Sentinel surveillance for HIV-1 infection: how representative are blood donors, outpatients with fever, anaemia, or sexually transmitted diseases, and antenatal clinic attenders in Mwanza Region, Tanzania?
OBJECTIVE
To assess the validity of extrapolation from sentinel data by comparing the HIV-1 prevalence of various sentinel groups with that of the general population in Mwanza Region, Tanzania.


METHODS
In a population survey, 4161 individuals were selected in a stratified random cluster sample. Sentinel groups (all in the age group 15-54 years) included blood donors (n = 1090); patients examined at district hospitals for the presence of malaria parasites (n = 1488), anaemia (n = 1339), or syphilis (n = 33); and antenatal clinic attenders (n = 1193). The HIV-1 serostatus of individuals selected from the population survey was tested using enzyme-linked immunosorbent assay (ELISA) and Western blot; 51% of the blood donors were tested using HIVCHEK, and all others using ELISA. HIV-1 prevalence was standardized for age, sex, and urban/non-urban location.


RESULTS
HIV-1 prevalence (standardized by age, sex, and residence) in Mwanza Region was 4.0% (3.0% in non-urban areas and 11.3% in town). The standardized HIV-1 prevalences in the sentinel groups were: blood donors, 4.5%; patients with fever, 11.6%; patients with anaemia, 8.9%; urban sexually transmitted disease patients, 27.1%; urban antenatal clinic attenders, 11.8%. The crude prevalence in blood donors was 6.0%.


CONCLUSIONS
Blood donors who are related to blood recipients appear to be a representative sentinel group in this region, provided that data are standardized for age, sex, and urban/non-urban location. Patients with fever and antenatal clinic attenders may reflect trends, but data from patients with fever markedly overestimate, and data from antenatal clinic attenders underestimate, population HIV-1 prevalence. Because self-selection of blood donors may become more pronounced, this comparison should be repeated later or elsewhere, should the opportunity arise.
National Institute for Medical Research, Mwanza, Tanzania.
M
M
Borgdorff
L
L
Barongo
E
E
van Jaarsveld
A
A
Klokke
K
K
Senkoro
J
J
Newell
A
A
Nicoll
F
F
Mosha
H
H
Grosskurth
R
R
Swai
D000293:Adolescent; D000328:Adult; D000554:Ambulatory Care Facilities; D000740:Anemia / Q000150:complications; D001782:Blood Donors; D004812:Epidemiologic Methods; D005260:Female; D005334:Fever / Q000150:complications; D015658:HIV Infections / Q000150:complications / Q000453:epidemiology; D015528:HIV Seroprevalence / Q000639:trends; D015497:HIV-1; D006801:Humans; D008297:Male; D008875:Middle Aged; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000453:epidemiology; D013636:Tanzania / Q000453:epidemiology