The American Red Cross has appealed to prospective donors who have visited Zika outbreak zones to wait at least 28 days before giving blood, but said the risk of transmitting the virus through blood donations remained "extremely" low in the continental United States.
The "self-deferral" notice for blood donors should apply to those who have visited Mexico, the Caribbean, or Central or South America during the past four weeks, the Red Cross said in a statement.
The Washington-based nonprofit disaster relief agency also asked that donors who give blood and subsequently develop symptoms consistent with Zika within 14 days of donating to notify the Red Cross so the product can be quarantined.
Cases of the Zika virus, a mosquito-borne illness linked to a dangerous birth defect called microcephaly - marked by abnormally small head size - and to a serious autoimmune disorder called Guillain-Barre syndrome that can cause paralysis, has been reported in more than 30 countries and territories.
The most common symptoms of infection are flu-like, such as aches and fever. About 80 percent of people infected show no symptoms whatsoever, said Susan Stramer, a microbiologist for the Red Cross.
There is no quick blood test for the virus.
Still, "the risk of transmission through blood donation continues to be extremely low in the continental U.S.," the Red Cross said in its statement.
The travel-related donor self-deferral notice, the first measure of its kind taken by the Red Cross for a mosquito-borne disease, came a day after the American Association of Blood Banks, an accrediting organization, called for action, Stramer said.
On Tuesday Dallas health officials said they'd confirmed a case of Zika that appears to have been spread through sexual transmission.
