Federal and international health officials confessed Tuesday to an encyclopedic list of unanswered questions about the fast-spreading Zika virus, which in a matter of months has become an international public-health crisis.
In a bleak assessment of their ability to confront the disease, epidemiologists, public-health experts, scientists, and researchers told a conference on Zika of their concerns that too little was known about diagnosing the disease and about how it might be spread.
Among the unknowns: which animals other than humans can be infected with the Zika virus, how often has it been spread by sexual contact, and whether, for sure, it’s the cause of devastating birth defects and other neurological disorders, as suspected.
Scientists don’t know the role that climate change might have had in Zika’s rapid spread through the Americas. They don’t know whether the virus has changed in some way that makes it more dangerous for humans.
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“We don’t, at a very basic level, know whether the virus has mutated and that is a cause of the explosive epidemic potential,” said Ronald Rosenberg, acting director for the Division of Vector-Borne Diseases at the Centers for Disease Control and Prevention.
At the request of the U.S. Department of Health and Human Services, the leading scientists and researchers met at the National Academy of Sciences in Washington to identify research priorities and try to hammer out a strategy for a response should an outbreak occur in the United States.
Marcos Espinal, director of the Department of Communicable Disease and Health Analysis at the Pan American Health Organization, said it might be months before researchers had determined for certain one of the main public concerns — whether Zika is linked to microcephaly, a birth defect that causes newborns to have small heads and other neurological disorders. But for now, he said, all indications are that there is a connection.
“The evidence points to, until proven guilty, it’s Zika,” Espinal said.
Victor Dzau, president of the National Academy of Medicine, called the Zika virus a “wake-up call” and pressed world leaders to stop thinking of the epidemic as strictly a health issue.
The potential economic losses from a pandemic could amount to $60 billion a year, he said. Those costs are consequences of policy and behavior changes associated with fears – rational and irrational – that can lead to travel bans, quarantines and blocks on trade.
“It’s more than just health,” Dzau said in an interview. “Airports get shut down. Borders get shut down. People stop traveling.”
More than 30 countries and territories across the Americas have reported local transmissions of the Zika virus since it was first discovered in Brazil last May. There have been 52 U.S. cases in 16 states and the District of Columbia, Puerto Rico and the U.S. Virgin Islands. At least 21 cases have been discovered in Florida, the most in any state, including seven in Miami-Dade and four in Broward County.
Florida is among the U.S. locations where mosquitoes are active year-round, and it is also a destination for travelers from the Latin American and Caribbean nations where the virus has spread so quickly. So far, however, mosquitoes in the mainland United States have not been implicated in the spread of the disease, and there have been no locally acquired cases of Zika on the mainland. None of the confirmed U.S. cases involves pregnant women.
Thomas Monath, chief scientific officer for BioProtection Systems/NewLink Genetics Corp., which has been working on an Ebola vaccine, pointed to climate change as a possible factor that might help Zika and other mosquito-borne viruses spread further into the continental United States. Warmer temperatures, he said, mean larger mosquito populations, longer lives and more mosquito bites.
The risks Florida faces because of its subtropical temperatures might spread to Northern states as temperatures rise, he warned.
Citing Florida’s vulnerabilities, Rep. Curt Clawson, a Republican from Florida’s Gulf Coast, said he was planning to introduce legislation to help fight Zika.
The World Health Organization has declared the rapidly spreading virus an international public health emergency, but the designation did not come until several leading scientists complained about the slowness of the response, which they compared to the recent West Africa Ebola epidemic, which killed more than 11,000 people.
Last week, two U.S. women suffered miscarriages after being infected with the Zika virus while traveling abroad, according to CDC officials. Zika was found in the placenta of one of the women.
President Barack Obama has asked Congress for more than $1.8 billion in emergency funding to fight Zika domestically and internationally. The money would be used for testing and surveillance to help control any potential outbreak. It would also be put toward finding a vaccine.