An explosive epidemic of DENV-3 in Cairns, Australia

Ritchie, Scott A., Pyke, Alyssa T., Hall-Mendelin, Sonja, Day, Andrew, Mores, Christopher N., Christofferson, Rebecca C., Gubler, Duane J., Bennett, Shannon N., and van den Hurk, Andrew F. (2013) An explosive epidemic of DENV-3 in Cairns, Australia. PLoS ONE, 8 (7). e68137. pp. 1-12.

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Abstract

From November 2008-May 2009 Cairns Queensland Australia was struck by an explosive epidemic of DENV-3 that exceeded the capacity of highly skilled dengue control team to control it. We describe the environmental, virological and entomological factors associated with this outbreak to better understand the circumstances leading to its occurrence. Patient interviews, serological results and viral sequencing strongly suggest that the imported index case was infected in Kalimantan, Indonesia. A delay in notification of 27 days from importation of the index case until Queensland Health was notified of dengue transmission allowed the virus to amplify and spread unchecked through November 2008. Unseasonably warm weather, with daily mean temperatures exceeding 30 °C, occurred in late November and would have shortened the extrinsic incubation period of the virus and enhanced transmission. Analysis of case movements early in the outbreak indicated that the total incubation period was as low as 9-11 days. This was supported by laboratory vector competence studies that found transmission by Aedes aegypti occurred within 5 days post exposure at 28 °C. Effective vector competence rates calculated from these transmission studies indicate that early transmission contributed to the explosive dengue transmission observed in this outbreak. Collections from BG sentinel traps and double sticky ovitraps showed that large populations of the vector Ae. aegypti occurred in the transmission areas from November - December 2008. Finally, the seasonal movement of people around the Christmas holiday season enhanced the spread of DENV-3. These results suggest that a strain of DENV-3 with an unusually rapid transmission cycle was able to outpace vector control efforts, especially those reliant upon delayed action control such as lethal ovitraps.

Item ID: 29451
Item Type: Article (Research - C1)
ISSN: 1932-6203
Additional Information:

© 2013 Ritchie et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Funders: Queensland Health
Date Deposited: 31 Oct 2013 01:03
FoR Codes: 11 MEDICAL AND HEALTH SCIENCES > 1108 Medical Microbiology > 110804 Medical Virology @ 100%
SEO Codes: 92 HEALTH > 9204 Public Health (excl. Specific Population Health) > 920404 Disease Distribution and Transmission (incl. Surveillance and Response) @ 100%
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