Clustering, climate and dengue transmission

Abstract

Dengue is currently the most rapidly spreading vector-borne disease, with an increasing burden over recent decades. Currently, neither a licensed vaccine nor an effective anti-viral therapy is available, and treatment largely remains supportive. Current vector control strategies to prevent and reduce dengue transmission are neither efficient nor sustainable as long-term interventions. Increased globalization and climate change have been reported to influence dengue transmission. In this article, we reviewed the non-climatic and climatic risk factors which facilitate dengue transmission. Sustainable and effective interventions to reduce the increasing threat from dengue would require the integration of these risk factors into current and future prevention strategies, including dengue vaccination, as well as the continuous support and commitment from the political and environmental stakeholders.

Keywords:

• climate
• clustering
• contacts
• dengue
• global warming
• globalization
• herd immunity
• rainfall
• risk factors
• temperature

Acknowledgements

We would like to thank L Lee for the kind assistance in editing of the manuscript.

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending or royalties.

Key issues

• Dengue virus (DENV) infection has resulted in increasing public health burden over the past decades in tropical and sub-tropical regions.

• Current strategies to prevent and reduce dengue transmission are neither efficient nor sustainable as long-term interventions.

• Clustering of population and climate change are parts of the main drivers for dengue transmission.

• Dengue clusters are generally focal in nature and are influenced by the changing anti-DENV immune profile, mobility of the population within a community and the limited flight and feeding behaviors of A. aegypti.

• The dengue infection rate within a cluster decreases as the distance between the residences of secondary cases and the index case increases. In rural area, dengue clusters occurs over a significantly shorter distance and period of time compared with dengue clusters in urban area, in general.

• Clustering of a particular serotype dengue infections results in a reduction in future homotypic infections for a significantly longer period of time than heterotypic cases in that vicinity.

• Human behavior is one of the main drivers for the introduction of dengue clusters into a new susceptible population. This is often facilitated by globalization, increased air travel and well-connected highways.

• Individuals living in areas where vector abundance is high may not necessarily have a greater risk of dengue infection compared with individuals who travels more frequently within dengue-endemic regions.

• El Niño Southern Oscillation, temperature, rainfall and humidity affects vector growth and dynamics, and are risk factors for dengue transmission. However, the direct relevance of each of these risk factors differs over different spatial and temporal dimensions.

• Global warming is likely to facilitate dengue transmission into new geographical areas in the next 5 years.

• Clustering and climatic risk factors should be taken into consideration to develop a more sustainable and efficient dengue prevention strategies.