Active mosquito-transmitted infections of the Zika Virus are being documented in several U.S. territories, a major change since the last time we updated our readers on the spread of the virus about one month ago. As of March 16, the U.S. Centers for Disease Control reported 258 travel-associated Zika infections on U.S. soil, meaning people who contracted the virus while traveling outside of the country. Of these individuals, 18 are pregnant women, and 6 of the 258 were people who were infected through sexual transmission.
These numbers and explanations have raised concerns for both us and many of our readers. While we’ve seen many articles that address one question or another, we wanted to provide our readers with an updated Q&A opportunity to get some fresh answers, all in one place. This week, we posed your questions to Dr. Tara C. Smith, an infectious disease epidemiologist. Here’s what she had to say:
“I’ve been feeling under the weather since I returned from vacation [in the Caribbean]. How do I get checked for Zika or rule it out?”
“I’m pregnant now and scared that I might have the virus. What should I do? Will the tests harm my unborn baby?”
Again, the first test a physician would likely order is a simple blood test, which poses no risk to your fetus. If that test does come back positive, additional tests of the amniotic fluid may be ordered, which do carry a small risk. They may also order additional ultrasounds or other non-invasive tests to check on the fetus. The first step is to consult your doctor and discuss the potential that you may be infected.
“Should I be worried about sexual transmission of Zika? I’m currently 6 months pregnant and my partner has been to Brazil on business, what is the risk to me and the baby if we have sex?”
This is still a growing area of research, and we’re not sure. We know that Zika can be transmitted by sexual contact from a man to a woman, but it’s not certain how long the virus remains transmissible in semen, or how risky it is to a developing fetus to be exposed in this manner. The safest bet would probably be to abstain, or use condoms if you do have sex. I’ll also note that transmission via oral sex has not been documented, but that doesn’t necessarily mean it’s safe. You and your partner could also speak with your doctor and see if testing for Zika should be pursued.
“I read one article that says that Zika is the cause of microcephaly and then I read another that says that scientists can’t say that Zika is to blame. Which one is right?”
Both are. It is looking more likely as scientists are carrying out more surveillance for both the virus and for possible neurologic issues associated with Zika infection that the virus is indeed the cause of microcephaly and other problems (including Guillain-Barré syndrome in adults and possibly other neurologic complications during pregnancy). However, a few questions still linger that are waiting for larger studies of the phenomenon, and for more information on mechanisms by which Zika can cause these issues. So scientists are very concerned that Zika is causing these, and it appears increasingly likely that’s the case, but the evidence is still accumulating. In the meantime, it’s responsible to say that we’re still investigating before we say anything is certain.
“Why are we just seeing the problems with Zika now? Has the virus mutated? Did no one make the connection until now?”
It’s more likely to be simply an issue of a new population rather than a mutation in the virus. Zika has probably been in parts of Africa and Asia for decades, centuries, or longer, but likely infected people as children, so by the time women were of childbearing age, they had immunity. As the virus moved into new areas, such as the large outbreak in Brazil, it encountered populations that lacked immunity to the virus. This included pregnant women and their developing fetuses, and an increase in microcephaly was noted. This is what first sounded the alarm about possible severe complications from Zika infection. Retrospectively, Zika-associated microcephaly cases were also found from an earlier outbreak in French Polynesia. But because this was a smaller infected population, a “spike” in these cases was not noticed at the time.
“If Zika is just like Yellow Fever and is transmitted by the same mosquitoes, how come my Yellow Fever vaccination doesn’t work for it? And will there ever be a vaccine?”
Zika is in the same viral family as yellow fever (which also includes dengue and West Nile viruses), but it’s not “just like” it. The viruses are different enough that the body’s immune system doesn’t recognize one just because you’ve been infected with the other. There is ongoing work on a vaccine, but it’s not an easy feat. Dr. Anthony Fauci of the National Institutes of Health is hoping that some safety tests could start this fall, but even if that shows the vaccines are safe, additional testing will be needed to show that they’re effective before releasing them to the general public.
“I’m 32 weeks pregnant and anemic and my doctors have started to talk about blood transfusions because I haven’t responded to any other treatment. Do I need to worry about Zika infected blood? What would be the risk to my baby if I received Zika through a blood transfusion now?”
The possibility of Zika-infected blood is a very low risk. The American Red Cross has updated its health history questionnaire to capture possible Zika infections or exposures and is closely monitoring the outbreak. Additionally, recent research has suggested that infection during the first trimester is associated with the highest risk of microcephaly, but another study also showed that the effects Zika appears to have on the developing fetus extend beyond microcephaly and may cause other developmental issues as well. We don’t know for sure if there is ever a “safe” window to have Zika while pregnant.
“If I catch Zika, recover, and then get pregnant later, is my baby safe? Will my pregnancy be normal?”
We don’t know. Zika doesn’t appear to linger in the body like some other viruses do, so it is likely that later pregnancies would not be affected. This is another of those open questions that is being investigated currently.
“I have a trip to South America for family reasons I can’t cancel. But with fertility issues, I can’t wait much longer to get pregnant. What do I do?”
This is something to discuss with your family and your physician. I can provide information, but putting that information to use and determining how comfortable you are with risks that are still somewhat unclear is something only you can decide.