Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at September 15, 2016

Dysentery is an infection of the gastrointestinal tract that causes intestinal inflammation and severe diarrhea that may contain blood or mucus. In developed countries, most cases of dysentery tend to be mild and resolve within a few days; however, the condition must be reported to local health authorities. In severe cases, untreated dysentery can lead to life-threatening dehydration.


Definition & Facts

According to the World Health Organization, there are two forms of dysentery. Bacillary dysentery is caused by the Shigella bacterium. Shigellosis is the most common form of dysentery in developed countries and among people who have not recently traveled to the tropics.

About 120 million cases of Shigella-related dysentery are reported globally each year, and approximately 1.1 million people die from the condition annually. The majority of these infections and deaths occur in young children.

Amoebic dysentery is commonly found in the tropics and is the result of a protozoan infection, that is, an infection by protozoa, which are single-celled organisms.

Symptoms & Complaints

Symptoms of bacillary dysentery typically appear after a one to three-day incubation period. For most patients, the symptoms are mild and include a stomach ache and diarrhea. The symptoms are often so mild that the patient does not even bother seeing a doctor, and most patients fully recover in a few days.

Although not as common, the patient may develop severe abdominal pain, fever, nausea, and vomiting. There may also be visible bloody stool or mucus in the stool.

The symptoms of amoebic dysentery also appear within a few days of infection and include the following:

Most patients with amoebic dysentery recover in a few days; however, some patients experience symptoms for several weeks. Without treatment, the amoebas can continue to live in the body, which increases the chances of a recurrence.

If the diarrhea causes dehydration, the patient may also experience decreased urine output, muscle cramps, dry skin and dry mucous membranes, and increased thirst. Loss of consciousness or changes in mental status, rapid heart rate (tachycardia), and dizziness are signs of life-threatening dehydration that requires immediate medical attention.


Both bacillary and amoebic dysentery are highly contagious and transmitted through the feces of an infected person. In cases of amoebic dysentery, the organisms group together to create cysts that pass out of the body through the infected individual’s stool. These cysts are able to survive outside of the body for a considerable amount of time and can contaminate food and water supplies. Dysentery is thus a waterborne illness and foodborne illness.

The most common means of infection for both forms of dysentery is through the fecal-oral route. This can occur when a person does not wash their hands properly after toileting and then touches surfaces, objects, food, or another person. In areas with poor sanitation, dysentery can be spread through eating or drinking contaminated food or contaminated water and by swimming in contaminated water.

Dysentery can also be transmitted through anal sex or anal/oral sex. In developed countries, dysentery caused by Shigella is most common in schools and daycare settings where large groups of people are in close contact.

Diagnosis & Tests

The physician will start with a detailed medical history that includes asking the patient about the type, severity, and duration of their symptoms along with questions regarding recent activities and travel. This is followed by a physical examination. In some instances, a stool culture may be ordered to determine the specific type of infection. This is especially relevant if the individual has recently traveled to a warm, tropical area.

If a bacterial infection is believed to be the cause of the dysentery, an antibiotic sensitivity analysis may also be performed to determine which antibiotic will be most effective against the infection.

If the patient’s symptoms are severe or do not respond to the normal treatments, other diagnostic tests, such as an ultrasound or endoscopy, may be used to rule out other health conditions. An ultrasound uses sound waves to create images of various body structures. Endoscopy involves inserting a thin, flexible tube with an attached camera into the body to allow the doctor to visualize the internal organs.

Treatment & Therapy

Patients experiencing dysentery-related diarrhea or vomiting are encouraged to drink extra fluids to prevent dehydration. Sports drinks containing electrolytes and warm vegetable broths are good options for replacing fluids, nutrients, and essential minerals. In extreme cases, intravenous fluids may be necessary.

Mild cases of bacillary dysentery may be allowed to resolve without medical treatment. Medications are typically not prescribed until stool culture and sensitivity tests identify the cause of the infection.

If it is not possible to determine if the infection is caused by an amoeba or a bacterium, treatment usually involves a combination of amoebicidal and antibiotic medications. A 10-day course of metronidazole is often used to treat amoebic dysentery. This may be followed by paromomycin, iodoquinol, or diloxanide furoate to ensure that no amoebas remain in the body after the symptoms resolve.

Bacillary dysentery is treated with antibiotics, including ceftriaxone, ciprofloxacin, and trimethoprim-sulfamethoxazole. Over-the-counter pain relievers may be used to treat pain and reduce fever. Over-the-counter anti-diarrheal medicines should be avoided as they can actually make the problem worse. Individuals diagnosed with dysentery should remain at home for at least 48 hours following the last episode of diarrhea to avoid passing the infection to others.

Prevention & Prophylaxis

The best way to prevent dysentery is to practice good personal hygiene. This includes washing the hands thoroughly with soap and water after toileting, before handling food or eating, and throughout the day. It is important to avoid sharing towels with infected individuals and to wash the infected person’s laundry separately on the hottest setting possible.

Travelers should avoid drinking or brushing their teeth in the local water if they are not sure it is clean. It is also a good idea to avoid having iced drinks where the ice may be made with local water. It is best to avoid purchasing foods and drinks from street vendors and to only eat fruits and vegetables that can be washed and peeled before eating