TB Infection Control
Prevention of nosocomial transmission of extensively drug-resistant tuberculosis in rural South African district hospitals: an epidemiological modelling study
In this study, Basu et al. modeled the plausible effect of rapidly available infection control strategies on the overall course of the XDR tuberculosis epidemic in the rural community of Tugela Ferry in South Africa.
Assessments were done with a mathematical model incorporating over 2 years of longitudinal inpatient and community-based data. The model simulated inpatient airborne tuberculosis transmission, community tuberculosis transmission, and the effect of HIV and antiretroviral therapy.
Here are some notes on the study’s findings that I included in “Overview of Airborne Infections and Control Strategies”, a presentation given in July 2008 to introduce the 2008 "Engineering Methods for the Control of Airborne Infections: An International Perspective" course that took place at the Center of Continuing Professional Education at Harvard School of Public Health.
We are finalizing the planning for the 2009 course. I will share information on this with the community soon.
Findings:
* Estimate that with no interventions, 1300 XDR cases in Tulega Ferry by the end of 2012.
– More than 50% nosocomially transmitted
– 72-96% among HIV infected persons.
* Situation in much of rural Sub-Saharan Africa:
– Crowded single room 30-40 patient wards
– 40% beds occupied by HIV-infected patients
– Restricted budgets for technological interventions
* Also modeled community transmission
* Intervention and Estimated % XDR averted:
Intervention: Community-based treatment and deferred hospitalization
Estimated % XDR averted: <10%
Intervention: Rapid drug susceptibility assays
Estimated % XDR averted: 2-4%
Intervention: Involuntary detention (without isolation rooms)
Estimated % XDR averted: 3%
Intervention: Improved natural ventilation, air filtration, UV air disinfection
Estimated % XDR averted: 33%
Intervention: Personal protective measures
Estimated % XDR averted: 2% total cases
Intervention: Respirators and masks - enforced
Estimated % XDR averted: 1/3 cases in staff
Intervention: Voluntary counseling and testing with ARV therapy
Estimated % XDR averted: 1% of admitted patients; 24% in the community
* Intervention combinations and estimated XDR % averted:
Intervention: Reducing length of stay + enforced use of respirators and masks
Estimated % XDR averted: 28% (21-33%)
Intervention: Add natural ventilation
Estimated % XDR averted: 37% (26-40%)
Intervention: Add drug susceptibility assay, hospital based VCT with ARV, and separation of patients in 5 bed units
Estimated % XDR averted: 48% (34-50%)
(Full text available to registered users - free to register)
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