[Decreasing incidence of HIV infection in intravenous drug users in Aquitaine: 1985-1993].

OBJECTIVE

To describe trends in the incidence of HIV infection diagnosis since 1985 in different at-risk groups in Aquitaine, south-west France.

METHODS

We analyzed the data from two regional surveillance systems on HIV infection: the hospital-based system of the Groupe d'Epidémiologie Clinique du SIDA en Aquitaine (GECSA) and the laboratory-based system of the Observatoire Régional de la Santé d'Aquitaine (ORSA). The number of intravenous drug users (IVDUs) in Aquitaine was estimated from two sources: a study performed by the GECSA in IVDUs treatment centers (1990-1991 data) and the annual surveys undertaken by the Ministry of Health (SESI) in all the health facilities and social services of the region from 1988 to 1993.

RESULTS

As of December 31st, 1993, 3478 HIV-infected patients had been reported to the GECSA, including 3031 Aquitaine residents. Among those, 1096 were IVDUs without any other at-risk behavior (36.2%), the largest transmission category. The annual incidence of HIV diagnoses has steadily and considerably changed over time for IVDUs: 175 new cases diagnosed in 1985, 218 in 1987, then falling to 38 in 1993. During the same period, there was no marked decrease for homosexuals and the incidence of diagnoses of heterosexually-acquired HIV infections increased. Between 1989 and 1993, the number of HIV tests performed by the laboratories involved in the ORSA surveillance system increased steadily from 80,310 to 176,250 per year, when the number of first positive tests in Aquitaine residents decreased from 744 to 319 per year (-57%). This decrease was greater for IVDUs (-80%) than for the other groups. The survey performed by the GECSA estimated that 990 IVDUs were followed annually by treatment centres in Aquitaine in 1990-1991. This figure was stable and in agreement with the results of the SESI surveys performed throughout the period.

CONCLUSION

The incidence of new diagnoses of HIV infection has been decreasing in Aquitaine since 1988, particularly among IVDUs, suggesting that the epidemic is slowing down. It is essential to maintain these systems of epidemiological surveillance as a component of the HIV prevention program.