Is the public health response to the Zika virus appropriate?

Post date: Feb 7, 2016

As an infectious disease epidemiologist, I’ve been asked several times my opinion on Zika (pronounced zEEka). Like most, I hadn’t heard of the virus until a few weeks back, and since that time have read and heard a great deal about the potential pandemic we’re believed to be in the midst of (reminds me of West Nile scare from several years back, or the media frenzy surround Ebola from the last years). What we know about the virus and disease is from a very limited body of research, but the virus is not new. It has been around since at least the mid 1900s, was first isolated in the Zika forest of Uganda, and most recently emerged as an epidemic infection in Oceana, a collection of islands in the tropical Pacific Ocean. It’s an arbovirus, meaning it’s transmitted from mosquito to human, and appears to be predominately endemic (or native) to South and Central America. The genus of mosquito that transmits the virus is known as Aedes, and is also responsible for transmitting such diseases as Dengue and Chikungunya. In addition to initial infection from the mosquito, it has also been associated with vertical transmission from mother to child during pregnancy, and horizontal transmission via sexual intercourse and possibly through other bodily fluids. There is no known treatment or vaccine at present.

For the majority of adults (~80%), the virus will infect without symptoms or cause only minor fever, joint or muscle pains, and possibly rash, for less than a week. The virus clears in a few weeks, and does not linger in the blood for any longer duration. There is a suggested association with the much more serious Guillain–Barre syndrome, but that causal relationship is unclear, and still very rare, as is any serious complication from infection. In an intriguing analysis by Bogoch and colleagues, they simulated the international spread of Zika based on travel patterns, and habitat of the mosquito. Orange areas in the map on the right represent endemic habitat for the mosquito, and thus greater risk, and yellow areas represent seasonal habitat. Particular to the US, normal mosquito prevention activities should minimize the threat, particularly in mosquito prone areas like Florida, which incidentally has declared a state of emergency to secure funds for prevention activities.

The media has been throwing around the word microcephaly (a small head circumference possibly with associated abnormal brain development), and if you listen to the reports you would think there is going to be an epidemic of microcephalic, tiny-headed babies. Well, as it is microcephaly is not exactly a rare condition (because of how its diagnosed, it's over-reported), and in many cases is non-pathologic, without neurodevelopmental complications. The present concern is the cluster of infants with pathologic microcephaly in Zika-endemic areas in Brazil, and its potential to occur in pregnant women elsewhere that are exposed to Zika (either directly or indirectly). Although Zika-associated microcephaly is potentially pathologic with harmful outcomes, as of January CDC has only confirmed four infections in Brazilian pregnancies and the overall incidence of pathologic microcephaly in Brazil is < 6 in 10,000 births, still pretty rare. Most of the cases of microcephaly have been attributed to other (non-Zika) causes. Current recommendations to limit travel for pregnant women may be beneficial to those who can reschedule; otherwise standard mosquito precautions like DEET-based insect repellant, long sleeved shirt and pants, and using screening/mosquito nets will afford some protection.

As this point more is unknown about its relationship to pregnancy outcomes than known. But, we are seeing recommendations to reconsider travel to Zika-endemic areas, use condoms or abstain from sex upon returning, and some countries have even suggested women who are considering getting pregnant to wait until after the epidemic subsides, which is an absurdly naïve statement. Coupled with the recent CDC alcohol recommendations that imply women of childbearing age who want to consume alcohol use contraceptives, public health appears to be stigmatizing women and further creating much undue anxiety surrounding pregnancy. And I’m sure that any woman going through pregnancy has enough anxiety already without worrying about Zika. Is this an appropriate public health response, to create anxiety? Public health should focus on alleviating fears through knowledge: that Zika in the US will not harm the majority of adults, and that for women considering pregnancy the risk of harmful outcomes from Zika pale in comparison to much more significant health threats (domestics partner violence and influenza, to name a few) that don’t receive the same kind of attention from the media.

Addendum, Feb 10, 2016: Since posting earlier this week, this has quickly become the most popular blog post on the site. Normally I don't update these posts for typos or editorial comments, but I wanted to share some other articles expressing a similar sentiment. Dr. Ronald St. John, Former Director General of the Centre for Emergency Preparedness and Response, Public Health Agency of Canada, wrote an excellent commentary about the media response to Zika [see section entitled Current Concerns]. The UN has appropriately pointed out that some countries responses to Zika are violating women's human rights. Lastly, as an example of the ridiculous assertions that garner media attention were the quarantine remarks made during the presidential primary debates, which would also violate basic human rights. So where does one turn for reliable information? The Centers for Disease Control and Prevention and World Health Organization have Zika-response pages intended for the public, and the very latest info can always be obtained by reading the communications from ProMED (the Program for Monitoring Emerging Diseases), an "Internet-based reporting system dedicated to rapid global dissemination of information on outbreaks of infectious diseases."