25 years ago, hospitals paid $65 for a unit of red blood. Today’s cost is $220. Inflation, yes, but a big factor is the requirement for 13 screening tests. The FDA is considering a 14^th test, for Chagas disease. The malady affects 11 million people in Mexico, and Central and South America. Borne by a parasite, it can be fatal. That would add as much as $12 to the cost. The hospitals often can’t pass on the increase. The non-profit Blood Source in Sacramento collects donated blood and sells it to 39 hospitals in the area, and their worry is a shrinking pool of eligible donors.