Zika virus: What you should know

The mosquito-borne virus has exploded across Latin America, and researchers have linked the infection to a wave of severe birth defects in Brazil.

Thirty-one travelers in 11 states and the District of Columbia have been diagnosed with Zika virus infections. The tally includes a case confirmed Wednesday in Minnesota.

U.S. health officials said Thursday that they expect many more travel-related Zika cases in the coming months.

Here are answers to some crucial questions about the outbreak:

What do we know about the Minnesota case?

The case involves an Anoka County woman in her 60s who had returned recently from Honduras. She is expected to make a full recovery, and she didn't need to be hospitalized.

How does Zika virus typically affect people?

Most people might not even know they have it. Four out of five people don't have symptoms.

But it appears the virus can cause major problems for some developing fetuses. That's why the U.S. Centers for Disease Control and Prevention are urging pregnant women to postpone travel to Zika outbreak areas.

What is the risk to fetuses?

There has been an alarming number of babies born in Brazil with microcephaly — a condition where the baby's brain and skull are smaller than normal and in these cases can be severely disabling.

U.S. health officials said Thursday that the risk for this condition is probably greatest during the first trimester, when early brain development occurs. But Dr. Anne Schuchat of the CDC said experience with the rubella virus suggests there are possible risks for later in a pregnancy, too.

"A number of problems including hearing loss and vision loss as well as heart defects and even major, major brain damage," Schuchat said. "And there are different effects at different times during pregnancy."

The Minnesota Department of Health said Wednesday that it has sent several samples from pregnant women to the CDC for testing. Those results haven't come back yet. A few OB-GYN clinics in the metro area say they have gotten lots of calls from worried patients. But others say they haven't heard much concern from their patients.

Are there other ways Zika is spread?

There is some evidence that Zika virus can be spread sexually. U.S. health officials say there is one reported case of possible sexual transmission. And there is another case in which the virus was found in a patient's semen two weeks after his Zika infection.

The Food and Drug Administration is also looking at whether this outbreak poses a risk to the nation's blood supply. But public health officials don't think infected blood would be a major source of risk because the virus usually clears from a person's bloodstream in a week or less.

How much is the U.S. spending on research?

An official with the National Institutes of Health said Thursday that the agency is accelerating its funding for existing research on this class of virus, which includes dengue, West Nile, yellow fever and chikungunya virus.

Is there a vaccine for Zika and the rest?

Ideally, researchers would like to find a vaccine or treatment that's effective against all of these mosquito diseases that have really established a foothold in our hemisphere in the past 20 years.

They think they might have a potential candidate with a West Nile vaccine that appeared promising a few years ago, but didn't attract any investment from drug companies. If they can use that technology for Zika virus, they could jump-start the process and be in early clinical trials by this fall.

But even then, it would probably be several years before a safe and effective vaccine was available to the public.