Federal health officials have identified 465 measles cases this year, nearly 100 more than last week.
Since January 1, there have been confirmed cases in 19 US states, the Centers for Disease Control and Prevention (CDC) reported on Monday.
Measles was declared ‘eradicated’ in the US in 2000.
But the disease has since had a resurgence, with a record 667 cases in 2014 – and just four months into 2019, this year’s tally is quickly catching up.
The highly infectious disease has been spreading among people who are unvaccinated or live in states that allow non-medical exemptions for vaccines.
Since January 1, the CDC has identified 465 measles cases in 19 US states, nearly 100 more than last week
Cases have been confirmed in: Arizona, California, Colorado, Connecticut, Florida, Georgia, Illinois, Indiana, Kentucky, Massachusetts, Michigan, Missouri, Nevada, New Hampshire, New Jersey, New York, Oregon, Texas and Washington.
Of those states, six – Arizona, Colorado, Michigan, Oregon, Texas and Washington – allow exemptions for philosophical and/or personal beliefs.
Washington and New York, particularly, have been struggling to contain the disease.
In January, Washington declared a public health emergency after a measles outbreak that has affected 73 people in Clark County and one in King County, where Seattle is located.
Sixty-three of the cases are in residents who have not been vaccinated. Fifty-three cases are in children aged 10 and under.
Meanwhile, in New York, there have been at least 426 confirmed cases in Brooklyn, Queens and Rockland County since October 2018 – most in Orthodox Jewish communities.
Two weeks ago, officials in Rockland County issued a State of Emergency, banning unvaccinated people under age 18 from public places.
Additionally, the county is offering free MMR (measles, mumps, rubella) vaccines for residents six months and older.
Many anti-vaccination hotspots – such as Rockland County and Portland, Oregon – are known for insular and, in some instances, ultra-religious.
Additionally, a 2018 study from George Washington University in the District of Columbia revealed that Twitter bots and Russian trolls have been fueling the global anti-vaxxer movement online.
Measles is a highly contagious infection caused by the measles virus.
When someone with measles coughs, sneezes or talks, infected droplets are sprayed into the air, where other people can inhale them and may get infected.
Symptoms present themselves between 10 to 14 days after infection and include fever, cough, runny nose and a whole-body skin rash.
For most, measles is not life-threatening. However, in some cases, people can suffer from serious complications including pneumonia and brain swelling.
Once common, the disease is now rare thanks almost entirely to the MMR vaccine, which was introduced in 1963.
The CDC recommends children receive the first dose at 12 to 15 months old and the second dose at four to six years old.
The vaccine is about 97 percent effective. But those who are unvaccinated have a 90 percent chance of catching measles if they breathe the virus in, according to the CDC.
Before the measles vaccine was available, more than 500,000 cases were diagnosed in the US every year, with about 500 annual deaths.
A report published by the World Health Organization (WHO) in January said measles has seen a 30 percent increase in cases around the world from 2016.
WHO also revealed that nearly 83,000 people contracted measles in Europe in 2018, the highest number in a decade.