Zika virus continues to be a cause for concern, especially now that the virus has been detected in the United States.

A baby in Oahu, Hawaii was born with microcephaly, a condition marked by an abnormally small head linked to Zika virus infection, making it the first reported case in the country.

The Centers for Disease Control and Prevention (CDC) confirmed that the baby was previously infected. It is likely that the newborn's mother was infected at the time when she was staying in Brazil in 2015 and the baby may have been infected from inside the womb, according to the news release from the Hawaii Department of Health.

Both the mother and the baby are not infectious, the department assured, adding that there's no risk of transmission in the state.

As a precautionary measure, the CDC on Friday has issued a travel warning to pregnant women who may head to areas where the virus is present, particularly in Central American, South American, and Caribbean territories.

Zika virus is spread through the bite of a mosquito, commonly the Aedes species, which is infected with the virus. It produces symptoms that resemble flu, but concern for the virus started last year, when the infection is linked to microcephaly in several babies in Brazil.

A direct connection between Zika virus and the birth defect has not been established, but the rise in number of microcephaly cases made researchers think that a connection actually exists.

As a precautionary measure, the CDC issued the travel warning. In cases wherein traveling to those regions is necessary, the CDC advises people to observe measures to avoid mosquito bites. Such measures include using insect repellents; wearing appropriate outdoor clothing like long sleeves and pants; and using mosquito nets when staying or sleeping outdoors.

Currently, no vaccine exists to prevent transmission of Zika or medicine to treat an infection.