What is Zika virus?
Zika virus is an illness transmitted to people through bites from mosquitoes of the Aedes species -- the same mosquitoes that spread dengue and chikungunya viruses. It not communicable from person to person but can be transmitted when a mosquito bites someone who's infected and then bites someone else.
The virus was first discovered in Uganda in 1947 and named after the forest in which it was found.
Officials say the current Zika outbreak in Brazil began last May. Authorities there estimate that since then, between 440,000 and 1.3 million people have caught it. Zika has spread to other countries in Latin America and the Caribbean, including Colombia, Venezuela, Honduras and Mexico. Puerto Rico reported its first case of locally transmitted Zika virus in December.
What are the symptoms?
According to the CDC, the most common symptoms of Zika virus are fever, rash, joint pain, and conjunctivitis. Other symptoms can include muscle pain, headache, pain behind the eyes, and vomiting.
Symptoms are usually mild, lasting from a few days to a week. Many people infected with the virus experience no symptoms at all. In rare cases, symptoms can become severe and require hospitalization.
A number of Zika patients in Brazil have also gone on to develop a rare autoimmune condition called Guillain-Barré syndrome, which can cause at leasttemporary paralysis. Health officials are investigating the possible connection.
Is there a vaccine or cure?
There is no vaccine to prevent Zika virus. The U.S. National Institutes of Health is ramping up efforts to develop one, but the process will take time.
"It is important to understand we will not have a widely available safe and effective Zika vaccine this year and probably not in the next few years," said Dr. Anthony Fauci, director of the NIH's National Institute of Allergy and Infectious Diseases.