Scientists are examining the link between a mosquito-borne illness and a congenital condition that causes newborns to have unusually small heads after noticing a spike in both maladies in Brazil, according to the Centers for Disease Control and Prevention.

Mosquito-borne illness possibly linked to birth defects

The Zika virus has been linked to at least one American case of microcephaly, a birth defect, according to the Hawaii State Department of Health.

Microcephaly is a birth defect where a baby’s head is smaller than expected when compared to babies of the same sex and age. Babies with microcephaly often have smaller brains that might not have developed properly.

Read more: Lip balm maker sued after claims of blisters, rashes

Officials said a baby was recently born in Oahu with an unusually small head.

"The mother likely had Zika infection when she was residing in Brazil in May 2015 and her newborn acquired the infection in the womb," according to the Hawaii State Department of Health. "Neither the baby nor the mother (is) infectious, and there was never a risk of transmission in Hawaii."

How the virus spreads

The virus is spread through mosquito bites and typically causes fever, rash, joint pain and red eyes, said Dr. Lyle Peterson, director of the CDC’s division of vector borne disease. The illness is typically mild and can present symptoms for as long as one week.

"Brazil has been combating a large outbreak of Zika since last year," Peterson said. "Officials there have noted a rather significant increase in cases of microcephaly."

Scientists with the CDC said Friday they tested samples from two pregnancies that ended in miscarriages and from two infants diagnosed with microcephaly who died shortly after birth in Brazil.

"They determined that all four cases were positive for Zika virus infection, indicating that the babies had become infected during pregnancy," Peterson said.


Authorities in Hawaii sent samples to the CDC from the child born in Oahu with microcephaly after "an astute Hawaii physician recognized the possible role of Zika virus infection," according to the state Department of Health.

On Friday, the CDC released an interim travel advisory warning pregnant women to postpone travel to areas where Zika virus transmission is ongoing. The countries include Brazil, Colombia, El Salvador, French Guiana, Guatemala, Haiti, Honduras, Martinique, Mexico, Panama, Paraguay, Suriname and Venezuela, as well as Puerto Rico.

Read more: These airlines have the worst safety records

It was not immediately clear how likely the virus was to spread to the U.S.

"Many areas of the United States have mosquitoes that can become infected with and transmit Zika virus," Peterson said. "However, recent chikungunya and dengue outbreaks in the United States suggest that Zika outbreaks in the U.S. mainland may be relatively small and focal."

According to the CDC, doctors first saw the Zika virus in U.S. travelers in 2007. From then until 2014, the CDC noted a total of 14 returning U.S. travelers suffered from the illness. Scientists continued to test samples from travelers who became ill in 2015 and 2016 but so far have identified 12 Americans who caught the virus abroad.

Read all the latest health news here.