West Aussies versus the local mozzies

This is a special guest post from Dr Abbey Potter, Senior Scientific Officer, Environmental Health Hazards, WA Health. I’m currently mentoring Abbey as part of The Public Health Advocacy Institute of WA (PHAIWA) Mentoring Program. Its been a great experience as we navigate through some of the strategies to raise awareness of mosquito-borne disease and advocate for better approaches to addressing the public health risks associated with mosquitoes.

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Living in WA, we’re all too familiar with the pesky mosquito. We know they bite but what we often don’t consider is that they can transmit serious and sometimes deadly diseases. In fact, a recent survey of locals indicated that knowledge of mosquito-borne disease is pretty limited, particularly among younger adults aged 18-34 years and those living in the Perth Metro. It’s pretty important we’re aware of the risks posed by these pint-sized blood suckers and how you can avoid them… and here’s why!

The Facts

On average, more than 1,000 people will be infected with a mosquito-borne disease in WA every year. Our mossies can transmit Ross River virus, Barmah Forest virus, West Nile virus (Kunjin substrain) and Murray Valley encephalitis virus. All four cause diseases that are debilitating at best, causing weeks to months of symptoms. Murray Valley encephalitis is limited to the north of the State but is so serious it can result in seizures, coma, brain damage and even death.

Forget the bush, most people bitten in their own backyard. West Aussies are all very prone to getting eaten alive while socialising outdoors but if you’re up in the north of the State, you’ve also got a much higher likelihood of being bitten while boating, camping or fishing or working outside, compared to the rest of the state.

And don’t think you’re off the hook when you head off on holidays. A further 500 WA residents return from overseas travel with an exotic mosquito-borne disease every year. Heading to Bali? Beware of dengue, especially young adult males who return home with the illness more than others. There is limited mosquito management in many overseas countries where disease-transmitting mozzies can bite aggressively both indoors and throughout the day. This catches West Aussies off guard, as we are accustomed to mozzies biting outdoors, around dusk and dawn. When you’re in holiday mode it’s likely that you’ll be relaxing, having a couple of drinks and not thinking about applying repellent. Oddly enough, mosquitoes may actually be more attracted to people whose body temperature is higher. This happens naturally when you consume alcohol, so best pull out the repellent before you crack your first beer.

Despite our attractiveness to mosquitoes, we aren’t really aware of the most effective ways to avoid bites or how we can do our bit to reduce breeding in our own backyards. If you live by the mantra Cover Up. Repel. Clean Up you’ll have no problems!

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Western Australia has some amazingly beautiful wetlands but these saltmarshes around Mandurah can produce large populations of nuisance-biting mosquitoes!

Cover Up

If you know you are going to be outdoors when mosquitoes are active, wear loose, long-fitting clothing that is light in colour. Believe it or not, mosquitoes can bite through tight pants as tough as jeans – I’ve witnessed it!

If you’re staying in accommodation that isn’t mosquito-proof, consider bed netting.

Try to keep children indoors when mosquitoes are most active. If exposure can’t be avoided, dress them appropriately and cover their feet with socks and shoes. Pram netting can also be really useful.

Admittedly, it’s not always practical to wear long sleeves during our warm summer nights, so there are going to be times when you need to use repellent. Choose a product that actually works and apply it appropriately so it does the job. Despite our best intentions, this is where we often go wrong. There are a few basic things to cover here, so stick with it!

Ingredient: Science tells us that the best active ingredient for repelling mosquitoes is diethyltoluamide (DEET for short) or picaridin. You need to look for either one of these names on the repellent label under the ‘active constituents’ section.

Unfortunately, natural repellents and anything wearable (e.g. bands, bracelets or patches) have very limited efficacy. Experts don’t recommend you use them and I consider this very wise advice. It only takes a single mosquito bite to become infected and chances are you will receive at least one if you rely solely on a product of this nature. It just isn’t worth the risk.

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Percentage: The next thing to consider is the percentage of the active ingredient. This can range anywhere from 7% to 80% which can make choosing a repellent confusing. Just remember, the higher the percentage, the LONGER the product will remain active for. It doesn’t mean it will repel mosquitoes better.

