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 criticised 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 realise 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 WHO declaration. “The WHO faced heavy criticism for waiting too long to declare theEbola outbreak a public health emergency and they should be congratulated for being far more proactive this time. Today’s declaration will give the WHO the authority and resources it needs to lead the international response to Zika,” saidDr Jeremy Farrar, director of the Wellcome Trust.
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 kneejerk 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 emergency 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”.
The microcephaly clusters so far have appeared in Brazil and – in 2014 before anybody realised the significance – Polynesia. That, said Heymann, shows “it appears to be spreading”.
Brazil’s president, Dilma Rousseff, has put her country on a war footing against the virus, mobilising 220,000 troops and signing a measure on Monday allowing health officials access to any building to eradicate breeding grounds for a mosquito spreading Zika.
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 also request backup from police to raid any building suspected of being a mosquito breeding ground.
Brazil’s health minister, Marcelo Castro, said that the Zika virus outbreak was proving to be worse than initially believed because most cases showed no symptoms but that improved testing should allow the country to get a better grip on the epidemic.
Brazil would start mandatory reporting of cases by local governments next week when most states will have labs equipped to test for Zika, Castro added. “Eighty per cent of the people infected by Zika do not develop significant symptoms. A large number of people have the virus with no symptoms, so the situation is more serious that we can imagine,” Castro told Reuters.
With no Zika vaccine available for the foreseeable future, Brazil’s only option is to eradicate the mosquito that has spread the virus, and the government is mobilising all possible resources and people to destroy its breeding places, he said.
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 in the poverty-stricken northeastern region of Brazil. The Pan-American Health Organisation said the virus has 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 aegypti 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 get studies up and running – and funded – to work out exactly what is going on. “There is an urgent need to do more work to find out where there is a definitive association with the Zika virus,” said Chan. But, she 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,” he said.
Surveillance needs to be strengthened, said Chan. 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 declaration will also encourage research and development of a vaccine against the virus and reliable diagnostic tests.
Originally Posted as Zika virus: World Health Organisation declares public health emergency