Delay effect and burden of weather-related tuberculosis cases in Rajshahi province, Bangladesh, 2007–2012

Abstract

Tuberculosis (TB) is a potentially fatal infectious disease that continues to be a public health problem in Bangladesh. Each year in Bangladesh an estimated 70,000 people die of TB and 300,000 new cases are projected. It is important to understand the association between TB incidence and weather factors in Bangladesh in order to develop proper intervention programs. In this study, we examine the delayed effect of weather variables on TB occurrence and estimate the burden of the disease that can be attributed to weather factors. We used generalized linear Poisson regression models to investigate the association between weather factors and TB cases reported to the Bangladesh National TB control program between 2007 and 2012 in three known endemic districts of North-East Bangladesh. The associated risk of TB in the three districts increases with prolonged exposure to temperature and rainfall, and persisted at lag periods beyond 6 quarters. The association between humidity and TB is strong and immediate at low humidity, but the risk decreases with increasing lag. Using the optimum weather values corresponding to the lowest risk of infection, the risk of TB is highest at low temperature, low humidity and low rainfall. Measures of the risk attributable to weather variables revealed that weather-TB cases attributed to humidity is higher than that of temperature and rainfall in each of the three districts. Our results highlight the high linearity of temporal lagged effects and magnitudes of the burden attributable to temperature, humidity, and rainfall on TB endemics. The results can hopefully advise the Bangladesh National TB control program and act as a practical reference for the early warning of TB cases.

Temperature and humidity associated with increases in tuberculosis notifications: a time-series study in Hong Kong

“…The association of lower average temperature with increased risks of TB cases was also shown in research in Brazil, Bangladesh, Vietnam and mainland China [4, 5, 7, 9, 27]. But to our knowledge, only three studies have considered lag effects of lower temperature on TB cases [7, 9, 27]. The effects of lower average temperature on TB cases occurred at lagged 2 months in Southwest China [7], at a lag of two quarters in Vietnam [27], and at lags of one–to–six quarters in Bangladesh [9].…”

“…Particularly, the risks became higher as it varied from 16.3 to 17.3 °C at lags of 13–15 months, and reached the greatest risk when it was 16.8 °C at lagged 14 months. The association of lower average temperature with increased risks of TB cases was also shown in research in Brazil, Bangladesh, Vietnam and mainland China [4, 5, 7, 9, 27]. But to our knowledge, only three studies have considered lag effects of lower temperature on TB cases [7, 9, 27].…”

Climate change and infectious diseases in Australia's Torres Strait Islands

“…Tuberculosis can increase occurrence through increases humidity, rainfall and temperature – factors that are exacerbated by climate change 39,63 . Although Australia has one of the lowest rates of tuberculosis incidence globally, 64 there is a discrepancy.…”

Tuberculosis case notifications in Malawi have strong seasonal and weather-related trends

“…Although some of our results are similar to what others have previously reported on the influence of seasonality and weather on TB notifications, some differences and limitations exist. For instance, in Bangladesh, TB incidence was significantly associated with both lower rainfall and temperature 36 . Given the differential effects of weather on TB CNRs by setting, future studies could collate all the estimates of the temporal effects of weather on TB CNRs globally using routine programmatic notification data to further understand relationship differences.…”