38 CLINICAL FOCUS
38 CLINICAL FOCUS
8 MARCH 2024 ausdoc . com . au
| THE | PREVENTIVE MEDICINE SPECIAL
Therapy Update
As the world warms , dengue thrives
Travel medicine
Professor Nick Zwar is a GP and executive dean at the faculty of health sciences and medicine , Bond University , Queensland .
Despite the progress made in limiting the threat of dengue fever , this virus continues to pose a threat to travellers and those in endemic regions .
FOR a range of reasons , dengue fever is the world ’ s fastest growing mosquito-borne disease . It is estimated that more than four billion people worldwide across more than 120 countries are currently at risk , and that an additional two billion will be at risk by 2080 . 1
The spread of dengue is driven by a number of a factors , including climate change , urbanisation and the spread of infection though international travel . Climate change is a factor through more frequent severe weather events , such as floods , and with global warming changing the distribution of mosquito vectors .
So it is unsurprising that this infectious disease continues to surface in global outbreak news . The Travax database , which collates travel medicine data from international disease-monitoring organisations , health ministries , journals and news media , reported significant increases in cases in the second half of 2023 . These cases occurred in the Koshi province of Nepal , Kerala state of southern India , Thailand , several African countries ( Burkina Faso , Chad , Côte d ’ Ivoire ), Panama , Guatemala , the Bahamas and a small number of locally acquired cases in the Lazio and Lombardy regions of Italy and in Florida , US . This has continued into 2024 , with increasing numbers of cases reported from numerous countries , including South America ( Brazil , Paraguay and French Guiana ), several islands in the Caribbean and , closer to home , from Laos , Thailand and Singapore .
As a result , attention remains keenly focused on developments to reduce the risk and prevent this potentially devastating condition .
Epidemiology
The major mosquito species responsible for spread of dengue is Aedes aegypti . This species transmits yellow fever and more than 20 other arboviruses , as well as being the major
vector for the chikungunya and Zika viruses .
The global number of dengue infections is difficult to estimate , as most cases are asymptomatic , and many symptomatic cases go unreported or are misclassified . It has been estimated that 390 million infections occur per year worldwide , of which 96 million have clinical manifestations . 2 In
Latin America , 19 countries that were dengue-free between 1952 and 1965 are once again classified as endemic areas .
But the largest area of risk is in our region , with Asia representing around 70 % of the global disease burden . 3 More than 70 % of the world ’ s population at risk of dengue live in South-East Asia and the Western Pacific . Outbreaks occur on a regular basis across the region , with many thousands of cases reported , especially in large urban population centres . Of those infected , approximately two million — mostly children — develop severe dengue , including the potentially deadly complication of dengue
Recent La Niña conditions in eastern Australia resulted in emerging and re-emerging mosquito-borne diseases .
haemorrhagic fever ( DHF ). Severe dengue is rare in travellers , as it typically occurs in second or subsequent infections .
Australian dengue developments
A perspective on dengue epidemiology in Australia was presented to the
NEED TO KNOW
Dengue fever is an increasing global threat as the planet warms and urbanises , and as international travel resumes as usual .
The number of annual clinical cases worldwide is estimated to be 96 million .
Asia represents around 70 % of the global disease burden , which means travellers to and from this region are at particular risk .
The Wolbachia method — introducing a bacteria to culprit Aedes aegypti mosquito populations that reduces flavivirus replication and transmission by the insect — shows great promise as a strategy to help reduce the risk of transmission .
Vaccine development efforts continue to seek a safe and effective vaccine for those who have previously been exposed to the virus , as well as unexposed hosts .
Personal preventive strategies remain key to reducing risk , and are worth discussing with travellers to at-risk regions .
International Society of Travel Medicine in 2023 by Dr Sarah McGuinness , an infectious diseases physician at the Alfred Hospital and research fellow at the school of public health and preventive medicine , Monash University , Melbourne . 4
For Australian travellers , the top three countries for acquisition of dengue in 1999-2012 were Indonesia , Thailand and Timor-Leste . 5 More recent data for 2012-22 showed the major region of
Used tyres can store stagnant water and become breeding grounds for mosquitoes .