WEDNESDAY, Jan. 20, 2016 (HealthDay News) -- U.S. health officials issued guidelines Tuesday to doctors whose pregnant patients may have traveled to countries -- especially Brazil -- where the mosquito-borne Zika virus has been linked to birth defects in babies.
The officials recommend that doctors ask all their pregnant patients about recent travel and certain symptoms -- such as a sudden fever or a rash. If Zika virus infection is possible, doctors should have their patients tested for Zika virus disease, the Centers for Disease Control and Prevention said.
If testing shows signs of Zika virus infection, ultrasounds should be considered to monitor the fetus' development. And a referral to a maternal-fetal medicine or infectious-disease specialist with expertise in pregnancy management also is recommended, the agency said.
Last Friday, the CDC issued a travel warning for 14 countries and territories exposed to the Zika virus, which has been linked to a torrent of birth defects in Brazil.
The travel alert targets pregnant women and those who want to become pregnant and follows reports that thousands of babies in Brazil were born last year with microcephaly, a brain disorder experts associate with Zika exposure. Babies with the condition have abnormally small heads, resulting in developmental issues and in some cases death.
The CDC alert listed the following countries and regions in Central and South America and the Caribbean: Brazil, Colombia, El Salvador, French Guiana, Guatemala, Haiti, Honduras, Martinique, Mexico, Panama, Paraguay, Suriname, Venezuela, and Puerto Rico.
The alert recommends that women who are pregnant postpone travel to those areas, and that women wanting to become pregnant consult their doctors before setting out on any trip to those areas. In all cases, the alert said, women should take steps to avoid mosquito bites.
"We believe this is a fairly serious problem," Dr. Lyle Petersen, director of the CDC's Division of Vector Borne Infectious Diseases, said during an evening press conference Friday.
"The virus is spreading fairly rapidly throughout the Americas and a large percentage of the population may become infected," he said. "Because of the growing evidence that there is a link between Zika virus and microcephaly, we thought it was very important to warn people as soon as possible."
Also Friday, the first case of Zika virus-linked brain damage in the United States was reported by health officials in Hawaii.
The Hawaii State Health Department said a baby born in an Oahu hospital with microcephaly had been infected with the virus. The CDC confirmed the presence of the virus.
The infant's mother had lived in Brazil last May and probably was bitten by a mosquito then, when she was early in her pregnancy, the health department said.
There have been no confirmed cases of Zika virus transmission within Hawaii or elsewhere in the United States.
Petersen said he had no idea when the travel advisory might be lifted, noting it would probably still be in effect when the Summer Olympics begin in Brazil in August.
Although new test results provide new evidence of a link between Zika and microcephaly, it isn't known if Zika alone is responsible or if other risk factors might be involved, Petersen said, adding more studies are planned to examine the link.
Between 2007 and 2014, 14 cases of Zika virus were confirmed among travelers returning to the United States from South America, Petersen said. In 2015 and so far in 2016, 12 cases have been diagnosed, he added.
The U.S. government action follows reports that at least 3,500 cases of microcephaly appeared in Brazil between October 2015 and January 2016, the CDC said.
Dr. Marc Siegel, an associate professor of medicine at NYU Langone Medical Center in New York City, thinks a travel warning is wise, but said people shouldn't assume they will get infected if they visit Brazil.
"It's extremely rare, but it's not impossible for a pregnant woman to get Zika on a trip to Brazil," he noted in comments made before the alert was issued.
Meanwhile, the World Health Organization is reportedly conducting research to determine how Zika affects fetuses. Brazilian health officials think the greatest risk of microcephaly and malformations happens during the first trimester of pregnancy.
The Zika virus is spread by the Aedes mosquito -- the same one that carries other diseases that infect humans, including yellow fever, West Nile, chikungunya and dengue.
The virus typically causes relatively mild symptoms -- fever, headache, skin rash, red eyes and muscle aches, according to the CDC. Symptoms usually clear up within a few days. There is no vaccine or specific drug to treat this virus.
Besides South America and Puerto Rico, outbreaks of Zika virus have been reported in the past in Africa and Southeast Asia.
For more on Zika virus, visit the U.S. Centers for Disease Control and Prevention.