The value of active follow up of a newly acquired hepatitis B infection - lessons for current approaches.

Abstract: The standard practice of blood borne virus (BBV) follow-up in New South Wales is a passive approach of general-practitioner-led testing. The value of this approach is unknown. We undertook an active contact tracing method with the aims of investigating a potential hepatitis B source, along with accurately measuring the participation rate, to consider the value of this and other follow-up methods for future BBV investigations. Investigation of a newly-acquired hepatitis B infection was undertaken at a dental practice identified as a possible exposure site. To screen for hepatitis B infection among potential source or co-exposed clients, we actively followed up with staff and clients of the practice to request they undertake hepatitis B serology. Eligible staff and clients received up to four phone calls and were provided with a pathology request form by the public health unit (PHU). Access to free serology was offered to people who did not have access to Medicare. Reminder calls were made if serology results were not received by the PHU. As the ordering doctor, the public health physician was responsible for providing results and referring for follow-up care. Of 160 clients, 63 (39%) undertook hepatitis B serology. Of these 63, none were found to have hepatitis B infection. It was estimated the active investigation involved an extra 430 hours of PHU staff time at a cost in Australian dollars of $30,000. Active follow-up allows an accurate participation rate to be documented. Despite intense active follow-up, only 39% of clients undertook testing, bringing into question the yield of the usual approach in which active follow-up of potential mass BBV exposures is not undertaken. While active follow-up is resource intensive, it should be considered where the risks and consequences from the BBV infection are high.

An epidemiological investigation into an outbreak of rash illness among methadone maintenance clients in Australia.

In late 2004, NSW Health received several reports of a serious desquamating rash among clients of the methadone program. We sought to identify the extent and likely cause of this outbreak. We initiated active surveillance for cases throughout Australia, a survey of dosing points in NSW, and a case control study of clients receiving methadone syrup (MS) at two clinics. Between October 2004 and March 2005, 388 cases were identified, largely in NSW. The dosing point survey found almost all cases were clients prescribed MS (attack rate 4.5%). In multivariate analysis of data from dosing points that dispensed MS, use of take away doses or location of the dosing point in greater western Sydney were associated with illness. In the case control study, MS injection, use of street MS, high doses of MS, frequent takeaway doses, or use of benzodiazepines were associated with illness. Testing found no abnormality in associated batches of MS. Batches of MS temporally associated with the outbreak were quarantined from use and the outbreak subsided. While a direct causal link could not be established, available evidence suggests that a contaminant may have caused the outbreak. Epidemiological analyses are important for assessing concerns about product safety following marketing approval.