Objective: To determine the absolute and proportional prevalence of du
al seroreactivity to HIV-1 and HIV-2 in female sex workers in Abidjan,
to determine risk determinants for this serologic profile, and to des
cribe the associated clinical and immunological characteristics. Desig
n: Cross-sectional study. Setting: Confidential clinic for female sex
workers in Abidjan. Participants: Female sex workers. Main outcome mea
sures: HIV serostatus, CD4+ counts, women with AIDS, behavioural and s
ociodemographic characteristics. Results: Among 1209 women tested, the
overall HIV seroprevalence was 80%, while the prevalence of dual sero
reactivity was 30%. Dual seroreactivity accounted for 38% of all HIV i
nfections. Compared with women reacting to HIV-1 only, dually seroreac
tive women were significantly more likely to have been in sex work for
a longer period, to be aged greater than or equal to 20 years, and to
charge less money for intercourse. No difference in mean CD4+ count w
as noted between women with dual seroreactivity (561 x 10(6)/l) and HI
V-1-seropositive women (588 x 10(6)/l). Conclusions: Female sex worker
s in Abidjan had the highest absolute (30%) and proportional rate (38%
) of dual seroreactivity yet described in any population. Increased se
xual exposure is associated with an increased risk of dual Seroreactiv
ity. Although better molecular diagnostic techniques are required, a s
ubstantial proportion of female sex workers in Abidjan is likely to be
infected with both HIV-1 and HIV-2.