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acquisition was South-East Asia , with 41 % of cases from this region originating from Indonesia .
Not surprisingly , there was a major drop in imported cases in 2020 and 2021 , but numbers picked up again in 2022 as Australians resumed international travel ,
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replace wild populations , which is another important key to the effectiveness of the program .
Since the program commenced , there has been a dramatic decrease in dengue cases in North Queensland . Following the proof-of-concept studies in
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However , further analysis of the trial data found that the subset of participants who had not been exposed to dengue virus infection prior to vaccination had a higher risk of severe dengue and hospitalisations , compared to unvaccinated participants , regardless of age . As a result , the WHO has |
to be warned that measures to protect against mosquito bites are important to minimise the risk of these infections . Prevention methods include appropriate clothing ( to cover exposed skin ) and use of personal insect repellent ( usually containing DEET or picaridin ). If travellers are |
Dengue virus cells : it is estimated 390 million infections occur annually worldwide . |
including to Bali . |
Australia , there have been field releases |
recommended pre-vaccination screening |
using both sunscreen and insect repellent , |
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The importance of Bali as a source of imported dengue is demonstrated by surveillance in Western Australia . Of all cases |
of wMel-infected Aedes aegypti in 12 countries , with 10.9 million people reached by December 2022 . 9 |
so that only people with evidence of past dengue infection are vaccinated . 11 This screening could be based either on an anti- |
it is more effective to apply the sunscreen first and then the repellent .
Other measures include staying in
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reported nationally , WA reports more |
Dr McGuinness noted that the program |
body test or on laboratory-confirmed den- |
air-conditioned or screened accommoda- |
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than 50 % of cases that originate from |
tion and use of sprays or mosquito coils |
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Indonesia , and more than 80 % of these are acquired in Bali . 5 , 6
Dr McGuinness also presented data on locally acquired dengue in North Queensland . The pattern prior to 2016 was for periodic outbreaks of local dengue every
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More work is needed on dengue vaccines , and a vaccine that would be safe and effective in travellers is still some way off . |
indoors .
It is important that travellers understand that these protective measures need to be followed during the day , not just dusk to dawn . Aedes mosquito species that carry dengue are daytime biters and are
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6-7 years , with a large outbreak occurring |
most active several hours after daybreak |
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in 2009 . Recent La Niña conditions with |
began in Bali in mid-2023 along with con- |
gue infection in the past . To date , there is |
and several hours before dark . |
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associated heavy rainfall in eastern Australia resulted in emerging and re-emerging mosquito-borne diseases such as |
sultation with the local community . The aim is to expand this to all areas of Bali by 2025 . |
no data on the use of this vaccine in travellers , and Dengvaxia is not approved for travellers living in non-endemic areas or |
Conclusion
Substantial inroads have been made in the
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Japanese encephalitis and Murray Valley encephalitis . 7
However , at the same time , local trans-
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Vaccine efforts
Given the global burden of dengue , there
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visiting endemic areas . Another dengue vaccine , QDENGA
( TAK-003 ), was developed in Japan and
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push to limit the threat posed by dengue fever worldwide , especially as the planet warms and urbanises , and as interna- |
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mission of dengue in northern Australia has been decreasing . This is likely due to the success of the Wolbachia method . |
has also been substantial work on developing vaccines . 10 A major challenge is producing a vaccine that is effective across all |
has been approved in a number of countries , including by the Indonesian drug regulator in August 2022 . The trial data |
tional travel resumes as usual . However , this virus still poses a significant threat to those living in endemic regions and trav- |
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This approach involves injection of Aedes |
four serotypes of the virus . The first den- |
showed good efficacy for those with previ- |
ellers , particularly in South-East Asia and |
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aegypti eggs with Wolbachia bacteria |
gue vaccine , Dengvaxia , was licensed in |
ous dengue exposure but variable efficacy |
the Western Pacific . |
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( wMel strain ) taken from fruit flies . These injected eggs subsequently hatch into Wolbachia-carrying Aedes aegypti mos- |
Mexico in 2015 for use in endemic areas . This is a live recombinant tetravalent dengue vaccine given as a three-dose series |
across serotypes in dengue-naive populations . 10 Again , it is not approved for use in travellers . |
Preventive measures remain a mainstay of protection , while efforts focus on the expansion of vector modification to |
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quitoes . Replication of dengue , Zika and |
over 12 months . The phase 3 trials of this |
So , more work is needed on dengue vac- |
reduce transmission , as well as develop- |
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yellow fever viruses are reduced in Wol- |
vaccine involved more than 30,000 partic- |
cines , and a vaccine that would be safe and |
ment of an effective and safe vaccine for |
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bachia-carrying mosquitoes , resulting in |
ipants aged 2-16 years across five countries |
effective in travellers is still some way off . |
at-risk residents and travellers alike . |
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reduced transmission . 8 Mosquitoes with Wolbachia also have a reproductive advantage and gradually |
and found reduced risk of virologically confirmed severe dengue and hospitalisations due to dengue . |
Prevention is key
Travellers to dengue-endemic areas need
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References on request from kate . kelso @ adg . com . au |
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