HIV-1 Strain and Primary Drug Resistance in Canada
Surveillance Report to June 30, 2002

[Previous] [Table of Contents] [Next]

National HIV Reference Services

Background

The provincial public health laboratories, the Canadian Blood Services, and HÉMA-QUÉBEC test thousands of samples each year and thus serve as crucial partners in the CHSDRSP. A number of factors can cause serologic tests to yield fallible results: samples originating from seroconverters; samples that are cross-reactive, for example to HIV-2; and, as seen in 1993 with the failure of some diagnostic kits in France to detect HIV-1 subtype O, the appearance of divergent strains of HIV-1. Furthermore, genetic variants of HIV can be problematic for HIV PCR and viral load tests, often leading to discordant findings with serologic testing.

As a part of their reference services, the national HIV laboratories test samples showing unusual serologic, PCR or other virologic test results. This function of the national HIV laboratories is crucial in addressing one of the goals of the CHSDRSP - protection of the blood supply - since screening tests should be able to detect all circulating strains of HIV in Canada. This relationship between the provincial  and national laboratories may also serve other programs of the national HIV laboratories, including quality assurance and diagnostic kit monitoring.

As of June 30, 2002, 38 diagnostic samples from untreated individuals from five provinces have been submitted for subtype analysis through the sentinel arm of the CHSDRSP. Results from 25 samples that were successfully amplified and subtyped are shown in Table 23. It is of note that mutation L90M associated with resistance to the protease inhibitors nelfinavir and saquinavir was identified in one sample from Ontario taken from an individual infected with HIV-1 subtype C.

HIV - 2 infections

There is currently no active surveillance for HIV-2 in Canada. An informal survey of provincial public health laboratories indicated that between 1988 and November 2002, 56 new cases of HIV-2 infection had been identified in Canada. The majority of these cases were identified in Ontario and Quebec. This number is likely to be an underestimate, since it is very possible that, because the only approved HIV western blot kit is HIV-1 specific, HIV-2 cases have been reported as HIV-1. Discussions are currently under way to explore the need (if any) to enhance surveillance for HIV-2.

[Previous] [Table of Contents] [Next]