6 Things to Know About Shigella, the Infection That Causes Diarrhea

Shigella is a group of bacteria that causes an intestinal infection known as shigellosis. The infection can lead to diarrhea, stomach pain and fever, and it spreads easily when tiny amounts of infected stool enter another person’s mouth.

Although Shigella is commonly associated with contaminated food, water and person-to-person transmission, it can also spread during sexual activity involving exposure to stool. Here are six important things to know about the infection.

1. Shigella Can Spread Through Sexual Contact

Shigella is not exclusively a sexually transmitted infection. It can spread through contaminated food, water, hands, surfaces and objects, as well as through sexual activities that expose someone to infected stool.

Activities involving oral-anal contact can create opportunities for transmission. The bacteria may also be present on skin around the anus, genitals, buttocks and thighs, even when contamination is not visible.

According to the U.S. Centers for Disease Control and Prevention (CDC), only a small amount of Shigella bacteria is needed to cause illness.

2. Common Symptoms Include Diarrhea, Fever and Stomach Pain

Symptoms of shigellosis usually begin one to two days after exposure, although timing can vary. Common symptoms include diarrhea, abdominal pain, fever and a persistent feeling that you need to pass stool even when your bowels are empty.

Diarrhea may be watery, bloody or prolonged. Some infected people have no noticeable symptoms, which means the absence of obvious illness does not always rule out infection.

Symptoms commonly last around five to seven days, but some people may take longer to recover.

3. Good Hygiene Can Help Prevent Infection

Handwashing is one of the most important ways to reduce the spread of Shigella. Wash your hands with soap and water after using the toilet and before eating or preparing food.

During sexual activity, washing hands, genitals and the anal area before and after contact can help reduce transmission. Using barriers during oral-anal contact, cleaning sex toys and avoiding sexual contact while ill can also reduce the risk.

4. A Healthcare Professional Can Help Confirm the Diagnosis

Because Shigella symptoms can resemble those caused by other intestinal infections, symptoms alone cannot confirm the diagnosis. A healthcare professional may request a stool sample to identify the organism and determine the most appropriate treatment.

Seek medical advice if diarrhea is bloody, lasts more than three days, or occurs alongside severe stomach cramps, fever or significant illness. Prompt evaluation is especially important for people with weakened immune systems or other conditions that increase the risk of complications.

If symptoms follow sexual contact, share that information with the clinician so they can assess whether additional testing is needed.

5. Many People Recover, but Some Cases Need Treatment

Many people with shigellosis recover within five to seven days without antibiotics. Drinking plenty of fluids helps replace the water lost through diarrhea and reduces the risk of dehydration.

In more serious cases, a healthcare professional may prescribe antibiotics. However, some Shigella strains are resistant to commonly used antibiotics, so treatment decisions may depend on laboratory testing and local resistance patterns.

People with bloody diarrhea should not take anti-diarrheal medicines such as loperamide without medical guidance, as these medicines can make the illness worse.

6. Shigella Can Spread Even After Diarrhea Stops

Feeling better does not necessarily mean that Shigella has completely cleared from the body. The bacteria can continue to be present in stool for up to two weeks after diarrhea ends, creating a risk of transmission.

Anyone who develops signs of dehydration, severe abdominal pain, bloody diarrhea or persistent fever should seek medical attention.

Final Thoughts

Shigella is a preventable intestinal infection that can spread through several routes, including sexual contact involving exposure to infected stool. Recognising its symptoms, practising good hygiene and seeking timely medical advice can help reduce the risk of complications and further transmission.

Because some strains are resistant to antibiotics, avoid self-medicating with leftover antibiotics. If you suspect shigellosis, consult a healthcare professional for appropriate testing and treatment.

Sources: CDC: About Shigella Infection; CDC: Signs and Symptoms of Shigella Infection; CDC: Treatment of Shigella Infection.