Four countries have been added to the list of regions affected by the Zika virus. Level-2 notices advising travelers to“practice enhanced precautions” were issued March 10 by the Centers for Disease Control and Prevention (CDC) for Angola, Guinea-Bissau, the Maldives and the Solomon Islands. The Zika virus is spread by mosquitoes. The best way to avoid Zika virus infection is to prevent mosquito bites during travel and for three weeks upon return from travel to an affected region, even if no symptoms (such as fever, rash, joint pain or red eyes) are present. Because the virus can also be sexually transmitted, safe-sex practices are recommended. In related news, the CDC reported today that it is working with other agencies to help reduce the risk of spreading Zika virus through blood transfusions and tissue transplants. The CDC and the Food and Drug Administration define areas of active transmission as having two or more locally acquired cases of Zika virus infection within 45 days. Defined areas of risk can be different from areas for which CDC has issued travel guidance because of concerns about potential risk for blood and tissue safety. The following are areas of active transmission for the purpose of blood and tissue safety intervention: Miami-Dade County listed as of July 29, 2016 Cameron County, Texas listed as of Dec. 9, 2016 Palm Beach County was listed until Nov. 2, 2016. To learn more, visit the CDC’s Zika virus website.