In 2016, the Zika virus alarmed both researchers and the public with its unexpected spread across the Americas, and Davidson Hamer, a professor at Boston University’s School of Public Health, School of Medicine (MED), and Center for Global Health & Development, had a front-row seat to the epidemic. Through a system of clinics and hospitals called GeoSentinel, Hamer saw how travelers carried the virus to new nations and how important it was for doctors around the world to communicate what they were learning about this relatively unknown disease.
Hamer is the primary investigator for GeoSentinel, which links together travel and tropical medicine centers around the world and shares patients’ travel and disease information, looking for early signs of an outbreak. By sharing information (or data) on their patients’ travel history, clinical findings, and lab results, GeoSentinel site directors are able to identify diseases in patients coming from abroad—and what symptoms to monitor. He is also the lead author of a February 2016 paper in the Annals of Internal Medicine on how Zika spread through the Americas as travelers crossed international borders. Through GeoSentinel, Hamer and others saw, early on, where the disease was advancing, and they demonstrated how important these medical networks can be.
In 2016, Hamer and GeoSentinel couldn’t tell exactly how much Zika virus was spreading, but they could tell that something big was happening.
“We started seeing just one report after another,” says Hamer. “We recognized that there was a large outbreak happening, and that it was rapidly spreading from country to country.”
Zika began to progress so quickly, says Hamer, that they had to turn off GeoSentinel’s alerts for the disease—GeoSentinel has special alerts for rare diseases, and that no longer applied to Zika. The network was the first to record pregnancy complications associated with Zika and also reported the first diagnoses in some countries, like Costa Rica.
“The Costa Ricans said, ‘Oh, there is no Zika here, you must be wrong, that has to be a mistake,’” says Hamer. “But, a couple of days later, they recognized an outbreak in that area.”
Even with a network of other clinics to rely on, diagnosing a virtually unknown disease can be difficult. Countries and clinics have different access to medical resources. While Boston Medical Center (BMC) might be able to confirm a diagnosis with DNA analysis and tests of blood and/or urine, a rural clinic in Brazil may have to rely on much less. There can even be major differences between two developed countries, says Elizabeth Barnett, a co-author on the Annals study, MED professor of pediatrics, and GeoSentinel’s local site director at BMC. This is especially true early in an outbreak, when things move quickly and standard diagnostics have not yet been agreed upon.
“There was information coming out of Europe that we simply didn’t have in this country, because we didn’t have the same diagnostic capabilities,” says Barnett. (Certain in vitro diagnostic tests were not available in the US until February 2016.) “And so, we were able to learn from the cases reported to the European sites what was happening in these Central and South American countries where we see a lot of travelers going,” she says.
By sharing diagnostic information, Hamer, Barnett, and other researchers spotted a new symptom of Zika: an extremely itchy rash. Rashes had been associated with Zika, but not the itchy feeling like, as Hamer put it, “their skin is crawling.”
Researchers are still far from understanding the virus’ full impact. They now know that Zika is not only spread by mosquitoes—it can be transmitted through body fluids, too, including semen, saliva, and breast milk. Zika’s neurological impact may also not be limited to children; there is evidence that the virus can damage adult brains, though the damage is harder to detect and takes place over a longer period of time.
Hamer’s next focus is Zika’s spread around the rest of the world. He says that he is especially worried about how the virus will impact Asia, which has had the virus for awhile but has not yet experienced a large outbreak—although it is unclear why. If the answer turns up at one of the GeoSentinel sites around the world, Hamer will know soon enough.