Hepatitis A virus and injecting drug misuse in Aberdeen, Scotland: a case-control study.

To describe an epidemiological investigation of an outbreak of hepatitis A virus (HAV) infection among injecting drug users in Aberdeen, Scotland. A case-control study to determine whether transmission was facilitated by poor personal hygiene or through sharing injecting equipment. Cases were more likely to report not washing their hands after using the toilet [odds ratio (OR) = 12.9, 95% confidence interval (CI) = 1.58-105.89] or before preparing food (OR = 4.0, 95% CI = 1.01-15.8), and less likely to have washed their hands prior to preparing drugs (OR = 10.67, 95% CI = 2.14-53.07). Cases were also more likely to report recipient sharing of needles/syringes (OR = 8.27, 95% CI = 1.68-40.57), and to have had injecting contact with someone who was jaundiced (OR = 29.4, 95% CI = 3.18-271.44). The results indicate that the lack of hygiene within the context of individuals gathering to prepare and inject drugs provides ample opportunity for the transmission of HAV. Although the promotion of good hygiene and the avoidance of sharing injecting equipment are important measures in preventing HAV transmission, they are unlikely to effect major behavioural change. Such measures should, therefore, be reinforced by routinely offering HAV vaccine to injectors.