Effect of ventilation improvement during a tuberculosis outbreak in underventilated university buildings

Chun Ru Du, Shun Chih Wang, Ming Chih Yu, Ting Fang Chiu, Jann Yuan Wang, Pei Chun Chuang, Ruwen Jou, Pei Chun Chan, Chi Tai Fang

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

The role of ventilation in preventing tuberculosis (TB) transmission has been widely proposed in infection control guidance. However, conclusive evidence is lacking. Modeling suggested the threshold of ventilation rate to reduce effective reproductive ratio (ratio between new secondary infectious cases and source cases) of TB to below 1 is corresponding to a carbon dioxide (CO2) level of 1000 parts per million (ppm). Here, we measured the effect of improving ventilation rate on a TB outbreak involving 27 TB cases and 1665 contacts in underventilated university buildings. Ventilation engineering decreased the maximum CO2 levels from 3204 ± 50 ppm to 591-603 ppm. Thereafter, the secondary attack rate of new contacts in university dropped to zero (mean follow-up duration: 5.9 years). Exposure to source TB cases under CO2 >1000 ppm indoor environment was a significant risk factor for contacts to become new infectious TB cases (P <.001). After adjusting for effects of contact investigation and latent TB infection treatment, improving ventilation rate to levels with CO2 <1000 ppm was independently associated with a 97% decrease (95% CI: 50%-99.9%) in the incidence of TB among contacts. These results show that maintaining adequate indoor ventilation could be a highly effective strategy for controlling TB outbreaks.

Original languageEnglish
JournalIndoor Air
DOIs
Publication statusAccepted/In press - Jan 1 2019

Keywords

  • carbon dioxide
  • contact investigation
  • isoniazid preventive therapy
  • outbreak control
  • tuberculosis
  • ventilation

ASJC Scopus subject areas

  • Environmental Engineering
  • Building and Construction
  • Public Health, Environmental and Occupational Health

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