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What is Zika Virus, and Do Americans Need to Worry?

Q&A with Davidson Hamer, MD
Director of the Travel Clinic, Boston Medical Center


Davidson Hamer, MD, director of the Travel Clinic at BMC, and professor of global health and medicine at the Boston University School of Public Health and School of Medicine, is a board-certified specialist in infectious diseases, with a particular interest in tropical infectious diseases. He has 20 years of field experience in neonatal and child survival research. He recently returned from a trip to Zambia, where he is conducting clinical trials on neonatal sepsis and integrated management of childhood illness. Here, we talk to Dr. Hamer about the Zika virus to learn more about what it is, and who is at risk.

Q. What is the Zika virus and how is it spread?

A. Zika is a member of the Flavivirus family (which includes dengue, yellow fever, and West Nile and other less common viruses) which is spread primarily by the bite of infected mosquitoes. Less common modes of transmission include transplacental (mother-to-child during pregnancy) and possibly through unprotected sexual contact and contaminated blood products, though researchers are still determining if those are legitimate pathways to transmission.

Q. What does it mean when the World Health Organization (WHO) declares a public health emergency (as it has done with Zika virus)?

A. The WHO may declare a public health emergency when there is a plausible risk of harm or death to a large segment of a specific group of people, or to the general population. In this case, the risk of pregnant women transmitting the virus to their unborn child, and possibly causing microcephaly is a big enough concern to warrant the WHO's declaration. However, this does not mean that people should panic, but rather such a declaration allows the WHO to help coordinate international surveillance efforts, such as recording cases of Zika virus, microcephaly and other neurological complications, to better track the illness and its worldwide impact and ultimately to develop and disseminate resources where needed, when available and appropriate.

There is currently limited to no risk of Zika virus here in Boston as the infected species of mosquitoes are not found here.

Q. Do we have to worry about it here in Boston/in the US?

A. There is currently limited to no risk of Zika virus here in Boston as the infected species of mosquitoes are not found here. However, both the Aedes aegypti Ae. albopictusspecies of mosquitoes are present in the U.S., particularly in southern states with warmer climates, and the latter species can be found as far north as New Jersey and Pennsylvania. Thus there is a definite risk for introduction of Zika virus into the U.S. with local transmission when the weather warms up.

Q. What are the symptoms of Zika virus?

A. Many patients who are infected with Zika virus are asymptomatic. Of those who do show symptoms, the most common are fever, rash, conjunctivitis and joint pains.

Q. Is Zika virus fatal or otherwise dangerous, and what is the typical prognosis?

A. It is usually a mild illness that resolves spontaneously after three to five days (though it can last up to two weeks). The prognosis is excellent (outside of pregnancy where there may be a risk to the fetus) although there is a small but growing body of evidence that the neurological illness Guillain-Barre syndrome (ascending paralysis) can rarely occur.

Q. What can we do to protect ourselves against Zika virus?

A. To protect yourself against Zika virus, be sure to use personal protection measures, which includes wearing long-sleeved clothing, using insect repellent that contains DEET or picaridin, and staying indoors in screened areas. On a population level, environmental control (draining breeding sites, using larvicides) and insecticides can be used to control the mosquito populations.

Q. Do all mosquitoes carry it?

A. No, only certain members of the Aedes family of mosquitoes can transmit the Zika virus.

Q. Are children or other populations more susceptible to Zika virus?

A. Not as far as we know at this point, with the possible (still to be conclusively proven) association with adverse pregnancy complications (microcephaly).

Q. What if I get bitten by a mosquito, is there anything I should do?

A. It depends on where you are! If you are in an area with ongoing Zika transmission, there are guidelines for screening for exposure that the Centers for Disease Control and Prevention (CDC) has developed, and that the American College of Obstetrics and Gynecology has modified and circulated for pregnant women. The first step is testing for infection. If positive, then a fetal ultrasound needs to be done.

Q. What is the treatment for Zika virus? Is there a vaccine or a cure?

A. Treatment is symptomatic (such as ibuprofen to help reduce pain and fever). There is no specific treatment and therefore no cure, and currently there is no vaccine for Zika virus.

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