(CNN) A Hawaii newborn born with microcephaly , an unusually small head, had been infected with the Zika virus. The case could be the first one reported in the United States linking the birth defect with the virus.

The Centers for Disease Control and Prevention confirmed that the baby recently born in Oahu was infected in the past.

"The mother likely had Zika infection when she was residing in Brazil in May 2015 and her newborn acquired the infection in the womb," Hawaii's health department said.

"Neither the baby nor the mother are infectious, and there was never a risk of transmission in Hawaii."

The Zika virus has been in the news a lot lately in connection with microcephaly. Here are a few points to help you better understand it.

Why are we hearing so much about Zika?

Until recently, the Zika virus was not widely associated with the congenital brain condition.

But in the past four months, microcephaly cases in Brazil rocketed to 3,500, and 46 babies died. For comparison, there were only 147 cases altogether in 2014.

Health officials feared the jump may have something to do with pregnant women getting infected with Zika virus, which had also been spreading in Brazil.

Out of an abundance of caution, the CDC advised pregnant women last week to put off travel to more than a dozen Central American, South American and Caribbean countries, including Puerto Rico, where the virus is currently spreading.

Out of abundance of caution pregnant women advised to consider postponing travel to areas w #Zika virus transmission https://t.co/DmwQkXuhSz — CDC (@CDCgov) January 16, 2016

Researchers have not definitively nailed down the connection between microcephaly and the virus and need more studies to figure out the relationship, the CDC says. But the jump in microcephaly cases is alarming, and researchers are focused on the likelihood that there is actually a connection.

"That's a pandemic in progress," said Dr. Anthony Fauci, director of The National Institute of Allergy and Infectious Diseases. "It isn't as if it's turning around and dying out, it's getting worse and worse as the days go by."

What is microcephaly?

Microcephaly is the underdevelopment of an infant's head, brain or both that usually occurs during pregnancy but can also occur shortly after birth. Until recently, a Zika virus infection was not commonly thought of as a possible cause.

The condition has also been attributed to problems in the formation of the skull, genetic issues, Down syndrome or a lack of oxygen to the brain, says the Mayo Clinic. Drugs, alcohol and exposure to some chemicals during pregnancy can also contribute to an embryo suffering from microcephaly.

But there are also viral infections that can cause it, such as rubella and chickenpox.

How does the Zika virus spread?

A worker fumigates against the Aedes aegypti mosquito to prevent the spread disease.

The Zika virus is usually transmitted by the Aedes aegypti mosquito -- a common culprit in infecting humans with viruses. The same insect passes on the viruses that cause dengue fever and yellow fever, the CDC says.

If the mosquito bites one infected person, it can carry the virus to the next person and transfer the infection.

The Aedes mosquito lives mostly in subtropical and tropical areas but can survive in other climates, too. It usually bites indoors, during the daytime, and prefers humans.

If pregnant women have to travel to areas where Zika is spreading, say, for a family emergency or unavoidable business, the CDC advises that they take common precautions to keep mosquitoes away, like using repellant or wearing long sleeves and pants.

CDC map illustrates areas affected or possibly affected by the spread of Zika virus

How dangerous is a Zika virus infection?

Only about one in five people who get the virus break into symptoms, and they're usually mild. They can include mild fever, rashes, pink eye and joint pain.

It's the potential longer range effects that are slowly causing concern -- like this new fear that the virus infecting a pregnant woman could be connected to the baby suffering from the microcephaly birth defect.

Researchers are also looking into a possible link between Zika and another neural disorder called Guillan-Barre syndrome, the CDC says.

GBS is a rare disorder that causes the body's immune system to turn on its nerves. It can start off with weakness and tingling, the Mayo Clinic says. But it can eventually become a medical emergency, paralyzing the entire body.

"Most people recover from Guillain-Barre syndrome, though some may experience lingering effects from it, such as weakness, numbness or fatigue," the Mayo Clinic says.

Any danger of it spreading in the U.S.?

The CDC does not expect the virus to spread in the United States.

We can thank air-conditioning, window screens and cold weather for that, things mosquitoes don't like.

The Aedes mosquito is present in many areas of the U.S. mainland, but if it were really dangerous to the population, there would be reports of widespread infections with other diseases that it spreads like dengue or chikungunya, and spates of these infections have been small and short-lived.

The CDC has confirmed just one case of an infection that occurred on U.S. territory, Puerto Rico.

There have been at least 22 imported cases recorded in the United States -- meaning that people traveled abroad and came back with the virus. Fourteen were recorded between 2007 and 2014.

At least eight more imported cases were confirmed by CDC in 2015 and 2016, and it is still running tests on specimens from returning U.S. travelers who became ill last year and this year, so that number could rise.

In Hawaii, which has a climate more agreeable to the mosquitoes, health officials are telling citizens to pay attention to CDC travel recommendations and, at home, to double down.

"Mosquitoes can carry serious diseases, as we know too well with our current dengue outbreak and it is imperative that we all Fight the Bite by reducing mosquito breeding areas, avoiding places with mosquitoes, and applying repellant as needed."