Nonpathogenic intestinal protozoa are single-celled parasites commonly found in the intestinal tract but never associated with illness. They do not harm the body, even in people with weak immune systems. Prevalence for the non-pathogenic intestinal protozoa species were 42.9% for E. coli, 17.5% for E. nana, 12.9% for E. hartmanni, 8.2% for I. bütschlii and 6.7% for C. mesnili. Among the symptomatic patients only 10% will develop severe dysentery or invasive disease. Some of this difference in disease etiology can be explained by genetically distinct E. histolytica isolates (Table). Molecular, biochemical and immunological data indicate that E. histolytica actually consists of two distinct species: one is capable of causing an invasive disease and the other is non-pathogenic. The 2.2% difference in their rRNA sequences is approximately the same as the difference observed between mice and humans indicating that the two amoebas are quite diverged.
Infection with single or multiple species of intestinal protozoa is common in humans and can result in either asymptomatic colonization or symptoms of intestinal disease. Entamoeba histolytica serves as a paradigm for invasive colonic protozoal infection. The key to diagnosis and treatment of amebiasis is knowledge of the epidemiologic risk factors and clinical manifestations, a rational approach to diagnosis, and an understanding of the sites of action and uses of anti-amebic drugs. To help prevent the spread of the disease around the home :
• Wash hands thoroughly with soap and hot running water for at least 10 seconds after using the toilet or changing a baby's diaper, and before handling food.
• Clean bathrooms and toilets often; pay particular attention to toilet seats and taps.
• Avoid sharing towels or face washers.