Reported acute cases of hepatitis A and hepatitis B haven't been this low since the government started keeping hepatitis records in 1966.
Reported acute cases of hepatitis C are also at a record low, but those records don't date back as far, according to the CDC.
" ... There are still a larger number of infections that are out there than are caught by our surveillance," says CDC epidemiologist Annemarie Wasley, ScD.
However, "The fact that we're seeing declining numbers of new symptomatic cases indicates that the number of new infections is also declining," Wasley, who works in the CDC's division of viral hepatitis, tells WebMD.
The CDC estimates that about 113,000 people in the U.S. became infected with one of these three hepatitis viruses in 2005.
The statistics appear in the CDC's Morbidity and Mortality Weekly Report: Surveillance Summaries.
Types of Hepatitis
Hepatitis confuses many people because there are so many different types.
Also, people with hepatitis often have no symptoms, although viral hepatitis infections can be detected with a blood test.
Hepatitis A is an inflammation of the liver caused by infection with the hepatitis A virus. Poor sanitary conditions and personal hygiene practices contribute to spread of the disease.
Hepatitis A is not a chronic disease, and once you have gotten over a hepatitis A infection, you can't get it again.
Inflammation of the liver can also be due to noninfectious causes of hepatitis such as alcohol and certain medications.
Drop in Hepatitis A
In 2005, the CDC got reports of 4,488 people ill with hepatitis A. That equals 1.5 cases per 100,000 people -- the lowest rate since the government began tracking hepatitis in 1966.
That compares to an average of 28,000 cases of acute hepatitis A reported each year from 1987-97.
Including the unreported cases, the CDC estimates 42,000 new cases of hepatitis A infection in 2005.
Starting in 1999, 17 states have recommended hepatitis A vaccination for all children. Those states saw a greater decline in reported childhood hepatitis A illness than other states.
The CDC now recommends the hepatitis A vaccine for all children age 12-23 months.
The hepatitis A vaccine is also recommended for people at high risk of contracting the disease (including men who have sex with men, people who use illegal drugs, people with chronic liver disease, and people traveling to countries where the hepatitis A virus is common).
Drop in Hepatitis B
In 2005, the CDC received reports of 5,494 people ill with hepatitis B. That translates to 1.8 cases per 100,000 people -- also a record low.
The CDC estimates there were 51,000 new cases of hepatitis B infection in the U.S. in 2005, including unreported cases.
The decline in hepatitis B started in the mid-1980s and incidence of the disease has dropped an estimated 80% since 1991, when the U.S. government launched an effort to curb it.
The greatest drop in hepatitis B cases occurred in children less than 15 years old. Those kids were in the first generation of children for whom universal vaccination against hepatitis B was recommended.
Drop in Hepatitis C
Wasley explains that the CDC only began tracking hepatitis cases that weren't hepatitis A or B in 1982. Many of those combined cases were likely due to hepatitis C.
The CDC began tracking hepatitis C separately in 1995, when a reliable test for hepatitis C antibodies became widely available, Wasley says.
Reported cases of people ill with hepatitis C have dropped steadily since peaking in the late 1980s.
There is no hepatitis C vaccine. The drop in reported cases of hepatitis C is likely due to a decline in needle sharing among intravenous (IV) drug users, according to the CDC.
IV drug use was the most common risk factor among the 671 hepatitis C cases reported to the CDC in 2005.
"For hepatitis C, the majority of people with new infections are asymptomatic," Wasley says. "We have a relatively small number of symptomatic cases that we identify, but there are many, many other asymptomatic infections that are occurring at the same time."
The CDC estimates there were about 20,000 new cases of hepatitis C infection in the U.S. in 2005, including unreported cases.