Background:  In August 2005, the World Health Organization (WHO) declared the African tuberculosis (TB) epidemic a regional emergency. Current TB control is failing as a result of the HIV epidemic. Additional control interventions require detailed understanding of the epidemiological relationship between these diseases at the community level.

Methods:  We examined age- and sex-specific trends in TB notifications and their association with HIV prevalence in a peri-urban community of 13,800 people in Cape Town between 1996 and 2004. A cross-sectional study to investigate TB and HIV prevalence in a representative sample of individuals over 15 years was performed in 2005. Cases already notified and receiving TB therapy were defined prevalent. Previously undiagnosed TB was defined as definitive if 2 positive smears/2 positive cultures/1 smear and 1 culture positive; or probable if 1 smear or culture positive with 2 TB symptoms.

Results:  TB notification rates increased 2.5-fold, reaching 1,468/100,000 in 2004 (p trend = 0.007). Affected most with TB notification rates were 20- to 39-year-olds, rising from 706/100,000 to 2600/100,000. In the cross-sectional study 1457 participants were selected, of which 959 individuals were able to be located, 197 declined to participate and 762 individuals (79%) constituted the study population; 174 (23%) were HIV infected, and 35 (4.6%) had TB; 11 (1.4%) were prevalent cases and of the previously undiagnosed, 9 (1.1 %) fulfilled the definitive and 16 (2.0%) the probable case definition. HIV prevalence of all those with TB was 45.7%, of those with prevalent TB, 70% and those with previously undiagnosed TB, 36%.

Conclusions:  This community has a very high prevalence of both TB and HIV and there are more individuals in the community with undiagnosed TB than individuals already on treatment. The majority of individuals with previously undiagnosed TB are HIV-uninfected, while the known cases are predominantly HIV-infected.