What Is Dysentery?

Dysentery is a gastrointestinal infection that causes bloody diarrhea. It is caused by bacteria or parasites in contaminated food or water or by touching contaminated surfaces and then touching your mouth. It leads to abdominal pain, cramping, loose, bloody stools, fever, nausea, and vomiting.

Dysentery is most common in developing countries with poor sanitation but still occurs in the United States, affecting approximately 450,000 people in the U.S. each year. It can be serious, especially in young children and people with weakened immune systems. Prompt treatment, including antibiotics and oral rehydration solutions, can help prevent complications. 

Types

There are two main types of dysentery, which are classified based on the type of microorganism causing the infection. Treatment varies based on which type of dysentery you have. 

Bacillary Dysentery 

Bacillary dysentery is caused by Shigella bacteria. It is one of the most common type of bacillary dysentery worldwide. The infection spreads through contaminated food or water, contact with the feces of an infected person (e.g., changing diapers), or by touching surfaces contaminated with the bacteria and then touching your mouth.

Amoebic Dysentery

Amoebic dysentery, or amebiasis, is caused by the single-celled parasite Entamoeba histolytica. This type of dysentery is more common in tropical areas of developing countries. The infection spreads through food and drinks contaminated with the parasite or by touching a contaminated surface or the feces of someone with it and then touching your mouth.

Dysentery Symptoms 

Symptoms of dysentery can vary, depending on the type and severity of the infection. Treatment can help manage symptoms and eliminate the infection. Certain symptoms are similar no matter which type of pathogen (e.g., bacteria, parasite) is causing the infection. 

Common dysentery symptoms include:

• Frequent diarrhea 
• Abdominal pain and cramping 
• High fever 
• Nausea 
• Vomiting 
• Fatigue 
• Weakness 

Bacillary Dysentery Symptoms 

Bacillary (bacterial) dysentery symptoms usually develop within 1-2 days after exposure and last about a week. Some people may have symptoms that linger for several months, even with treatment.

Bacillary dysentery symptoms include:

• Diarrhea containing mucus or blood 
• High fever 
• Abdominal pain or cramping 
• Nausea and vomiting 
• Painful urge to have a bowel movement, even when your bowels are empty 

Amoebic Dysentery Symptoms 

Symptoms usually develop within 2-4 weeks after infection and last about two weeks with treatment. Without treatment, symptoms may come and go until treated. Symptoms of amoebic dysentery include:

• Frequent, blood-streaked diarrhea 
• Abdominal pain or cramping 
• Excessive gas 
• Weight loss 
• Fever
• Vomiting 
• General discomfort (malaise)

Though rare, the Entamoeba histolytica (E. histolytica) parasite can enter the bloodstream and invade the liver, forming an abscess (a collection of pus). When this occurs, symptoms may include:

• Persistent hiccups 
• Yellowing of the skin and eyes (jaundice) 
• Sweating
• Loss of appetite 

What Causes Dysentery? 

Dysentery is a gastrointestinal infection that causes inflammation in the lining of the intestines, leading to symptoms like bloody diarrhea and abdominal pain. The two main types of dysentery have different causes. 

Bacillary dysentery is caused by bacteria, most commonly Shigella bacteria species. Shigella bacteria spread through ingesting contaminated food, water, or coming into contact with the stool of someone who has dysentery. Activities that can spread the bacteria include:

• Changing the diapers of someone with dysentery
• Engaging in oral-anal or anal sex 
• Touching surfaces contaminated with the bacteria and then touching your mouth. 

Amoebic dysentery is caused by a single-celled parasite called E. histolytica. It is less common than bacillary dysentery—only 10-20% of people who come into contact with this parasite become sick—but it can be more serious. The parasite or its eggs can enter the body through contaminated food, water, or contact with the stool of someone who has it. Common ways the parasite spreads include:

• Engaging in anal or oral-anal sex 
• Putting items in your mouth that have touched the stool of someone who has it
• Consuming contaminated food or water 
• Touching surfaces contaminated with infected feces or parasite eggs and then touching your mouth 

Risk Factors

Though dysentery is not as common in the United States as it once was, it still affects nearly half a million people in the U.S. annually. Dysentery is most common in areas with poor sanitation, such as a lack of clean water and minimal personal hygiene practices (e.g., handwashing).

