Dysentery is not a disease but a symptom of a potentially deadly illness. The term refers to any case of infectious bloody diarrhea, a scourge that kills hundreds of thousands of people worldwide every year. Most of the victims live in developing areas with poor sanitation, but sporadic cases can pop up anywhere in the world.

What causes dysentery?

Dysentery is the body’s response to an unwanted visitor in the digestive system. The possible culprits include a parasitic amoeba called Entamoeba histolytica or a number of bacteria, including salmonella and shigella. An infection of E. histolytica is called amebiasis, and any resulting bloody diarrhea is called amebic dysentery. Infections of shigella bacteria, called shigellosis, can lead to bacillary dysentery.

While cases of amebic dysentery tend to be isolated and sporadic, epidemics of bacillary dysentery can sweep through entire villages, cities, or regions. Every year, bacillary dysentery kills roughly six times as many people as amebic dysentery does.

How do people contract dysentery?

The E. histolytica amoeba and the shigella bacteria often thrive in food and water contaminated by human feces. Large outbreaks of bacillary dysentery have occurred in communities where sewage mixes with drinking water. Fruits and vegetables grown with contaminated water are another common source of disease. Infections can also spread through households when people don’t wash their hands after using the bathroom, after changing diapers, or before handling food. Shigella infections tend to be especially contagious.

What are the symptoms of amebic and bacillary dysentery?

People afflicted with amebic dysentery often suffer profuse, bloody diarrhea along with a fever, intense stomach pain, and rapid weight loss. Bacillary dysentery causes small, frequent stools mixed with blood and mucus. Cramps are common, and a patient may occasionally strain painfully, without success, to evacuate the bowels.

How is dysentery treated?

Anyone with bloody diarrhea needs immediate medical help. Treatment often starts with an oral rehydrating solution — water mixed with salt and carbohydrates — to prevent dehydration. (Emergency relief services often distribute inexpensive packets of sugars and mineral salts that can be mixed with clean water and used to restore lifesaving fluids in dehydrated children gravely ill from dysentery.)

If shigella is suspected and it is not too severe, the doctor may recommend letting it run its course — usually less than a week. The patient will be advised to replace fluids lost through diarrhea. If the shigella is severe, the doctor may prescribe antibiotics, such as ciprofloxacin or TMP-SMX (Bactrim). Unfortunately, many strains of shigella are becoming resistant to common antibiotics, and effective medications are often in short supply in developing countries. If necessary, a doctor may have to reserve antibiotics for those at highest risk for death, including young children, people over 50, and anyone suffering from dehydration or malnutrition.

Amebic dysentery usually calls for a two-pronged attack. Treatment should start with a 10-day course of the antimicrobial drug metronidazole (Flagyl). To finish off the parasite, the doctor will sometimes prescribe a course of diloxanide furoate (available only through the Centers for Disease Control and Prevention), paromomycin (Humatin), or iodoquinol (Yodoxin).

How can dysentery be prevented?

Good hygiene and a little common sense are the keys to avoiding dysentery. If you’re visiting or living in an area with poor sanitation, be especially wary of the water. Simply brushing your teeth with tap water or tossing a couple of ice cubes in a drink can be enough to make you sick. In many areas, the only safe beverages are boiled water, canned or bottled sodas, beer, wine, and tea and coffee (made with boiled water). If it’s not possible to boil your water, treat it with chemical disinfectants such as iodine or chlorine. For extra protection, strain the water through an “absolute 1 micron” filter (available at camping supply stores) before adding the disinfectant.

In many places, the food can be as risky as the water. You should be especially suspicious of salads, garnishes, uncooked fruits and vegetables, unpasteurized milk, raw meat, shellfish, and any foods sold by street vendors. In general, fruits that you peel yourself and hot meals are safer choices.

If you have the infection, you can protect others around you by washing your hands regularly with soap and water, especially after using the toilet, after changing diapers, and before preparing food.


Centers for Disease Control and Prevention. Amebiasis fact sheet.

World Health Organization. Epidemic dysentery fact sheet.

CDC. Shigellosis.

MayoClinic.com. Shigella infection.

© HealthDay

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