Changes in prevalence and incidence of HIV-1, HIV-2 and dual infections in urban areas of Bissau, Guinea-Bissau: is HIV-2 disappearing?
OBJECTIVE
To assess the changes in HIV prevalence and incidence between 1996 and 2006 in urban areas of Bissau.


METHODS
A cross-sectional survey of 384 randomly selected houses within a community-based follow-up study of HIV-1 and HIV-2.


METHODS
A total of 3242 individuals aged at least 15 years were eligible for inclusion. Participants were interviewed about behavioral and socio-economic factors and had a blood sample drawn. A total of 2548 individuals were tested for antibodies to HIV-1 and HIV-2, of whom 649 had taken part in a similar survey in 1996.


RESULTS
With 0.5% HIV dual reactions included, the overall HIV-1 prevalence was 4.6% (118 out of 2548) and the HIV-2 prevalence was 4.4% (112 out of 2548). The prevalence of HIV-1 increased more for women than men especially in the 25-34-year age group. HIV-2 prevalence decreased below 45 years of age but not for individuals more than 45 years old. The incidence rate between 1996 and 2006 was 0.5 per 100 person-years for HIV-1 and 0.24 per 100 person-years for HIV-2. Compared with a previous period from 1987 to 1996, the incidence of HIV-2 is declining whereas no significant increase in the incidence of HIV-1 was observed.


CONCLUSIONS
The present study shows an increasing prevalence of HIV-1 and a decreasing prevalence of HIV-2 in Guinea-Bissau. HIV is generally a bigger problem for women. Despite the general decline in prevalence, HIV-2 may continue as an infection in older people, especially women.
da Silva
Zacarias J
ZJ
Bandim Health Project, Indepth Network, Bissau, Sweden. z.dasilva@bandim.org
Oliveira
Inês
I
Andersen
Andreas
A
Dias
Francisco
F
Rodrigues
Amabélia
A
Holmgren
Birgitta
B
Andersson
Sören
S
Aaby
Peter
P
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D005260:Female; D006169:Guinea-Bissau / Q000453:epidemiology; D015658:HIV Infections / Q000453:epidemiology*; D015497:HIV-1; D015498:HIV-2; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D014504:Urban Health