What’s the Scoop on Zika?
(Updated August 2, 2016)
Zika virus has been in the news with some regularity over the past few months. This is a relatively new public health threat so we are still learning about what it is, how it affects us and what to do about it. This is our best effort at providing you with accurate and timely information, but please keep in mind that this is an evolving picture. If and when this article gets updated, we will adjust the dateline above and try to put any new information in boldface to make it easier to find. We’ll also try to keep this limited to practical information rather than a lot of microbiological background. (“Zika is a positive RNA virus belonging to the Flavivirus group ….. <snore>”)
The most dramatic and terrifying aspect of Zika is its potential to cause severe brain damage to unborn children—a condition called microcephaly where the brain is severely underdeveloped. This can occur when pregnant women get infected and the virus spreads to the fetus in the womb. The chances of this happening are still unknown, largely because 80% of people who get infected have no symptoms. (To get a handle on the risk, you have to know how many pregnant women are infected and then determine how many of their babies have complications. However, it’s hard to know how many pregnant women have been infected if the vast majority of them don’t have any symptoms!)
Luckily, there has been NO transmission of the disease by mosquitoes in the USA to date. (Update: Officials in Florida are now investigating four cases of “locally transmitted”—i.e., mosquito borne—Zika infection, two in Miami-Dade County and two in Broward County. It is important to note that these have not yet been confirmed as mosquito transmitted infection, but if confirmed would represent the first cases in the U.S. that are not travel related) The only confirmed U.S. cases are either from sexual activity or from patients who contracted the disease in another country. We can only hope it stays this way, but the climate in the southeastern United States is acceptable for the species of mosquito that transmit the disease to survive, so we will have to wait and see. (Update: Well, we knew this was coming. Officials have now confirmed 14 cases of mosquito-borne Zika infection near Miami, Florida as of this writing and we can expect that there will be more. The CDC has now issued a travel advisory for pregnant women and their partners to avoid travelling to the area— Continue to practice mosquito-discouraging measures such as those outlined below.)
What if you and/or your family are travelling to an endemic area (Olympics, anyone)? The best thing to do is try to prevent getting infected in the first place:
- First and foremost, pregnant women should strongly consider whether a trip to an endemic area is truly necessary.
- Use insect repellent—DEET is the most effective and the CDC recommends that you use 30% concentration. It lasts longer and is more effective than the lower concentrations. What about reports that DEET can be neurotoxic in high concentrations? Those experiments were done on animals or cells isolated in culture—not on humans. In addition, in such studies, DEET was applied more directly, akin to ingesting it rather than just spreading it on the skin. In adults DEET has been used by literally billions of people, and if applied as directed is considered safe to use. We tend to be more conservative about use in children, but there actually is no evidence that 15% is any safer than 30%, so in light of recent increases in mosquito borne diseases, the AAP (American Academy of Pediatrics) recommendations have been liberalized to allow the use of 30% concentration on children down to the age of 2 months. Kim generally feels more comfortable with the older (to be fair, some would say “outdated”) recommendations of a 15% ceiling on children 6 months of age or older, and the use of screened tents for younger infants.
- If you are travelling to an endemic area, consider wearing clothing treated with permethrin, an insecticide. You can purchase clothes that are pretreated or treat them yourself, although you must follow the instructions carefully if you choose to treat your own clothes. Do NOT apply permethrin directly to your skin.
- Wear long sleeved shirts, long pants, socks and, ideally, a hat. Tuck shirts into pants and pant legs into socks.
- Stay/sleep in an air-conditioned room with the windows closed. Failing that, make sure that you have adequate mosquito netting around wherever you will be sleeping.
- Remove mosquito breeding sites to the extent possible in nearby premises. This largely means trying to get rid of standing water—discard old tires/debris, empty water out of lawn ornaments/birdbaths/trash cans, etc.
- Finally, men who return from an endemic area who have no symptoms are advised to practice abstinence for 8 weeks, while those who have symptoms are suggested to refrain from sex for 6 months (there are case reports of symptomatic males transmitting the virus to partners 6 weeks after symptoms developed!). These recommendations, however, are subject to change as we are currently not entirely sure about how long the virus remains viable in semen. These guidelines are designed to provide an abundance of caution. (Update: A case of female-to-male transmission has now been reported in New York.)
There is extensive intense work being done to develop a vaccine for Zika. Considering that there is no treatment and mothers could walk around with the infection without even knowing they have it or that it could affect their baby, this is very welcome news. We will try to keep you abreast of developments on this front.
While there is no treatment for Zika, remember that 80% of people who get infected have no symptoms. For the one out of five people who do develop symptoms, they are usually mild and limited to less than a week of fever, an itchy rash that spreads from the head down the body, red eyes (without discharge) and fatigue. Other symptoms can include headaches, body aches, gastrointestinal upset and a little swelling. While more serious consequences are possible, they are generally quite rare. (By the way, if you are unlucky enough to develop these symptoms, do NOT take any aspirin until the diagnosis is confirmed. Zika illness can mimic certain other diseases that can cause bleeding problems that aspirin would make worse.)
Bottom line, currently in our neck of the woods, Zika is still highly unlikely to result from a mosquito bite. Major concerns about contracting the disease would be almost exclusively for people who travel to endemic areas or have intercourse with travelers to endemic areas. Finally, remember that knowledge is progressing rapidly in this area, so it is quite possible that some of the above information may need to be revised as we learn more.