WHO convenes emergency panel over Zika virus

Margaret Chan WHO
Margaret Chan WHO

WHO Director-General Margaret Chan., Juan Manuel Herrera, OAS / Flickr cc

World Health Organization (WHO) Director-General Margaret Chan, MD, MPH, today announced she has convened an emergency committee to discuss the growing Zika virus threat in the Americas that has been strongly associated with microcephaly and other neurologic complications.

Committee to meet Feb 1

Chan's announcement came during her opening statement before a special briefing on the virus before the WHO's executive board, which is meeting in Geneva this week to hammer out the agenda and resolutions for the World Health Assembly in May. Chan said the committee will meet on Feb 1 in Geneva to discuss whether the developments warrant a public health emergency of international concern (PHEIC) declaration under the International Health Regulations.

Besides assessing the need for an emergency declaration, WHO emergency committees also draw attention to emerging global health issues and lay out a set of recommendations to assist member countries.

Amid growing concerns about a possible microcephaly connection and rapid spread of the virus in the Americas, the WHO has recently faced pressure to convene an emergency committee for Zika virus. Concerns have heightened in the wake of last year's criticism that the agency moved too slowly in acknowledging the Ebola threat.

Microcephaly is a condition of undersized heads and underdeveloped brains in newborns.

Chan said a causal relationship between the virus and microcephaly and neurologic syndromes had not yet been established, but it is strongly suspected. She added that the rationale and urgency for pulling together an emergency committee is also based on further spread of the virus, lack of population immunity, and absence of vaccines and diagnostic tests.

"The possible links, only recently suspected, have rapidly changed the risk profile of Zika, from a mild threat to one of alarming proportions," Chan told the board. "The increased incidence of microcephaly is particularly alarming, as it places a heartbreaking burden on families and communities."

PHEIC declarations are still in effect for Ebola and polio. WHO emergency committees typically meet every 3 months or as needed. An emergency committee to gauge the threat of Middle East respiratory syndrome coronavirus (MERS-CoV) has met 10 times since 2013 but so far has not recommended pulling the PHEIC trigger.

Insights from hard-hit areas

One of main questions swirling around Zika virus discussions is whether the microcephaly pattern will be seen in other countries in the Americas reporting local spread.

The pattern wasn't obvious in an earlier outbreak in French Polynesia in 2013 and 2014, but there were reports of neurologic complications such as Guillain-Barre syndrome (GBS) in some patients. Brazil's outbreak started last May, with first suspicions of a link to microcephaly noted in October.

Pan American Health Organization (PAHO) Director Carissa Etienne, MD, said results from monitoring of pregnant women in Colombia, which was hit after Brazil, in the months ahead will tell a lot.

"Although we are still working to establish causality with Zika, we cannot tolerate the prospect of more babies being born with neurological and other malformations, and more people facing the threat of paralysis due to Guillain-Barre syndrome," she said.

At the executive board meeting and press briefing that followed, regional health officials made some rough case estimates, based on adapted dengue virus modeling. They projected that Zika virus has likely sickened 500,000 to 1.5 million people and that cases in the Americas could total 3 million to 4 million within a year.

Marcos Espinal, PhD, PAHO's spokesman for the Zika outbreak, said there are plenty of questions about the virus and its spread, and that the group is organizing two meetings—one in Puerto Rico and the other in Washington, DC—to set a research agenda.

Lyle Petersen, MD, MPH, the director of the US Centers for Disease Control and Prevention's (CDC's) Division of Vector-Borne Diseases, said 31 travel-related Zika virus cases have been reported in the United States, a number that is growing rapidly. He added that US territories have logged 20 cases so far due to local spread: 19 in Puerto Rico and 1 in the US Virgin Islands.

He also said the CDC has epidemiology teams on the ground in Brazil to help find answers to some of the key questions. Researchers have already launched a case-control study to explore the possible GBS connection to Zika virus infection and that another case-control study to explore the microcephaly link will launch in the next few weeks.

Research challenges

At a media briefing afterward, Sylvain Aldighieri, MD, PAHO's Zika incident manager, said case investigations, cohort studies, and ecologic studies are also ongoing to help fill in knowledge gaps about the virus.

He alluded, however, to the tall challenges researchers face. For example, it's difficult to even come up with an attack rate—a key metric in infectious disease outbreaks—because cases can only be confirmed in a short window of time of about 5 days, he said. Also, serologic tests to look for past infections are problematic because of cross-reactions with other mosquito-borne viruses that are common the areas, such as dengue.

Another challenge is that about 75% people who are infected by the virus don't have obvious symptoms, making it difficult to assess the outbreak's scope, Aldighieri said.

Bruce Aylward, MD, MPH, the WHO's assistant director-general, told reporters that the numbers will change over time as researchers and responders get a better fix on the outbreak.

He said he doesn't anticipate that the WHO will recommend that women postpone pregnancies, as some countries have done. Rather, he said its advice will probably be based around avoiding mosquito bites, which he said is a good public health measure anywhere in the world where disease-carrying mosquitos are a threat.

See also:

Jan 28 WHO press release

Jan 28 Margaret Chan speech

Jan 28 Carissa Etienne remarks to the WHO executive board

Jan 28 WHO video archive of executive board briefing

Jan 28 WHO audiofile of media briefing

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