What’s really scary about the Zika virus are the things we don’t know

The FDA guidelines may seem strict to some, but keeping Zika completely out of the blood supply could be tricky. Four out of five people who contract it never show symptoms, and as a result, 80 percent of transmissions are never diagnosed, says the Centers for Disease Control and Prevention. So, a blood donor carrying the virus can feel just fine, think nothing is wrong and end up unwittingly passing on the virus when they give blood.

Anyone who has had a confirmed infection, possibly been exposed to the Zika virus or traveled to areas where the virus is being transmitted, should postpone donating blood for the four week period, the FDA said. Also, people who have had sexual contact with someone who has been to an area where the virus is actively being transmitted should also wait as long to donate. The virus is currently actively being transmitted in mostly tropical and subtropical areas, particularly in South and Central America, central Africa, and South East Asia, the CDC says.

Concern about Zika erupted in recent months, although the virus was first identified in 1947, according to the World Health Organization. In the past, Zika generated less fear because if an infected person developed symptoms, they were usually mildly flu-like, run their course then disappear. But then last year, researchers began seeing cases of a usually rare but cruel birth defect balloon in tandem with a Zika outbreak in Brazil.

But then last year, researchers began seeing cases of a usually rare but cruel birth defect balloon in tandem with a Zika outbreak in Brazil. Thousands of babies of mothers who had been infected during pregnancy were born with heads markedly smaller than normal, combined with incompletely formed brains, a condition called microcephaly.

Scientists have not yet been able to confirm that Zika causes the microcephaly, but the parallel surges in both have accelerated research and prompted public health officials to make recommendations as though they are directly connected. Albert Ko, an epidemiologist and infectious disease expert at the Yale University School of Public Health who spent time in the Brazilian city of Salvador last December, recently told The Washington Post: “We strongly believe that the cases of microcephaly we are identifying during this outbreak are due to Zika virus.”

One reason this latest Zika outbreak is causing so much concern is because its arrival in Brazil appears to have coincided with a surge in the number of cases of microcephaly, a rare neurological condition which leaves children with unusually small heads. In many cases of microcephaly, the child’s brain may not develop properly. In Brazil, there has been an abundance of more severe cases, including a number of cases where the child died shortly after birth.

Mosquitos may not be the only culprit. The Centers for Disease Control and Prevention recently confirmed that sexual transmission of the Zika virus was “possible” and Dallas health officials have said that one local resident was infected with Zika after having sex with a person who had contracted the disease while traveling.