Tropical Diseases - Microscopic Hazard

Amebiasis, a disease caused by a microscopic protozoa spread through dirty water, infects as many as 500 million individuals in the developing world. The disease kills about 70,000 people annually.

The protozoa can live in the large intestine and not cause damage to the host. But it is also capable of causing ulceration of the colonic wall and damage to the liver and other organs, including the brain.

The disease is spread through water contaminated by fecal matter, by contaminated flies, or by other contaminated substances. Hosts swallow cysts, which divide in the small intestine and again in the large intestine to form amoebae. These amoebae divide and form trophozoites, which feed on fecal bacteria. These trophozoites form cysts and are passed out in the feces of the host. This entire cycle takes from 48 hours to four months.