Spring 1996 Volume 1, Number 1		Huge Oregon HAV outbreak waning (Portland) The largest outbreak of hepatitis A ever reported in Oregon is beginning to wane, says Katrina Hedberg, MD, MPH, Deputy State Epidemiologist for the Oregon Health Division. The outbreak began in late 1994, and climbed to 2,956 cases during 1995 (94 per 100,000). In 1995, the Oregon rate was over eight times higher than the U.S. rate of 11 per 100,000. Three Oregon counties, Linn, Douglas, and Lane, had rates of more than 200 per 100,000 in 1995. The highest rates in the outbreak have occurred in the 20-29 and 30-39 age groups. Illicit drugs play a major role As part of routine case investigations in Oregon, local health departments have sought information about illegal drug use. Illegal drug use is commonly associated with adult-based communitywide hepatitis A epidemics, especially the use of methamphetamine. According to Oregon's publication, CD Summary, in 1995 illegal drug use was admitted by 17% of Oregon cases overall, and by 24% of cases in the 20-39 age group. An even higher proportion of cases in the heavily affected counties admitted to drug use. The drug most commonly cited was marijuana, with methamphetamine a close second. The current outbreak is epidemiologically similar to the large 1989-91 outbreak in the Pacific Northwest, where illicit drug use played a major role. IInnovative study In November, the Oregon Health Division, in cooperation with local health departments in two counties, Douglas and Linn, began an experimental pilot project aimed at halting the epidemic. SmithKline Beecham contributed hepatitis A vaccine to the study. "We hope to establish whether this epidemic can be halted by providing immunizations to specific, selected populations," said Dr. Hedberg. The project targeted the extended social network of hepatitis A cases in the two counties, especially drug users. Persons in these social networks were offered free vaccine and were asked to complete a detailed questionnaire. Vaccine was also offered to various high-risk populations in the two counties, such as prison inmates and drug-rehabilitation clients. Blood samples for anti-HAV were drawn on all participants. The project will compare the pre- and post-intervention incidence rates of hepatitis A in the vaccinated counties to rates in unvaccinated counties. Questionnaire data will be used for a case-control study of risk factors for HAV infection. Data collection and vaccine administration for the study is mostly completed. Although rates have dropped in the two study counties, it is too early to say whether the decreases can be attributed to the intervention. Approximately 3,000-4,000 persons have received the first dose of vaccine. Preliminary results from the study are expected in several weeks.