Zika virus, a mosquito-borne pathogen that may cause birth defects when pregnant women are infected, has been “spreading explosively” in South and Central America, the head of the World Health Organization said Thursday.
“The level of alarm is extremely high,” WHO director general Margaret Chan said Thursday in a statement. Chan said she will convene an emergency meeting on Feb. 1 in Geneva to consider whether to declare the outbreak a “Public Health Emergency of International Concern,” which can coordinate government responses to direct money and resources at the virus.
While there is no approved vaccine, a top U.S. health official said the government could start work on an experimental one as soon as this year.
“We’re already talking with a few companies to partner with us in advanced development,” Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases, said Thursday during a conference call. Researchers are also working closely with counterparts in Brazil to understand the virus, its impact on people, and how to control it.
The WHO now estimates that there could be 3 million to 4 million cases of the virus in the region, and the travel industry has begun to feel the first impacts of worried vacation and business customers who are changing plans to avoid affected areas.
Chan emphasized that researchers are still working to determine the exact link between the virus and birth defects such as microcephaly, which causes babies to be born with abnormally small heads and potential developmental problems.
“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 members of the WHO executive board in Switzerland.
The virus, which has long been present in Africa and equatorial Asia, has spread to 23 countries in the Americas, according to the WHO. While many populations where the virus has long been present have immunity, that’s not the case in newly affected areas. Without a vaccine or effective treatment, some countries have told women to put off getting pregnant for several years. The WHO said it doesn’t anticipate giving similar advice, though does suggest that pregnant women take steps to avoid mosquitoes.
Zika virus usually causes mild symptoms, such as fever, rash and joint pain. The U.S. has seen 31 cases in 11 states and Washington, and an additional 19 cases in Puerto Rico and the U.S. Virgin Islands, said Anne Schuchat, principal deputy director of the Centers for Disease Control and Prevention.
All of the U.S. cases were in travelers from affected areas outside the country, she said. No mosquito-borne transmission has been seen in the United States, and while that’s being monitored closely, there is currently no known risk of getting Zika virus locally, officials said.
Researchers are also investigating how the virus might be linked to microcephaly, Schuchat said. While the condition usually begins in the first trimester of pregnancy, other infections can cause birth defects in the second and third trimester, she said. Researchers are also trying to determine how long after an infection women remain at at risk, she said.
The outbreak is already affecting business and leisure travel. Pregnant women who have planned “babymoon” vacations to the region have altered plans, and business conferences have been canceled. That could place “significant pressure” on the hotel industry, Gregory Fine, chief executive officer of the Turnaround Management Association, said at a conference in Florida hosted by the M&A Advisor.
Airlines have offered refunds to customers who have tickets to affected regions, and Delta Air Lines Inc. said Wednesday that it would let some customers change destinations, travel dates or ask for money back. The CDC has suggested that pregnant women consider delaying travel to affected areas, and has listed 24 countries and territories to a travel alert, including Brazil, the host of the 2016 Summer Olympics.
The Pan American Health Organization, which is affiliated with the WHO, said it’s not recommending travel restrictions. “Currently PAHO is not recommending any restrictions on travel or trade because they would not slow the spread of the virus,” said Donna Eberwine-Villagrán, a spokeswoman.
The WHO said t is working to increase surveillance and diagnosis of the virus to spot new cases. Public health officials may also work on methods of mosquito control, hoping to control the virus’s spread by reducing the vector it uses to travel from host to new victim.
That could be difficult because of the El Nino weather pattern, Chan said, which will bring unusually heavy rains, creating puddles and pools where the bugs can breed. The impact of changing weather patterns on mosquito populations can be difficult to predict, NIH’s Fauci said.
Lauren Coleman-Lochner contributed.