The changing natural history of tuberculosis and HIV coinfection in an urban area of hyperendemicity.

Tuberculosis (TB) has proven to be difficult to control in regions with a high prevalence of human immunodeficiency virus (HIV) infection. We previously described high prevalence of HIV infection among adults (23%) and rapidly escalating TB notification rates in a peri-urban township, Site-M in Cape Town, South Africa. The combination of delineated boundaries, a well-characterized population, centralized TB record keeping, and high levels of HIV testing make this population uniquely suited for TB epidemiologic and transmission studies. The driver of the HIV and TB coepidemic appears to be a high annual risk of Mycobacterium tuberculosis infection in this community. A high annual risk of M. tuberculosis infection may be the result of unrecognized infections coupled with intense social interaction and crowding. New non-facility-based interventions will be required, with emphasis on community-based case finding and contact tracing to decrease the infective TB pool. There is a need for better understanding of the transmission dynamics of TB and the intensity of social interactions, which have exacerbated an HIV and TB epidemic in this community of hyperendemicity.