A report just released by the BC Centre for Disease Control (BC CDC) identifies a decrease in new positive HIV tests in people who use injection drugs in BC. The figures, from 2008, evaluate 350 new cases of HIV, focussing on the 325 for which the transmission route was known.
They found that the number of new positive HIV tests among people who use injection drugs (IDU) decreased from 117 cases in 2007 to 56 cases in 2008. At the same time, the numbers of cases for heterosexual adults and homosexual men was stable. Moreover, this trend was seen in most Health Authorities though the largest being Vancouver Coastal, Vancouver Island and Fraser Health.
The growth of HIV/AIDS in Vancouver is the subject of a study by Colin W. McInnes et al from the British Columbia Centre for Excellence in HIV/AIDS. Published in early 2009, the work describes the growth of HIV/AIDS in Vancouver (particularly) as an epidemic. The authors did not focus on one method of transmission.
The study describes the history of HIV in Vancouver as showing two distinct periods of rapid increase. The first, in the 1980s, was due to the high incidence among men who have sex with men (MSM). The second occurred in the next decade due to a high incidence among injection drug users.
Coming right at the end of the McInnes study period, the BC CDC report highlights what could be positive news: that transmission among injection drug users is decreasing. There are various reasons this may be happening.
Under-reporting new positive HIV results is one possibility, but it is easy to discount as a reason for reduced numbers because of how tests are taken and handled at all stages.
Changing patterns of drug use offer a potential explanation. There is a trend to increased smoking of crack cocaine, seen both in B.C. and other jurisdictions in Canada. This would mean less injecting overall and reduced opportunities for transmitting HIV among IDU.
A third reason, harm reduction and other HIV prevention programs for injection drug users have demonstrated effectiveness and have likely contributed to the decline in new positive HIV tests among this population.
There may be multiple reasons for the decline in new HIV cases among injection drug users, but without more data and on behaviours and trends among IDU, finding the reasons is not simple. It is, however, critically important. If something is working, we should make sure to encourage and continue it.
The McInnes findings, though focussed on Vancouver exclusively, offer cautions for the whole region. They conclude that "evidence-based prevention and harm reduction strategies, particularly those targeted at high-risk population subgroups, should continue to be expanded and evaluated."
Dr. Paul Martiquet is the Medical Health Officer for the Sea to Sky.
