Strides Made With Understanding Zika, But More Questions Remain

While the medical community knows far more about the Zika virus now compared with earlier this year, many questions still remain unanswered, according to experts.

“For instance, we have established a causal association between the virus and microcephaly, and we understand more about the risk period during pregnancy,” said Aubree Gordon, PhD, MPH, assistant professor in the Department of Epidemiology at the School of Public Health, University of Michigan.
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Recent studies have indicated that the main concern for microcephaly and other adverse outcomes evident during pregnancy or at birth is the infection in the first or second trimester, she said.

“Essentially, 6 months ago we knew Zika virus’s phylogenetic relationship to other flaviviruses and not much more,” said Matthew Aliota, PhD, associate scientist in the Department of Pathobiological Sciences, University of Wisconsin-Madison. “Now, we know far more about the immune response to Zika, adverse outcomes in pregnancy, transmission routes, and duration of infection.”

Researchers still don’t know whether there may be other developmental deficits in children born to women infected with Zika during pregnancy that only become apparent later, such as mild and moderate developmental problems, Dr Gordon said.

Zika vaccines have progressed into phase 1 clinical trials, Dr Aliota noted. “There has been a rapid push to move these forward.” However, he believes it still will be some time until one is licensed for general use. Dr Gordon agreed, anticipating 2018 as the earliest a vaccine would be available.

“Likewise, there have been promising results with antivirals that warrant follow up,” Dr Aliota said, “but again, this requires time to test safety and efficacy.”

With no approved treatments or vaccines currently on the market, additional outbreaks likely will occur in the United States this summer, Dr Gordon said. The Centers for Disease Control and Prevention (CDC) recently issued a travel guidance to the Wynwood neighborhood of Miami, Florida, because of active Zika spread, recommending among other things that pregnant women not visit the area.

Dr Aliota could see Zika continue to spread across Florida and to Texas and other Gulf Coast states. The virus is currently a public health emergency in Puerto Rico, with more than 5000 reported cases as of early August.

For primary care providers, the level of worry for Zika will likely depend on their specific geographic region, he said. “In Southern states, it should be something that definitely is on their radar. In Wisconsin, for example, it really is not something that should be a cause for concern.”

If providers have a suspected Zika case, they should follow guidelines established by their state public health laboratories or the CDC for correct diagnostic procedures, Dr Aliota said. They also should collect any travel history on both the suspected infected patient and the patient’s sexual partners.

“The biggest implications for Zika virus in the US are for pregnant women or those individuals considering pregnancy,” Dr Aliota said. “If they live in areas where local transmission is occurring, they need to take precautions to avoid mosquito bites. If not, they need to think about upcoming travel plans and be informed about the potential risks of traveling to Zika-endemic areas.”

—Mike Bederka