Around 90 per cent of Salmonella and C. perfringens cases are thought to arise from contaminated food, compared to potentially 50 per cent of Campylobacter and E. coli O157 cases. Only about 5 per cent of norovirus cases are thought to be transmitted via food.12

Vomit and excreta, especially liquid stools, can be highly infectious, and may still carry pathogens even if the person has no symptoms. Faecal-oral transmission occurs through not washing hands properly, or inhaling entrained droplets, such as if someone has vomited creating an aerosol effect, or infected droplets have splashed onto a surface.3,13

The pathogen may also be present in food contaminated at source, such as chicken, oysters or raspberries. Melons, particularly cantaloupes, can cause outbreaks, usually Salmonella or norovirus, as the textured rind means pathogens cannot be easily removed by washing. They then get cut into the fruit’s flesh when it is being prepared.13,26,27