The World Health Organization declared an international emergency on Monday over the explosive spread of the mosquito-borne Zika virus, which is linked to birth defects in the Americas, saying it is an "extraordinary event."
The U.N. health agency convened an emergency meeting of independent experts in Geneva to assess the outbreak after noting a suspicious link between Zika's arrival in Brazil last year and a surge in the number of babies born with abnormally small heads.
"After a review of the evidence, the committee advised that the clusters of microcephaly and other neurological complications constitute an extraordinary event and public health threat to other parts of the world," WHO Director-General Margaret Chan said.
The organization said last week that the virus was “spreading explosively" and is now becoming more of a threat. Since Brazil reported its first case in 2015, the virus has been detected in 22 other countries and territories. WHO estimates there could be up to 4 million cases of Zika in the Americas in the next year.
According to The Centers for Disease Control and Prevention, no locally transmitted cases of the virus were reported in the United States. Health officials have found cases in travelers in several states, including New York, Massachusetts, Illinois and Texas.
The CDC says Zika is transmitted through infected mosquitoes. It can also be passed on from a pregnant mother to her child, which may result in a rare birth defect. Babies born with microcephaly, which causes babies to be born with an abnormally small head, have been increasing in Brazil. Although there is no definitive proof that the virus is in any way related to birth defects, WHO says it “strongly” suspects a causal relationship.
The illness is usually mild, according to the CDC, and those infected don't realize they have the virus. Symptoms include rash, fever and joint pain.
Experts said they are are currently working on a vaccine that could be ready for clinical trials by the end of the year. But a widely available vaccine won't be ready for several years.
"It is to our advantage we already have existing vaccine platforms to use as a sort of jumping off point," said Dr. Tony Fauci, head of the National Institute for Allergy and Infectious Diseases (NIAID).
Concern over the spread of the illness has prompted worldwide concern.
Athletes preparing for the 2016 Summer Olympics in Rio say they’re taking precautions, including staying indoors and using mosquito repellent. The IOC issued a warning to all national Olympic committes to prepare for and address the problem.
Airlines have been offering refunds to passengers for travel to Zika-affected areas, according to The Associated Press.
Earlier this month, the CDC issued an alert, warning pregnant women to avoid countries where the virus was in active transmission.
Anyone who believes they may have the virus is urged to get plenty of rest, drink liquids and see a doctor.
The last time such public health emergency was declared was for the devastating 2014 Ebola outbreak in West Africa, which killed more than 11,000 people.