Hygiene Is Most Potent Force In Tackling Deadly Diseases

Using a mathematical model of severe acute respiratory syndrome (SARS), the scientists examined how untreatable infectious diseases that spread rapidly in a hospital environment could best be dealt with. They found that inexpensive and easily implemented hospital-wide contact precautions are the most potent of all disease control measures, and can even substitute for alternative approached such as expensive isolation facilities, quarantine, and sequestration of healthcare workers. Their findings have significant implications for all countries and particularly those with limited resources.

"New, untreatable infectious diseases pose a growing risk as globalisation leads to unprecedented human mobility, and they will continue to challenge public health systems worldwide. Our study examined priorities and trade-offs – how one measure can compensate for another which isn't available in a given setting – between alternative strategies of disease control," says scientist James Lloyd-Smith.

Healthcare workers comprised an alarmingly high proportion of SARS cases – 61 per cent in Hanoi and around 50 per cent in Toronto – so the study focuses on hospitals and their surrounding communities. The model shows that hospital-wide infection controls are more important than, for example, precautions specific to known SARS patients, since hospital-wide precautions block transmission in unidentified cases as well. In every scenario examined, a breakdown in general infection control was more damaging to disease containment efforts than a breakdown in any other transmission-reducing measure. The scientists' findings will help health authorities make decisions about how to allocate limited resources in the future.

Following global alerts and media attention about SARS, health authorities worldwide imposed strict control policies and largely prevented new outbreaks. The two notable exceptions, in Taiwan and Toronto, were both linked to lapses in hospital infection control procedures, even though these were quickly rectified and brought under control. While the scientists say that the combination of hospital-wide contact precautions with respiratory isolation of known SARS patients is always preferable, for developing countries that cannot afford the latter, stringent contact precautions alone can be an effective substitute.

"It was fortunate for Britain that SARS did not arrive until after the alarm was sounded so there was time to prepare and avoid a local outbreak. We can't assume it, or other countries, will be so lucky in the future. Our research demonstrates that rapid response and effective, well-disciplined infection control are the key factors that will enable countries to tackle these outbreaks successfully," concludes Lloyd-Smith.

'Curtailing transmission of severe, acute respiratory syndrome within a community and its hospital', by James Lloyd-Smith; Alison Galvani and Wayne Getz, University of California, Berkeley, USA.