Shigella and other gut bugs are bacteria that cause bowel infections. Shigella is very infectious and is easily passed on. Infection is spread when tiny particles of shit enter the mouth. This can happen by rimming or putting contaminated objects like food, pens, and cigarettes in your mouth. Symptoms can include stomach cramps, diarrhoea (sometimes with blood and/or mucous), fever and nausea. Generally shigella is left to run its course (usually 4-7 days). In severe cases, especially with HIV-positive people, hospitalisation may be needed. Avoid dehydration by increasing fluids, antibiotics can be used to treat shigell.

Source: http://www.thedramadownunder.info