Molecular epidemiology of a large outbreak of hepatitis B linked to autohaemotherapy

Background Unregulated skin-piercing procedures potentially facilitate the transmission of bloodborne pathogens. In February, 1998, a patient who had recently received autohaemotherapy at an alternative medicine clinic in the UK was diagnosed with acute hepatitis B. The autohaemotherapy procedure in volved the drawing of 1 mL of the patient's blood, mixing with saline, and reinjection of the autologous blood mixture. We investigated the extent of hepatitis B virus (HBV) infection in patients and staff of the clinic. Methods Patients who had attended the clinic between January, 1997, and Feb ruary, 1998, were tested for serological markers of HBV, and for HBV DNA by PCR. HBV DNA was sequenced to assess the relatedness of the virus identifi ed in the cases. We analysed the number and dates of visits with regard to HBV status. Findings Serum samples were received from 352 patients and four staff membe rs. Serological evidence of exposure to HBV was found in 57 (16%). Of the 3 3 patients and staff who were positive for hepatitis B surface antigen, 30 (91%) showed complete nucleotide identity in the DNA segments derived from the surface and core genes. Five patients with linked infection had markers of chronic hepatitis B, and one of these was regarded as the likely source of the outbreak. The attack rate was associated with the number of visits (p<0.0001) and the week of visit (p=0.011). Contaminated saline in a repeat edly used bottle was the probable vehicle of transmission. Interpretation We have described a large community-based outbreak of hepati tis B due to transmission by a single HBV variant. Our findings emphasise t he continuing risk of transmission of bloodborne viruses in all health-care settings where skin-piercing procedures are used.