Transmission of drug-susceptible and drug-resistant tuberculosis and the critical importance of airborne infection control in the era of HIV infection and highly active antiretroviral therapy rollouts

Abstract

Comprehensive and successful tuberculosis (TB) care and treatment must incorporate effective airborne infection-control strategies. This is particularly and critically important for health care workers and all persons with or at risk of human immunodeficiency virus (HIV) infection. Past and current outbreaks and epidemics of drug-susceptible, multidrug-resistant, and extensively drug-resistant TB have been fueled by HIV infection, with high rates of morbidity and mortality and linked to the absence or limited application of airborne infection-control strategies in both resource-rich and resource-limited settings. Airborne infection-control strategies are available--grouped into administrative, environmental, and personal protection categories--and have been shown to be associated with decreases in nosocomial transmission of TB; their efficacy has not been fully demonstrated, and their implementation is extremely limited, particularly in resource-limited settings. New research and resources are required to fully realize the potential benefits of infection control in the era of TB and HIV epidemics.

Figure 1

The effect of opening increasing numbers of windows and doors and of wind speed on rates of natural ventilation in health care facilities. Natural ventilation was measured in 368 experiments in 70 rooms in which patients with tuberculosis (TB) might be found in 8 hospitals in Lima, Peru. These included respiratory isolation rooms (n =13); wards for TB (n =13), respiratory (n =9), general medical (n =8), and HIV and infectious diseases (n =4) patients; emergency departments (n =8); outpatient consulting rooms (n =6); TB clinics (n =5); nebulizer rooms (n =2); an autopsy room; and a respiratory outpatient waiting room. Five hospitals were built before 1950, and 3 were constructed during 1970–1990. Wind speed was measured at the window; “n” refers to the number of experiments.

Figure 2

Extensively drug-resistant (XDR) tuberculosis (TB) cases averted during 2007–2012 in Tugela Ferry, South Africa, with use of combinations of available strategies [43]. Efficacy of rapidly available combinations of strategies to reduce nosocomial transmission of XDR-TB. 5 pt, isolation of patients in groups of 5 patients; LOS, reduction in mean duration of stay to 5 days; Mask, both staff N95 respirators and patient masks with adherence enforcement; MODS, microscopic observed drug-susceptibility assay; VCT, voluntary counseling and testing of admitted patients, with subsequent antiretroviral therapy to those who qualify; Vent, improvements in natural ventilation.