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CATIE News - British Columbia's success at reducing new HIV infections among injection drug users
2010 Sept 30 - Potent combination treatment for HIV (commonly called ART or HAART) has led to dramatic declines
in AIDS-related infections, particularly in high-income countries. Researchers increasingly expect HIV-positive people in these countries to have
near-normal life spans as a result of HAART. Anti-HIV therapy works by greatly suppressing production of HIV, which in turn allows the
immune system to partially repair itself. These repairs, although partial, are sufficient to keep AIDS-related infections at bay.
By decreasing the amount of HIV, HAART can probably reduce a person's infectiousness, at least some of the time. When these effects are assessed
on a grand scale-at the level of tens of thousands of people in a region-it is likely that a portion of HIV infections that might have otherwise occurred
are prevented. However, transmission at the level of the individual is still an issue.
Testing people for HIV infection and then providing care and treatment for the purposes of reducing transmission is a strategy
called "Test and Treat" or sometimes "Seek and Treat." This strategy has been proposed in the past several years but not formally
proven. Some researchers hope that Test and Treat strategies in regions or communities where rates of HIV infection are
high-such as in Southern Africa or in Vancouver's Downtown East Side, a largely low-income community where
injecting street drugs is relatively common-can help reduce new cases of HIV infection.
University of British Columbia professor Julio Montaner, MD, recent past president of the International AIDS Society and one of the world's
leading HIV researchers, has been a proponent of Seek and Treat, particularly as a way of reducing new HIV infections among injection drug users
(IDUs). One of Dr. Montaner's teams recently analysed data collected on the use of ART and trends in HIV infection in B.C. Their findings reveal
that at the level of an entire province, the increasing use of ART has significantly decreased rates of new HIV infections, especially among
IDUs. This is a major advance against the HIV epidemic. Hopefully Dr. Montaner's results can be reproduced in other regions around the world.
Study details
Researchers reviewed health-related information collected in two databases at the following Vancouver-based institutions:
- British Columbia Centre for Disease Control (BCCDC)
- British Columbia Centre for Excellence in HIV/AIDS
The review period was between 1996 and 2009.
Results
- In the study period, the number of people using HAART rose from 837 to 5,413-an increase of 547%. While this happened, new HIV diagnoses
generally declined.
- When researchers assessed data by focusing only on people who were IDUs, between 1999 and 2009 there was a 50% decrease in new HIV
diagnoses among IDUs. However, among people who were not IDUs the level of new cases of HIV infection remained stable.
- Over time the proportion of people using HAART who had a viral load less than 500 copies/ml rose from less than 10% in 1996 to more
than 50% in 2009.
- Researchers found a statistical link between the use of HAART and subsequent new diagnoses of HIV. Specifically, they found that for
every 100 people on HAART, one new HIV infection was prevented.
- According to the Vancouver team, this decrease in new infections was driven "to a large extent by the subset of individuals with
a documented history of injecting drug use, in whom new HIV diagnoses per year decreased by nearly 50% during the study."
- In contrast to their findings with IDUs, the Vancouver researchers found that "rates of new infections among men who have sex with
men increased after 2003 and then remained stable until 2008."
Good news
The Vancouver researchers generously acknowledge the limitations of their study design-an observational study. Such studies, no matter
how large, cannot prove a link between cause and effect. That is, observational studies cannot prove that the widespread availability of HAART
and the suppression of HIV viral load at the level of a large population of IDUs did indeed reduce the spread of HIV among this community.
However, there is a clear trend throughout the study of decreasing infections and intuitively their findings make sense.
The findings from the B.C. study suggest that expanding the number of eligible people who receive HAART in a community can help reduce
the rate of new infections among IDUs.
Another observational study, from Southern Africa, also suggests, at least in the short-term, that a reduced risk of HIV transmission
among heterosexual people occurs because of HAART.
Hopefully the results from B.C. can be extended to other regions and communities where HIV is relatively common. And more research is
needed to find ways of decreasing the spread of HIV among men who have sex with men.
For more information about treatment as prevention, see CATIE's Prevention in Focus at: http://www2.catie.ca/en/pif/winter-2010/treatment-prevention-we-ve-all-heard-about-it-what-does-it-really-mean
-Sean R. Hosein
REFERENCES:
- Montaner JS, Lima VD, Barrios R, et al. Association of highly active antiretroviral therapy coverage, population viral load, and yearly new HIV diagnoses in British Columbia, Canada: a population-based study. Lancet . 2010 Aug 14;376(9740):532-9.
- Le Vu S, Le Strat Y, Barin F, et al. Population-based HIV-1 incidence in France, 2003-08: a modelling analysis. Lancet Infectious Diseases . 2010; in press.
- Wilson DP, Jin F, Jansson J, et al. Infectiousness of HIV-infected men who have sex with men in the era of highly active antiretroviral therapy. AIDS . 2010 Sep 24;24(15):2420-1.
- El-Sadr WM, Mayer KH, Hodder SL. AIDS in America-forgotten but not gone. New England Journal of Medicine . 2010 Mar 18;362(11):967-70.
- Bezemer D, de Wolf F, Boerlijst MC, van Sighem A, et al. A resurgent HIV-1 epidemic among men who have sex with men in the era of potent antiretroviral therapy. AIDS . 2008 May 31;22(9):1071-7.
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CATIE-News is written by Sean Hosein, with the collaboration of other members of the Canadian AIDS Treatment Information Exchange, in Toronto.
From Canadian AIDS Treatment Information Exchange (CATIE). For more information visit CATIE's Information Network at http://www.catie.ca
Source: CATIE: CANADIAN AIDS TREATMENT INFORMATION EXCHANGE
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