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Zika Virus Declared Public Health Emergency by World Health Organization

An estimated 1.5 million Brazilians have caught Zika, which may be responsible for a large numbers of babies born with abnormally small heads.

Photo Credit: corlaffra/Shutterstock

The World Health Organization has declared that the clusters of brain-damaged babies born in Brazil — linked to but not proven to be caused by the Zika virus — constitute a public health emergency of international concern.

The declaration, made by the WHO director Margaret Chan, will trigger funding for research to try to establish whether the Zika virus, spread by mosquitoes, is responsible for the large numbers of babies born with abnormally small heads in Brazil. It will also put resources behind a massive effort to prevent pregnant women becoming infected and, through mosquito control, stop the virus spreading.

Chan called the birth of thousands of babies with microcephaly “an extraordinary event and a public health threat to other parts of the world." She was speaking following a meeting of the WHO’s international health regulations emergency committee, summoned to advise the director general on whether to make the declaration, which calls in international resources and expertise.

“Members of the committee agreed that the situation meets the conditions for a public health emergency of international concern. I have accepted this advice,” she said.

Chan, who was criticized for being slow to make a similar declaration while Ebola spread across west Africa, sidestepped the question when asked if she felt that was a factor in the response to the Zika crisis in Brazil.

“It is important to realize that when the evidence first becomes available of such a serious condition like microcephaly and other congenital abnormalities, we need to take action, including precautionary measures,” she said.

Tropical disease experts involved in the Ebola epidemic applauded the declaration. “The WHO faced heavy criticism for waiting too long to declare the Ebola outbreak a public health emergency and they should be congratulated for being far more proactive this time,” said Dr. Jeremy Farrar, director of the Wellcome Trust. “Today’s declaration will give the WHO the authority and resources it needs to lead the international response to Zika.”

Chan called for countries to refrain from imposing any sort of travel restrictions on those Latin American countries where the Zika virus is spreading.

Jonathan Ball, professor of molecular virology at Nottingham University, said: “A knee-jerk response would be to ban travel and trade with countries affected, but the truth is that the potential problem is much wider. It wouldn’t really be feasible to lock down the affected countries to try to stop the spread of a virus that is carried by the Aedes mosquito, especially when affected and unaffected countries border one another.

“Until populations can build up sufficient immunity, either through natural infection or through vaccination, then the risk to pregnant women is real and therefore this group need to take extra care to avoid becoming exposed.”

Prof. David Heymann, chair of the emergency committee, stressed that the most serious issue was not the Zika virus itself, which causes a mild illness, but the microcephaly cases in babies. “Zika alone would never be a public health emergency of international concern,” he said. “It is not a clinically serious infection.” For that reason, he said, it was a very difficult decision.

Brazil has dispatched hundreds of thousands of troops on mosquito-eradication campaigns in the the worst affected areas, but the government is struggling to comprehend let alone cope with the epidemic.

While reported cases have spiked since the virus was first identified in the country last year, officials admit their estimate of 1.5 million cases is based on guesswork.

“Eighty percent of the people infected by Zika do not develop significant symptoms,” the health minister Marcelo Castro told Reuters. “A large number of people have the virus with no symptoms, so the situation is more serious that we can imagine.”

The microcephaly clusters so far have appeared in Brazil and — in 2014 before anybody realized the significance — Polynesia. That, said Heymann, showed “it appears to be spreading."

In an effort to get a clearer picture, the authorities have instructed local health authorities to report on all cases from next week, when most states should have the equipment and personnel to carry out Zica tests. It will ban people who have the virus from donating blood.

Despite the lack of reliable data, Castro said researchers were convinced that the virus was the cause of a spike in reported cases of microcephaly. A link has not been proven, but concerns are growing because the disease and the abnormality have both risen sharply.

Brazil’s president, Dilma Rousseff, acknowledged at the weekend that the country was losing the battle. “We do not have a vaccine for Zika yet. The only thing we can do is fight the mosquito,” she told reporters during a visit to the emergency headquarters of the anti-Zika campaign. “As long as [the mosquitoes] are reproducing, we are all losing the battle. We have to mobilize to win it."

Public health officials, backed by 220,000 troops, have stepped up efforts to kill breeding grounds of the Aedes mosquito, particularly in the poverty stricken northeast, where most cases have been concentrated.

On Monday, Rousseff signed a law allowing health officials access to any building to eradicate breeding grounds.

The new law allows health officials access to all homes, and public and private buildings, even if the property’s owner cannot be located. Officials can request backup from police to raid any building suspected of being a mosquito breeding ground.

An estimated 1.5 million Brazilians have caught Zika, a virus first detected in Africa in the 1940s and unknown in the Americas until it appeared in May. The Pan-American Health Organization said the virus had since spread to 24 countries and territories in the hemisphere.

By next month, the labs will have a test that can detect all three viruses borne by the Aedes mosquito – dengue, Chikungunya and Zika. The test, however, will only be effective during the initial infection period of five days.

One of the main drivers of the WHO’s declaration of an emergency is to fund and launch studies to find out where there is a definitive association with the Zika virus. Chan said: The evidence is growing and it is getting stronger. We need a coordinated international response to get to the bottom of this.”

“It is a very complicated issue,” said Heymann. “To figure out the link with Zika virus, large numbers of cases of microcephaly have to be traced and assessed and the exposure of the mother to Zika virus has to be established. But the USA is working with Brazil and studies will start in the next two weeks.”

Chen said surveillance needed to be strengthened. Scientists involved in the studies will need reliable reports of every case of microcephaly, which may not automatically be reported to doctors, especially in remote and poorer areas of Latin America. The WHO declaration will also encourage research and development of a vaccine against the virus and reliable diagnostic tests.

However, the Brazilian president’s chief of staff said on Monday it would take researchers between three and five years to develop a vaccine against the virus.

Jacques Wagner told reporters that Brazilian researchers are working with researchers in the United States.

In his words, “If we are really lucky, it could be three years. But it could be between three and five years.”

Sarah Boseley is the Guardian's health editor.

Jonathan Watts is the Guardian's Latin America correspondent.

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