Another Zika Worry: Donated Blood Officials say 2 Brazilian patients contracted the virus from blood transfusions By Michael Harthorne, Newser Staff Posted Feb 4, 2016 5:00 PM CST 15 comments Comments The Zika virus, which is usually spread by mosquitoes, was found in two Brazilian patients following blood transfusions. (AP Photo/Andre Penner) (Newser) – First mosquitoes; then sex; now blood transfusions. On Thursday, officials in Brazil announced two cases of patients receiving the rapidly spreading Zika virus through donated blood, Reuters reports. According to the Wall Street Journal, the first case was in March after a patient received a blood transfusion during a liver transplant. The second case was in April after the patient was shot and needed multiple transfusions. “The capacity of Zika to spread through blood transfusions needs to be evaluated, as well as the blood protection measures that should be adopted based on the new findings,” Brazil's Health Ministry says. A Brazilian infectious disease specialist tells the Journal "there is no reason for panic." A number of countries are issuing stricter rules for blood donations in the face of the Zika outbreak. The Health Ministry is reiterating that blood banks shouldn't accept any donations from people who've had Zika until 30 days after they've fully recovered. And the American Red Cross says people who've been to Central or South America, Mexico, or the Caribbean should wait 28 days before donating blood. Still, the Red Cross states the risk for Americans receiving blood transfusions is "extremely low." Zika first appeared in Brazil last year. Since then, it's infected an estimated 500,000 to 1.5 million Brazilians and popped up in 30 countries. The virus only rarely causes serious symptoms in those who contract it, but it has been linked to thousands of cases of microcephaly in Brazilian babies.