By Dennis Thompson
TUESDAY, June 30, 2015 (HealthDay News) -- New cases of hepatitis C are drastically underreported to federal officials, researchers contend in a new study.
The new study found that only one out of 183 Massachusetts residents diagnosed between 2001 and 2011 with acute hepatitis C infection was reported to the U.S. Centers for Disease Control and Prevention.
The rest went unreported, either because their test results didn't come back quickly enough or because the results didn't meet the strict CDC definition for hepatitis C infection, said senior study author Dr. Arthur Kim, director of the Viral Hepatitis Clinic at Massachusetts General Hospital in Boston.
"We were shocked to find only one made it to the CDC, reported as an acute hepatitis C case," Kim said. "This indicates that only a small fraction of cases ever get reported to the CDC. They might be seeing only what amounts to the tip of a very large iceberg."
The findings were published June 29 in the Annals of Internal Medicine.
Reported new cases of hepatitis C have more than tripled in recent years, rising from 694 cases in 2005 to 2,138 cases in 2013, according to the best CDC estimates.
However, the CDC believes the actual number of new hepatitis C cases is about 14 times the number of reported cases in any given year, due to the reporting troubles.
Based on that assumption, the CDC estimates that the "real" number of new hepatitis C infections in 2013 was anywhere between 23,500 and 101,400, rather than the reported number of 2,138.
Acute hepatitis C infection is a short-term illness that occurs within the first six months of exposure to the hepatitis C virus, according to the CDC. Drug abuse is a leading cause of hepatitis C infection, because the virus can spread through the sharing of tainted syringes, the researchers said.
Very few people die from acute hepatitis C infection, but about three out of four cases evolve into a chronic infection that remains in a person's body for the rest of their lives, said Dr. David Bernstein, chief of hepatology at North Shore University Hospital in Manhasset, N.Y.
If left untreated, chronic hepatitis C infection can cause long-term liver damage and might result in liver cancer. Drug cocktails can treat chronic hepatitis C, but the course of treatment can run as high as $93,000, a recent analysis found.
"It's really no surprise that so few cases are being reported," Bernstein said. "Most people who get hepatitis C acutely don't get sick, and the standard testing we use for hepatitis C is an antibody, which may not become positive for several months after being exposed."
In the new report, researchers analyzed data from a government-funded study that followed a group of 183 Massachusetts patients diagnosed with acute hepatitis C between 2001 and 2011.
Researchers found that only 149 of those cases had been reported to the Massachusetts Department of Public Health and entered into the agency's automated database. Of those cases, 130 were classified as a confirmed present or past hepatitis C infection, based on state-level case definitions, and 43 were investigated as potential acute hepatitis C cases.
However, only a single case fully met the definition of a confirmed CDC-reportable case. The others were disqualified because of factors such as the absence of specific symptoms or not meeting threshold lab test results.
"Massachusetts has a robust system of capturing new hepatitis C cases," Kim explained. "However, it was very hard for our state health department to classify them as acute hepatitis C."
Unless a better way of identifying hepatitis C is discovered, public health officials will find themselves ill-prepared to deal with a silent but growing epidemic, Kim said.
"We believe the multiplier might be even higher than that being used by the CDC, and the downstream cost of dealing with those new cases will be immense. We must be able to count cases accurately, so we know the true burden of the disease," Kim cautioned.