What is Shigella infection? Cause, Prevention, Treatment

The Kerala health department on May 3 identified Shigella bacteria as the cause for the food poisoning incident in Kasaragod, which claimed the life of a 16-year-old girl and led to 30 others being admitted to hospital.

The presence of the bacteria was confirmed in the blood and faeces of people undergoing treatment after they consumed chicken shawarma from an eatery at Cheruvathur in Kasaragod. Police have arrested the owner and staff of the eatery.

What is Shigella?

Shigella is a bacterium that belongs to the enterobacter family — a group of bacteria that reside in the intestine, not all of which cause disease in humans. It mainly affects the intestine and results in diarrhoea, sometimes bloody, stomach pain, and fever.

It is a food- and water-borne infection, and can happen when someone consumes contaminated food, unwashed fruit or vegetables.

How infection spreads?

The infection spreads easily as it takes only “a small number of bacteria to make someone ill”, says the US Centres for Disease Control and Prevention (CDC).

The disease is easily spread by direct or indirect contact with the excrement of the patient. You can get the infection if you swim or take a bath in contaminated water.

How widespread is Shigella infection?

Shigellosis happens, but it is not a very common infection. We usually see infections like typhoid and cholera because of contaminated foods. Perhaps one in 100 cases of diarrhoea in our hospital would be shigellosis.

Shigella outbreaks appear to be exacerbated during pregnancy and in children under five years of age, and in those with weakened immune systems.

Types of Shigella Bacteria

There are four types of Shigella bacteria that affect humans — Shigella sonnei, Shigella flexneri, Shigella boydii, and Shigella dysenteriae. The fourth type causes the most severe disease because of the toxin it produces.

Is the Shigella infection severe?

The infection is not fatal, unless the patient has a weak immune system or the pathogen is resistant to the antibiotics that are prescribed. If a patient reaches hospital on time they can effectively be treated using IV antibiotics.

Shigella produces a lot of toxins that can affect all other organs. So, if the bacteria continue to proliferate in the body even after giving the antibiotics, it will continue to produce toxins, which can then affect the kidney, cause seizures, lead to multi-organ failure, and shock, and even turn fatal.

This, however, does not happen in most cases. The mortality of the infection is less than 1%.

Prevention of Shigella Infection

The measures to prevent a Shigella infection are the same as that of any other food- and water-borne infection –

  • Wash your hands thoroughly before and after a meal.
  • Wash your hands properly after a bowel movement.
  • Ensure the water that you drink is clean and the fruits and vegetables are fresh.
  • Products such as milk, chicken, and fish can get infected easily and must be kept at a proper temperature. They must also be properly cooked.