Experts
Cynthia Gyamfi-Bannerman, MD, MSc, Associate Professor of Obstetrics and Gynecology, College of Physicians & Surgeons
Ian Lipkin, MD, the John Snow Professor of Epidemiology (Mailman School of Public Health) and Professor of Neurology and Pathology and Cell Biology (College of Physicians & Surgeons); and Director, Center for Infection and Immunity, Mailman School of Public Health
Stephen Morse, PhD, Professor of Epidemiology, Mailman School of Public Health
Jeffrey Shaman, PhD, Associate Professor of Environmental Health Sciences, Mailman School of Public Health
What is Zika virus?IL: Zika is a mosquito-borne virus that was originally identified in Africa over 60 years ago. More recently it has spread to South America and the Caribbean. It’s not usually associated with severe disease—many people who are infected with this virus are going to have no symptoms of it all, or they’ll have symptoms that are mild and consistent with the flu or any wide range of other very common diseases.
But in some pregnant women, the virus has been linked with a condition known as microcephaly, in which the baby’s head and brain do not develop normally, and in some individuals the virus has been linked with an autoimmune disease called Guillain-Barre syndrome, which is associated with loss of motor control.
How is Zika transmitted?SM: We know the mosquito is a major transmitter of this virus. There have been a few reports of potential sexual transmission, and there has been one report of blood-borne transmission following a blood transfusion. But almost always, it’s the mosquito that’s causing the trouble.
Is there a test to see if I have the virus?SM: If you’ve had high risk travel and you think you were bitten, there is a way for your doctor to test you. There is a test that determines if you have the virus in your bloodstream. If you’ve been sick and have since recovered, there is another test to see if you have antibodies to the virus. These tests have to be done by health departments. In New York City, for example, if a physician thinks they’re seeing a case of Zika, they have to call the New York City Health Department, who will make the arrangements.
CG: I think that most pregnant women in the United States are not at risk. In addition to the viral tests, ultrasound can help to determine whether your developing baby’s head meets the very strict criteria for microcephaly.
Is there a treatment for Zika?SM: At present, we really don’t have any specific treatments. Treatment is basically symptomatic. For those people who have symptoms—that would be a rash, fever, bloodshot eyes, or possibly fever and headache, or joint pains—doctors can treat the symptoms of Zika infection. The vast majority of adults are likely to recover without any ill effects, other than not feeling well for a week or two.
Is there a way to prevent Zika infection?IL: People can reduce their risk by avoiding exposure to the mosquito that carries Zika. One way is to wear insect repellent, which reduces the risk that a mosquito is going to find you attractive. We are also hoping to prevent the virus from spreading by using methods to decrease the mosquito population.
SM: There isn’t a vaccine, but there’s work being done on the vaccine. There are some candidates based essentially on modifying the yellow fever vaccine. I don’t know whether it’s ever going to actually get into the field, as determining that it’s safe and effective and then scaling up production frequently requires years.
What is microcephaly?CG: Microcephaly is a condition in which a baby is born with an abnormally small head. The criteria for diagnosing microcephaly are very specific and can only be determined in a formal ultrasound unit by someone who’s trained in doing these measurements. If you think your baby is at high risk for this condition, your doctor can refer you to a unit where the baby can be properly measured. Microcephaly is fairly rare.
We don’t yet understand the link between Zika and microcephaly. I think that it’s more of an association at this point. Microcephaly has been the most commonly reported birth defect among women who were infected with Zika during pregnancy. We don’t have enough information, including long-term outcomes, to determine if Zika is the actual cause of this condition.
Should I travel to affected areas?If I’m pregnant or trying?
CG: We don’t know during which trimester of pregnancy that transmission may pose the most serious risk to a developing fetus. If you’re pregnant or actively trying to become pregnant, and you’re planning to travel to one of the potentially affected areas, the first thing that you should do is go to the CDC website and see what the status of that country might be. If it’s currently affected and this is non-essential travel for you, then you probably should not take that trip.
I’d like to have a baby someday, but not now?
CG: The virus is self-limited, so once you’ve been infected there’s no long-term effect from this virus. If you think you want to get pregnant someday but you’re not actively trying at this point, it should be okay to travel. You should still use the same precautions in terms of avoiding being bitten by mosquitoes, but there’s no reason to delay your travel to these areas.
Are there any other reasons to be cautious about traveling?
CG: If you’re not a woman of childbearing age, the risk of severe disease as a result of exposure to this virus is much lower. I would recommend that you use precautions in terms of mosquito bites. Otherwise, you should be able to travel with no other problems.
Where did Zika come from?SM: Zika was once considered an obscure virus. It was discovered in 1947 in an infected monkey in Uganda. At that time, there were no known human cases of the disease. A few years later in Africa, there were reports of Zika infection in some humans, and the virus began to spread. In the last few years, there was an outbreak of the virus in Polynesia and Micronesia. Within the past few months, Zika has spread throughout much of the Caribbean and most of South America.
When people began to see Zika, there was a little bit of maybe complacency about it because we’ve never really seen severe disease. Dengue was much worse. Chikungunya seemed worse. Now in Brazil suddenly we are beginning to see abnormalities in newborns. There are almost 4,000 cases—only about 400 have been proved to be due to the virus, the rest are suspected.
Will Zika cause an outbreak in the United States?SM: The virus usually requires a mosquito to transmit it. Rarely, it may be transmitted via a blood transfusion or by sexual contact. That’s not going to happen very often. We will see imported cases here, but it’s extremely unlikely that it’s really going to go anywhere if the right mosquito isn’t present.
JS: The species that can carry the virus, Aedes Aegypti, is found only in the south of the Gulf States, basically in Florida. Another species, Aedes Albopictus, can be found as far north as Chicago, and it’s been argued that that one may also be capable of transmitting Zika. We do not expect the virus to gain a foothold in the U.S. because our infrastructure prevents widespread interaction between mosquitoes and people. We may have some isolated cases of Zika virus here, many of them imported.
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