Using conventional and molecular epidemiological analyses to target tuberculosis control interventions in a low incidence area.

Abstract

To consolidate the gains made in controlling tuberculosis in industrialized countries in the past five years, we must analyse carefully the epidemiology of the disease and the effectiveness of various control interventions. In San Francisco we have performed conventional and molecular epidemiological analyses that have shown that there are in essence two parallel epidemiological patterns, one in the foreign-born population and the second among US-born persons, with little interaction between them. Most tuberculosis in the foreign-born population is a result of endogenous reactivation of latent infection, whereas recent infection with rapid progression to illness is a more frequent course in US-born cases. Among the US-born cases specific risk factors--homelessness, HIV infection, drug abuse--are highly prevalent. Although there has been a progressive reduction in the number of cases and in the proportion resulting from recent infection in San Francisco in the past five years, there continues to be a high proportion of cases that result from recent infection among US-born persons. These findings suggest that existing control interventions should be tailored to specific target groups and that new interventions are needed to provide for increased efficacy.