Families travelling overseas during the school holidays should ensure their measles vaccinations are up to date, South Australian health authorities warn.

SA Health chief medical officer Paddy Phillips says there have been 50 cases of measles in Australia so far this year, many of which were acquired in Bali or on flights.

"There are measles outbreaks in a number of countries in Southeast Asia and in Europe, including Britain, so it is vital that people travelling to these regions confirm they have had two doses of the measles vaccine before leaving home," Prof Phillips said on Friday.

"If you're not sure whether you've had two measles vaccinations or if you're travelling soon, I'd recommend not taking the risk and have another vaccination so measles doesn't ruin your holiday."

Measles is highly contagious but the disease can be avoided if a person is vaccinated within three days of exposure.

Prof Phillips said many people born in the late 1960s to mid-1980s have received only one measles vaccine instead of the required two and people born during or after 1966 should visit their GP to confirm their status.

"Immunisation provides the best protection against measles and it's vital that people have two doses of the measles vaccine to protect themselves and the community," he said.