Secondary attack rate of tuberculosis in urban households in Kampala, Uganda

• Published in: PloS one 2011-02, Vol.6 (2), p.e16137-e16137
• Main Authors: Whalen, Christopher C, Zalwango, Sarah, Chiunda, Allan, Malone, LaShaunda, Eisenach, Kathleen, Joloba, Moses, Boom, W Henry, Mugerwa, Roy
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Age; Aged; Aged, 80 and over; Antitubercular agents; Bacillus Calmette-Guerin vaccine; BCG; Biology; Child; Child, Preschool; Confidence intervals; Consent; Deoxyribonucleic acid; Disease transmission; DNA; Epidemiology; Family Characteristics; Family medical history; Female; Glaucoma; Health aspects; Health risks; Health surveillance; HIV; Hospitals; Households; Humans; Incidence; Infections; Infectious diseases; Low income groups; Male; Medical diagnosis; Medical research; Medical treatment; Medicine; Microscopy; Middle Aged; Mycobacterium tuberculosis; Neighborhoods; Public health; Recurrence; Risk; Risk Factors; Surveillance equipment; Surveillance systems; Surveys; Tuberculosis; Tuberculosis - epidemiology; Tuberculosis - etiology; Uganda - epidemiology; Urban Population - statistics & numerical data; Vaccination; Young Adult
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0016137

Tuberculosis is an ancient disease that continues to threaten individual and public health today, especially in sub-Saharan Africa. Current surveillance systems describe general risk of tuberculosis in a population but do not characterize the risk to an individual following exposure to an infectious case. In a study of household contacts of infectious tuberculosis cases (n = 1918) and a community survey of tuberculosis infection (N = 1179) in Kampala, Uganda, we estimated the secondary attack rate for tuberculosis disease and tuberculosis infection. The ratio of these rates is the likelihood of progressive primary disease after recent household infection. The secondary attack rate for tuberculosis disease was 3.0% (95% confidence interval: 2.2, 3.8). The overall secondary attack rate for tuberculosis infection was 47.4 (95% confidence interval: 44.3, 50.6) and did not vary widely with age, HIV status or BCG vaccination. The risk for progressive primary disease was highest among the young or HIV infected and was reduced by BCG vaccination. Early case detection and treatment may limit household transmission of M. tuberculosis. Household members at high risk for disease should be protected through vaccination or treatment of latent tuberculosis infection.