Shigella infection, also known as shigellosis or bacillary dysentery, is caused by 4 species:
S. boydii and S. dysenteriae are not indigenous to the UK and occur as travel associated cases. S. sonnei and S. flexneri are endemic in the UK, although they can also be travel associated. Primarily a disease of children, over the past 10 years in England and Wales, non-travel associated cases in adults aged 16- to 60-years-old have risen, to account for a majority of all cases reported. Outbreaks of S. sonnei and S. flexneri have been linked to person-to-person spread among men who have sex with men.