A repellent containing 16-20% DEET will provide around 4-6 hours of protection, and is a good place to start. Repellents labelled ‘tropical strength’ usually contain greater than 20% DEET – they are useful when you spend longer periods exposed to mosquitoes or if you are heading to a region where dengue, malaria or Zika is problematic. Kids repellents usually contain picaridin or <10% DEET.

Sometimes it can be tricky to work out the percentage of the active ingredient. You can see the Bushmans example below states this clearly, but the other bottles list the ingredient in grams per litre (g/L). No need for complex maths – just divide by 10 and you have the magic number! For example, the RID label below reports the product contains 160g/L of DEET. This would convert to 16% DEET – easy!

You can see a few examples here of effective repellents:

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How to Apply: No doubt we would all prefer if repellents didn’t feel quite so gross on our skin or didn’t smell so bad. Even I have to admit that before I moved into this field, I was guilty of putting just a dab here and a dab there. Unfortunately, this is flawed logic that will only result in you being bitten!

Repellents must be applied correctly to be effective. That means reading the label and applying it evenly to all areas of exposed skin. Remember to reapply the product if you are exposed to mosquitoes for longer than the repellent protects you for. You’ll also have to reapply the repellent after sweaty activity or swimming.

For more information on repellent use in adults and children, click here.

Clean Up

Mosquitoes need water to breed, but only a very small amount. Water commonly collects in a range of things you may find in your backyard including pot plant drip trays, toys, old tyres, trailers and clogged up gutters. Mosquitoes also love breeding in pet water bowls, bird baths and pools if the water is not changed weekly or they are not well maintained. Rain water tanks can also be problematic so place some insect proof meshing over any outlets. When you’re holidaying, cover up or remove anything that may collect water.

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If you need more official info from WA Health about mosquito-borne disease or simple ways to prevent being bitten click here. And if you want to read more about how much West Aussies know (or don’t know) about mossies, check out Abbey’s excellent paper here! Joint the conversation too on Twitter by following Abbey and Cameron.

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Don’t let mozzie bites spoil your tropical “Schoolies” celebrations

With cheap international travel luring plenty of school leavers away from traditional “Schoolies” locations, concerns have been raised regarding a new set of health risks.

Traditionally, the Gold Coast in QLD was the main destination for “end of school” celebrations. Commonly known as “Schoolies”, these celebrations are generally portrayed in the media as pretty wild affairs. It is estimated that around 30,000 people will travel to the Gold Coast in 2013 (around 10,000 will celebrate an hour or so further south in Byron Bay). In recent years, there have also been discussions about alternatives to traditional “Schoolies” activities.

There are plenty of health concerns every year for those partying and this year, CSIRO has teamed up with local health authorities to create a tool to reduce the strain on hospitals. The software predicts how many patients will arrive at emergency, their medical needs and how many will be admitted or discharged. As the Brisbane Times reported:

The most common injuries among 17 to 19 year-olds are expected to include acute drunkenness from alcohol, grazes and cuts to feet, hands and heads, ankle and foot sprains, drug poisoning, asthma attacks, reaction to severe stress, lower abdominal pain and broken noses.  Intoxication is the single biggest reason schoolies turn up to hospitals or at medical tents for treatment, with the number of schoolies presenting for alcohol intoxication tripling between 2011 and 2012.

Lets hope that with a bit of help from some new technology, there is a downturn in injuries and hospitalisations this year. There has even been the suggestion that day-time naps could help prevent many injuries!

While the Gold Coast and Byron Bay continue to be popular destinations, cheap overseas holiday options in Bali are also attracting plenty of school leavers.

Don’t try to shake off that “Schoolies” hangover with a trip to McDonalds, try the local street food in Bali (Photo: Streetfood Blog)

Taking celebrations overseas

While there are many health risks associated with “Schoolies” celebrations across Australia, many are now looking to travel to Bali. Additional concerns are then thrown into the mix.

Health authorities have been issuing warnings about increased measles risks in Bali and encouraging travellers to ensure that they’re vaccinated. The Australian Government’s “Smart Traveller” website warns of measles, magic mushrooms and potentially poisoned drinks.

In addition, there are warnings on the risk of rabies and a range of mosquito-borne diseases (e.g. dengue, Chikunguya, Japanese encephalitis). In particular, there have been reports of surging dengue activity in Bali in recent years. Notwithstanding the risk to travellers, the burden of disease on local communities, particularly children, is significant.

