Objective: To investigate the clinical and immunologic effects, and pa
ttern of mortality associated with HIV-2 infection. Setting: A rural c
ommunity in Guinea-Bissau. Methods: Serologic screening of 2774 subjec
ts aged > 14 years followed by studies of the prevalence of clinical a
nd immunologic abnormalities among 133 subjects with HIV-2 infection a
nd 160 seronegative controls, and surveillance of mortality among all
subjects who were screened during a mean of 2 years of follow-up. Resu
lts: Generalized lymphadenopathy was the only clinical abnormality sig
nificantly associated with HIV-2 infection. Infection was associated w
ith lower CD4 counts and higher beta(2)-microglobulin and neopterin le
vels. During follow-up, 5.5% of infected subjects died compared with 1
.8% of the seronegatives (rate ratio adjusted for age and sex, 3.5; 95
% confidence interval ((CI), 1.8-6.7). Proportional hazard regression
analysis showed that the rate ratio varied with age (P=0.003) and ther
e was some evidence that the excess of mortality in infected subjects
was, in absolute terms, least in the oldest subjects (trend test; P=0.
08). Conclusions: The findings support previous suggestions that HIV-2
is less pathogenic than HIV-1; the data also suggest that mortality a
ssociated with infection may be lower in older subjects.