Music festivals including Glastonbury have become a hotbed of measles this summer, Public Health England has warned.
Large events where people are in close proximity to one another 'provide the ideal place for the infection to spread', Public Health England have said.
The organisation has urged young people attending events to get their MMR vaccination.
Anyone who thinks they may have the infection should not attend upcoming events as they may pass it on, it added.
The health body said there have been dozens of suspected measles cases reported in people who attended events in June and July.
Measles is a highly-infectious virus which causes a rash and cold-like symptoms for most people, but it can be deadly.
The say festivals are the "ideal place" for the infection to spread because of the large numbers of people mixing together.
The cases were linked to:
- Glastonbury festival: 16 cases
- NASS festival: 7 cases
- Triplicity Music and Arts Festival: 6 cases
- Tewkesbury Medieval Festival: 3 cases
- Nozstock: The Hidden Valley: 2 cases
- Noisily Festival: 2 cases
- Secret Garden Party festival: 1 case
- Yeovil Show: 1 case