On Zika's trail in Brazil

'Nobody knows why babies are turning out like this'

As CDC examines several possible cases of Zika-linked birth defects in the United States, teams of investigators are fanning out across Brazil to study the virus in the communities it has hit hardest.

On Friday, CDC said at least nine pregnant women in the United States had tested positive for Zika virus. One gave birth to a baby with microcephaly, a rare neurological condition characterized by an unusually small head and incomplete brain development.

Scientists have not proved that Zika causes microcephaly, but a link is strongly suspected.

To prove—or disprove—the connection, the United States is working with investigators in Brazil, one of the countries hardest hit by the Zika outbreak. As CDC Director Tom Frieden said in a hearing last week, "There are many things we wish we knew and are working hard to find out."

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On the ground in Brazil

The on-the-ground effort in Brazil features eight teams, each pairing a CDC "disease detective" with three Brazilian health workers, Jenny Barchfield reports for the Associated Press.

The goal is to study 100 mothers who recently gave birth to a baby with microcephaly, as well as a control group of several hundred mothers who gave birth to healthy babies.

The teams must work in challenging conditions and under intense pressure to find answers. Many of the hardest-hit Brazilian communities are racked by poverty, hobbled by poor infrastructure, and struggling with a range of other public health issues.

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Last week, bad weather, crumbling roads, and scheduling difficulties hampered some teams as they ventured into areas like Taipa, a shantytown. The mosquito that spreads Zika is endemic in such areas, "where omnipresent trash provides breeding grounds in discarded margarine tubs, yogurt containers, and plastic bottle caps," Barchfield writes.

"Obviously, we've seen the problems of logistics," saysAlexia Harrist, a pediatrician who works for the CDC's Epidemic Intelligence Service. But she adds, "If things take longer, things take longer… we're all really dedicated to getting it done."

Finding answers

When the teams identify a prospective study participant, they begin a lengthy questionnaire.

Rob Stein, of NPR's "Goats and Soda," observed Camila Alves, 22, speaking with investigators. As she answered, Camila cradled her two-month-old, Maria, who has microcephaly. "Was she exposed to any toxins? Pesticides? Insecticides? Rat poison? No. No. No," Stein writes. But then a key detail: Camila suffered from a fever and rash, possible Zika symptoms, during her first trimester of pregnancy.

The investigators took blood samples from both mother and daughter to test for Zika virus.

As the researchers prepared to leave, Camila explained why she volunteered for the study. "I wanted to know if [my daughter] really was born this way because of Zika," she said. "Nobody knows why babies are turning out like this."

Researchers say they will need at least one month to collect enough data to begin looking for answers. But Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine, says that for practical purposes the answer is already clear: Zika and microcephaly are linked. "The [United States] obstetrics community needs to prepare accordingly," he warns (Barchfield, AP/Sacramento Bee, 2/24; Stein, "Goats and Soda," NPR, 2/25; Dennis/Eunjung Cha, "To Your Health," Washington Post, 2/26; Tavernise, New York Times, 2/26).

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