The World Health Organization (WHO) declared an international emergency on Monday in response to the spread of the mosquito-borne Zika virus, which may be linked to birth defects in the Americas, saying it is an "extraordinary event."
The United Nations health agency convened an emergency meeting of medical experts in Geneva to assess the outbreak after noting a suspicious link between Zika's arrival in Brazil last year and a surge in the number of babies born with abnormalities.
The last such public health emergency was declared for the 2014 Ebola outbreak in West Africa, which killed more than 11,000 people.
Such emergency declarations are meant as an international SOS signal and usually trigger increased money and efforts to stop the outbreak, as well as prompting research into possible treatments and vaccines.
WHO officials say it could be six to nine months before medical science proves or disproves any connection between Zika and the spike in the number of babies born in Brazil with birth defects.
"After a review of the evidence, the committee advised that the clusters of microcephaly and other neurological complications constitute an extraordinary event and public health threat to other parts of the world," WHO Director-General Margaret Chan said.
"It is important to understand, there are several measures pregnant women can take," Chan said. "If you can delay travel and it does not affect your other family commitments, it is something they can consider.
"If they need to travel, they can get advice from their physician and take personal protective measures, like wearing long sleeves and shirts and pants and use mosquito repellent."
WHO, which was widely criticized for its slow response to the 2014 Ebola crisis in West Africa, has been eager to show its responsiveness this time. Despite dire warnings that Ebola was out of control in mid-2014, WHO didn't declare an emergency until August, when nearly 1,000 people had died.
WHO officials say that up to 4 million cases of Zika could turn up in the Americas within the next year.
But as The Christian Science Monitor noted after the ebola outbreak in West Africa, such estimates often vary widely. In 2014, the WHO and the Center for Disease Control (CDC), projected the number of ebola cases would be anywhere between 151,000 and 1.4 million.
Disease projections numbers are part of a political context, and impact the success and funding of health agencies and programs. So there’s an incentive to estimate high.
“The effectiveness of your response probably will be much larger against the scenario of 1.4 million cases than the 20,000 we’ve predicted,” Helleringer says.
CDC Director Tom Frieden stated clearly this week that high projection rates like 1.4 million are designed to catch the world’s attention and urge greater action.
“Part of the point of having a projection of what might happen if we don't take urgent action is to make sure that it doesn't happen. And that's what we hope and anticipate this will result in,” he said
Zika was first identified in 1947 in a Ugandan forest but until last year, it wasn't believed to cause any serious health effects; about 80 percent of infected people never experience symptoms.
"Of course, the world and the World Health Organization have all learned from the Ebola crisis," WHO spokesman Christian Lindmeier said earlier Monday before the emergency was declared. "That's why we are trying to bring in the best experts we can gather for this event, to try to establish what steps to take and what the way forward should be."
Lindmeier credited authorities in Brazil for being "extremely transparent" since the Zika outbreak turned up there in May. He said WHO first raised the possible connection between the virus and health issues for babies back in October — a prospect that has sown fear among many would-be mothers and pregnant women.
Brazilian officials shared lab samples with foreign experts and brought in scientists from abroad, he said.
"What we know so far is that the only microcephaly cases we see currently are from Brazil," Lindmeier said, noting that abnormalities in newborns can have many causes — such as the effects of herbicides, alcohol use, or drugs and toxins. "This is exactly what is the concerning question: why do we see this in Brazil?"
Jimmy Whitworth, an infectious diseases expert at the London School of Hygiene and Tropical Medicine, said we might soon see other babies born with defects as the virus becomes entrenched in other countries.
"It could be that we're getting the strongest signal in Brazil," he said before WHO's annoucement. "But having these cases occurring and pinning it to Zika is tough."
Whitworth said it was important for WHO to act quickly, despite a lack of definitive evidence that Zika is responsible for the surge in microcephaly cases.
"For situations like this, you have to essentially have a 'no regrets' policy," he said. "Maybe this will be a false alarm when more information is available months later, but it's serious enough on the evidence we have right now that we have to act."