By Dr Eddy Bajrovic, Medical Director, Travelvax Australia.
Do you know someone who has been flattened by an insect, their holiday deflated by a tiny puncture that made them very, very sick? If you don’t yet, the chances that you will are increasing.
In the first 13 weeks of this year, 567 Australians were told they have dengue fever. By year’s end we could pass the 1844 infections recorded last year – itself the highest number recorded in recent decades.
Another 86 Aussie have been treated for malaria. Last year there were 414 cases – the vast majority a memento of travel in Asia or Africa.
Chikungunya fever reached a record 133 cases last year, with 12 to date this year. Australia’s first case of Zika virus was reported recently in Queensland after a traveller was infected in the Cook Islands, the latest holiday destination in the Pacific to report an epidemic of this ‘new’ mozzie-borne disease.
We even had 4 cases of the relatively rare Japanese encephalitis last year – as many as we’ve seen in Australia in the preceding decade.
What is even more worrying is that these cases are the proverbial tip of the iceberg. Some people put their illness down to flu or ‘some virus’, others may see a doctor but their disease is never confirmed through a blood test.
An Asian holiday memento
Diagnosed or not, most travel-related insect-borne diseases – with the exception of malaria – recorded in Australia are contracted in a tropical or sub-tropical region of Asia. Being our favourite holiday ‘playground’, it’s not surprising that more Aussies get sick there than anywhere else – especially when it comes to diseases transmitted by insects.
Of course, you don’t need to travel overseas to pick up an insect-borne disease. We have plenty of our own.
Outbreaks of dengue occur every year in North Queensland, usually when a traveller returns with the disease only to get bitten by a local Aedes aegypti mozzie, which in turn passes on the virus to an unsuspecting family member or neighbour – or both. (It’s highly likely the dengue virus will become a permanent fixture in Australia, especially if, as expected, another species which can carry it, Aedes albopictus also becomes established in our tropical north.)
Even domestic travellers visiting Australia’s southern states aren’t free from risk.
Already this year, 1554 people have been diagnosed with the equally debilitating – if less lethal – Ross River virus, while a whopping 4300 cases were recorded nationwide last year.
Still the Lucky Country
Mosquitoes, flies, sand flies, lice, fleas, ticks, mites, and other insects make up one major group of transmitters of ‘vector-borne diseases’, the term used to describe infections that can be passed from one human, animal, or micro-organism to another.
They usually pass on a virus or parasite when they siphon off blood from an infected human or animal ‘host’, become infected themselves, and then bite another host.
Despite the steady rise in insect-borne diseases, we are undoubtedly the Lucky Country in comparison to many others, particularly those in the developing world. While relatively few deaths occur in Australia, the cycle of infection between insects and humans causes tens of thousands of cases of severe illness and deaths every day across the globe.
So serious is the threat and reality of the broader range of vector-borne diseases being taken that they were the focus of World Health Day on Monday. This year’s theme, ‘Small Bite, Big Threat’ said it all.
Here are the key statistics from the World Health Organisation on vector-borne diseases:
– They account for more than 17% of all infectious diseases world-wide.
– Half of the world’s population is at risk.
– They kill more than 1 million people a year.
Size belies danger
For such tiny creatures, insects can be remarkably dangerous – even lethal. (It’s often said that the most dangerous thing in Africa isn’t the lion but the mosquito.)
As part of World Health Day, the WHO listed some of the diseases transmitted by insects. They include:
Mosquitoes: Aedes species – Dengue fever, Rift Valley fever, Yellow fever, Chikungunya; Anopheles – Malaria; Culex – Japanese encephalitis, Lymphatic filariasis, West Nile fever.
Sand flies: Leishmaniasis, Sand fly fever (phelebotomus fever).
Ticks: Crimean-Congo haemorrhagic fever, Lyme disease, Relapsing fever (borreliosis), Rickettsial diseases (spotted fever and Q fever), Tick-borne encephalitis, Tularaemia.
Triatomine bugs: Chagas disease (American trypanosomiasis).
Tsetse flies: Sleeping sickness (African trypanosomiasis).
Fleas: Plague (transmitted by fleas from rats to humans), Rickettsiosis.
Black flies: Onchocerciasis (river blindness).
Increasing global concern
In the past 2 decades, vector-borne diseases have re-emerged in, or spread to, new parts of the world. Environmental changes, the explosion of international travel and trade, changes in agricultural practices, and rapid unplanned urbanisation are behind the increases.
So, not only are more people living with the threat of vector-borne diseases, the risk of infection has never been higher for tourists and business travellers, too.
The WHO says more than 2.5 billion people in over 100 countries are now at risk of contracting dengue fever. In recent times, it’s surfaced in China, Portugal and the US state of Florida.
Despite the partial success of costly control measures in recent years, malaria still causes more than 600,000 deaths every year around the world – most of them children aged under 5.
A new malaria vaccine is expected to become available on a limited basis in Africa this year. Plans are also well advanced for the release of the first dengue vaccine next year.
While we wait with great anticipation to see just how effective these new drugs will be, what can travellers do to protect themselves from insect-borne diseases?
Travellers can reduce risk
As we remind travellers every week in the Travelvax Report and the accompanying country disease outbreak news, the only sure way to avoid the risk of getting an insect-borne disease is to avoid getting bitten.
Minimise the number of bites and you greatly reduce your risk of infection.
Insect repellent remains a traveller’s best defence against all biting or stinging bugs. You just need to be sure the product you choose is going to protect you.
Check the label to see that it contains a proven active ingredient, such as diethyltoluamide (commonly known as DEET), Picaridin, IR3535, or oil of lemon eucalyptus.
Apply it to all areas of exposed skin ANY TIME you’re outdoors – day or night. Get into the habit of carrying a tube of repellent in your bag whenever you step outside, especially if you’re leaving your hotel or resort.
Other smart moves include:
– Sleeping under a bed net that’s been treated with permethrin if your room is not screened and/or air-conditioned.
– Covering up with long sleeves and pants, and shoes and socks, when biting insects are most active.
– Moving indoors when insects are most active – especially around dusk.
For more on insect repellents, contact insecticides, and protecting travellers of all ages from insect bites, as well as vaccination advice, contact Travelvax Australia’s free travel advisory service on 1300 360 164 (toll-free for landlines). You can also read about avoiding insect bites on our website and order repellents and treated bed nets at https://www.travelvax.com.au/store/