Springtime is coming, and with it, mosquito season.
US health officials met with a sense of urgency in Atlanta on Friday to step up the effort against Zika—a mosquito-borne virus that's been linked to microcephaly, a devastating birth defect, and other neurological problems. Since it was first reported spreading in Brazil in May 2015, the virus has ripped like wildfire through most of the Americas. Now, with the weather getting warmer, experts worry it could start to spread locally in parts of the US.
But there isn't a firm plan in place, at every level of government, on how to proceed.
"Right now, there's no definition of a complete plan," Dr. Tom Frieden, director of the Centers for Disease Control, told reporters in a press conference at the meeting. Local and state governments are working furiously to prepare for the eventuality of Zika landing in their district. (Several Americans have been infected, but most caught the virus while travelling outside the country.)
The Obama administration has requested $1.9 billion from Congress to fight the epidemic.
One challenge is that Zika is a moving target, and still isn't well understood. It was just ten weeks ago, Frieden said, that the CDC issued its very first travel advisory warning pregnant women to stay away from countries where it was spreading. Since then, "we've learned an enormous amount," he said, including that the virus can be transmitted sexually much more readily than was originally thought: at least six people in the US have caught Zika from having unprotected sex, two of them pregnant women.
The CDC urges any men infected with Zika to wear a condom for at least six months. The UK has gone further, saying that any man who visits a country with Zika should wear a condom for 28 days after returning—whether they have symptoms or not.
Mosquito control is still a patchwork across the country: effective in some places, less so in others.
And the Aedes mosquito, which spreads Zika, is a lot trickier to eliminate than other kinds of bug, Dr. Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine, told Motherboard. Although fogging campaigns have worked against Culex mosquitoes, which spreads West Nile, Aedes bugs like to live inside and around houses.
The Zika virus has actually been known to scientists since the 1940s, when it was first spotted in Uganda. But it was ignored for a long time because it was thought to be harmless, causing only mild symptoms like fever, rash, and joint pain. Since appearing in the Americas, it's become clear that this virus is a lot more dangerous than anybody thought.
It's the poorest neighbourhoods that will be hardest-hit
Scientists are finally beginning to understand the virus better—on Thursday, a team published the first detailed 3D map of Zika—and the race is on to make a vaccine. But so far there aren't any treatments or cures, and a vaccine could still be a ways off.
"I think it's very doable. I do not think it's going to be technically challenging," Hotez said. "The problem will be safety testing. Because your target population is women of childbearing age and pregnant women, where there's the highest bar [for safety] set by the FDA."
The CDC is monitoring 21 pregnant women in the US who've been infected with Zika, Frieden said. He and the other experts in Atlanta agreed that there's a shrinking window of opportunity in which to stop the virus from gaining a foothold, and urged every level of government to work together. The summit, he said, is meant to accelerate efforts.
Zika is already spreading in Puerto Rico. If it lands in the continental US, it's the poorest neighbourhoods of Florida and the Gulf—where the Aedes bugs live—that will be hardest-hit. These places are more likely to have torn window screens, dilapidated housing, and standing water for mosquitoes to breed. Dengue, a virus that's related to Zika and spread by the same type of mosquito, has been found in parts of Houston.
"If there are clusters of microcephaly cases in Houston and New Orleans," Hotez said, "that's going to be spoken about in the same terms as Katrina or the BP oil spill."