An international health emergency has been declared over Zika, as reports continue to mount citing the devastating birth injuries caused by the virus that began spreading in Caribbean and Latin American countries and now appears to be entering the United States.

The disease is transmitted primarily by mosquitos, but also can be transferred by males to females via sexual contact.

Public health officials are bracing for the virus’ rapid emergence in the United States, and many expect doctors to soon be inundated with questions about the virus and whether they should delay pregnancy until the spread of the disease is contained.

Meanwhile, pregnant women who have traveled to any country currently on the Zika watch list are encouraged to be tested for the virus.

The birth defects that the Zika virus causes are truly awful and the list of possible negative outcomes seems to grow by the day.

Let’s take a look at some of the most frequently asked questions about the Zika virus:

What exactly is this Zika Virus? Is it new?

Actually, no.

The Zika virus was first discovered in 1947, named after the forest in Uganda where it was originally isolated. Zika is a mosquito-transmitted disease that didn’t begin spreading to the western hemisphere until very recently.

In the eastern hemisphere, where the virus originated, many humans have developed immunity to the virus. But that is most certainly not the case in the western hemisphere. The disease began ravaging South America in 2015 and has begun a fervent path northward.

What are the symptoms of Zika?

Most infected people will actually have no symptoms, and those that do experience negative symptoms see them abated relatively quickly. These include fever, mild rashes, headaches and joint pains.

While the symptoms for infected persons are relatively mild, the consequences on developing fetuses that come in contact with the virus are devastating.

What are the consequences for infants?

Though scientists are still studying the true cause and effect relationship between Zika and birth defects and injuries, the consensus now is that the virus is able to penetrate the placenta and attack fetal nerve cells, causing catastrophic damages to the developing brain. One study indicated that Zika infected fetuses had normal appearing brains early in the pregnancy, but brain development was halted entirely once the virus took hold.

The scientific community has recently concluded that Zika causes a destructive condition known as microcephaly.

What is microcephaly?

Microcephaly causes babies to be born with incredibly small heads, and often is accompanied by catastrophic brain damage. Zika appears to cause a form of microcephaly that is far more powerful and destructive than observed prior to this.

Microcephaly was once a very rare condition that hospitals rarely dealt with, but that has changed drastically in areas where Zika has taken hold. Brazil, for instance, has seen a monumental surge in the number of babies born with microcephaly symptoms. In fact, it was this surge in abnormal births that first caused researchers to look at the Zika virus as the cause.

Other negative effects of Zika are thought to be shrunken placentas, fetal nerve damage, blindness, and most frequently death of the infant.

Have cases of Zika-caused microcephaly occurred in the United States?

Unfortunately, yes. Reports of babies being born in Florida, Texas and other southeastern areas of the United States have already been reported. Pregnant women in these areas in particular are encouraged to get tested. Experts also believe the virus is likely to continue to move into other areas of the continental United States.

Where will Zika take a stronger hold in the U.S.?

Zika is caused by a certain type of mosquito (the same kind that transmits yellow fever) that is typically only found in the Gulf Coast region and occasionally up and down the eastern seaboard. However, there is some evidence that other strains of mosquitos can transmit the virus, and these mosquitos can be found throughout the continental United States.

What’s this I hear about Zika being an STD?

It appears to be true. While experts believe that the vast majority of Zika instances have occurred because of mosquito bites, sexual transmission appears to be one way of transmitting the disease. Thus far, all known instances of sexual transmission have been via males to females, as the virus is thought to be carried in semen. Zika is thought to be transmittable via vaginal, anal and oral sex.

Men who have traveled to a Zika affected country are encouraged to abstain from sex with women who are pregnant or trying to become pregnant. If sexual activity does occur, health officials recommend that men are extra vigilant about using condoms.

How do I know if I’ve been infected?

Since symptoms are frequently so benign that infected persons do not realize they have the virus, blood and urine tests need to be conducted to determine if infection has taken place.

Who should be tested?

At this point officials are encouraging all pregnant women who have visited areas with Zika to be tested regardless of symptoms. The recommendation is that two or three tests are conducted during the course of the pregnancy for women who live in or have visited infected areas. If a woman has traveled to a Zika infected country prior to conception are not thought to be at risk for Zika.

Newborns should also be tested if the mother visited or lived in an outbreak affected country during the pregnancy.