Risk factors for dysentery include:

• Spending time in early childcare centers (e.g., daycare, preschool) 
• Having a weakened immune system
• Experiencing homelessness
• Having anal sex or oral-anal sex 
• Traveling to tropical areas with poor sanitation 
• Living in a crowded and unsanitary environment 

Diagnosis

To diagnose dysentery, your healthcare provider will perform a physical examination, review your medical history, and ask about your symptoms and recent travel. They may ask for a stool sample to run diagnostic tests to rule out other possible causes of diarrhea, such as food poisoning. 

Commonly used diagnostic tests for dysentery include:

• Stool culture: Identifies whether bacteria is causing symptoms and, if so, which is responsible for the infection.
• Stool microscopy: Uses a microscope to examine the stool and look for the presence of blood, mucus, and parasites. 
• Stool antigen test: Detects the presence of certain bacteria in the stool to determine whether the infection is dysentery or another condition (e.g., giardia) causing symptoms.
• Blood tests: Blood tests, such as a complete blood count (CBC), can check for dehydration and electrolyte imbalances.

Treatments for Dysentery  

Sometimes, dysentery resolves without treatment within 3-5 days. If you develop a fever or have persistent or worsening symptoms, you likely need treatment to eliminate the infection. Dysentery can be fatal if left untreated in young children and people with weakened immune systems, so it’s always best to see a healthcare provider for diagnosis and treatment. 

Dysentery treatment approaches vary, depending on the severity of symptoms and whether a bacteria or parasite is causing it. Primary treatment methods include antibiotics and rehydration therapy.

Antibiotics

Both bacillary and amoebic dysentery are treated with antibiotics. Antibiotics target and eliminate the bacteria or parasites causing dysentery. Which antibiotic you take will depend on the type of dysentery you have. Commonly prescribed antibiotics for bacillary dysentery include:

• Zithromax (azithromycin)
• Cetraxal (ciprofloxacin)
• Levaquin (levofloxacin)
  

Amoebic dysentery may require two antibiotics to treat, such as:

• Metrogel (metronidazole)
• Tindamax (tinidazole)
• Alinia (nitazoxanide)
• Aralen (chloroquine)
  

Rehydration Therapy 

Persistent diarrhea and vomiting can lead to dehydration and serious complications. Rehydration therapy helps replace the water and electrolytes lost due to diarrhea and vomiting. This may include:

• Oral rehydration solution (ORS) is a mixture of clean water, electrolytes (salts), and carbohydrates (sugars) to help replenish water and electrolytes you lose when sick. 
• Intravenous fluids: If you show signs of severe dehydration (e.g., lethargy, irritability, rapid heart rate), intravenous fluids can quickly rehydrate your body.

Prevention

The best way to prevent dysentery is to practice good hygiene. If you are traveling to an area where dysentery is common, you can lower your risk of getting sick by making informed choices about the food and water you consume and taking the following precautions:

• Wash your hands thoroughly with soap and water after using the toilet, before handling food, and after changing diapers
• Drink water that has been boiled or filtered
• Eat only cooked or washed and peeled fruits and vegetables
• Avoid contact with people who are sick with dysentery
• Avoid eating food from street vendors 

Complications 

Untreated dysentery can lead to complications, especially in young children, older adults, and people with weakened immune systems. Possible dysentery complications include: 

• Dehydration: Prolonged diarrhea and vomiting can lead to dehydration, which occurs when the body loses more fluids than it takes in. Symptoms may include thirst, dry mouth, headaches, dizziness, and fatigue. Severe dehydration can cause confusion, rapid heart rate, fainting, and shock.
• Post-infectious arthritis: A small number of people infected with bacillary dysentery develop joint pain, eye irritation, and painful urination due to dysentery. In many cases, this is short-term, but for others, especially those with a genetic predisposition to arthritis, these symptoms become chronic.
• Blood infections: If the bacteria damage the intestinal lining and enter the bloodstream, a bloodstream infection called sepsis can occur.
• Liver abscess: If the parasite causing amoebic dysentery invades the liver, it can cause pus to collect in the liver (abscess), leading to pain in the upper right abdomen, fever, and jaundice.

A Quick Review

Dysentery is a gastrointestinal infection that causes inflammation of the intestines and bloody diarrhea. Either bacteria or a parasite causes it. Symptoms of dysentery include frequent bloody diarrhea, abdominal pain, nausea, vomiting, and fever. Dysentery spreads through contaminated food or water or contact with an infected person’s stool. It is most common in tropical areas with poor sanitation.

Antibiotics are the standard treatment for dysentery. Some people may need rehydration therapy to restore their body’s fluids and electrolytes. Dysentery can be serious, especially in young children, older adults, and people with weakened immune systems. Early diagnosis and treatment is the best way to prevent complications.