Festivalgoers have been urged to make sure they are vaccinated against measles after a spike in the number of cases linked to major events.
Officials said "a significant number of cases" have been picked up at events attended by thousands of people, with 16 linked to Glastonbury.
So far, another seven have been linked to the NASS festival near Bristol in July; six to June's Triplicity Music and Arts Festival in Devon; three to the Tewkesbury Medieval Festival; two each to Nozstock in Herefordshire and Noisily in Leicestershire and one each to Cambridgeshire's Secret Garden Party and the Yeovil Show.
Public Health England (PHE) said large events provided the "ideal place for the infection to spead".
The NHS says the virus can be "very unpleasant and sometimes lead to serious complications."
Symptoms include a rash, general flu-like symptoms, fever, a lack of energy and sore eyes.
It can be very serious in children and causes thousands of deaths a year worldwide.
Most babies are now vaccinated but older children or young people who did not received two doses of the MMR vaccine as infants or were not previously infected with the disease may be vulnerable to infection.
PHE said any young people worried they may be at risk and due to attend a festival should visit their doctor to get an MMR vaccination.
It added that anyone who thinks they may have the infection should not attend upcoming events as they may pass it on.
Dr Mary Ramsay, head of immunisation at PHE, said: "Measles is a highly infectious viral illness that can be very unpleasant and sometimes lead to serious complications.
"So, if you think you might have measles, please don't go to any of these big events."