AIRBORNE INFECTION RESEARCH (AIR) FACILITY: TRANSMISSION DYNAMICS OF MULTIDRUG-RESISTANT TUBERCULOSIS AND EVIDENCE-BASED POLICIES FOR ENVIRONMENTAL CONTROL

Abstract

ISEE-429 Introduction: Tuberculosis (TB), still one of the world's greatest killers, is predominantly spread indoors by the airborne route. Despite effective drugs and disease control strategies, multidrug-resistant TB (MDR-TB) has emerged as a global public health threat. Little is, however, known about transmission of MDR-TB and the infection control measures necessary to prevent its spread in congregate settings, particularly where HIV/AIDS renders individuals exquisitely susceptible to infection. Methods: A unique, state-of-the-art Airborne Infection Research (AIR) Facility has recently been established in South Africa as a joint partnership between the MRC, CSIR, CDC and Harvard University. This facility is used to study transmission dynamics of MDR-TB within the context of HIV infection and to develop evidence-based infection control strategies relevant to high-burden TB and HIV settings. The AIR Facility involves extraction of infectious air from patient wards to exposure chambers housing guinea pigs, which serve as quantitative samplers of human-generated infectious aerosols, representing the only biological proxy of TB and MDR-TB transmission currently available. Results: Fundamental questions about the infectiousness of MDR-TB, the role of HIV and the effectiveness of environmental controls to curtail transmission are answered by measuring the number of guinea pigs infected over time, and linking guinea pig infections to individual patients by means of molecular techniques. State-of-the-art systems for ventilation, heating and cooling, and electronic monitoring further enable the study of MDR-TB transmission under different environmental conditions, enabling scientific blue-prints for design of safer health care facilities and development of improved building and construction standards. The impact of new therapeutic agents, development of novel mechanisms for air disinfection and environmental controls, and validation of innovative detection methods for diagnosis of MDR-TB are also envisaged. Conclusion: Aside from the unanswered questions around MDR-TB transmission and the effectiveness of infection control mechanisms being addressed in the AIR Facility, lessons learnt about the aerobiology of TB as a prototype airborne infectious agent will be applicable to other airborne agents of immediate global concern, notably influenza, SARS and smallpox.