Food-Borne Diseases: Shigella


Shigella is a bacterium that thrives in the intestines and causes sudden, severe diarrhea. It was discovered more than 100 years ago by a Japanese scientist named Kryoshi Shiga.

Shigella is spread in foods like salads, raw vegetables, milk and other dairy products, and poultry; but it can also be spread from person to person. There are 25,000 reported cases in the United States every year, but it is probably seriously underreported. Some estimates are as high as 450,000 cases per year.

Children and those with HIV infections are more susceptible to Shigella infection. The disease usually comes and goes fairly quickly, but antibiotics help to cure it more quickly.

Infectious Knowledge

One million people a year die from Shigella infection worldwide. The majority of them are children in developing countries.

You Guessed It: More Diarrhea

The symptoms of a Shigella infection are fever, stomach cramps, and diarrhea that is bloody and has mucus in it.

The incubation period is 12 hours to six days, but people usually get sick in one to two days.

Shigella multiplies in the gut, invades cells, and causes tissue destruction. It's more severe than most other food-borne illnesses, because the poisons the bacteria secrete can do severe damage.

The disease usually goes away in about a week, but it can be months before someone who was sick feels normal again.

Some cases of Shigella require hospitalization. These more serious cases have symptoms like dehydration, seizures, rectal bleeding, and bacteria in the bloodstream.

Source of Infection

Shigella is passed from the infected stool of a previously infected person. It's spread through person-to-person contact (80 percent of infections) or in contaminated food or water (20 percent of the time).

Like E. coli, an infection can occur with only a small number of bacteria entering the body.

Like the other food-borne diseases, Shigella is diagnosed by laboratory analysis of a stool sample.

It's sometimes hard to isolate Shigella bacteria because they are similar to other bacteria that normally live in our colons.

Shaking Down Shigella

To prevent Shigella infection …

  • Always wash hands after going to the bathroom and before eating. Adults need to wash their own hands carefully and supervise children so they wash their hands properly as well.
  • When changing diapers, be sure to dispose of them properly, wash hands with warm, soapy water, and clean the surface where the baby was changed.
  • Maintain proper levels of chlorine in pools.
  • Practice basic food safety.
  • When traveling in the developing world, drink only bottled water, avoid ice, and eat only food that has been cooked.

Shigellosis can usually be treated with antibiotics such as ampicillin and ciprofloxacin. However, many Shigella strains are resistant to antibiotics, which limits the effectiveness of therapy. Using antibiotics to treat shigellosis without proper evaluation of drug susceptibility will further exacerbate the resistance problem.

book cover

Excerpted from The Complete Idiot's Guide to Dangerous Diseases and Epidemics © 2002 by David Perlin, Ph.D., and Ann Cohen. All rights reserved including the right of reproduction in whole or in part in any form. Used by arrangement with Alpha Books, a member of Penguin Group (USA) Inc.