Shigellosis: How It Spreads & Ways to Prevent It

March 28, 2025

Shigellosis is an acute infection of the gut that is also known as bacillary dysentery. A bacteria known as Shigella causes this infection. Its symptoms include abdominal pain, fever, and bloody mucoid stool.¹
It is commonly spread by fecal-oral route, person-to-person contact, sexual contact,t, and contaminated water.

What Is Shigellosis?

Shigellosis is an acute diarrheal infection that is very common in developing countries. Its key symptom is bloody mucoid diarrhea, along with abdominal pain, fever, and tenesmus. Its cause is a gram-negative bacillus known as Shigella. Shigallae are resistant to stomach acid, so they reach your gut, where they produce Shiga toxin along with other enterotoxins. These toxins cause symptoms like bloody and watery diarrhea and abdominal pain.²

Incidence Of Shigellosis

The incidence of shigellosis worldwide is 188 million cases, in which one lac sixty-four thousand people die from it.³
Shigella is the most common cause of bacillary dysentery. In addition, it is the most common cause of dysentery in children aged four to five months. It is usually prevalent in middle-income and overcrowded countries and high-temperature areas.

How Does Shigellosis Occur?

Shigellosis occurs when a gram-negative bacillus known as Shigella enters your body. It may enter by various routes because it is resistant to acid in your stomach. It enters your small intestines, multiplies there, and then enters your colon. In the gut, it activates the inflammatory cascade and causes inflammation by producing enterotoxins in your gut. These enterotoxins include Shiga toxin, Shiga enterotoxin 1, and Shiga enterotoxin 2. The Shiga toxin causes bloody diarrhea, and enterotoxins produce other symptoms like fever and malaise.⁴
Initially, the patient experiences abdominal pain, and then mucoid diarrhea occurs, which is followed by bloody diarrhea.

Mode Of Transmission Of Shigellosis

Shigellosis spreads through the feces of an infected person. The most common mode of transmission is the feco-oral (from feces to mouth) route. It may also spread from one person to the other person by direct contact, contaminated water, and food. In addition, it can also transfer through anal sex, and it is common in men who have sex with men. ⁵

You can also get Shigellosis by touching contaminated surfaces. Young children, elderly people, people living in close quarters, and people with weak immune systems are more prone to develop this disease.⁶

Symptoms Of Shigellosis

Some common symptoms of Shigellosis include:

Diarrhea (The patients have mucoid bloody or watery diarrhea)
Abdominal pain
Fever
Vomiting (some people can have vomiting as well)
Feeling to pass stool even when your intestines are empty
Some people may experience headaches, fatigue, loss of appetite, and rectal pain.

Diarrhea and abdominal pain in Shigellosis

How Does Your Doctor Diagnose Shigellosis?

Diagnosis of Shigellosis requires complete history, examination, and investigations.

History:

Your doctor may ask you the following questions:

Did you have any exposure to any causative factor, like physical or sexual contact with any person having a similar condition?
Do you have any recent travel history? What is the source of water, and is there any history of drinking contaminated water?
What symptoms do you experience? Since when did you develop bloody or mucoid diarrhea, and how many episodes do you have per day? Do you have any symptoms like pain or frequent urge to go to the bathroom along with diarrhea?

Examination:

Your doctor will take your vitals, measure your temperature, check for tachycardia or tachypnea, and perform a complete physical examination. These steps are important for the assessment of hydration status. They also check the signs of dehydration, including dryness of mouth, skin pinch test, thirst, and confusion. They examine your gastrointestinal system. While examining your abdomen, they look for tenderness, distension, and increased bowel sounds. In severe disease, the patient may experience severe symptoms like confusion, altered level of consciousness, encephalopathy, seizures, coma and organ failure, so they assess your neurological status as well.

Investigations:

Investigations for Shigellosis are:

Stool Culture & Examination

Stool culture is confirmatory for Shigellosis. It is more accurate and diagnostically important than rectal swabs. The stool samples in Shigellosis show blood and leukocytes.

Stool culture is confirmatory for Shigellosis

Stool alpha antitrypsin levels may be elevated in the acute phase of shigellosis. Moreover, they can also be elevated if medical therapy fails.
In some cases, other diagnostic tests, such as ELISA (enzyme-linked immunosorbent assay) and PCR (Polymerase chain reaction), may be required.

Blood Culture

Blood culture may be required in patients with severe Shigellosis. It helps diagnose severe bacteremia due to Shigellosis.

Laboratory Investigations

Laboratory investigations may be needed for severe cases of Shigellosis where there are signs of dehydration in the patient.

A complete blood picture shows leukocytosis and thrombocytopenia (increased platelet count).
Mild aminotransferase levels may be elevated in severe Shigellosis.
Serum electrolyte levels are also altered in severe Shigellosis.
Hyponatremia (decreased sodium levels) is common in Shigellosis.
C reactive protein (CRP) levels may also be elevated.

