Shigellosis is caused by a Gram-negative bacillus with 4 main serogroups: Shigella dysenteriae (group A), S. flexneri (group B), S. boydii (group C) and S. sonnei (group D). Incubation period is 1-3 days. Transmission occurs when individuals fail to thoroughly wash their hands after defecation and spread infective particles to others, either directly by physical contact, including sexual behaviors, or indirectly by contaminating food. Infection may occur with ingestion of as few as 10 organisms. Common symptoms include diarrhea, fever, nausea, vomiting, and tenesmus. Stool may contain blood or mucous. In general, the elderly, the immunocompromised, and the malnourished are more susceptible to severe disease outcomes.
Fact Sheet http://www.cdph.ca.gov/HealthInfo/discond/Documents/Shigellosis.pdf
Shigellosis for Kids http://kidshealth.org/teen/infections/bacterial_viral/shigellosis.html