The causative agent of shigellosis (shigellosis, shigella dysentery) is a species of bacteria called Shigella. It is a gram-negative bacterium that belongs to the Enterobacteriaceae, genus Shigella. There are several species of Shigella bacteria that can cause different types of shigellosis. The most common types of Shigella that cause shigellosis, which are divided into the following serogroups according to biochemical characteristics and specific O antigens:
- Group A: Shigella dysenteriae
- Group B: Shigella flexneri
- Group C: Shigella boydii
- Group D: Shigella sonnei
Shige- what?!
Shigella can be found all over the world and shows a characteristic upsurge in the warm months. The most frequently occurring species here in Germany are S. sonnei (share currently about 70 %) and S. flexneri (share currently about 20 %). They usually lead to milder diseases that are highly acute and infectious at the beginning. Children and young adults (20–39 years) are mainly affected. The majority of shigellosis infections are imported by travellers (about 60-70% of reported cases), often from Egypt, Morocco, India, China and Turkey. (Sources: https://www.rki.de/DE/Content/Infekt/EpidBull/Merkblaetter/Ratgeber_Shigellose.html)(english info: https://www.cdc.gov/shigella/index.html)
This article is about the symptoms, causes, diagnosis, treatment and prevention of shigellosis. It is not intended to be professional advice. We are not doctors, psychologists, social workers, etc. and can only explain the terms and the context and refer to support services. For specialist treatment etc., please contact a help centre near you.
Causes of Shigella
Shigella is transmitted by ingesting food or water that is contaminated with the bacterium. The infection usually occurs when a person ingests food or water that has come into contact with infected food. This can happen when people with shigellosis do not wash their hands thoroughly after using the toilet and then prepare food or touch other people.
The Shigella bacteria can also be transmitted by direct person-to-person contact. Especially in situations with poor hygiene, such as in crowded community settings like nurseries or nursing homes.
Infection can also be caused by eating raw or insufficiently cooked meat or poultry contaminated with the bacterium. It is also possible to become infected with Shigella through contact with contaminated surfaces or objects, such as doorknobs or toilets.
The pathogen can also be transmitted during sexual anal contact and occasionally through medical equipment. There have been repeated outbreaks of Shigella in large cities, in men who have sex with men.
Symptoms of Shigella
The symptoms of shigellosis can range from mild to severe and vary depending on the severity of the infection. Typically, symptoms appear within 1 to 3 days of exposure, but can last up to a week in some cases. The most common symptoms are:
- Watery or bloody diarrhoea
- Abdominal cramps and pain
- Nausea and vomiting
- Fever and headache
- Loss of appetite
- Fatigue
Particularly in patients with immune suppression (including HIV), severe relapses can occur. Shigellosis leads to dehydration, weight loss, anaemia and various complications. These may include:
- Reactive arthritis (inflammatory joint disease)
- Haemolytic-uraemic syndrome (HUS), a rare but serious condition that can lead to kidney failure
- Toxic megacolon, a severe inflammation of the colon that requires immediate medical treatment
It is important to note that not all people infected with Shigella develop symptoms. Some may be asymptomatic, meaning that they have no obvious signs of infection.
Infectivity persists during the acute infection and as long as the bacteria are excreted in the stool. This can be the case 1–4 weeks after the acute phase of the disease.
Get tested!
Diagnosis is based on a combination of factors. Including the patient’s symptoms, medical history, travel or exposure history, and the results of laboratory tests.
First, the healthcare professional will ask the patient about their symptoms, medical history and possible sources of exposure. A stool sample analysis can then be performed to detect the presence of Shigella bacteria in the stool. This analysis can be done either by microscopic examination of the stool or by culture, in which the stool is placed on a special nutrient medium to allow bacteria to grow. The culture can also be used to identify the Shigella species.
In some cases, a blood test may be performed to detect signs of infection, such as elevated inflammation markers in the blood.
It is important that proper diagnosis and treatment is done, as other conditions such as ulcerative colitis or Crohn’s disease can have similar symptoms to shigellosis.
Therefore: Get tested regularly!
Treatment of Shigella
Shigellosis can usually be treated with antibiotic therapy. The choice of antibiotic depends on the severity of the infection, the age of the patient and local resistance patterns. Early treatment can shorten the duration of symptoms, reduce the severity of the infection, and prevent the spread of the bacterium to others.
In addition to antibiotics, the choice of the antibiotic depends on the age of the patient and local resistance patterns.
In addition to antibiotic therapy, measures can be taken to relieve symptoms. This may include maintaining a good fluid intake to avoid dehydration and eating a proper diet to provide the body with nutrients.
Because of its easy transmissibility, shigellosis can spread rapidly with close personal contact and poor hygiene, especially in communities of any kind. It is important to note that shigellosis is a notifiable disease and that proper hygiene practices can help prevent its spread. If there is evidence of infection, measures should be taken immediately to identify the source(s) of infection and transmission factors involved (e.g. food) and to prevent further spread. This includes washing hands regularly with soap and water, especially after using the toilet and before eating or preparing food. Food should be properly cooked and cooled to avoid contamination. And contact with infected people and objects should also be avoided.
Preventive measures
There are a few different preventive measures that can help avoid infection
- Hand hygiene: Regular and thorough handwashing with soap and water is one of the most important preventive measures, wash your hands regularly, especially after going to the toilet, before eating or preparing food.
- Food safety: food should always be properly cooked and heated to avoid contamination with Shigella bacteria, do not eat raw food, especially meat and seafood, good kitchen hygiene should also be observed
- Water hygiene: drink only water from a safe source or boil the water before drinking it, also avoid swimming or bathing in contaminated water, especially in developing countries
- Avoid contact with infected people: Avoid contact with people suffering from shigellosis, especially if they have acute diarrhoea, also avoid sharing personal items such as towels or cutlery
Vaccination: There is no vaccine against Shigella, but there are vaccines against some serotypes of Shigella that are available in some countries and may be recommended for certain populations
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