A liver infection known as hepatitis C is causing increased concern following a study showing that 18 percent of patients tested in the Johns Hopkins emergency room carried the potentially deadly virus.
Called "astounding" by one emergency room doctor, the high rate came to light when physicians re-examined frozen blood samples that had been collected for a 1988 study charting the prevalence of the human immunodeficiency virus, which causes AIDS.
Hopkins plans to survey a new sample of patients in the summer to see if hepatitis C has since increased or declined.
"HIV is already known to be ravaging certain minority populations," said Dr. Gabor Kelen, acting director of emergency medicine at Hopkins. "What is particularly alarming are the extraordinary rates of hepatitis C virus among minorities in the population."
For instance, half of the black men between the ages of 25 and 44 were infected with hepatitis C. And about 60 percent of the men in that group tested positive for the AIDS virus, hepatitis C, its cousin, hepatitis B -- or combinations of the three.
Hepatitis C may initially cause fever and jaundice. About half of all infected people will not suffer any long-term problems, but half will develop a chronic disease that gradually destroys the liver. The virus also puts people at high risk for developing liver cancer.
"About 10 percent will die of associated complications," said Dr. Kelen.
Dr. Kelen said the study gives a glimpse of a serious health problem facing inner-city Baltimore, although the virus is surely less prevalent in the general population than it was among the emergency room patients. This is because people needing emergency attention are generally a sicker population.
The study also is a graphic reminder that health-care workers should observe the "universal precautions" against blood-borne infections, Dr. Kelen said.
These include the wearing of plastic face shields, surgical gloves and gowns to ward off transmission from open cuts and blood splashes.
The federal Centers for Disease Control estimate that 150,000 to 170,000 people across America are infected annually with hepatitis C. But Dr. Carmen Deseda, an epidemiologist with the agency's hepatitis branch, said it is unclear whether the disease is on the increase or decline because scientists lacked the ability to track it until two years ago.
Until the late 1980s, doctors did not know what caused the ailment. They simply observed patients who suffered from a mysterious liver disease that couldn't be traced to any known hepatitis strain.
The virus was discovered in 1989. A year later, blood banks started using a new screening test to eliminate blood from infected donors. Greater awareness of the virus prompted the Hopkins team to take a new look at its stored blood samples, which had already been tested for the virus that causes acquired immune deficiency syndrome.
In the study, physicians looked at blood samples taken from 2,523 emergency room patients over the age of 15 who needed to have blood drawn for other purposes related to their treatment.
One-quarter of the patients tested in the Hopkins study carried either of the two hepatitis strains or HIV. Considered separately, 5 percent carried hepatitis B, 6 percent carried HIV while 18 percent were infected with hepatitis C.
Doctors believe hepatitis C is transmitted by contaminated drug needles, unprotected sex and tainted blood products -- the same methods responsible for the spread of HIV and the hepatitis B virus.
In the study, about a third of the infections were traced to drug use, and another third to sexual practices and a combination of risk factors.
But the doctors could not find a risk factor for a third of the infections. Dr. Kelen said this is probably because of the difficulties physicians can have getting accurate information about a patient's drug and sexual histories -- particularly if their risk behaviors weren't recent.
A few of the infections were traced to transfusions, although the screening test should now greatly reduce the risk of tainted blood products.
The study, reported in yesterday's New England Journal of Medicine, found extraordinarily high rates of infection among intravenous drug users.
Eighty-three percent of the drug users carried the virus, along with 21 percent of transfusion recipients and 21 percent of homosexual men.
"Certainly, drug users are almost tapped out," Dr. Kelen said.
"Their rates are so high there aren't many more left who haven't gotten it. The group we feel might be particularly at risk are those who don't have any other risk than possible heterosexual relations with others who have it.
"If a heterosexual has sex with a drug user, the risk of acquiring it is probably very high."