Scope of the Problem

These statistics are presented not to scare you, but to emphasize that
the risk is genuine.
Human Immunodeficiency Virus
World Prevalence: Over 47 million people worldwide have been infected
with HIV since the start of the epidemic. In 1998, HIV caused
over 2 million deaths. In some countries in Africa, 1 in 4 people is infected
with HIV. Ninety-five percent of cases occur in the developing
world.
Prevalence in the U.S. Approximately 1 in 200 people carries HIV.

Hepatitis B Virus
World Prevalence. There are over 350 million chronic carriers of HBV
worldwide. In developing nations, 8–15% of the population are chronic
carriers. This percentage drops to less than 5% in developed nations.
Five to ten percent of chronically infected people will develop chronic
liver disease that may lead to death.
Prevalence in the U.S. Approximately 1 million people are chronically
infected with HBV.
Hepatitis C Virus
World Prevalence. Three percent of the world’s population is infected
with HCV. There are more than 170 million chronic carriers of HCV.
About 50–70% of infected people will develop chronic liver disease.
HCV infection is the leading disease necessitating liver transplantation.
Prevalence in the U.S. Approximately 4 million people are chronically
infected with HCV.
Delta Hepatitis Virus
The delta hepatitis virus (HDV) primarily affects patients infected with
HBV. Apatient infected with both HBV and HDV has an increased risk
for the development of fulminant hepatitis compared with a patient infected
with HBV alone (the risk doubles to 20%). About 70–80% of
people infected with HBV and HDV develop chronic hepatitis.
Prevalence in the U.S. Unknown