You can be infected from Shigella by
- Eating food or drinking beverages contaminated by food handlers infected with Shigella who didn’t wash their hands properly after using the bathroom
- Eating vegetables grown in fields containing contaminated sewage
- Eating food contaminated by flies bred in infected feces
- Swimming in or drinking contaminated water
Even if you have no symptoms of shigellosis, you can still pass the bacteria to others. An extremely low number of bacteria,10 to 100, are needed to transmit the infection. Therefore, it is commonly transmitted by food handlers who are sick or infected but have no symptoms and who do not properly wash their hands after using the toilet.
If you know you have shigellosis, you should not prepare food or beverages for others until laboratory tests show you no longer carry Shigella bacteria.