Aedes aegypti most likely originated in Africa; since then, the mosquito has been transported globally throughout the world, through global trade and shipping activities. It's a very good transmitter of Zika virus, along with dengue and Chikungunya virus.
Aedes aegypti most likely originated in Africa; since then, the mosquito has been transported globally throughout the world, through global trade and shipping activities. It's a very good transmitter of Zika virus, along with dengue and Chikungunya virus. Photo courtesy, CDC

UNC experts tally the toll women bear from gaps in understanding about Zika virus.

By Catherine Clabby

The World Health Organization recently ruled that the rise of the Zika virus is no longer a global public health emergency.

But the mysterious pathogen remains a threat globally, including to North Carolinians who travel to places where mosquitoes transmit Zika or who have sex with infected partners.

No matter where or how infection occurs, it’s women of childbearing age who are shouldering the worst of the risks and uncertainties Zika infections bring, UNC School of Medicine experts say.

“That is not what we’re used to thinking of mosquito-borne diseases,” said Helen Lazear, a UNC School of Medicine microbiologist who this week participated in a panel, “Unraveling Zika,” that took place at Carolina’s FedEx Global Education Center.

Zika Cases Reported in the United States, data as of Nov. 30, 2016. Map courtesy: CDC

Among the issues panelists raised:

· Pregnant woman infected by Zika can give birth to a baby with serious birth defects, including microcephaly, a disabling condition where brain growth is stunted.
· It’s not certain when during pregnancy that infection is most dangerous.
· Not all infants born to women infected by Zika are born with obvious physical damage.
· Long-term effects from Zika-related congenital damage are not yet known.
· Confirming a Zika infection can take four weeks, a length of time that could push American woman wanting to abort a pregnancy after Zika infection beyond time limits imposed in some states. (That limit is 20 weeks in North Carolina.)

UNC microbiologist Helen Lazear. Photo courtesy: UNC Chapel Hill School of Medicine

A virus on the move

Zika virus, thought to originate in Africa, is a newcomer to the Western Hemisphere, detected first only in 2015. It did not take long for mosquitoes to spread it rapidly throughout Latin America and the Caribbean.

People have been infected by Zika in only two U.S. states, Florida (184 cases) and Texas (1 case), most frequently from mosquito bites, says the Centers for Disease Control and Protection. People living in the U.S. territory of Puerto Rico have been hit harder, with more than 32,000 local infections recorded.

Research and disease surveillance have showed mosquitoes have not spread Zika in North Carolina, but people have been diagnosed with the virus here. All 81 North Carolina cases reported to federal officials have been linked to exposure during travel to other places, said state Department of Health and Human Services spokeswoman Kate Murphy.

DHHS does not disclose how many of those cases include pregnant women, Murphy said.

UNC physician Elizabeth Stringer recently returned from a decade working in Africa to work in the U.S. She’s worked on tracking Zika in Nicaragua. Photo courtesy UNC Chapel Hill School of Medicine.

Risks and opportunities

Elizabeth Stringer, a maternal and fetal medicine doctor, has observed pregnant women responding to Zika exposure in Chapel Hill and Nicaragua, the latter location as part of a research project. Recently in her UNC clinic she’s seen more women exposed in Puerto Rico but she cannot inform them definitively of the risks—if any—that their developing fetuses face.

“We don’t know how many fetuses are going to be infected by women who infected during a pregnancy,” Stringer said. “Of babies who are infected, how many will be affected? That’s something we don’t know.”

Lazear said one good thing is that research into Zika, including queries into exactly how and when it harms the brains of some developing fetuses, is progressing relatively quickly. That is true, in part, because Zika does not pose the same biohazard infection risk in a laboratory as some other pathogens, such as  Ebola or Lassa viruses, which require expensive equipment to contain the risk, she said.

Physician Anne Lyerly works at the Center for Bioethics at UNC Chapel Hill’s School of Medicine. Photo courtesy UNC.

Anne Lyerly, a gynecologist and ethicist, said she hopes that Zika’s effects on pregnant women will nudge everyone involved in vaccine research to find ways to include those women in vaccine trials and more biomedical studies in general. Pharmaceutical companies and scientists have shied away from testing new drugs on pregnant women due to liability risks if anything harms a developing fetus.

“That is where I see Zika being both something tragic and also an opportunity to start thinking hard about… advancing science,” Lyerly said. “This may be the moment we needed to sail into a storm we should have sailed into a long time ago,” Lyerly said.

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Catherine Clabby

Catherine Clabby (senior environmental reporter) is a writer and editor. A former senior editor at American Scientist magazine, Clabby won multiple awards reporting on science, medicine and higher education...