By Dr Eddy Bajrovic*
Our Games athletes and officials have been advised to pack a mosquito-proof bed net when they travel to Brazil for the 2016 Olympics in August.
Australian organisers want to ensure our team members avoid mosquito-borne viruses such as Zika, dengue, chikungunya, and yellow fever. Malaria is also present in areas of the northern Amazon states.
But, it’s Zika that is creating global headlines. The WHO yesterday declared Zika a Public Health Emergency of International Concern and has urged a coordinated international response.
There have been an estimated 1.5 million cases in Brazil in the past 10 months and the virus is now spreading rapidly throughout neighbouring countries of the Americas and the Caribbean. At least 26 nations have reported Zika to date, while dengue and chikungunya are well entrenched in every country in the region.
What’s added a tragic twist to the Zika tale is the strong suspicion that the virus is behind hundreds of cases of microcephaly in infants born to mothers infected during pregnancy, as well as (much rarer) cases of the auto immune disease, Guillain-Barré syndrome. Scientists also believe it can be passed on in semen, breast milk and through blood transfusions.
Despite this, for 80% of people who get the virus the symptoms are either mild or completely absent. But, even without the rash, red eyes, low-grade fever and joint pain lasting up to a week, anyone with the virus in their bloodstream can pass it on if an Aedes mosquito bites them and then bites someone else.
Marauding mozzies are hard to avoid
For travellers staying in mid-level or budget accommodation at a Games venue in Brazil or in any tropical country, packing a bed net is a smart move too.
The same Aedes mozzies that spread Zika also transmit dengue, and chikungunya and yellow fever (the latter in South America’s Amazon Basin and sub-Saharan African countries). They bite throughout the daylight hours – but particularly around dusk and dawn. Conversely, the malaria-transmitting Anopheles mosquitoes bite after dark, although dawn is a peak feeding time for them, too.
Only female mosquitoes bite: they need blood to produce viable eggs. Aedes mozzies have evolved to prefer human blood, which is why they breed and feed in and around homes.
When mozzies appear at dusk, it’s best to go inside. If that’s not possible, the alternative is to protect yourself with a fresh application of insect repellent, and change into long sleeves and pants.
However, at dawn chances are you will still be asleep and at the mercy of marauding mozzies – unless you’re under a bed net.
Your bed net checklist
Before you invest in a bed net, find out a few things:
- Will your accommodation be air conditioned or screened (both windows and door). If it is, you don’t need a net, rather ‘knockdown’ spray to use before bedtime to kill any insects that may have snuck into your room during the day.
- Does your accommodation come with a bed fitted with a net? If so, it probably means your room has no screens or air con. Ask about your net: Is it new or ‘pre-loved’? If you’re in any doubt, take your own net. (Anyone who has slept in hostels or other budget accommodation in a country with heavy duty, disease-packing insects will be familiar with the ‘Claytons’ bed net – the net you’re having when you’re not having a net. Unfurling your net for the first time at bedtime only to find it riddled with holes is the stuff of nightmares.)
- Does your room have no screens, no air con, and no net? If so, bring your own. There are a couple of options here. (1) Some nets need to be suspended from the ceiling and some places may not be too happy for you to screw one in. As a compromise offer to leave the hook behind for the next guest to use. (2) A speed net comes with its own supporting frame and sits on top of the bed (or in a tent or the open air) – no hook needed. Without a net, knockdown spray becomes even more important.
Treatment makes nets doubly effective
A bed net treated with a contact insecticide is twice as effective – a real gold medal performer. It will both repel insects and kill any that land on treated fabric, as this YouTube clip shows.
Permethrin is always on the podium whenever scientists assess what works (and what doesn’t) when it comes to products that repel or kill insects. It is safe for use with kids from as young as 2 months old.
Other safety-tested insecticides recommended for treating fabrics include deltamethrin, lambda-cyhalothrin, alpha-cypermethrin, cyfluthrin, and etofenprox.
Pre-treated long-life insecticidal nets (LLIN) are widely available – Travelvax Australia sells quality single and double nets, as well as speed nets, online and from our clinics.
Long-life net a good investment
The long-life treatment process can only be done in a factory.
Because LLINs keep working continuously for at least 3 years, paying the extra cost is worthwhile if you are planning a long trip or regularly travel to places where mozzies pose a consistent risk of disease.
The alternative is to treat your own net. DIY treatment doesn’t last as long (up to 6 months or 4 washes) but that’s long enough for the Games, plus a side trip in the region.
On the plus side, when you soak an untreated net in the bucket of permethrin solution there is usually enough left to soak a shirt or two.
Or, you can buy a second DIY kit and soak a selection of clothes to wear late in the afternoon or early evening. The treatment maintains its effectiveness through several washes.
But, don’t forget an effective repellent
Your treated bed net and clothing should be used in conjunction with an effective topical (rub on) insect repellent – not as an alternative.
As with all repellents and insecticides, it’s important to follow the directions for safe usage.
However, the experts universally agree that the scientifically proven protection that treated nets and effective repellents used together provide far outweigh any risks.
But, lots of claims are made about the products on the market to help humans avoid biting insects. Some work really well, others simply don’t work at all.
What DOES work
Your first line of defence should be a personal repellent with a tested and proven active ingredient such as DEET, Picaridin, or oil of eucalyptus (PMD). DEET formulations containing 40% active ingredient will protect for 6 hours, 20%-30% DEET = 4 hours, 10% = 2 hours. Picaridin and PMD are equally effective and safe. Travelvax stocks a range of these repellents.
What DOESN’T work
- Wristband repellents.
- Phone apps of all descriptions.
- ‘Natural’ alternatives to the active ingredients mentioned. (Their safety, efficacy and longevity are unproven, plus some may irritate your skin.)
- Taking vitamin B. (Nothing you can eat, drink or swallow will stop insect bites.)
- Mosquito coils and sticks. (At best, these may reduce bites. Beware - burning them overnight in an enclosed room can be toxic.)
Read more on the insect-borne viruses found in tropical countries like Brazil, and on how to get the best from insect repellents and other measures to avoid biting insects.
Before you fly, find out about mozzie diseases or other health risks at your destination by calling Travelvax Australia’s travel health advisory service on 1300 360 164 (toll-free from landlines). You can also make an appointment for a one-stop pre-travel medical consultation and receive any vaccinations needed for the trip from medical professionals experienced in travel medicine at a Travelvax Australia clinic near you.
* Dr Bajrovic is Medical Director of Travelvax Australia.