Hemophilia is primarily treated by replacing the
absent or abnormal clotting factors in the blood. One of the major sources for
clotting factors is donated blood. Prior to 1985, many
people with hemophilia became infected with the
human immunodeficiency virus (HIV) because they
received blood products that were contaminated from infected donors. Beginning
in 1985, donated blood was routinely tested and screened for HIV and other
viruses, such as
hepatitis B and
hepatitis C.
The blood supply is now much safer because of better donor screening
tests and new purification techniques that kill viruses in blood. Viruses
sometimes are still spread through donated blood, but HIV and other viruses
that cause chronic hepatitis are almost always detected during the careful
screening process. The purification process also destroys most viruses that are
not detected.
Some viruses are more difficult to detect even with careful
screening. Viruses that are occasionally transmitted through blood supplies
include
hepatitis A, parvovirus (the virus that causes
fifth disease),
Epstein-Barr virus (EBV), and
cytomegalovirus (CMV).
Some people develop antibodies to the injected clotting factor.
These antibodies are called
inhibitors, and they may make it more difficult to
treat bleeding episodes. Up to 20% of children with hemophilia receiving fresh
frozen plasma or cryoprecipitate clotting factor develop inhibitors.1