The World Health Organization declared the Zika virus, and its possible link to an explosion of birth defects in Latin American countries, a public health emergency in need of a coordinated international response on Monday.
Even though the connection between the mosquito-borne virus and congenital defects in newborns is not fully proven, WHO Director-General Margaret Chan said it was enough to sound the emergency alarm.
In Brazil and French Polynesia, outbreaks of microcephaly in newborns last fall caused concern among health workers, who also witnessed a rise in Zika cases. Babies with microcephaly have abnormally small heads associated with incomplete brain development. There also is a suspected connection between the Zika virus and the paralyzing neurological condition known as Guillain-Barre syndrome.
Health experts at the WHO emergency meeting in Geneva on Monday determined that the new clusters of microcephaly alone were sufficient to declare a Public Health Emergency of International Concern “because of its heavy burden on parents on mothers and on the community and society,” Chan said at a press conference following their meeting. “There is urgent need to do a lot more work and establish whether or not there is a definitive association” with the Zika virus.
“Can you imagine if we do not do all this work now and wait until the scientific evidence comes out, then people would say that ‘why didn’t you take action?’” said Chan.
WHO was criticized after the Ebola virus outbreaks in 2014 and 2015 primarily in West Africa for not reacting quickly enough. The world body instituted new procedures to try to avoid a similar health crisis.
In Brazil alone, health workers saw 4,000 cases of microcephaly suspected of being caused by Zika virus in the mother, and in 270 of those cases, the link was confirmed, said Bruce Aylward, WHO’s executive director of outbreaks and health emergencies.
So far, two dozen countries and territories have reported outbreaks of the Zika virus, including most recently the U.S. Virgin Islands. (See a full list on WHO’s website.)
The mosquito that spreads Zika, known as Aedes aegypti, typically lives in tropical and subtropical regions in the world.
The same mosquito spreads dengue fever and chikungunya diseases, which also are exploding in record numbers in Central and South America, said Laurie Garrett, senior fellow for global health at the Council on Foreign Relations. Researchers will be trying to figure out if those diseases are connected in some way to the growing number of cases of microcephaly and Guillain-Barre syndrome, she said.
Studies examining cases of Zika, pregnant women and neonatal malformations already are underway in countries such as Brazil, Colombia and El Salvador, said Aylward. The U.S. is expected to start case-control studies, comparing patients who have the disease and those who don’t, in the next two weeks.
WHO stopped short of issuing a warning to pregnant women traveling to countries with known Zika cases as the U.S.-based Centers for Disease Control and Prevention has done. Instead, WHO says women should consult with their physicians and take personal protective measures, such as using mosquito repellent, staying indoors when possible, wearing long sleeves and pants when outdoors, and sleeping under mosquito nets.
“The committee found no public health justification for restrictions on travel or trade to prevent the spread of Zika virus,” said Chan. “At present, the most important protective measures are the control of mosquito populations and the prevention of mosquito bites in at-risk individuals, especially pregnant women.”
The mosquitoes that spread the disease feed primarily during dusk and dawn, so pregnant women can avoid being outside during those times, Garrett said. And on the question of whether people should avoid going to Brazil for the Olympics during Aug. 5-21, she said it will be winter in Rio de Janeiro, a time when mosquitoes generally die. “So there’s no good reason at this time to link this disease to any action” regarding the Olympics.