Aedes aegypti (Photo: Stephen Doggett)

One of the key mosquitoes internationally that is responsible for the spread of dengue viruses, Aedes aegypti (Photo: Stephen Doggett)

From a mosquito perspective, the big difference between the Gold Coast and Bali is the presences of mosquitoes that can transmit dengue and Chikungunyna viruses. The risks are different, not only due to the activity of these pathogens but the mosquitoes display a different pattern of biting activity. They bite during the day as opposed to most “Aussie Mozzies” that bite in the late afternoon and evening. This has implications for the effectiveness of topical mosquito repellents against these mosquitoes/pathogens.

In the latest issue of the Broad Street Pump (Newsletter of the Centre for Infectious Diseases and Microbiology & Marie Bashir Institute of Infectious Diseases and Biosecurity), I wrote a piece titled “Are we providing the right advice on personal protection measures against endemic and exotic mosquito-borne diseases?”. The thrust of the paper is that we should be providing specific advice on how to choose and use repellents in these dengue-receptive regions.

The most important issue is that topical repellents should be applied in the morning, and reapplied during the day, to provide protection from mosquito bites. It is equally important that travellers aren’t complacent about the risks of mosquitoes in urban areas. While the preventative measures against malaria (i.e prophylaxis and bed nets) are well know, I suspect that they are mostly associated with travel to rural and “jungle” locations. The problem is, dengue is a disease of urban areas. Perhaps Australian travelers are being complacent?

Rather than being associated with wetlands or rice paddies, the mosquitoes that spread dengue and Chikungunya viruses are closely associated with “man made” water holding containers. Pot plant saucers, discarded tyres, rainwater tanks, uncovered water drums and, probably most importantly, discarded containers ranging from takeaway food containers to bottles and cans.

It isn’t just the parties, the wonderful surf in Bali is surf to attract a few extra Australian travellers to “Schoolies” celebrations (Photo: Aquabumps)

Australia has seen a steady rise in travellers returning with dengue and chikungunya infections. Dengue infection in returning travelers is not uncommon. The majority of dengue infections have occurred in Indonesia. This increase in imported cases may also be a risk to trigger local epidemics in QLD.  Even the movement of infected mosquitoes on aircraft have caused suspected cases of “airport dengue” in NT and WA.

It is important to note that there are some regions in Australia where mosquitoes responsible for the spread of dengue viruses are present. In particular, Far North Queensland experiences annual activity of dengue with occasional small clusters of locally acquired cases. Local mosquitoes typically pick up the virus by biting an infected traveller and then, subsequently, spreading to local residents. There have been about 30 cases of locally acquired dengue in FNQ since the start of the year.

Across Australia, according to the statistics provided by Australian National Notifiable Diseases Surveillance System, we are currently on track to record the highest number of dengue and Chikungunya cases. As of 16 November 2013, there had been 1563 cases of dengue reported and 121 cases of Chikungunya. Compared to the number of cases of dengue, Chikungunya may not seem so bad, until you realise that the highest number of cases previously was only 63 in 2010. The reasons for this increase are probably due to increasing movement of Australian travellers to dengue endemic regions as well as increasing activity of dengue and Chikungunya at these destinations.

What do you do?

Firstly, you head off to Bali to have a great time and, as well as celebrating the end of school with your friends, get a chance to experience another culture (and possibly some good waves). As they say, be alert but not alarmed.

Here are three tips on protecting yourself against mosquito-borne disease:

1. Protect yourself against day-biting mosquitoes. Apply a repellent before breakfast.

2. Take repellent with you. Australian repellents must be registered with the Australian Pesticides and Veterinary Medicines Authority who test for efficacy and safety. You may not be able to get a hold of similar products overseas. Use a repellent that contains either diethyltoluamide or picaridin. These two products are most effective.

3. Apply the repellent like sunscreen, not perfume. An even coating on exposed skin is required. Don’t bother applying it to clothing or “spraying it around the room”, that won’t protect you from bites.

Don’t forget to check out Smart Traveller before heading off to Bali…or anywhere else for that matter. Consult your GP before traveling regarding the appropriateness of anti-malarial drugs. This is particularly the case if you’re traveling to rural areas in Indonesia or heading off to another tropical location for celebrations.

The photo at the top of this post was taken from the 2012 piece “Sex, drugs, cheap beer and ignorance – schoolies completely lose it in Bali