What's Driving the Decline in Tuberculosis in Arkansas? A Molecular Epidemiologic Analysis of Tuberculosis Trends in a Rural, Low-Incidence Population, 1997–2003

• Published in: American journal of epidemiology 2007-09, Vol.166 (6), p.662-671
• Main Authors: France, Anne Marie, Cave, M. Donald, Bates, Joseph H., Foxman, Betsy, Chu, Toby, Yang, Zhenhua
• Format: Article
• Language: English
• Subjects: Adult; Age Factors; Aged; Aged, 80 and over; Analysis. Health state; Arkansas; Arkansas - epidemiology; Bacterial diseases; Biological and medical sciences; Chi-Square Distribution; Cluster Analysis; cohort effect; Disease control; DNA Fingerprinting; DNA fingerprints; Epidemiology; Female; General aspects; Genotype; Human bacterial diseases; Humans; Incidence; infection control; Infectious diseases; Male; Medical sciences; Middle Aged; Miscellaneous; molecular; Molecular biology; Mycobacterium tuberculosis; Mycobacterium tuberculosis - genetics; Poisson Distribution; Polymorphism, Restriction Fragment Length; Population Surveillance; Public health. Hygiene; Public health. Hygiene-occupational medicine; Risk Factors; rural health; Rural health care; Rural Population; Tuberculosis; Tuberculosis - epidemiology; Tuberculosis - ethnology; Tuberculosis and atypical mycobacterial infections
• ISSN: 0002-9262; 1476-6256
• DOI: 10.1093/aje/kwm135

Incident cases of tuberculosis may result from a recently acquired Mycobacterium tuberculosis infection or from the reactivation of a latent infection acquired in the remote past. The authors used molecular fingerprinting data to estimate the relative contributions of recent and remotely acquired infection to the yearly incidence of tuberculosis in Arkansas, a state with a largely rural population where the incidence of tuberculosis declined from 7.9 cases per 100,000 population to 4.7 cases per 100,000 between 1997 and 2003. The authors used a time-restricted definition of clustering in addition to the standard definition in order to increase the specificity of the clustering measure for recent transmission. The greatest overall declines were seen in non-Hispanic Blacks (from 13.8 cases per 100,000 in 1997 to 6.5 cases per 100,000 in 2003) and persons aged 65 years or more (from 19.9 cases per 100,000 in 1997 to 8.5 cases per 100,000 in 2003). In both groups, the incidence of nonclustered cases declined more dramatically than the incidence of clustered cases. This suggests that the decline in rates resulted primarily from declining rates of disease due to reactivation of past infections. Declines in the overall incidence of tuberculosis in a population may not necessarily result from declines in active transmission.