BRASILIA/GENEVA – Brazilian health authorities confirmed on Thursday a case of transmission of Zika through a transfusion of blood from a donor who had been infected with the mosquito-borne virus that is spreading rapidly through the Americas.
The health department of Campinas, an industrial city near Sao Paulo, said a man with gunshot wounds became infected with Zika after multiple blood transfusions in April 2015. Officials said they determined that one of the people whose donated blood was used in the transfusion had been infected with Zika.
Zika is usually contracted via mosquito bites, so transmission of the illness through blood transfusions adds another concern to efforts to contain the outbreak. Some countries have tightened procedures for blood donations, to protect blood supplies.
Zika has been reported in 30 countries since it first appeared in the Americas last year in Brazil, where it has been linked to thousands of babies being born with microcephaly. This is a condition where infants have abnormally small heads and often have underdeveloped brains.
Campinas health officials said the donor of the contaminated blood developed symptoms afterward that were mistaken for dengue, a virus borne by the same mosquito that transmits Zika. A blood test that showed he had Zika was not completed until Jan. 28 this year.
The blood center at the University of Campinas said a second person who donated blood in May developed symptoms and tested positive for Zika, though the recipient of the contaminated blood has not developed symptoms of the virus.
Brazil’s Health Ministry said the first recipient died of his wounds and not from the Zika infection. It said it was reinforcing instructions to blood banks that people infected with Zika or dengue not be permitted to donate blood for 30 days after full recovery from the active stage of Zika infection.
On Tuesday, the American Red Cross urged 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 was “extremely” low in the continental United States. The agency asked donors who give blood and subsequently develop symptoms consistent with Zika within 14 days to notify the Red Cross so the product can be quarantined.
Also causing concern is the possibility of transmission through sexual contact. Health officials in Texas reported on Tuesday that a person in Dallas became infected after having sex with another person who had traveled in Venezuela, where the virus is circulating.
The World Health Organization on Thursday also advised countries against accepting blood donations from people who had traveled to regions affected by the Zika virus.
“With the risk of incidence of new infections of Zika virus in many countries, and the potential linkage of the Zika virus infection with microcephaly and other clinical consequence, it is estimated as an appropriate precautionary measures to defer donors who return from areas with Zika virus outbreak,” the WHO told AFP in a statement.
Canada and Britain have already moved to protect their blood supplies.
Canadian blood agencies earlier Wednesday announced that anyone who had traveled to a Zika-risk area will be ineligible to give blood for three weeks upon their return.
The 21-day waiting period also applies to cord blood and stem cell donors who have traveled to Zika-affected areas.
In Britain, the National Health Service Blood and Transplant agency has said that from Thursday, anyone returning from Zika-affected countries will be made to wait 28 days before being allowed to donate blood, as a “precautionary measure.”
“The safety of the blood supply is paramount and it is important we implement any precautionary blood safety measures agreed here as a result of an increasing prevalence of infectious diseases found around the globe,” a spokeswoman said.
The mosquito-borne Zika virus has spread to 26 countries in South and Central America and the Caribbean. It holds little danger for most people but has been linked to a surge in cases of microcephaly, a condition that causes babies to develop abnormally small heads, leading to permanent disability or death.
Zika symptoms resemble those of a mild case of flu — headache, muscle and joint pain, mild fever, and a rash. In 70 to 80 percent of cases, the disease goes unnoticed.