Shigellosis Bacterial dysentery

Acute infectious disease of intestine caused by dysentery bacilli(genus shigella) Place of lesion: sigmoid & rectum

Etiology S. dysenteriae: the most severe S. flexneri: the epidemic group and easily turn to chronic S. boydii: tropical and subon S. sonnei: the most mild

Epidemiology

Epidemic features: season: summer & fall Flexneri, Soneii, dysentery age: younger children

Pathogenesis number of bacteria toxicity invasiveness immunity attachment penetration multiplication immunity

Signs and Symptoms Infectious disease causing diarrhea (bloody), fever, and stomach cramps Usually resolves in 5-7 days. Children and elderly may have diarrhea so severe they need to be hospitalized. A severe infection in a child less than 2 may have seizures. Some show no signs at all, but still pass the Shigella bacteria to others.

Clinical manifestation Incubation period: 1-2 day, (hours to 7 days) Acute dysentery common type mild type toxic type

common type: (typical type) acute onset , shiver, high fever abdominal pain(tenderness) diarrhea: stool mixed with mucus, blood & pus tenesmus, 1 week

chronic dysentery: > 2 months

Laboratory Findings WBC count increase, (10~20×109/L) Blood picture: WBC count increase, (10~20×109/L) neutrophils increase Stool examination: gross examination: stool mixed with mucus, blood & pus.

Sigmoidoscopy: direct microscopic examination: WBC, RBC, pus cells bacteria culture: PCR:DNA Sigmoidoscopy: chronic patients shallow ulcer scar polyp

Treatment and Prevention Can usually be treated with antibiotics There is no vaccine to prevent shigellosis Frequent hand washing can help Food safety and regular drinking water treatment is best prevention Vegetables could be contaminated by crops harvested from a field with sewage, flies bred in infected feces, and food handlers that are not properly washing their hands