Modeling drug-resistant tuberculosis amplification rates and intervention strategies in Bangladesh.

Md Abdul Kuddus,Emma S Mcbryde,Michael T Meehan,Lisa J White,Adeshina I Adekunle,Hasnain Seyed Ehtesham

doi:10.1371/journal.pone.0236112

Abstract

Tuberculosis (TB) is the seventh leading cause of morbidity and mortality in Bangladesh. Although the National TB control program (NTP) of Bangladesh is implementing its nationwide TB control strategies, more specific and effective single or combination interventions are needed to control drug-susceptible (DS) and multi-drug resistant (MDR) TB. In this study, we developed a two strain TB mathematical model with amplification and fit it to the Bangladesh TB data to understand the transmission dynamics of DS and MDR TB. Sensitivity analysis was used to identify important parameters. We evaluated the cost-effectiveness of varying combinations of four basic control strategies including distancing, latent case finding, case holding and active case finding, all within the optimal control framework. From our fitting, the model with different transmission rates between DS and MDR TB best captured the Bangladesh TB reported case counts. The estimated basic reproduction number for DS TB was 1.14 and for MDR TB was 0.54, with an amplification rate of 0.011 per year. The sensitivity analysis also indicated that the transmission rates for both DS and MDR TB had the largest influence on prevalence. To reduce the burden of TB (both DS and MDR), our finding suggested that a quadruple control strategy that combines distancing control, latent case finding, case holding and active case finding is the most cost-effective. Alternative strategies can be adopted to curb TB depending on availability of resources and policy makers’ decisions.

Highlights

TB is an airborne bacterial infection that causes millions of deaths worldwide each year [1]
We developed a deterministic transmission dynamics mathematical model of DS and multi-drug resistant (MDR) TB strains between the following mutually exclusive compartments: susceptible individuals, S (t); those exposed to TB or latently infected, L(t), representing those that are infected and have not yet developed active TB; the infectious I(t), containing individuals with active TB that are infectious; the recovered R(t) who were previously infected and successfully recovered either naturally or through treatment
We presented a two strain TB compartmental model with amplification to understand the transmission dynamics of DS and MDR TB in Bangladesh

Summary

Introduction

TB is an airborne bacterial infection that causes millions of deaths worldwide each year [1]. Infectious person coughing, sneezing, speaking or singing thousands or tens of thousands of droplet nuclei are created [4]. These minute droplet nuclei can remain suspended in the air for several minutes to an hour, allowing spread to other persons through inhalation [4, 5]. The lifetime risk of progression to active TB for a person with LTBI is around 5–15%, depending on the age at infection For those who do progress from LTBI to active TB, the majority will do so within the first two years of initial infection [6]

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