Introduction
Tuberculosis (TB) remains a major global health problem. Globally, the incidence and mortality of TB were 122 and 18 per 100 000 population in 2012, while TB notification and death rate were 67.9 and 2.8 per 100 000 population in Hong Kong. With improvement in diagnosis and case finding, the TB incidence, prevalence and mortality rate were descending. Also, TB treatment success and detection rates were increasing.
TB is still an infectious disease leading to considerable burden in Hong Kong. Many studies have found seasonal pattern of TB in other countries or cities. However, the reason of seasonality of tuberculosis is still remain unknown. This dissertation assessed yearly trends and seasonal variability of tuberculosis and the potential impact of meteorological variables on seasonality of TB in Hong Kong from 2001 to 2012. The finding could help us to better understand the pattern and the factors associated with seasonality of TB, and to inform future TB research and health policy strategies for TB control.
Method
Firstly, we did a literature review of seasonality of TB. Then we assessed the disease burden, trends and seasonality of TB. The data of TB age-specific and sex-specific notifications and notification rate, TB disease form-specific notifications and meteorological observations are mainly aggregated sources downloaded from public websites. Descriptive analysis methods were used to assess the characteristics of disease burden of TB and analytical analysis methods were used to assess the trends of TB age-specific, sex-specific notification rates and disease form-specific TB notifications in Hong Kong from 2001 to 2012. We assessed the seasonality of TB in Hong Kong from 2001 to 2012 with a Serfling model. Lastly, we used linear regression model to assess the potential impact of the meteorological predictors on the seasonality.
Results
The mean TB notification rate and death rate were 83.4 and 3.6 per 100, 000 population respectively in 2001 -2012. The overall trends of TB notification rate and death rate are descending in Hong Kong for the period. The disease burden of TB was much higher but decline faster for men than that for female. For age-specific descending trends of disease burden of TB, the trends were faster as the age groups getting older.
In most of the reviewed studies from 1971 to 2012,the peak of TB cases was mainly in spring and summer and trough in winter. The seasonal pattern of TB of some countries and cities had different characteristics stratified by factors such as gender, sex, latitude and disease form. Most of the studies suggested that vitamin D deficiency, indoor activities, meteorological observations and health care seeking behaviour are the main possible factors contributing to seasonality of TB.
TB notifications in Hong Kong exhibited a peak in summer and trough in winter. Except duration of sunshine, all meteorological variables including temperature, humidity, and solar radiation were significantly associated with monthly TB notification rate. The final predictive model included predictors such as time, temperature and solar radiation. 1 deg. C increase in monthly mean temperature was associated with 0.12(with 95% CI of (0.084, 0.16)) per 100, 000 population increasing of TB monthly notification rate, while 1 MJ/m2increase in monthly global solar radiation was associated with 0.064(with 95% CI of (0.005, 0.12)) per 100, 000 population decreasing of TB monthly notification rate. By comparing different models, temperature seemed to explain the observed seasonal pattern, while solar radiation had a more independent effect.
Conclusion
The study showed a higher TB disease burden in male which increases with age. The peak season of TB transmission should be in winter. We suggest more effective TB control strategies focusing on target groups including children, elders and relapse cases. As a general measure, we may encourage outdoor activities and more exposure to sunlight. We also suggest further studies to explore the relationship between humidity and vitamin D deficiency and seasonality of TB. / published_or_final_version / Public Health / Master / Master of Public Health
| Identifer | oai:union.ndltd.org:HKU/oai:hub.hku.hk:10722/206980 |
| Date | January 2014 |
| Creators | Xiao, Jingyi, 肖静怡 |
| Publisher | The University of Hong Kong (Pokfulam, Hong Kong) |
| Source Sets | Hong Kong University Theses |
| Language | English |
| Detected Language | English |
| Type | PG_Thesis |
| Rights | Creative Commons: Attribution 3.0 Hong Kong License, The author retains all proprietary rights, (such as patent rights) and the right to use in future works. |
| Relation | HKU Theses Online (HKUTO) |
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