How dangerous is Zika? Is it deadly? What is the risk of Zika virus to people within the U.S.?
Any infection can be serious, particularly in people with other health issues, but most people who become infected with Zika only mild symptoms or often display no symptoms.
As far as we know, no mosquitoes in the U.S. are carrying the Zika virus -- that is, there is no local transmission in the continental U.S. as of today.
Within the U.S., the risk is highest in the territory of Puerto Rico, which has been impacted significantly by other similar viruses previously (dengue, Chikungunya).
Because of these increased risks, all blood donors in Puerto Rico are being screened.
The Zika virus invades and disrupts the development of the fetal brain, but the effects on the brains of infants and young children are unknown.
“The biggest risk is to pregnant women,” Frieden said. “We now know that even women with asymptomatic infection can give birth to infants with microcephaly. The maximum point of vulnerability is probably late in the first trimester and beginning of the second trimester.”
What are the future risks for people who have been infected by Zika?
“From all the available evidence, the body has an excellent immune response to Zika,” Frieden said. “Therefore, once you get it once, you will never get it again.”
However, in males, the virus can persist, particularly in semen, and further studies are needed to determine how long this may persist. That is why it is important for men who have possibly been infected to engage in safe sex practices for six months to prevent transmitting the virus to their partners.
For young people and teenagers who are infected, there should not be a risk of birth defects for future pregnancies.
What about the risk of Zika at the Olympics?
From a public health standpoint, there is no need to move the Olympics.
The risk to the athletes is present, but very low, and risks of complications from the virus increase with age, so they are low in young, healthy people.
“There is always risk involved in travelling,” Frieden said. “Zika adds a little bit to that risk for people travelling to the Olympics. ... The risk is low; it’s not zero, but it’s low. We make one recommendation here: if you’re pregnant, don’t go.”
What are your hopes for Congress’ response to Zika?
Currently, resources have been diverted from other important projects toward Zika virus. Funds have been diverted from:
State and local government emergency response resources.
Efforts to keep Ebola under control in West Africa.
All of the existing staff working on dengue have been moved to Zika efforts.
“In the end, Congress did the right thing on Ebola, and I’m hopeful that they will do the right thing on Zika as well,” Frieden said. “We don’t want to take money from fighting one problem to fight another. ... It’s very important that Congress act quickly to give us the resources we need for a quick, sustained, robust response.”
What is on the horizon in terms of combating Zika?
The National Institutes of Health is leading vaccine development, which may begin trials later this year, but it would still be 1 to 2 years before a vaccine is available
Regardless of vaccine availability, controlling mosquito populations will be key.
“In addition to the message about personal health, this is another example of an emerging disease,” Frieden said. “This is another example of why it’s important to help other countries be prepared, to help them with their early response. It’s always going to be easier to fight them there than to try to fight them when they’ve spread over here.”
Dr. Jennifer Yui is an internal medicine resident at Mayo Clinic. She is a resident in the ABC News Medical Unit.