Two cases of Zika being transmitted through blood transfusions were reported in Brazil on Thursday, adding to concerns over the virus that has been linked to severe birth defects and is typically spread through mosquito bites.
The disclosure of the blood transfusion cases in the industrial city of Campinas near Sao Paulo came two days after Texas authorities said a person became infected through sex. Concern over the virus is mounting as Brazil prepares to host the Olympic Games in August, with tens of thousands of athletes and tourists anticipated.
There is no vaccine or treatment for Zika, which has caused outbreaks in at least 26 countries in the Americas. Brazil researchers hope to develop a treatment that could be tested in humans in a year.
Dr. Marcelo Addas Carvalho, director of the blood center at the University of Campinas, said genetic testing confirmed that a man who received a blood transfusion from a Zika-infected man in March 2015 became infected with the virus, although he did not develop symptoms.
Another man, who had suffered gunshot wounds, became infected with Zika after receiving multiple blood transfusions that included blood donated by an infected person in April 2015, Carvalho said.
Carvalho said that infection probably was caused by the transfusion but genetic tests have not yet been conducted to confirm it. He said it was very unlikely the infection was caused by a mosquito bite because the patient was in a hospital intensive care unit for three months.
The patient later died from his gunshot wounds and not the Zika infection, health officials and Carvalho said.