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Infectious Diseases


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What is Shigella?

Shigella are a group of bacteria. When ingested, these bacteria are capable of causing illness in humans. This illness is commonly referred to as Shigellosis.

How is it spread?

Shigella infections are very contagious. It only takes swallowing a small amount of these bacteria to make you sick, allowing it to be spread very easily.

People who are infected with Shigella pass the bacteria in their stool and may contaminate food, drink, surfaces and objects that you come into contact with every day, for example, door handles, light switches and restroom surfaces.

An infected food handler who does not properly wash their hands may contaminate ready-to-eat foods during preparation or serving.

You may be exposed to the bacteria if you are in direct contact with the stool of an infected person, child or infant (for example, during diaper changes) and then do not wash your hands well before touching your mouth, nose or eyes, or before preparing or eating food.

Fruits and vegetables can become contaminated if they are harvested from a field with contaminated sewage.

Shigella infections can be acquired by drinking or swimming in contaminated water. Water may become contaminated if sewage runs into it or even if someone with shigellosis swims or bathes in the water.

What are the symptoms?

Most people experience watery diarrhea (that may have blood in it), fever, nausea, vomiting, headache, and stomach cramps. In some cases you will begin to feel these symptoms a day after you are exposed, but sometimes it may take up to a week.

Certain types of Shigella bacteria may cause more severe illness, especially in young children, the elderly or those with weakened immune systems.

In a mild case of Shigellosis you will start to feel better within a week, without taking any medication. In more severe cases, medication may be necessary.

What is the treatment for Shigellosis?

Consulting your health care provider is recommended as he/she may suggest antibiotics or treatment focused on symptoms, such as fluid replacement to prevent dehydration.

Antibiotics may help you recover quicker and may also shorten the length of time that you will shed the bacteria in your stool and risk spreading your illness to others.

How do I protect myself and others?

  • Wash your hands before and after using the toilet, before preparing or eating meals and after changing diapers.
  • Wash fresh fruits and vegetables thoroughly with clean running water to remove any bacteria present.
  • Drink only pasteurized milk.
  • Drink water from an approved or chemically treated source.
  • Take precautions when travelling in countries where hygiene and sanitation may be inadequate.
    • Make sure fresh fruits and vegetables have been washed with clean water or peel them yourself.
    • When eating cooked foods, make sure they are still hot when they are served
    • Avoid beverages or ice that may have been prepared with untreated water.

Are there any special concerns about Shigella?

If you are infected with Shigellosis, and you are a food handler, healthcare or child care worker, you should not go to work while you are having symptoms. In addition, you may have to stop working until a stool sample or rectal swab collected least 24 hours after cessation of symptoms is returned negative or 48 hours after completion of treatment. It is possible that even after you are feeling better you may still have bacteria in your stool for a period of time.

For data on the incidence of Shigellosis in Simcoe Muskoka and Ontario, please visit the Shigelosis page on the health unit’s HealthSTATS site

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