Background: As the second largest burden country, China displays a high incidence of tuberculosis with frequent occurrence of outbreaks. Summarizing and analyzing the characteristics of tuberculosis outbreaks can help to quantify the transmissibility and to evaluate the effectiveness of intervention measures, providing thus technical support for prevention and control.
Methods: We collected data on 4 tuberculosis outbreaks in Changsha city, Hunan Province. Susceptible-Exposed-Infectious-Recovered (SEIR) model was used to fit collected data and calculate transmissibility. Susceptible-Exposed-Infectious-Quarantined-Recovered (SEIQR) model was used to evaluate the effect of isolation. Effective reproduction number and prevalence rate were used to quantify the transmissibility of tuberculosis.
Results: The number of male patients was higher than that of female patients in 4 outbreaks. Most student cases were distributed in high grades of high school and universities. The Reff of the 4 outbreaks were 15.22, 12.87, 13.47 and 2.70, respectively. Isolating 100% of the patients at first month could reduce the number of cases by 96.45%, 96.36%, 97.08% and 100.00%, respectively. The median Reff of 4 outbreaks in Changsha city was 13.17 (IQR 10.33-13.91).
Conclusions: Early detection and isolation of cases are effective methods of prevention of tuberculosis outbreaks.