How Zika spreads (and who’s to blame)
As the number of confirmed cases of Zika continues to grow, so do concerns about the virus infiltrating the nation’s blood supply.
Two blood transfusion-transmitted cases confirmed in early February in the Brazilian city of Campinas have prompted the U.S. Food and Drug Administration to issue guidelines last week calling for restrictions of certain blood donations.
Both the American Red Cross and OneBlood, the primary blood bank of South Florida, have asked those who have traveled to Mexico, the Caribbean or Central or South America to postpone donating blood until 28 days after their return to the continental United States. Twenty-eight countries or territories in Latin America have confirmed cases of Zika. Brazil is the biggest target, with an estimated 1.5 million cases reported since the virus was first diagnosed there in May 2015.
The nonprofit OneBlood, which serves all South Florida hospitals and operates a dozen stand-alone donation centers in Broward and Miami-Dade counties, as well as other areas in the state, requests that the following groups self-defer for four weeks:
▪ Donors with a history of Zika infection.
▪ Donors with symptoms associated with Zika (rash, fever, pink eye, joint pain) within two weeks of traveling to an area where the virus is active.
▪ Donors who’ve had sexual contact with a man who, in the past three months, was diagnosed with Zika or traveled to, or resided in, an area where Zika is active. (Although rare, Zika has been transmitted through sexual relations.)
OneBlood also asks all donors to report recent travel history. According to manager of media and public relations Pat Michaels, questionnaires are being updated to include Zika-specific questions.
“The public should take great comfort in knowing our local blood supply is safe and meets the highest possible standards mandated by the FDA,” he said.
In Florida, all incidences of Zika — 26 cases as of Friday, including 10 in Miami-Dade — have been travel-related, and there have been no reports to date of the virus entering the U.S. blood supply. But “the risk of blood transmission is considered likely,” FDA spokesperson Tara Goodin wrote in an email.
Official guidelines for donation centers are particularly important for safeguarding blood supply because of the virus’ predominantly asymptomatic nature, Goodin said. Four out of five of those infected with Zika do not become symptomatic, according to the FDA.
The FDA urges those who donate blood and later experience Zika-related symptoms or are diagnosed with the virus to immediately contact the center where they donated so the blood sample can be quarantined.
Dr. Paola Lichtenberg, who directs UHealth’s tropical diseases program, said FDA approval of tests would be a major step in the fight against Zika. Currently, all blood samples must go through the Florida Department of Health or the Atlanta-based federal Centers for Disease Control and Prevention, which “makes things very difficult,” she said. No one can say for certain how long it will take the FDA to approve and roll out testing kits.
“Given the urgency of the situation we remain optimistic it will be approved in the near future,” Michaels of OneBlood wrote in an email.
In its new guidelines, the FDA said it is “prioritizing the development of blood screening and diagnostic tests that may be useful for identifying the presence of the virus.’’
Developing a blood test to screen the virus is critical. In the early days of AIDS in the 1980s — before a test was developed to screen AIDS-tainted blood — the HIV virus was transmitted to hundreds of people through blood transfusions.
The FDA’s new guidelines may impact some regions of the country more than others, the FDA’s Goodin said. South Florida, for example, could be disproportionately affected as it is home to hundreds of thousands of Latin and Central Americans, as well as multiple airports that usher flights to and from the affected areas multiple times a day. Florida has more confirmed cases of Zika than any other state.
Lichtenberger of UHealth is skeptical that the area’s demographics will impact blood donation volume.
“If you see the population that actively travels back and forth, it’s not enough to decrease volume,” she said. Additionally, blood can be transported across regions, so the chances of a shortage are nil, she added.
What’s important, Lichtenberger said, is to remember that study of the virus is ongoing and quickly evolving.
“At this point there isn’t much information for how long the Zika virus persists in certain fluids. And that information will change with time,” she said. “So it’s better to take precautions.”