What is Zika?
Zika is a mosquito-borne virus that is sweeping through South and Central America. Its initial symptoms are mild. The main ones, according to the U.S. Centers for Disease Control and Prevention, are "fever, rash, joint pain and conjunctivitis" or red eyes. Severe cases can linger for up to a month and sometime send patients to the hospital.
The real threat, according to the CDC, seems to be a link between Zika and a serious birth defect called microcephaly, in which the baby’s head is unusually small "compared to babies of the same sex and age." The defect has shown up in the babies of women infected with Zika during pregnancy.
"We’re doing everything we can to understand a little bit more about many of the basics — how often does it happen, what are the risk factors, are there certain things that make this transmission from pregnant women to babies more likely," Dr. Beth Bell, director of the National Center for Emerging and Zoonotic Infectious Diseases at the CDC, told VOA.
"Based on what we know of other infectious causes of congenital malformations, and also based on some preliminary information and what we know about when, during a pregnancy, the fetal brain develops, we think that it’s likely that the risk will be higher in the first trimester, and perhaps with decreasing risk as the pregnancy develops," she added. "But we still do not have really good information about this."
The World Health Association says the virus’ arrival in Brazil also has been associated with a rise there in cases of Guillain-Barre syndrome, a rare disorder that can produce muscle weakness and even paralysis.
The CDC says that "knowledge of the link between Zika and these outcomes is evolving." Until more is known, it recommends "special precautions for the women who are pregnant or trying to become pregnant."
Likewise, the WHO says "a causal relationship between Zika virus infection and birth defects and neurological syndromes has not been established but is strongly suspected." It’s convening an emergency meeting Monday in Geneva on the virus.
FILE – A neurologist measures the head of a baby suspected of having microcephaly, at Mestre Vitalino Hospital in Caruaru, Pernambuco state, Brazil. The condition may be linked to the mosquito-borne Zika virus.
Where did it come from?
Zika was discovered in 1947 in Uganda's Zika forest. Up until 2007, outbreaks were rare and narrowly confined to areas of Africa and Southeast Asia. But in the past decade, epidemics have been reported in Micronesia and Polynesia, Easter Island, the Cook Islands and New Caledonia.
"There are over 20 countries where we’ve identified Zika, and I’m quite sure that this number will grow," Bell said.
The first case in South America was identified last May in Brazil. Since then, the disease has spread rapidly through most of Central and South America. Brazil’s health ministry recently reported more than 4,000 suspected cases of microcephaly since October, compared with less than 150 in all of 2014, the Associated Press reported this week.
How many cases have been reported?
So far, more than 1 million Zika cases have been reported in Brazil alone. But the WHO says it expects the disease to affect between 3 million and 4 million people before it runs its course.
The question of endemic transmission in the United States — where mosquitoes and humans are spreading the disease in a community without someone having traveled to an area where the virus is circulating — "this is something that might certainly happen in a very limited way, in a few small communities around the United States, but we think it’s highly unlikely that there’s going to be wide-scale transmission in the United States," Bell said. "This has certainly been our experience with Dengue and with Chikungunya, which are both other viruses carried by the same mosquitoes.
"And it’s likely due to a number of reasons. Certainly some of them are related to our lifestyle here in the United States, where most homes in the southern part of the United States have screens and there’s air conditioning. The population density is considerably less than in many other parts of the world. And these are all factors that make it very, very unlikely that there’s going to be widespread transmission in the United States."
What is the treatment?
There is no vaccine or medical treatment currently available for Zika. The WHO and the CDC recommend rest, plenty of fluids and acetaminophen for fever and pain.
"One of our very highest priorities is to work hard to speed up development" of vaccines and treatments, Bell said.
The CDC also recommends that infected patients avoid mosquitoes because "Zika virus can be found in the blood and passed from an infected person to another mosquito through mosquito bites."
What can I do to avoid getting the disease?
Only an estimated one in five people exposed to the disease will become ill, but all of them can transmit the disease through mosquitoes feeding on them and then infecting other people.
"These kinds of mosquito-borne viruses, unfortunately, have this capacity for very rapid spread, and there are some modern day factors — urbanization, large cities, international travel — that tend to promote this sort of spread," the CDC's Bell said.
The CDC has issued a Level 2 alert and has urged travelers to Central and South America to practice "enhanced precautions" to avoid getting bitten by mosquitoes. This includes wearing long-sleeved shirts and long pants, using insect repellents containing DEET or permethrin-treated clothing. Finally, sleep in covered or air-conditioned areas.
"These Aedes aegypti mosquitoes bite indoors, not just outdoors, and during the day, not just at night," Bell said. "So that means, these prevention measures, it’s important to take these measures all the time."
Bell noted that these mosquitoes "live inside as well as outside. They can breed in very, very small amounts of water, really tiny amounts of water. There are some things that we can do, and are done, to reduce breeding sites for these mosquitoes and some application of insecticides, but it’s unfortunate that vector control is not a solution to these mosquito-borne infections."
Also, women who are pregnant, in any trimester, should consider postponing travel or at least talk with a doctor about the best ways to avoid mosquito bites. The same goes for women who are trying to become pregnant.
FILE - A graduate student analyzes samples to identify the Zika virus in a laboratory at the Fiocruz institute in Rio de Janeiro, Brazil, Jan. 22, 2016.
What is being done to stop Zika?
Any number of researchers and research institutions are looking for a vaccine and a treatment. Until they’re successful, the best way to fight the disease is to combat the mosquitoes that carry the virus.
Officials in Brazil and some of the 22 other countries reporting Zika cases are conducting mass spraying of pesticide and urging citizens to empty any standing water containers as a way to prevent breeding grounds for mosquitoes.
At the CDC, "we’ve been working very closely with partners in Brazil and other parts of South and Central America and with the Pan American Health Organization," Bell said. "One of the things we’ve been doing is helping ... with laboratory testing. ... A a very important component of being able to detect and respond is having the laboratory capacity to be able to diagnose. We’ve been in Brazil recently, training [staff] on how to do the lab tests and to provide that sort of technical assistance to other countries in the area."
VOA's Carol Pearson contributed to this report.