HIV prevalence and incidence in rural Tanzania: results from 10 years of follow-up in an open-cohort study.
BACKGROUND
Tanzanian antenatal clinic surveillance data suggest stabilizing HIV levels. Data from an open cohort in northern Tanzania provide robust estimates of prevalence and incidence.


METHODS
Between 1994 and 2004, 19 rounds of household-based demographic surveillance and 4 rounds of individually linked HIV serologic surveys were conducted. Longitudinal knowledge of individuals' testing histories is used to allow for effects of selective participation on prevalence estimates; multiple imputation procedures allow for interval censoring effects on incidence.


RESULTS
A total of 16,820 adults donated blood for HIV testing in at least 1 of 4 serologic surveys. HIV prevalence increased steadily from 6.0% in 1994/1995 to 8.3% in 2000/2001, leveling out thereafter. HIV incidence increased sharply from 0.8% in 1994 to 1997 to 1.2% per thousand in 1997 to 2000, remaining high (1.1%) in 2000 to 2003. In roadside areas, incidence fell in the last interval, especially among women, but in remote rural areas, incidence rose slightly.


CONCLUSIONS
HIV spread is continuing in rural areas, suggesting a need for more intensive HIV prevention efforts and antiretroviral interventions. The leveling off in prevalence is attributable to a combination of high mortality among HIV-infected persons and a slight decrease in incidence in roadside villages.
Wambura
Mwita
M
National Institute for Medical Research, Mwanza Branch, Mwanza, Tanzania. wmwita@yahoo.com
Urassa
Mark
M
Isingo
Raphael
R
Ndege
Milalu
M
Marston
Milly
M
Slaymaker
Emma
E
Mngara
Julius
J
Changalucha
John
J
Boerma
Ties J
TJ
Zaba
Basia
B
D000293:Adolescent; D000328:Adult; D005260:Female; D015658:HIV Infections / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D008297:Male; D015995:Prevalence; D012424:Rural Population; D016036:Seroepidemiologic Studies; D013636:Tanzania / Q000453:epidemiology