Sixteen years of HIV surveillance in a West African research clinic reveals divergent epidemic trends of HIV-1 and HIV-2

Maarten F Schim van der Loeff, Akum Aveika Awasana, Ramu Sarge-Njie, Marianne van der Sande, Assan Jaye, Saihou Sabally, Tumani Corrah, Samuel J McConkey, Hilton C Whittle

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BACKGROUND: The HIV-1 epidemic in West Africa is characterized by a slower rise than that in Eastern and Southern Africa. The HIV-2 epidemic in West Africa may be declining, but few long-term data exist.

METHODS: In a research clinic in The Gambia, HIV-1 and HIV-2 prevalence trends among all new patients being tested for HIV were examined over a 16 year period (1988 till 2003). In newly diagnosed patients a baseline CD4 count was done.

RESULTS: An HIV test was done in 23 363 patients aged 15 years or older. The prevalence of HIV-1 was 4.2% in 1988-91 and rose to 17.5% in 2001-03 (P < 0.0001, chi(2)-test for trend). The prevalence of HIV-2 was 7.0% in 1988-91 and declined to 4.0% in 2001-03 (P < 0.0001). HIV-1 prevalence increased and HIV-2 prevalence decreased with time in logistic regression models adjusting for age, sex, and indication for test (P < 0.0001). Baseline CD4 counts were available for 65% of patients. The median CD4 count was 215 cells/mm3 [interquartile range (IQR) 72-424] for HIV-1, and 274 (IQR 100-549) for HIV-2 infected patients. There was no marked trend of rise or decline in baseline CD4 count in either HIV-1 or HIV-2 infected patients over the study period. Forty-five per cent of newly diagnosed HIV patients had a CD4 count <200 cells/mm3.

CONCLUSIONS: These data suggest that HIV-1 prevalence is rising in The Gambia, and that HIV-2 is declining. HIV patients in The Gambia present late and almost half of patients would qualify for anti-retroviral treatment at their first visit.

Original languageEnglish
JournalInternational Journal of Epidemiology
Issue number5
Pages (from-to)1322-1328
Number of pages7
Publication statusPublished - 2006


  • Adolescent
  • Adult
  • CD4 Lymphocyte Count
  • Disease Outbreaks
  • Female
  • Gambia/epidemiology
  • HIV Infections/epidemiology
  • HIV-1
  • HIV-2
  • Humans
  • Male
  • Middle Aged
  • Population Surveillance
  • Prevalence
  • Sex Work


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