CDC Issues Clinical Guidance for Zika Virus in Pregnant Women

Janis C. Kelly

January 19, 2016

The Centers for Disease Control and Prevention (CDC) issued interim guidance today for obstetricians and other healthcare providers caring for pregnant women returning to the United States from areas affected by the Zika virus.

The new guidance, published online today in Morbidity and Mortality Weekly Report, follows a travel alert issued by the agency late on Friday. In that advisory, the CDC advised women who are or might become pregnant not to travel to 14 countries and territories in Central and South America and the Caribbean where the Zika virus is spreading.

OB/GYNs Asked to Screen, Test for Zika in Pregnancy

Working in consultation with the American Congress of Obstetricians and Gynecologists and the Society for Maternal Fetal-Medicine, CDC advised clinicians to ask all pregnant women about recent travel to areas where Zika virus transmission is ongoing. Those who report such travel and develop fever, rash, muscle aches, or conjunctivitis during or within 2 weeks of travel should be tested for Zika virus infection, and positive tests for Zika should be reported to the appropriate local or state health department.

Maternal serum from symptomatic women can be tested using reverse-transcription-polymerase chain reaction (RT-PCR) within 1 week of symptom onset. Antibody testing is not recommended 4 or more days after symptom onset, as there can be cross-reactivity to other flaviviruses (eg, dengue or yellow fever). Amniotic fluid can also be tested using RT-PCR, but the sensitivity and specificity are unknown at this time.

The agency notes that no test is currently commercially available, but testing can be done at the CDC and several state departments of health. Detailed instructions on Zika clinical evaluation and on Zika diagnostic testing, including detailed instructions for preparing and sending specimens, are provided in the CDC.gov website.

The CDC guidance recommends that clinicians who care for Zika-positive pregnant women should consider scheduling regular ultrasounds to monitor the growth of the fetus, as Zika has been linked to microcephaly.

There is as yet no effective antiviral treatment for Zika. CDC recommends symptomatic treatment, including acetaminophen for pregnant women who have fever.

First Confirmed Zika Microcephaly Case in US

The first confirmed case of Zika-related microcephaly in the US was reported this week and involved a mother who had lived in Brazil in May 2015 before moving to Hawaii.

In addition, public health officials have recently confirmed several cases of Zika in adults in the continental United States, including a woman in Harris County, Texas, who had travelled to El Salvador. There were also three cases confirmed in Florida, two in Miami-Dade County, in residents who had traveled to Colombia in December, and one in a Hillsborough County resident who had traveled to Venezuela in December.

All US Zika Cases From Travel to Other Countries — So Far

CDC press officer Candice Burns Hoffmann, from the National Center for Emerging and Zoonotic Infectious Diseases, emphasized to Medscape Medical News that so far there have been no cases of locally transmitted Zika in the US.

Hoffmann said, "The first travel-associated Zika virus disease case among U.S. travelers was reported in 2007. From 2007–2014, a total of 14 returning U.S. travelers had positive Zika virus testing performed at CDC. In 2015 and 2016, at least 12 U.S. travelers have had positive Zika virus testing performed at CDC. However, CDC is still receiving specimens for Zika virus testing from returning U.S. travellers who became ill in 2015 or 2016."

CDC expects to see more Zika virus cases among travelers visiting or returning to the US, which is likely to increase the risk for localized spread in areas such as the Gulf Coast, where there are mosquitoes capable of spreading the virus.

"CDC has been monitoring outbreaks in the Americas and is prepared to address cases imported into the United States and cases transmitted locally," Hoffmann said. She also noted that experience with recent chikungunya and dengue outbreaks in the US, vectored by the same mosquito species as the Zika virus, suggest that Zika outbreaks in the US mainland will likely be small and focal.

Increased Cases of Babies Born With Microcephaly in Brazil

Zika is a relatively mild problem for adults, only one in five of whom become symptomatic with fever, rash, arthralgia, or conjunctivitis, but represents a major risk for the developing fetus.

According to the CDC, "During the current outbreak in Brazil, Zika virus RNA has been identified in tissues from several infants with microcephaly and from fetal losses in women infected during pregnancy. The Brazil Ministry of Health has reported a marked increase in the number of babies born with microcephaly. However, it is not known how many of the microcephaly cases are associated with Zika virus infection and what factors increase risk to the unborn baby. Additional studies are planned to learn more about the risks of Zika virus infection during pregnancy. Guillain-Barré syndrome also has been reported in patients following suspected Zika virus infection."

Experts Warn of Brazil Summer Olympic Games Zika Risk

Kamran Khan, MD, and colleagues in the division of infectious diseases at the University of Toronto, Canada, modeled the anticipated international spread of Zika virus from Brazil and reported in the Lancet that from September 2014 to August 2015, 9.9 million travelers departed for international destinations from Brazilian airports in areas conducive to year-round Zika transmission. Of these, 65% traveled to the Americas, 27% to Europe, and 5% to Asia. In their paper, published online January 14 in the Lancet, the authors note that more than 60% of the populations of Argentina, Italy, and the US live in areas conducive to seasonal Zika transmission.

With no vaccine or antiviral therapy available, the main tools for fighting Zika remain personal protection such as insect repellents, community-level mosquito control measures, and disrupting the human-mosquito-human transmission chain by helping Zika-infected patients avoid being bitten by other mosquitoes.

"The summer Olympic Games in Brazil in August, 2016, heighten the need for awareness of this emerging virus" the authors concluded.

Dr Khan is founder of BlueDot, a social benefit corporation that models global infectious disease threats.

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