Treatment Of Shigellosis

The treatment of Shigellosis involves the following steps:

Fluids Administration:

The first step in managing Shigellosis is conservative management to correct dehydration and electrolyte imbalance, which involves fluid administration and rehydration. If you have mild dehydration, your doctor will advise you to take oral fluids like ORS (oral rehydration salt). However, in case of severe dehydration, intravenous fluid administration is the first option.

Antimicrobial Drugs:

While managing Shigellosis, antimicrobial drugs are unnecessary if you have mild Shigellosis. However, your doctor advises antimicrobial drugs if you have severe Shigellosis and need hospitalization. In addition, immunocompromised people, food handlers, septic patients, and children need antibiotics administration.
The choice of antibiotics is another important step. Your doctor prescribes you antibiotics after a complete history, examination and evaluation of antibiotic resistance.
The sexually transmitted strains of S flexneri are most resistant to antibiotics. They are penicillin and cephalosporin-resistant.

Choice Of Antibiotics

Considering the cases of antibiotic resistance, the treatment of choice for the treatment of Shigellosis is fluoroquinolones. Azithromycin and Trimethoprim-sulfamethoxazole are the treatments of choice for severe Shigellosis.⁷
Moreover, the doctors advise third-generation cephalosporins to high-risk patients like immunocompromised people, travelers, and those who have a history of sex with men.
However, Carbapenems are the treatment of choice for high-risk patients and people who have failed antimicrobial therapy. Extreme drug-resistant cases of Shigellosis require carbapenems for treatment.

Cefixime and cephalexin can be given as first-line treatment in the population of South Africa who have a history of antibiotic resistance.⁸
In addition, parenteral antibiotics are the treatment of choice for the pediatric population with fever and severe Shigellosis.

Preventive Measures:

To prevent Shigellosis, you will need to adopt preventative measures, such as washing hands, proper food handling, ensuring a clean environment, and other hygienic measures.

Complications Of Shigellosis

Shigellosis can result in severe complications like:

Dehydration:

Severe diarrhea causes dehydration, which may lead to sunken eyes, cold, clammy skin and drowsiness in severe cases.

Electrolyte Imbalance:

Diarrhea causes electrolyte imbalance in the body, as it results in the loss of minerals like sodium and potassium. Correcting this imbalance is important because it may result in metabolic acidosis or alkalosis and severe complications.

Intestinal Obstruction:

Shigellosis causes inflammation of your intestines. Chronic intestinal inflammation may cause intestinal obstruction.

Intestinal Perforation & Bleeding:

Intestinal Perforation and bleeding may occur in cases of severe Shigellosis.

Sepsis:

Bacterial infections may spread throughout your body, resulting in sepsis, which may cause shock and death.

Toxic Shock Syndrome:

The bacterial toxins released by Shigella can result in toxic shock syndrome. These toxins include Shiga toxin and Enterotoxin 1. They activate inflammatory cascades and result in severe inflammation and shock. The symptoms of toxic shock syndrome are fever, rashes, diarrhea, hypotension, vomiting, abdominal pain and multi-organ failure.
Its management involves aggressive fluid replacement, intravenous antibiotics, hospitalization, and early treatment of complications. The patient may need monitoring and proper intensive care unit (ICU) support. If your doctor does not manage it immediately, severe toxic shock syndrome occurs, and it may result in death.

Shigella Bacteria – A common cause of Bacillary Dysentery

Pregnant ladies, immunocompromised people, old people, and children are at a greater risk of developing toxic shock syndrome.

Bacteremia:

If bacteria enters your bloodstream, it causes severe bacteremia that results in shock and the death of a person.

Kidney Failure:

Toxins produced by Shigella cause kidney damage that results in acute kidney injury and renal failure.

Multiorgan Failure:

Severe untreated shigellosis can affect other organs of your body, like the lungs, brain, and kidneys, so multiorgan failure occurs.

Seizures:

High-grade fever and electrolyte imbalance in Shigellosis may result in febrile seizures.

Encephalopathy:

In Shigellosis, bacterial toxins and severe electrolyte imbalance cause brain damage that may result in encephalopathy.

Arthritis:

Shigellosis can lead to long-term complications. You may develop reactive arthritis, irritable bowel syndrome, and the risk of future infections.

Eye Problems:

Eye problems like conjunctivitis, uveitis, and other eye infections are common in Shigellosis.

Malnutrition:

Severe Shigellosis may cause malnutrition. It occurs due to malabsorption of nutrients due to chronic diarrhea.⁹

Prognosis Of Shigellosis

Shigellosis generally resolves in seven to eight days. It is self-resolving, but it may result in severe complications like bacteremia, shock, dehydration, encephalopathy, and seizures that prolong recovery time. In such cases, the patient needs hospitalization and proper treatment. The patient may even need Intensive care unit (ICU) care. Children, old age people, and immunocompromised people are at great risk of complications, and they have a poor prognosis.

How Can We Prevent Shigellosis & Its Transmission?

