Technical Information
Technical information is taken directly from the December 2001 CDC
Division of Bacterial and Mycotic Diseases: Shigellosis
Clinical Features
Watery or bloody diarrhea, abdominal pain, fever, and malaise.
Etiologic Agent
Four species of Shigella: boydii, dysenteriae, flexneri, and
sonnei.
Incidence
Approximately 14,000 laboratory confirmed cases of shigellosis and an
estimated 448,240 total cases (mostly due to S. sonnei) occur
in the United States each year. In the developing world, S. flexneri
predominates. Epidemics of S. dysenteriae type 1 have occurred
in Africa and Central America with case fatality rates of 5-15%.
Transmission
A 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 are poor. Epidemics may be foodborne or waterborne.
Shigella can also be transmitted by flies.
Risk Groups
In the United States, groups at increased risk of shigellosis include
children in child-care centers, contacts of children in child-care settings,
and persons in custodial institutions, where personal hygiene is difficult
to maintain; international travelers; and those in homes with inadequate
supplies for handwashing.
Surveillance
All reported cases are laboratory-confirmed in states or at CDC.
Trends
Decreasing incidence in cases since 1995; characteristically, S. sonnei
causes large periodic outbreaks.
Challenges
Increasing resistance to available antimicrobial agents among isolates
acquired domestically and abroad; absence of effective vaccines; modifying
handwashing behavior to control prolonged community-wide outbreaks.
Opportunities
A major initiative to strengthen laboratory, epidemiologic, and public
health capacity to detect and respond to epidemic S. dysenteriae type
1 in southern Africa could be duplicated in other regions at risk. Partnerships
with local health departments and communities may lead to investigations
of transmission and new prevention materials.
Additional Resources
Frequently
Asked Questions about Shigella Dysenteriae Type 1
Center
for Disease Control and Prevention Food Safety Threat
NOTE: All images taken from the CDC
Public Health Image Library website.
|
