Shigella is a genus of the bacterial family Enterobacteriaceae. Shigellae are Gram-negative, nonmotile, non-spore forming, rod-shaped bacteria, very
closely related to Escherichia coli.
Shigellosis is an infectious disease caused by various species of Shigella. People infected with Shigella develop diarrhea, fever, and stomach cramps
starting a day or two after they are exposed to the bacterium. The diarrhea is often bloody. Shigellosis usually resolves in 5 to 7 days, but in some
persons, especially young children and the elderly, the diarrhea can be so severe that the patient needs to be hospitalized. A severe infection with
high fever may also be associated with seizures in children less than 2 years old. Some persons who are infected may have no symptoms at all, but may
still transmit the Shigella bacteria to others.
Shigella are transmitted from an infected person to another who become infected. Shigella are present in the diarrheal stools of infected persons
while they are sick and for a week or two afterwards. Most Shigella infections are the result of the bacterium passing from stools or soiled fingers
of one person to the mouth of another person. This happens when basic hygiene and hand washing habits are inadequate. It is particularly likely to
occur among toddlers who are not fully toilet-trained. Family members and playmates of such children are at high risk of becoming infected. The spread
of Shigella from an infected person to other persons can be stopped by frequent and careful hand washing with soap, a practice that is important among
all age groups.
Part of the reason for the efficiency of transmission is because a very small inoculum (10 to 200 organisms) is sufficient to cause infection. As a
result, spread can easily occur by the fecal-oral route and occurs in areas where hygiene is poor. Epidemics may be foodborne or waterborne. Shigella
can also be transmitted by flies.
Shigella infections may be acquired from eating food that has become contaminated by infected food handlers. Vegetables can become contaminated if
they are harvested from a field with contaminated sewage or wherein infected field workers defecate. Flies can breed in infected feces and then
contaminate food. Shigella infections can also 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 or, much less, defecates, in it. |
The one friend who got a mild case, only ate a few of the bacteria, while the friend who got it bad, must have consumed a bunch.
