According to the Centers for Disease Control and Prevention (CDC), there are approximately 14,000 reported cases of shigella infection each year. But the CDC estimates that the number of infections could actually be as high as 280,000, because many mild cases are not reported or even diagnosed. Children between the ages of two and four years are most likely to become infected with shigella.
What Is Shigella?
Shigella is a gram-negative rod bacterium. According to Warren Levinson, M.D., Ph.D., Professor of Microbiology at the University of California in "Review of Medical Microbiology and Immunology," just a small number of shigella can cause an infection. Shigella sonnei is the species that most commonly causes shigellosis in the United States. Shigella dysenteriae is the species that causes the most severe form of the disease.
How Is Shigella Spread?
Shigella is spread when people do not practice good hygiene. The bacteria is present in feces for about two weeks after people no longer feel sick. Shigella can pass from the feces, or dirty fingers, of an infected person to the mouth of a healthy person. This is why children between the ages of two and four years are especially at risk. You can get a shigella infection when you eat contaminated food or drink contaminated water. When infected people handle food without washing their hands after they use the restroom, they can spread shigella. And you can become infected if you swim in contaminated water.
How Does Shigella Cause Disease?
Shigella has a toxin called an endotoxin. This toxin is in its outer membrane. It releases the toxin when it dies. George Brooks, M.D., Professor of Laboratory Medicine and Microbiology and Immunology at the University of California, states that this toxin probably helps to irritate the wall of the intestines. But shigella has another toxin as well, which is referred to as an exotoxin. The exotoxin is secreted by the live bacteria. It stops your cells from being able to make protein. It stops your small intestines from absorbing amino acids (proteins) and sugar, and it affects your nervous system.
Shigellosis
Burke Cunha, M.D., Professor of Medicine at the State University of New York, refers to shigellosis in "The Merck Manual for Healthcare Professionals" as dysentery that is caused by a bacterium. The symptoms of dysentery are fever, abdominal pain, spasms in the rectal area and a watery diarrhea. After a day or two, the diarrhea will have blood and mucus. Fluid and electrolyte loss can cause so much dehydration, especially in the elderly and in young children, that untreated shigellosis can be fatal.
References
- Centers for Disease Control and Prevention: Shigellosis
- "Jawetz, Melnick, & Adelberg's Medical Microbiology"; George Brooks, M.D., Karen Carroll, M.D., Janet Butel, Ph.D., Stephen Morse, Ph.D.; 2007
- "Review of Medical Microbiology and Immunology," Warren Levinson, M.D., Ph.D.; 2008
- The Merck Manual for Healthcare Professionals: Shigellosis
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