There are 4 subgroups of Shigella. It spreads through contaminated water, whether it’s drinking water or swimming‐pool water.


There are 4 subgroups of Shigella. Those subgroups are usually regarded as separate species. Shigella species,  include Shigella sonnei, S. boydii, S. flexneri, and  S. dysenteriae, are highly infectious agents. Some strains produce enterotoxins and Shiga toxin. The latter is very similar to the toxins produced by E. coli O157: H7. 

Humans are the only host of Shigella, but it has also been isolated from higher primates. Shigella spreads through water an infected person has been in. Food also can be contaminated, if the person handling food has the infectious agent or if vegetables and fruits are watered with contaminated water or when rinsing the products afterward.

Shigella Reservoirs&Transmission

Shigella Symptoms&Complications


The illness caused by the pathogenic bacterium Shigella is called shigellosis. Although shigellosis is a mild illness, it could cause serious complications. It may cause serious diarrhea (dysentery), and the affected person can lose serious amounts of fluids and minerals and could lead to significant dehydration and death. Shigella bacteria act as it invades the small intestine and the colon. More often, Shigella dysenteriae is associated with outbreaks and serious intestinal complications, such as perforation of the intestinal walls (due to the Shiga endotoxin). Fatality cases of Shigella dysenteriae among hospitalized are 20%. Shigellosis is endemic in both tropical and moderate climate. Shigella dysentariae may cause Hemolytic Uremic Syndrome and bloody diarrhea. The causative agent is the secreted Shiga toxin from the bacteria.

Susceptible Populations

All people are susceptible to shigellosis, but most at risk are children from 1 to 4 years old. Elderly, and immunocompromised people are also at higher risk.


Keep Clean: Wash your hands before, during and after handling food. Wash utensils, cutting boards, and any surfaces that food touches and wash with hot soapy water after each use. Wash fruits and veggies with running tape water. Use paper towels to clean up kitchen surfaces.

Separate Raw and Cooked: Use separate cutting boards, plates, and utensils for raw (uncooked) produce and raw (uncooked) meat, poultry, seafood, and eggs. Keep meat, poultry, seafood, and eggs separate from all other foods while shopping and in the refrigerator.

Cook Thoroughly and Keep Food at Safe Temperature: Only a food thermometer can make sure meat, poultry, fish, and casseroles are cooked to a safe internal temperature. For example, internal temperatures should be 145°F or 63°C for whole meats (allow the meat to rest after cooking for 3 minutes at least) and fish, 160°F or 71°C for ground meats, and 165°F or 74°C for all poultry. Eggs should be cooked until the yolk is firm.

Chill: Useappliance thermometers to be sure your refrigerator is at or below 40ºF or  4°C and your freezer is 0ºF (-17.78°C) or below. Between 40ºF or 4°C and 140ºF or 60°, C is the Danger Zone, when bacteria can multiply rapidly. Generally, the more bacteria, the more likely someone will get sick. Most refrigerators have just a colder/ warmer adjustment, so the only way to know is to put a thermometer inside.

Thaw Food Properly: Never thaw food at room temperature, such as on the countertop. There are three safe ways to defrost food: in the refrigerator, in cold water, and in the microwave. Food thawed in cold water or the microwave should be cooked immediately.

Use Safe Water and Raw Material: Always use safe water or treat it before use. 

The presented information is an extract from the Guidelines for the Investigation and Control of Disease Outbreaks. Porirua: Institute of Environmental
Science & Research Limited; Updated 2011