Zika Virus Outbreak Impacts Blood Donation Guidelines in US

— -- The effects of the Zika virus outbreak are already being felt in the U.S. as the American Red Cross announced new guidelines to blood donation policy due to the virus' rapid spread.

The American Red Cross, the largest blood collection organization in the nation, announced today that it is asking people to defer donating blood for 28 days if they have been in any country with Zika infection.

The virus is primarily spread through mosquito infection, though isolated cases have been reported where it spread through blood transfusion or sexual contact. The news comes as the U.S. Food and Drug Administration considers changing its guidelines around blood donation due to the Zika virus.

“The American Red Cross is dedicated to providing the safest, most reliable blood products possible to patients in need," said Dr. Susan Stramer, vice president of scientific affairs at the American Red Cross. "We are closely monitoring the spread of Zika virus."

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said during a news conference last week that the FDA is looking into changing its policy, which would affect all blood donations in the U.S.

"The FDA is looking at the issue of blood supply, blood donors and travelers," Fauci said. "We know it’s in the blood stream very briefly, most people have cleared the bloodstream of the virus after about a week."

An FDA spokeswoman confirmed to ABC News today that the agency is working with the U.S. Centers for Disease Control and Prevention as the agency considers changing the guidelines for blood donation.

The United Kingdom and Canada have already implemented changes to their blood donation policies in the face of the Zika virus outbreak. U.K. officials are asking prospective blood donors to wait 28 days after returning from a country with Zika virus transmission, while Canadian officials are asking potential donors to wait one month.

ABC News' Dr. Anand Venkatraman, a neurology resident at the University of Alabama at Birmingham and a resident at the ABC News Medical Unit, contributed to this report.