Measles is one of the most easily spread of all human infections — you can be infected with it simply by being in the same room as a person who has measles.

It's normally not a problem in Australia, as most Aussies are typically immunised against measles at a young age. Babies are given the combined MMR vaccine (measles, mumps and rubella) at 12 months of age, followed by a second dose at 18 months.

But the New South Wales, Victorian and Western Australian government departments of health recently issued warnings about measles outbreaks — traced to other countries where immunisation may be less common.

Even though a safe and cost-effective vaccine is available, measles is one of the leading causes of death in young children worldwide. In 2016 there were almost 90,000 deaths due to measles globally.

Where is measles in Australia... and who's at risk?

Measles outbreaks in Australia can often be traced back to people becoming infected while overseas.

An outbreak in Melbourne has infected up to 9 people and is probably linked to a flight from Kuala Lumpur to Tullamarine airport on March 7. There were 3 more cases of measles reported in Melbourne in March, not related to that flight. These infections were most likely acquired overseas, in different locations.

In NSW in March, 5 people were infected with measles, including 3 infants who acquired their infections while overseas.

Two adults returning to WA in March were infected with measles while on separate holidays in Southeast Asian countries.

Anyone born since 1966 — just before the vaccine was introduced to Australia — who has not been vaccinated, can't show documented evidence of immunity to measles, or has a weakened immune system, is at risk of infection.

It’s important to be vaccinated. If you were born during or after 1966 and are not sure if you have had two doses of measles vaccine, you can see your doctor about catch-up vaccinations. Most states and territories provide these catch-up vaccinations free of charge.

State health departments list known locations visited by people infected by measles (often visited before they realise they have it). You can check it here (in Victoria), here (in NSW) and here (in WA).

Look out for symptoms of measles, including rash

Measles is an airborne viral disease, meaning it's spread through the air. A person is usually infected when they breathe in the droplets of measles virus that have been coughed or sneezed into the air by a person who already has it.