(CNN) – An effort spanning two decades has resulted in a global first: The Americas have eliminated measles, theWorld Health Organization said this week. The battle was won through mass vaccination to prevent the viral disease, which can cause severe health problems including pneumonia, blindness, brain swelling and even death.
Measles affects primarily children. Symptoms include high fever, generalized rash all over the body, stuffy nose and reddened eyes. Considered one of the most contagious diseases, the measles virus can be transmitted through contact with the secretions or breathing airborne droplets from an infected person.
Children who are malnourished and people with weakened immune systems are more like to experience serious complications including encephalitis, severe diarrhea and ear infections.
A disease is declared eliminated when there has been no transmission is a specific geographic region for a year or more, according to the US Centers for Disease Control and Prevention. Once elimination is achieved in every region of the world, eradication is declared.
Before the start of a vaccination campaign in 1980, measles caused 101,800 deaths in the Americas for the years 1971 through 1979. Worldwide, measles resulted in nearly 2.6 million deaths annually prior to 1980. As a result of global efforts, only 244,704 measles cases were reported worldwide in 2015, more than half of them in Africa and Asia.
This historic milestone would never have been possible without access to life-saving vaccines, said Carissa F. Etienne, director of the Pan American Health Organization, a regional office of the WHO.
Measles is the fifth vaccine-preventable disease to be eliminated from the Americas, according to the World Health Organization. The region eradicated smallpox in 1971, poliomyelitis in 1994, and rubella and congenital rubella syndrome in 2015.
The last endemic, meaning locally infected, case of measles was reported in the Americas in 2002, but imported cases have arrived in some countries in the region. Regional health organizations soldiered on, continuing their vaccination campaign and vigilance. After that, there was a separate outbreak in Brazil in 2013 that lasted well into 2015.
Now, to maintain measles elimination, it is recommended that all countries in the region strengthen their surveillance efforts and maintain immunity through vaccination.
“We can not become complacent with this achievement,” Etienne said. “Measles still circulates widely in other parts of the world, and so we must be prepared to respond to imported cases.”