Australia is on track for its worst measles rate in five years, with 84 confirmed cases so far in 2019, compared to 103 for the whole of 2018 and 81 in 2017.

In NSW there has been 27 cases so far in 2019, with NSW Health issuing 18 alerts this year - issuing warnings to people who have frequented public places who may have come into contact with those infected.

The majority of the alerts were for Sydney suburbs - however a Woonona cafe was included in a list of places where an infant with measles visited with her parents back in January.

Illawarra Shoalhaven Local Health District (ISLHD) public health director Curtis Gregory said while there had been no confirmed cases in the region this year - and only one last year - it was important for residents to be vigilant.

"In 2014 Australia had eradicated measles - there was no internal transmission," he said.

"So all these cases are linked to people who have travelled overseas and brought the disease back from countries which don't have strong vaccination programs, like the Philippines where coverage rates have dropped right off."

The latest NSW Health alert was issued on Sunday, after two young adults were infected while visiting the Philippines. The two siblings, who were unvaccinated, spent time in a number of northern NSW locations while still infectious.

"There's a lot of domestic travel in Australia - with many people visiting the Illawarra and South Coast to enjoy their natural attractions," Mr Gregory said. "We also have many residents who commute to Sydney."

In the ISLHD vaccination rates are high - in five years or older the coverage rate is 96.6 per cent, while at 12 months the rate is 95.6 per cent.

However those born between 1966 and 1994 were at greater risk of being under-vaccinated, Mr Gregory said, due to changes to the immunisation schedule.

"Prior to 1966 most people were exposed to measles as it was so prevalent back then," he said.

"From 1966 to 1994 people may only have been given one dose, and after that the two-dose program was introduced.

"The two doses - at 12 months and 18 months - offer lifetime immunity as it's a very effective vaccine. If you're not sure you've had the two doses, see your GP for a free dose."

Mr Gregory said symptoms usually began with a cough, runny nose, and sore eyes, as well as fever. This was followed a few days later by a red, spotty, non-itchy rash which usually started on the head and neck and moved down onto the trunk and limbs.

"Measles is a serious viral illness, which is highly contagious," he said. "If someone has measles and they leave a room, half an hour later someone can walk in that room and still breathe in the viral droplets in the air, and become infected."

Complications such as diarrhoea, middle ear infection and pneumonia occur in up to one third of cases; while encephalitis (swelling of the brain) occurs in up to one in 1000 cases.

"A swab and blood test will be taken if you think you have symptoms - but we'd urge anyone who does to call the GP or emergency department first to alert them, so other people are not exposed," Mr Gregory said.

Those with confirmed cases get treatment for their symptoms - so rest, hydration and painkillers.

"And we'd advise them to stay at home, practice good hand and personal hygiene," Mr Gregory said. "Importantly don't go to work or school or public places - one person visiting a location can result in 10 or 15 more cases popping up."

Vaccination remains the best prevention, and anyone going overseas should discuss their travel plans with their GP. Those travelling with children under 12 months can also check with their GP, as the vaccination schedule can be adjusted.

"If mothers are up to date with their vaccinations then their newborns will carry that protection over," Mr Gregory said.

"We would also recommend any women planning a pregnancy to make sure they get the vaccine - and then wait four weeks until they try for a child.

"Meantime the 12-month MMR (measles, mumps, rubella) vaccination can be brought forward if infants under 12 months are travelling to high risk areas for measles."