This parasitic cause of traveler’s diarrhea is found basically worldwide; however tends to be more common in the tropics and in areas with questionable sanitation and poor nutrition. Africa, Asia and Central and South America is where the majority of illness and deaths tend to occur.
According to the Centers for Disease Control and Prevention (CDC), travelers to developing countries are at low but definite risk for amebiasis.
Data on travelers returning from the developing world were collected from 30 specialized travel or tropical-medicine clinics on six continents. The rate of acute amebic diarrhea ranged from 1.5% in travelers returning from Southeast Asia to 3.6% in those returning from Central America.
In industrialized countries, risk groups include male homosexuals, travelers and recent immigrants, and institutionalized populations. - amebiasis
People mostly get infected with the parasite from ingestion of fecally contaminated food and water containing the amebic cysts. The cysts are pretty resistant to chlorine.
Transmission can also occur through oral-anal contact with a chronically ill or asymptomatic carrier.
Amebiasis is caused by the protozoan parasite Entamoeba histolytica. The parasite may act as a non-pathogenic commensal or can invade tissues and give rise to intestinal and organ disease (rare).
Most infections with E. histolytica are asymptomatic. Intestinal infection can however cause acute and fulminating dysentery which includes fever, chills, bloody and mucoid diarrhea (amebic dysentery).
If the amoeba becomes invasive it can get into the bloodstream and be carried to the liver (most common), lungs or the brain. In these organs they can create abcesses (see photo of E. histolytica in liver tissue).
The incubation period is typically 2-4 weeks but may be several months or more.
Amebiasis can be diagnosed, though with some difficulty, by finding the characteristic cyst or trophozoites microscopically in stool. It must be differentiated from similar non-pathogenic amoeba.
The nonpathogenic Entamoeba dispar, however, is morphologically identical to E. histolytica, and differentiation must be based on isoenzymatic or immunologic analysis. A good indicator of E. histolytica is if the amoeba demonstrates ingestion of red blood cells. - Amebiasis
There are also antibody and antigen detection assays and molecular tests available.
There are several medications available for treating intestinal and extraintestinal amebiasis. See the Medical Letter for treatment options.
The CDC recommends the following to prevent infection while traveling:
• Drink only bottled or boiled (for 1 minute) water or carbonated (bubbly) drinks in cans or bottles. Do not drink fountain drinks or any drinks with ice cubes. Another way to make water safe is by filtering it through an "absolute 1 micron or less" filter and dissolving chlorine, chlorine dioxide, or iodine tablets in the filtered water. "Absolute 1 micron" filters can be found in camping/outdoor supply stores.• Do not eat fresh fruit or vegetables that you did not peel yourself.
• Do not eat or drink milk, cheese, or dairy products that may not have been pasteurized.
• Do not eat or drink anything sold by street vendors.
• Avoid sexual practices that may lead to fecal-oral transmission.
Amebiasis
