Shigella species are commonly transmitted through which of the following methods?

Shigella species are primarily associated with fecal-oral transmission, where the bacteria are spread through the unwashed hands of infected individuals. This can occur when an infected person does not practice proper hand hygiene after using the restroom and subsequently touches food or surfaces that others may come into contact with. This route of transmission is particularly significant in environments with close contact among individuals, such as daycare centers and nursing homes.

The other methods listed may contribute to foodborne illness in general but are not the primary transmission routes for Shigella. For example, while contaminated water supply can lead to various pathogens entering the food supply, it is not the most common source for Shigella. Cross-contamination from raw meat is more associated with pathogens like Salmonella or E. coli. Contaminated vegetables can carry several pathogens as well, but again, the specific association of Shigella with unwashed hands highlights the importance of hygiene in preventing its spread.