Mathematical modelling of tuberculosis transmission and impact of Isoniazid Preventive Therapy in Malaysia / Nurhuda Ismail
Tuberculosis remains one of the highest unresolved disease burden among re-emerging diseases in Malaysia for the last thirty years. The current treatment protocol guideline emphasizes treatment for only infectious tuberculosis patients. This study aimed to investigate tuberculosis transmission dy...
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| Format: | Thesis |
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2017
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| Online Access: | http://studentsrepo.um.edu.my/10364/ http://studentsrepo.um.edu.my/10364/4/nurhuda.pdf |
| Summary: | Tuberculosis remains one of the highest unresolved disease burden
among re-emerging diseases in Malaysia for the last thirty years. The current treatment
protocol guideline emphasizes treatment for only infectious tuberculosis patients. This
study aimed to investigate tuberculosis transmission dynamics exclusive to the
Malaysian environment and characteristics. This study applied the infectious disease
modelling techniques to study the progression of latent tuberculosis infection and assess
the likely impact of Isoniazid Preventive Therapy for latent tuberculosis high risk
subpopulations in reducing tuberculosis incidence in Malaysia. Methods: This study
explored the epidemiology of tuberculosis in Malaysia to develop a deterministic
compartmental age-structured tuberculosis model which incorporated treatment for
infectious as well as early preventive therapy for latent. The model assumed latently
infected individuals develop infectious state of tuberculosis as a result of primary
infection, endogenous reactivation and exogenous reinfection. This study assessed the
likely impact of interventions in Malaysia by formulating and analysing the model
under various scenarios. These included no intervention strategy then, extended to
incorporate the Isoniazid Preventive Therapy only, treatment of infectious tuberculosis
only and combination treatment of infectious tuberculosis and Isoniazid Preventive
Therapy. The equilibrium of the model was determined, and stabilities were analysed.
The model fitting and validation were performed. The national tuberculosis incidence
was estimated and projected from 1990 till 2050. The effective reproduction numbers
for the model were compared to assess the possible population benefits achieved by no
intervention, treatment of infectious tuberculosis only, Isoniazid Preventive Therapy
only and a combination treatment of infectious tuberculosis and Isoniazid Preventive
Therapy for the latents. The model further determined the effectiveness of Isoniazid
Preventive Therapy for early latent tuberculosis infection and quantified coverage of the
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strategy to eliminate tuberculosis, when used in conjunction with treatment of infectious
tuberculosis. The model then compared the selection of early latent tuberculosis
infection versus late latent tuberculosis infection to effectively reduce the incidence of
tuberculosis in Malaysia. Results: A transmission dynamic mathematical model of
tuberculosis exclusive to Malaysian environment and characteristics was developed.
The model projected a higher and increasing trend of national tuberculosis incidence till
year 2030 at annual increment rates from 1% to 5.5%. Application of this model
showed that combination treatment strategy of Isoniazid Preventive Therapy for early
high risk latent tuberculosis sub-populations with current treatment for infectious
tuberculosis is the most effective strategy for controlling tuberculosis epidemic in
Malaysia. However, a minimal ten percent coverage of Isoniazid Preventive Therapy in
population is required for effective reduction following eight to ten years of successful
implementation with expected cumulative incidence reduction of 27.21% by 2050.
Conclusion: Isoniazid Preventive Therapy may have substantial effect on controlling
tuberculosis epidemic in Malaysia when used in conjunction with current treatment
regime for infectious tuberculosis. However, a minimal ten percent coverage among the
early latent tuberculosis infection sub-populations must be ensured to achieve effective
reduction in incidence. This can be achieved by expansion of coverage to other high risk
latent tuberculosis sub-populations such as healthcare workers, close contacts and in
institutionalized settings, with comprehensive protocol and surveillance |
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