Health Highlights: Nov. 15, 2016

Here are some of the latest health and medical news developments, compiled by the editors of HealthDay:

U.S. Blood Banks Must Screen Donations for Zika

As of Friday, all blood banks in the continental United States will have to test donated blood for the Zika virus.

Under the Food and Drug Administration requirements, 11 states in high-risk areas are already doing the screening and those in other states must begin doing so by this end of the week, The New York Times reported.

So far, Zika infection appears extremely rare. Only about 40 of 800,000 blood donations tested in a dozen states in the past six months were initially positive for the virus.

“It is good news that we are avoiding the transmission of Zika,” Dr. Susan Rossmann, chief medical officer, Gulf Coast Regional Blood Center in Houston, told The Times.

She noted that blood banks have discouraged donations from people who recently traveled to regions where the virus is circulating.

Blood banks either perform the screenings themselves or pay a laboratory and pass the cost on to hospitals. The price ranges from $6 to $10 a unit, according to Rossman.

A 2011 survey found that after screening for pathogens, hospitals paid $210 on average for a unit of red blood cells, The Times reported.

When the FDA introduced the screening requirement in August, blood banks in Florida and 11 other states thought to be at high risk for Zika outbreaks had to comply within a month, while 38 other states were given three months.

The deadlines have been difficult for blood banks. It typically takes six to 12 months to introduce a new screening test for blood donations, The Times reported.

For example, the Rhode Island Blood Center got two new machines to screen 153,000 annual donations and trained 17 employees to do the screening.

Currently, the main threat to the U.S. blood supply is from the approximately 4,000 travelers infected with the Zika virus while abroad. In most cases, they have no symptoms. The number of such cases in the continental U.S. is “extraordinary,” Dr. Lyle Petersen, the director of the division of vector-borne diseases at the Centers for Disease Control and Prevention, has said.

The concern is not that these infected travelers will donate blood, but rather that they will infect others, most likely through sexual transmission.

In all cases examined by the CDC, “transmission from infected travelers to their nontraveler partners has occurred within 20 days of the first sexual contact,” according to Peterson.

Recently infected travelers have higher levels of Zika in their blood, semen and other bodily fluids, and are likely more infectious, The Times reported.

While the new screening program is costly, experts said it is necessary if the U.S. wants to prevent Zika transmission through contaminated blood transfusions.

“Compared to the overall cost of health care this is spit in the ocean,” Scott Greenwell, executive director of The Community Blood Bank of Northwest Pennsylvania and Western New York, told The Times.