Andy Wiesenthal is a Director in the provider practice in the San Francisco office. Before coming to the firm, he practiced pediatrics and pediatric infectious diseases for 35 years. He is board certified in both and has published book chapters and articles on a wide range of clinical and health services topics.
Zika virus is much in the news lately, having been declared a global public health emergency just this week by the World Health Organization. Many of our practitioners have been asking questions about the virus and its implications, so I thought that the time is right for a brief discussion of the facts.
Zika virus was discovered incidentally more than 40 years ago by researchers working on yellow fever in the Zika Forest of Uganda. It infects mosquitoes (more on them in a bit), and mosquitoes transmit it to other animals, including humans. It is therefore called an arbovirus, or arthropod (mosquito) borne virus. For the last 4 decades, it has not been particularly important from either a personal health or public health standpoint.
It has not been (and is not) important from a personal health standpoint because, as viral infections go, this one is generally quite mild. Only about 20 percent of people who are infected develop any symptoms at all. Of those who do develop symptoms, people commonly have fever, conjunctivitis (bloodshot eyes), muscle aches, and sometimes rashes, and then it all goes away. That’s a good thing, since there is no specific treatment for it. Complications in the infected person are uncommon and death is rare. In short, most people don’t get sick, those that do are mildly ill, and it all goes away by itself.
Our attitude toward Zika has changed quickly over the last several months, as reports of increasing numbers of births of babies with microcephaly (unusually small heads) associated with maternal Zika infection began to mount, especially from Brazil and the Caribbean. Microcephaly occurs when a baby’s brain fails to grow normally in utero. Some babies with microcephaly are perfectly normal otherwise. Many have moderate to severe developmental delays, and some go on to have permanent disabilities. I have seen microcephalic babies every so often during my career as a pediatrician, and there are a variety of causes. Zika is a new cause, and it has so recently manifested that it is not yet clear how severely affected most of these babies will be. It is not even clear what proportion of babies whose mothers have Zika virus infection while they are in utero will develop microcephaly or have any problems at all—it could range from a few to nearly all of them. Time and careful follow up will tell.
But wait—didn’t I say that the virus was first isolated in East Africa? What’s all this about Brazil and the Caribbean? Back to the mosquitoes. Presumably, travelers infected in East Africa became ill (the incubation period is about a week) and were bitten by local mosquitoes after arrival in the latter locations. The two species of mosquito that carry the infection in East Africa (Aedes albopictus and Aedes aegypti—I know, TMI, but I can’t help myself) are worldwide in their distribution, and they are certainly prevalent in Brazil and the Caribbean, where it appears the virus has now become widespread in mosquito populations. Unfortunately, these same mosquitoes are widespread in the US, and it is probably just a matter of time before the virus gets well established here (think West Nile virus).
So what do we do? First of all, unless you are pregnant or planning on pregnancy, don’t worry about it too much. The risk of a serious problem for you is quite low. Could you get it? Yes. Will you even know it if you do? Odds are, no. If you have symptoms, are they severe or dangerous? In normal people, that is very unusual. And if you are pregnant, or are planning to become pregnant? If you are very risk averse, don’t travel to the Caribbean or Brazil right now. If you must go there, or choose to go there, read up on mosquito precautions and exercise all of them—use repellent, wear long sleeves and pants, don’t spend more time outdoors than is necessary (and make sure the windows are either closed or screened if you are indoors), and don’t go out at dusk, when these mosquitoes are feeding most actively.
There have been reports that the virus has been transmitted through sexual contact. While it has happened, it will be an uncommon event. The sexual contact would have to take place during the few hours in which an infected person has the virus in their bloodstream in large numbers. Unlike other sexually transmitted diseases that are of great concern, there does not appear to be a carrier state for Zika, where a person has the virus in their blood for prolonged periods and could represent a risk to others. The exception to that rule might be infected babies, but of course they don’t represent a sexual transmission risk.
I hope this all helps, and please comment on the post if you have questions or concerns. As more information develops, we will keep you “posted.”