You can prevent Shigellosis by:

Hand Washing:

You can prevent Shigellosis and its transmission by properly washing your hands for twenty seconds after using the bathroom, changing diapers, or handling any food items. You should use hand wash, soap, or some sanitizer.

Filtered Drinking Water:

Drink filtered or bottled water, particularly when traveling. In addition, make sure that the source of your drinking water is away from sewage or waste disposal areas.

Food Items:

You should use properly cooked food and avoid undercooked or raw food. Moreover, you should wash food items properly before eating them.

Dairy Products:

Consume pasteurized milk, cheese, and other dairy products (heated to 100 Celsius for fifteen minutes). Do not use unpasteurized milk, cheese, and other dairy products.

Avoid Contact:

Avoid close contact with the infected individual. Don’t touch the surface contaminated by an infected person or the infected person’s feces. Moreover, avoid sharing personal items like razors, towels, and utensils.

Improved Sanitation:

Improved sanitation is needed to prevent shigellosis. Ensure proper sanitation, the use of latrines, proper waste disposal, and a clean environment.

Vaccine For Shigellosis

Yes, there is a vaccine for this infection, but doctors use it rarely as there is no licensed vaccine for worldwide use. Vaccination may be needed for immunocompromised people, people living in contaminated water areas, people with recurrent Shigellosis, and military people.
In addition to that, Shigellosis vaccination can be done to control epidemic outbreaks.

Does Shigellosis Occur in Pregnant Ladies?

Yes, this infection can occur in pregnant women. It occurs more frequently in these women, and there are more chances of developing complications compared to other patients. These women can protect their babies from Shigellosis by washing their hands properly, avoiding contact with the baby, and taking proper hygienic measures.

Conclusion

Shigellosis is an acute bacterial infection of the intestines. Its symptoms include bloody or mucoid diarrhea, abdominal pain, vomiting, fever, and tenesmus. It resolves itself in seven to eight days, but if it is severe, it may lead to many complications. Treatment includes rehydration, antibiotics in some cases, correction of electrolyte Imbalance, and preventive measures.

Refrences

1
DuPont, H. L., Levine, M. M., Hornick, R. B., & Formal, S. B. (1989). Inoculum size in shigellosis and implications for expected mode of transmission. The Journal of Infectious Diseases, 159(6), 1126–1128. https://doi.org/10.1093/infdis/159.6.1126
2
Stoll, B. J., Glass, R. I., Huq, M. I., Khan, M. U., Banu, H., & Holt, J. (1982). Epidemiologic and clinical features of patients infected with Shigella who attended a diarrheal disease hospital in Bangladesh. The Journal of Infectious Diseases, 146(2), 177–183. https://doi.org/10.1093/infdis/146.2.177
3
Kotloff, K. L., Riddle, M. S., Platts-Mills, J. A., Pavlinac, P., & Zaidi, A. K. M. (2018). Shigellosis. Lancet (London, England), 391(10122), 801–812. https://doi.org/10.1016/S0140-6736(17)33296-8
4
Mattock, E., & Blocker, A. J. (2017). How Do the Virulence Factors of Shigella Work Together to Cause Disease?. Frontiers in cellular and infection microbiology, 7, 64. https://doi.org/10.3389/fcimb.2017.00064
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Mason, L. C. E., Greig, D. R., Cowley, L. A., Partridge, S. R., Martinez, E., Blackwell, G. A., Chong, C. E., De Silva, P. M., Bengtsson, R. J., Draper, J. L., Ginn, A. N., Sandaradura, I., Sim, E. M., Iredell, J. R., Sintchenko, V., Ingle, D. J., Howden, B. P., Lefèvre, S., Njamkepo, E., Weill, F. X., … Baker, K. S. (2023). The evolution and international spread of extensively drug-resistant Shigella sonnei. Nature communications, 14(1), 1983. https://doi.org/10.1038/s41467-023-37672-w
6
DuPont, H. L., Levine, M. M., Hornick, R. B., & Formal, S. B. (1989). Inoculum size in shigellosis and implications for expected mode of transmission. The Journal of Infectious Diseases, 159(6), 1126–1128. https://doi.org/10.1093/infdis/159.6.1126
7
Williams, P. C. M., & Berkley, J. A. (2018). Guidelines for the treatment of dysentery (shigellosis): a systematic review of the evidence. Pediatrics and International Child Health, 38(sup1), S50–S65. https://doi.org/10.1080/20469047.2017.1409454
8
Rahman, M., Shoma, S., Rashid, H., El Arifeen, S., Baqui, A. H., Siddique, A. K., Nair, G. B., & Sack, D. A. (2007). Increasing spectrum in antimicrobial resistance of Shigella isolates in Bangladesh: resistance to azithromycin and ceftriaxone and decreased susceptibility to ciprofloxacin. Journal of health, population, and nutrition, 25(2), 158–167
9
Bennish M. L. (1991). Potentially lethal complications of shigellosis. Reviews of infectious diseases, 13 Suppl 4, S319–S324. https://doi.org/10.1093/clinids/13.supplement_4.s319

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