More than 70 measles cases have been reported in the US, with more than half of those linked to an outbreak at Disney theme park in California.
Measles is a highly-infectious virus that spreads through the air when sufferers sneeze or cough.
While most people in the UK and US are vaccinated against the virus - many receive the measles, mumps and rubella (MMR) vaccine in early life - the majority those affected by the US outbreak haven't been vaccinated.
The illness was declared eliminated in the U.S. in 2000, but many anti-vaccination communities have been forgoing vaccinations.
While a small proportion cannot be vaccinated due to medical reasons, some parents quote religious grounds or unsubstantiated claims that MMR vaccines can increase autism risk.
"The reduction in vaccination rates reveals one of the quirks of vaccines; they only protect a population if nearly everyone is vaccinated. This is the concept of herd immunity. The magic number for measles is 95, which means if at least 95% of people in a community are vaccinated, everyone is protected."
A few years ago, the UK faced a similar situation in Swansea, Wales.
During the measles outbreak, which lasted from November 2012 until July 2013, more than 1,200 people were affected, 88 visited hospital and one person died.
With this in mind, we decided to compile a list of symptoms and treatment.
According to the NHS, initial symptoms develop around 10 days after infection.
These can include:
- cold-like symptoms
- red eyes and sensitivity to light
- a high temperature (fever)
- greyish white spots in the mouth and throat
After a few days, a red-brown spotty rash will appear on head and neck, before spreading to the rest of the body.
Complications of measles can lead to pneumonia, diarrhoea, ear infection and convulsions. On rare occasions, measles has been linked to encephalitis and death.
There's no specific treatment for measles, but your immune system should fight off the infection within 7-10 days.
There are several things you can do to help make your recovery more comfortable, including:
- closing the curtains to help reduce light sensitivity
- using damp cotton wool to clean the eyes
- taking paracetamol or ibuprofen to relieve fever, aches and pains (aspirin should not be given to children under 16 years old)
- drinking plenty of water to avoid dehydration
Of course, if problems persist you should contact your GP immediately.