The Zika virus is the latest scourge to capture the public’s attention, Ebola now a vague memory.
Is this new contagion something to fear? As is often the case in infectious disease, the answer is both yes and no. It was not long ago (1793) that a similar virus (yellow fever) wiped out 10 percent of the population of Philadelphia, and most of the survivors fled the city. Zika is also a Flavivirus that is transmitted by mosquitoes, but it’s much less virulent.
Zika, named after Zika Forest Uganda where it was discovered, frequently causes no symptoms whatsoever. The threat was so underwhelming that nobody bothered much to study the virus, discovered in 1947, until recently.
If you were to catch Zika, there is a good chance you would never know. Symptoms, if any, would appear several days after a bite from an infected mosquito and possibly result in a rash, fever, muscle or joint aches, and conjunctivitis (red eyes). The symptoms would likely all be gone in a week, and you probably wouldn’t have missed a day of work.
Once you recovered, you would now have antibodies and immunity to the virus just as you would to any cold that a coworker gave you.
The big concern with Zika is timing. If you happen to catch Zika during the first trimester of pregnancy and are very unlucky, it can, in rare instances, be devastating to a fetus. About 1 percent of the time, the virus can be transmitted to a developing fetus where the virus can destroy neurons leading to brain damage and result in microcephaly, where an infant’s head is much smaller than it should be. A fetus in the first few months of gestation is in most danger from Zika.
Why all the attention now? In Uganda, for instance, the virus is everywhere, and there is no public risk or concern there. The difference lies in natural immunity. You don’t catch the same cold twice.
In Uganda, nearly everyone is immune to Zika before they are 10 years old. As such, pregnant woman are immune and have no risk from Zika.
In the Americas, on the other hand, there is no natural immunity. The virus was only recently introduced — perhaps by visitors to the 2014 World Cup.
It is spreading rapidly throughout the population right now because people with no natural immunity are more likely to catch and carry the virus.
Ironically what may slow or stop the spread are mosquitoes. Mosquitoes have to “catch” the virus before they can spread it, so they, too, must be susceptible. In Maine, we have Aedes vexans mosquitoes, while a different species — the Aedes aegypti mosquitoes — are best known for transmitting the Zika virus.
Though the virus has “jumped” species before, we just don’t know if that will happen here. If it does, Zika will be a problem in Maine, but not one that should incite panic.
We don’t have a lot of information about reservoirs either. The virus must have an animal species that can carry it, which mosquitoes feed on — as mosquitoes only live for a month or two. It is not known what animals might be susceptible to the virus.
The U.S. Centers for Disease Control and Prevention are in full swing, preparing for different possibilities. There are too many unknowns, however, to be able to predict accurately when or how much impact Zika will have on various regions of the U.S.
Remember, if you are not pregnant, Zika poses no significant risk.
If you are pregnant, it might be wise to avoid travel to areas where there is active pandemic. If you do travel to high-risk areas, take precautions to avoid mosquitoes and bites.
If you catch Zika fever, there is no cure or treatment, but you will be better in a week.
If you catch it while pregnant, you will likely need additional prenatal screening to assure your fetus develops a normal head circumference, among other things.
Men need to be careful, too, if their partner is or may be pregnant. Even after they fully recover from an infection, their seminal fluid can harbor the virus for weeks; they are at risk of sexually transmitting the virus to their partner. So if the male partner travels to a pandemic region, the couple should practice safe sex for weeks following return. Remember Zika may not cause symptoms.
Dr. Michael Coyne is a specialist in infectious diseases and wound care at St. Joseph Healthcare in Bangor.