The epidemiology of imported and locally-acquired dengue in Australia, 2012-2022.

BACKGROUND

Dengue is the most important arboviral disease globally, and poses ongoing challenges for control including in non-endemic countries with competent mosquito vectors at risk of local transmission through imported cases. We examined recent epidemiological trends in imported and locally-acquired dengue in Australia, where the Wolbachia mosquito population replacement method was implemented throughout dengue-prone areas of northern Queensland between 2011-2019.

METHODS

We analysed dengue cases reported to the Australian National Notifiable Disease Surveillance System (NNDSS) between January 2012 and December 2022, and Australian traveller movement data.

RESULTS

Between 2012 and 2022, 13 343 dengue cases were reported in Australia (median 1466 annual cases); 12 568 cases (94.2%) were imported, 584 (4.4%) were locally acquired and 191 (1.4%) had no origin recorded. Locally-acquired cases decreased from a peak in 2013 (n = 236) to zero in 2021-2022. Annual incidence of imported dengue ranged from 8·29/100000 (n = 917 cases) to 22·10/100000 (n = 2203) annual traveller movements between 2012 and 2019, decreased in 2020 (6·74/100000 traveller movements; n = 191) and 2021 (3·32/100000 traveller movements; n = 10) during COVID-19-related border closures, then rose to 34·79/100000 traveller movements (n = 504) in 2022. Imported cases were primarily acquired in Southeast Asia (n = 9323; 74%), Southern and Central Asia (n = 1555; 12%) and Oceania (n = 1341; 11%). Indonesia (n = 5778; 46%) and Thailand (n = 1483; 12%) were top acquisition countries. DENV-2 (n = 2147; 42%) and DENV-1 (n = 1526; 30%) were predominant serotypes.

CONCLUSION

Our analysis highlights Australia's successful control of locally-acquired dengue with Wolbachia. Imported dengue trends reflect both Australian travel destinations and patterns and local epidemiology in endemic countries.

FUNDING

AS is supported by a National Health and Medical Research (NHMRC) Postgraduate Scholarship (grant number 2002792), SLM by NHMRC Investigator Grants (grant number 2017229), KL by a NHMRC Senior Research Fellowship (grant number 1155005), and KLA by the Welcome Trust (grant number 224459/Z/21/Z).

Informations de copyright

© The Author(s) 2024. Published by Oxford University Press on behalf of International Society of Travel Medicine.