Two distinct epidemics: the rise of HIV-1 and decline of HIV-2 infection between 1990 and 2007 in rural Guinea-Bissau.
OBJECTIVE
To assess changes in HIV incidence and prevalence in Caió, a rural area of Guinea-Bissau, between 1990 and 2007.


METHODS
Three cross-sectional community surveys.


METHODS
In 1990, 1997, and 2007, surveys were conducted among adults. The prevalence of HIV-1 and of HIV-2 was estimated for each survey, and incidence rates were calculated for the first (1990-1997) and second period (1997-2007).


RESULTS
The HIV-1 incidence was approximately 4.5/1000 person-years in the two periods, whereas the HIV-2 incidence decreased from 4.7 (95% confidence interval 3.6-6.2) in the first to 2.0 (95% confidence interval 1.4-3.0) per 1000 person-years in the second period (P < 0.001). HIV-1 prevalence rose from 0.5% in 1990 to 3.6% in 2007, and HIV-2 prevalence decreased from 8.3% in 1990 to 4.7% in 2007. HIV-1 prevalence was less than 2% in 15 to 24 year olds in all surveys and was highest (7.2%) in 2007 among 45 to 54 year olds. The HIV-2 prevalence was fivefold higher in older subjects (> or =45 yr) compared with those less than 45 years in both sexes in 2007.


CONCLUSIONS
HIV-1 incidence is stable, and its prevalence is increasing, whereas HIV-2 incidence and prevalence are both declining. In contrast with what has been observed in other sub-Saharan countries, HIV-1 prevalence is lower in younger age groups than older age groups.
Medical Research Council Laboratories, Fajara, The Gambia. cvantienen@mrc.gm
Carla van
Cv
Tienen
Maarten Schim
MS
van der Loeff
Syed M A
SM
Zaman
Tim
T
Vincent
Ramu
R
Sarge-Njie
Ingrid
I
Peterson
Aleksandra
A
Leligdowicz
Assan
A
Jaye
Sarah
S
Rowland-Jones
Peter
P
Aaby
Hilton
H
Whittle
D000293:Adolescent; D000328:Adult; D000914:Antibodies, Viral / Q000097:blood; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004279:DNA, Viral / Q000737:chemistry / Q000235:genetics; D004196:Disease Outbreaks; D005260:Female; D006169:Guinea-Bissau / Q000453:epidemiology; D015658:HIV Infections / Q000453:epidemiology* / Q000821:virology*; D015497:HIV-1 / Q000235:genetics / Q000254:growth & development*; D015498:HIV-2 / Q000235:genetics / Q000254:growth & development*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D015995:Prevalence; D012044:Regression Analysis; D012424:Rural Population; D055815:Young Adult
D000914:Antibodies, Viral; D004279:DNA, Viral