Using dengue epidemics and local weather in Bali, Indonesia to predict imported dengue in Australia

Abstract

Background: Although the association between dengue in Bali, Indonesia, and imported dengue in Australia has been widely asserted, no study has quantified this association so far. Methods: Monthly data on dengue and climatic factors over the past decade for Bali and Jakarta as well as monthly data on imported dengue in Australia underwent a three-stage analysis. Stage I: a quasi-Poisson regression with distributed lag non-linear model was used to assess the associations of climatic factors with dengue in Bali. Stage II: a generalized additive model was used to quantify the association of dengue in Bali with imported dengue in Australia with and without including the number of travelers in log scale as an offset. Stage III: the associations of mean temperature and rainfall (two climatic factors identified in stage I) in Bali with imported dengue in Australia were examined using stage I approach. Results: The number of dengue cases in Bali increased with increasing mean temperature, and, up to a certain level, it also increased with increasing rainfall but dropped off for high levels of rainfall. Above a monthly incidence of 1.05 cases per 100,000, dengue in Bali was almost linearly associated with imported dengue in Australia at a lag of one month. Mean temperature (relative risk (RR) per 0.5 °C increase: 2.95, 95% confidence interval (CI): 1.87, 4.66) and rainfall (RR per 7.5 mm increase: 3.42, 95% CI: 1.07, 10.92) in Bali were significantly associated with imported dengue in Australia at a lag of four months. Conclusions: This study suggests that climatic factors (i.e., mean temperature and rainfall) known to be conducive of dengue transmission in Bali can provide an early warning with 4month lead time for Australia in order to mitigate future outbreaks of local dengue in Australia. 4 This study also provides a template and framework for future surveillance of travel-related infectious diseases globally.

Effects of El Niño Southern Oscillation and Dipole Mode Index on Chikungunya Infection in Indonesia

“…In Taiwan, temperature and precipitation influenced dengue incidence rates with a lag of 10–20 weeks [ 26 ]. In the context of dengue infection in Indonesia, studies have shown that dengue incidence is associated with temperature, rainfall, and humidity [ 45 , 46 , 47 ]. In this present study, those local climate variables (temperature, rainfall, and humidity), which might have had a stronger impact on chikungunya incidence, were not included.…”

Projecting the future of dengue under climate change scenarios: Progress, uncertainties and research needs

“…A salient example is the relationship between travel and the transmission of dengue [32][33][34]. In 2016, there were more than 1.2 billion international tourists and this number is still growing [35], raising concerns about the appreciable role that travel (particularly international travel [36]) may play in the future transmission of dengue. Second, increasing temperature has been widely used as the indicator of climate change in the prior studies projecting the future of dengue, with rainfall and humidity being under-researched.…”

Impact of recent climate extremes on mosquito-borne disease transmission in Kenya

“…This ultimately contributed to an increased risk of chikungunya transmission in France in 2014 [17]. Such a relationship held true for dengue as well, as researchers in Jakarta and Bali observed the number of dengue cases to increase with higher monthly mean rainfall up to 16.2 mm over the past decade [18]. As such, the relationship between rainfall and dengue transmission is not clearly delineated.…”

“…However, much remains unknown about whether such laboratory-measured temperature thresholds lead to defined thresholds in reality. A study examining the effect of climatic factors on dengue transmission between Bali and Australia observed the number of dengue cases in Bali to increase with increasing mean temperature [18]. Heat waves have also been associated with increased dengue transmission; between December 2010-February 2011, seasonal land surface temperatures were 5-20˚C above normal, and these above-normal temperatures were associated with the first known large-scale outbreak of dengue fever in East Africa [24].…”