Twenty-one more measles cases have been identified this week, bringing the total nationwide number to 1,022, US health officials reported today.
The new cases have stretched into two more states Idaho and Virginia, making the total number of states affected up to 28.
This means the 2019 outbreak is the worst since 1992, when 2,126 cases were recorded.
The US is on track to lose its 'elimination' status and will instead become a country where measles is considered active.
Measles has been spreading among people who are unvaccinated or live in states that allow non-medical exemptions for vaccines.
The CDC reported the total number of measles cases for the year has risen to 1,022 and has stretched into Idaho and Virginia, bringing the number of states infected up to 28
Measles was declared eliminated in the US in 2000, meaning there was no continuous transmission of the disease for a year.
Cases that were reported in the US since the new millennium were spread via travelers coming from countries where measles is common.
The Centers for Disease Control and Prevention (CDC) have warned that the country risks losing its measles elimination status if the ongoing outbreak, which began in October 2018 in New York, continues until October 2019.
Losing elimination status would mean a threshold would be crossed and health officials measles would be considered a perpetual threat.
This year's outbreak has been attributed to vaccine misinformation and US parents who refuse to vaccinate their children.
These parents believe, contrary to scientific evidence, that ingredients in the vaccine can cause autism.
'We cannot say this enough: Vaccines are a safe and
