Sixteen years of HIV surveillance in a West African research clinic reveals divergent epidemic trends of HIV-1 and HIV-2.
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.
MRC Laboratories, PO Box 273, Banjul, The Gambia. m.schim@iatec.com
Maarten F Schim
MF
van der Loeff
Akum Aveika
AA
Awasana
Ramu
R
Sarge-Njie
Marianne
M
van der Sande
Assan
A
Jaye
Saihou
S
Sabally
Tumani
T
Corrah
Samuel J
SJ
McConkey
Hilton C
HC
Whittle
D000293:Adolescent; D000328:Adult; D018791:CD4 Lymphocyte Count; D004196:Disease Outbreaks; D005260:Female; D005714:Gambia / Q000453:epidemiology; D015658:HIV Infections / Q000453:epidemiology* / Q000276:immunology / Q000635:transmission; D015497:HIV-1; D015498:HIV-2; D006801:Humans; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D015995:Prevalence; D011477:Sex Work