The US is reporting its highest number of measles cases in a single year since 1991, writes The Washington Post.

The country has had 2,295 cases so far this year, compared to a total of 2,289 last year. With just over five months left in the year, that is already the highest annual number since the disease was declared eradicated in the US in 2000.

According to experts The Washington Post has spoken to, the numbers are due to large outbreaks in the states of South Carolina and Utah earlier this year.

As vaccination coverage declines and measles spreads more widely, it is becoming more difficult to control the outbreaks, according to infectious disease experts.