Officials at the World Health Organization will hold an emergency meeting to discuss how to combat the unexpectedly rapid spread of the Zika virus.
According to The Washington Post, the WHO said the Aedes mosquito-borne illness is "spreading explosively" across the Americas, largely because the area is new to the virus and, therefore, has not had time to build up an immunity.
During a briefing in Geneva, Margaret Chan, director general of the WHO, reportedly said,
The level of alarm is extremely high, as is the level of uncertainty. Questions abound. We need to get some answers quickly.
Chan added the rapid spread is also due to increasingly high temperatures, allowing populations of the Aedes mosquito to flourish.
The virus first emerged in Brazil last May and is now present in 23 countries including Mexico, Puerto Rico, Guatemala and Colombia.
In the United States, 31 people in 11 states and the District of Columbia were reportedly diagnosed.
Lyle Petersen of the Centers for Disease Control and Prevention confirmed all of these individuals contracted the disease abroad.
He also noted the amount of cases in the US is "increasing rapidly."
Earlier this week, the WHO predicted Zika would reach every country in the Americas, except for Canada and Chile because those are the only two that do not contain the Aedes mosquito, which can also carry dengue fever, yellow fever and chikungunya.
Brazil is estimated to have up to one million Zika patients, The Guardian reports.
Marcos Espinal, director of communicable diseases and health analysis for the Pan American Health Organization, predicted up to four million cases of the virus will arise across the globe.
He believes the area of the US affected the most will be the South, where the Aedes mosquito previously spread dengue fever.
The WHO said potential vaccines are being crafted but developing them could take several months.
Several affected countries are, instead, concentrating on spraying houses for possible mosquito infestations and educating the public about using bug spray and sleeved clothing.
Some believe the WHO's delayed response is partially to blame for this crisis.