Questions and answers about Zika virus

DEAR READERS:

Not surprisingly, we’ve been getting lots of letters about the Zika virus. In today’s column, I’d like to answer the questions that many readers are asking.

WHERE DID ZIKA VIRUS COME FROM? Zika virus has been present for centuries in Africa. About 50 years ago it spread to Asia. So far as we know, it arrived in the Americas (primarily Brazil) only last year. That means that the vast majority of us in the Western Hemisphere have no immunity against it.

HOW DOES IT SPREAD? The virus is carried by mosquitoes, primarily one called Aedes aegypti. They pick up the virus when they bite a person who is infected with it. They spread it to other people when they bite those people. It is not clear that it can be spread directly from one person to another, as the influenza virus is spread when someone near you coughs, for example. There are a few cases in which the virus might have been spread by sex, but this appears to be very unusual.

WHAT IS THE DANGER FROM CATCHING THIS VIRUS? That depends on who you are. Most of us, even those of us in the Americas, don’t have any symptoms when we catch it. Some of us get aching joints, red eyes, fever and a rash, but it’s a mild, flu-like illness that typically lasts less than a week. Infection with the virus also may infrequently cause a nervous system disease in adults called Guillain-Barre.

But if you are a woman who is, might be, or might soon become pregnant, there is reason to worry. There is strong evidence from Brazil that when pregnant women catch the virus, there is a risk that their babies will be born with birth defects. The most serious of these is microcephaly — small heads and brains. (Several other infections also can cause this tragic complication of pregnancy.) Defects of vision and hearing may also occur.

CAN I BE TESTED FOR THIS VIRUS? Currently, only very specialized laboratories, like those at the U.S. Centers for Disease Control and Prevention in Atlanta, can test accurately for the virus. Also, the tests are not perfectly accurate: They can both under-diagnose and over-diagnose the infection.

ARE THERE TREATMENTS FOR THE VIRUS? As of now, there are no treatments, and no vaccines to prevent people from becoming infected. As you might expect, scientists all over the world are working to develop treatments and vaccines.

HAS THE VIRUS COME TO THE UNITED STATES AND CANADA? So far, there have been only a few cases of Zika virus infection among people in the U.S. and Canada, and they all caught the infection in a country south of the U.S. The virus would become a serious threat to the U.S. and Canada only if it was carried by mosquitoes in those countries. So far, that has not happened.

SO WHAT SHOULD I DO TO PROTECT MYSELF? In tomorrow’s column, I’ll address that question. I’ll also talk about how we can better protect ourselves against other potential epidemics that might strike us.