The number of measles cases worldwide nearly quadrupled in the first quarter of 2019 to 112,163 against the same period last year, the World Health Organisation says, citing provisional data.
Higher rates of the preventable but contagious disease - which can kill a child or leave it blind, deaf or brain-damaged - have been recorded in all regions, the United Nations agency said in a statement, appealing for better vaccination coverage.
Australia has also been hit. NSW has had 35 cases since Christmas and Queensland has seen 12 confirmed cases this year.
Fresh outbreaks have hit the Democratic Republic of Congo, Ethiopia, Georgia, Kazakhstan, Kyrgyzstan, Madagascar, Myanmar, the Philippines, Sudan, Thailand and Ukraine, "causing many deaths - mostly among young children", the WHO said on Monday.
It gave no figures for fatalities but noted it estimates that only one in 10 cases is reported globally.
"Over recent months, spikes in case numbers have also occurred in countries with high overall vaccination coverage, including the United States of America as well as Israel, Thailand, and Tunisia, as the disease has spread fast among clusters of unvaccinated people," the WHO statement said.
US federal health officials said on Monday the number of confirmed cases of measles in the United States this year jumped by nearly 20 per cent in the week ended April 11 - the country's second-worst outbreak in nearly two decades.
While 20 states have reported cases, New York has been the epicentre, The Associated Press reports. Nearly two-thirds of all cases have been in New York, and 85 per cent of the latest week's cases came from the state. Most of the New York cases have been unvaccinated people in Orthodox Jewish communities.
A growing and vocal fringe of parents in the US oppose measles vaccines in the belief, contrary to scientific evidence, that ingredients in the vaccines can cause autism or other disorders.
Increasing vaccination coverage maximises a population's protection, the WHO said.
Global coverage with the first dose has "stalled" at 85 per cent, against 95 per cent needed to prevent outbreaks, while 25 countries still do not include a second dose in their national programs, it said.
Australian Associated Press