Continuing outbreak of hepatitis A linked with intravenous drug abuse in Multnomah County.

A communitywide outbreak of hepatitis A occurred in Portland, OR, from 1983 through 1986. At the peak of the outbreak, the age- and sex-specific annual incidence rate approached 400 cases per 100,000 population among men ages 25 to 34, the highest risk group. The community incidence rate was nearly 10 times the relevant national incidence rate. A review of the records concerning cases of hepatitis A reported in the last 6 months of 1985 revealed that about half the number of young adults whose cases were investigated during that time reported a history of intravenous (IV) drug use--a proportion about 50 times greater than expected among persons in that age range. A simultaneous epidemic of overdose deaths from heroin and a concomitant increase in hepatitis B incidence rates led to the suspicion that this was a drug-abuse-associated epidemic of hepatitis among new IV drug users. Control of this outbreak was difficult because the population most at risk was distrustful of public health officials. Increased surveillance in food service establishments and schools might have prevented outbreaks from a common source in the general population; however, an increase of sporadic cases in the nondrug-using population clearly occurred.