockroaches, and rodents

Additional Information: The cysts are a relatively inactive form of the parasite, which can live in the soil or environment where they have been deposited in feces for several months. The microscopic cysts occur in soil, fertilizer, or water contaminated with infected feces. Food handlers can transmit cysts while they prepare or handle food.
They lodge in the digestive tract when cysts enter the body. They then release an invasive, active parasite form known as a trophozoite. In the digestive tract, parasites reproduce and migrate to the large intestine. There, they may burrow into the colon or the intestinal wall. That causes diarrhea, colitis, and tissue damage. The infected person can then spread the disease through infected feces, releasing new cysts into the environment.
Amoebic dysentery is a more dangerous form of amoebiasis, with frequent watery, bloody stools, and severe cramping of the stomach.

Note: E. Histolytica is a single-celled protozoan usually entering the human body when a person ingests cysts through food or water. It can also come into the body via direct contact with fecal matter. According to the Centers for Disease Control and Prevention (CDC), it only affects about 10 to 20 percent of people with amoebiasis. When symptoms occur, they tend to show up 1 to 4 weeks after cyst ingestion. Amoebiasis can be prevented by avoiding contaminated food and/or water, good sanitation techniques, and by avoiding contaminated food handlers and other parasite carriers. Animals can get a vaccine, and researchers are working on a human vaccine.