News

16-02-2016

For travellers, the current Zika Virus outbreak, rise in Dengue Fever, ongoing Malaria risk in many areas  and locally Ross River and Murray Valley Encephalitis, all have Health Authorities recommending avoiding mosquito bites to reduce the chance of infection.

1: Topical Repellents, what we need to know:

  • Roll-on,aerosol or cream products all need to be applied evenly over all exposed skin, it is advised not to apply directly to your face, but to apply to your hands and then to your face. Rubbing the products into the skin does not reduce their effectiveness.
  • The most highly recommended are those containing DEET (diethyltoluamide) or picardin, which have been found to have the longest lasting protection and are equally effective against the broadest range of mosquito species. Another recommended topical repellent is PMD ( p-menthane-3,8-diol), which is a product of lemon eucalyptus extract.
  • These products are considered safe for adult and children over three months of age ( advised to use barriers such as wraps, nets and clothing to protect them) DEET has few reports of toxic effects when used on the skin and has been available since the 1950's. ( although may damage plastics and synthetic materials)
  • Many naturally derived products and untested products sold in markets contain tea-tree oil which is highly irritant to skin and most of these products, including essential oils have been demonstrated as less effective than DEET. Most essential oils are highly volatile and have variable repellent effects with poor longevity as mosquito repellents.
  • The strength of a repellent refers to the length of time the protection lasts rather then the number of mosquitoes kept away ( on current evidence, concentrations of 20-50% of deet remains the first line choice of repellent, without further benefit at higher percentage concentrations)
  • Combination products with sunscreens have not been well tested yet as to their effectiveness The effectiveness of the repellent is reduced by sweating and evaporation, rain and higher ambient temperatures and requires re-application during times of exposure  ,similar to sunscreen
  • Citronella is highly volatile and provides protection for less than 2 hours and neem based preparations have low skin irritation, but has inferior protection to DEET products and has proven long term fertility concerns


2: Other Measures:

  • Wearing long -sleeved shirts and trousers create a physical barrier that has proven reduction in bites
  • Avoiding mosquito habitats late evening and early morning, and insecticide treated mosquito nets and clothing are useful adjuncts to topical repellents.
  • Reducing breeding sites around your house such as water in pots and containers
  • Wrist bands and patches provide only localised protection
  • Electric insect vaporizers or devices releasing pyrethroid insecticide remain effective for over 6 hours in reducing insect numbers in a room, but exposure to the chemicals inhaled may present a low-level harm to humans and there is no direct evidence of reduced malaria occurrence or insect transmitted infection as a result of their use. , essential oil candles and coils ( made from a paste of powdered insecticide)  do reduce bites from mosquitoes although safety concerns exist regarding their use. Burning a mosquito coil releases the same amount of particulate matter as burning 75-137 cigarettes and emits formaldehyde equivalent of 51 cigarettes. There is little evidence as to effectiveness of knockdown sprays.
  • There is no current evidence that phone apps using sound to repel mosquitoes are effective , garlic and vitamin B have no evidence of making human skin unpalatable to mosquitoes and should not be recommended to travellers

 

reference: onlinelibrary.wiley.com ( Expert review of the evidence base for arthropod bite avoidance)

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