Limiting the spread of tuberculosis by changing the way hospital wards are designed

Tuberculosis (TB) is a major health problem in South Africa. The CSIR, by re-designing the layout of hospitals and their ventilation systems, is helping to reduce the transmission of TB in hospitals. These innovative and effective solutions are now part of the standard guidelines for health care infrastructure in South Africa.

Tuberculosis (TB) is one of the leading causes of mortality in South Africa and the emergence of extremely drug-resistant strains is a risk to both patients and staff in public health care facilities. CSIR experts have formulated recommendations to the national Department of Health for the design of health care facilities, such as clinics and hospitals where TB patients, some of whom may be infectious, initially seek healthcare. They also provided technical advice on the construction of long-term accommodation, which are needed to admit drug-resistant TB patients, sometimes for months at a time.

South Africa, according to the World Health Organization, has one of the highest TB burdens in the world. TB is the most common opportunistic infection for HIV-positive patients, making active treatment and the prevention of cross-infection high priorities, especially since the emergence of extremely drug-resistant TB strains.

The decentralisation policy of TB treatment away from institutionalised care to a community-based system will result in TB patients visiting state clinics and hospitals, raising the need for effective infection control practices. Some patients, who are acutely ill with multidrug-resistant TB and or extremely drug-resistant TB, might also need long-term accommodation in TB facilities where staff and other patients need to be protected from cross-infection.

The CSIR is home to specialists in the field of building design, engineering and best practice for TB infection control. They are currently assessing health care facilities across South Africa with a focus on airborne infection control, and are also training architects, engineers and clinical professionals with the support of the United State Centers of Disease Control and Prevention and the University of Pretoria.

The spread of TB

TB is spread from person to person through the air by droplet nuclei (very small droplets 15 to 30 times smaller than a grain of sand). These are produced when a person who has an active TB infection, coughs, sneezes or has to produce sputum samples for TB tests. The droplet nuclei potentially contain highly infectious particles, which are so small that indoor air currents can keep them airborne for up to four hours, depending on the ventilation conditions. The particles can then be inhaled to replicate in the lungs.

Once infected, those with compromised immune systems are more susceptible to the disease. TB treatment normally requires taking medicine for six months and for those with resistant TB strains, between nine months and two years.

Assessing facilities

It is crucial that infectious TB patients in public health clinics are managed in a dignified and confidential manner while reducing the risk to others.

“A typical clinic assessment of a facility would include an evaluation of the ventilation conditions of the waiting areas, the fast-track capacity to quickly identify and refer an infectious TB patient, as well as evaluating the hospital programme to prioritise and reduce unnecessary travel through a facility,” says Jako Nice, a CSIR research architect.

Long-term accommodation

In an earlier project funded by The Global Fund, the national Department of Health approached the CSIR to research and facilitate the design of new long-term accommodation units for more than 400 TB patients at nine centres across the country. The project included the upgrading of existing buildings, where solutions were constrained by the existing structures, as well as the construction of new units where the experts had the freedom to introduce new infection control solutions in their designs.

The team of architects, engineers and health planners proposed various solutions. Where appropriate, they recommended the use of natural ventilation and environmentally sustainable design solutions. These designs were tested at the CSIR’s building performance laboratory, primarily through the use of computational fluid dynamics (CFD) modelling.

Using CFD software, researchers built a virtual model of facilities to simulate, visualise and analyse the ventilation performance of the design proposals. The key findings were that the ventilation efficiency depends on a building’s geometric design, the climate of the region, indoor temperature, the type of windows, indoor airflow, as well as occupancy of the space.

The aim was to ensure that there is sufficient movement of air through the buildings to effectively mix the air to reduce the concentration of the infectious droplet nuclei while providing sufficient thermal comfort levels for patients.

This work by the CSIR contributed to the development of health care infrastructure norms and standard guidelines, which were published in the Government Gazette in 2014 and will support future health care capital works projects.



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