CDC expands Zika virus travel warnings; more U.S. cases confirmed



Officials at the Centers for Disease Control and Prevention have issued an expanded travel alert for regions where travelers may be at risk of contracting Zika virus.

The mosquito-borne flavivirus may be associated with an increased risk of microcephaly and other intracranial and neurologic abnormalities in infants whose mothers were infected with Zika virus during pregnancy. Women who are pregnant or considering becoming pregnant should consider avoiding travel to countries included in the Zika virus alert.

The CDC’s expanded warning includes Barbados, Bolivia, Ecuador, Guadeloupe, Saint Martin, Guyana, Cape Verde, and Samoa. This is in addition to the previous travel alert for Puerto Rico (a U.S. territory), Brazil, Colombia, El Salvador, French Guiana, Guatemala, Haiti, Honduras, Martinique, Mexico, Panama, Paraguay, Suriname, and Venezuela.

In the United States, about a dozen cases of Zika virus have been reported, according to the CDC. States thus far where individuals have tested positive for the virus are Texas, Florida, Illinois, New Jersey, and Hawaii. These dozen cases include two pregnant women who tested positive for the Zika virus in Illinois this week. In Hawaii, a woman who had lived in Brazil while pregnant has given birth to a baby with microcephaly and congenital Zika virus infection. To date, all confirmed cases of Zika virus in the U.S. have been in individuals who traveled to areas with Zika virus transmission.

Zika virus, a member of the family of viruses that includes dengue fever, is spread by mosquitoes of the Aedes species, according to Dr. Amesh Adalja.

Dr. Adalja, a member of the public health committee of the Infectious Disease Society of America and an instructor in the department of infectious diseases at the University of Pittsburgh Medical Center, noted that though the virus has been known since the 1940s, “it was not considered a major public health threat” because of the generally mild course of the disease.

Infection is asymptomatic in 80% of individuals, he said. Symptoms of Zika virus infection, if they appear, include initial fever, a maculopapular rash, arthralgia, and sometimes conjunctivitis. There is no treatment for the disease and care is supportive.

A recent explosion of Zika virus cases in Brazil, however, has been associated with a large increase in cases of microcephaly in newborns. Though the association has not been confirmed, Zika virus has been found in infants born with microcephaly and in the placentas of mothers of babies with microcephaly.

The CDC has issued interim guidance for diagnosis, treatment, and management of suspected Zika virus in pregnant women. All pregnant women should be asked about travel to countries with known Zika virus exposure, with surveillance by fetal ultrasound and, in some cases, testing for Zika virus guided by symptoms and likelihood of exposure.

The CDC recommends vigilance against mosquito bites for pregnant women who do travel to areas with Zika virus activity, including the use of effective insect repellent, protective clothing, and remaining in and sleeping in air-conditioned rooms when possible.

In the United States, there is reason to be concerned about Zika virus, since “the scale of travel is very, very high” to the Central and South American and Caribbean countries where Zika virus transmission is active, Dr. Adalja said. However, since the same vector also transmits dengue fever and the Chikungunya virus – currently the focus of increasing concern in the U.S. – aggressive vector control measures are already underway in parts of the country where Aedes species mosquitoes are resident.

Though the consequences of the apparent association between maternal Zika virus infection and infant microcephaly are devastating, said Dr. Adalja, “it’s important that people put this in the proper public health perspective. Dengue fever kills thousands of people each year.”*

Dr. Adalja said that he expects commercially available testing for Zika virus to be developed; currently, testing is currently only available from the CDC and from some states’ departments of public health.

Additional resources for physicians

American College of Obstetricians and Gynecologists:


*Correction, 1/25/2016: An earlier version of this story misstated the number of deaths from dengue fever.

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