Pupils and staff at a primary school in Coventry are being offered vaccinations after a child was diagnosed with hepatitis A.
The Health Protection Agency (HPA) said all parents of children at Frederick Bird Primary School had been informed.
The vaccinations are a precautionary measure, a spokeswoman said.
Dr Sadhu Bardham, HPA consultant, said hepatitis A has become less common in the UK with most cases acquired during foreign travel.
The school said stringent cleaning measures had been put in place and "good hand hygiene" is being emphasised to reduce transmission.
Hepatitis A is a liver infection but is not normally long-term.