Mosquito Bite Avoidance
Avoidance of mosquito bites should always be considered as the first line of defence against mosquito-borne infections,especially malaria, dengue fever, chikungunya, zika and yellow fever.
Different types of mosquito bite at different times of day, and transmit different infections so preventive measures are advisable at all times.
- The mosquitoes which spread malaria tend to bite between dusk until dawn. Peak biting activity occurs around midnight in those mosquitoes that spread malaria in Africa. In South America and South East Asia the mosquitoes tend to bite in the evening.
- Mosquitoes responsible for spreading other diseases e.g. yellow fever, dengue fever and zika virus, tend to bite during the day.
There are many insect repellents available. The Advisory Committee for Malaria Prevention in Travellers for the (ACMP) strongly recommends DEET-based insect repellents. If DEET is not available or cannot be used then alternative preparations are available. However, few are as effective as DEET.
DEET has been in use as an insect repellent for around 50 years and it is available in different concentrations ranging from 20% up to 100%. The duration of protection varies depending on the concentration chosen. 20% DEET will give protection 1 to 3 hours, 30% DEET can last up to six hours and 50% can last up to 12 hours.
- When sunscreen and DEET are used together, DEET should be applied after sunscreen. The effectiveness of repellent reduces more rapidly than sunscreen, therefore, repellent may have to be reapplied on top of sunscreen.
- If using sunscreen and repellent together, use SPF 30-50 sunscreen to allow for the reduction in SPF caused by DEET repellent.
- DEET is not recommended for use in infants below 2 months of age.
- The use of DEET should not be avoided in pregnancy. Given the seriousness of malaria in pregnancy, it is recommended to use DEET at a concentration of 50% as part of the malaria prevention regime. DEET at a concentration of 50% may also be used in breast feeding and for infants and children over two months of age.
- Concentrations of below 20% DEET are not considered to be appropriate in any circumstance. DEET can cause damage to some synthetic materials e.g. plastics, nylon. Contact between synthetic materials and DEET should be avoided.
Icaridin (KBR3023) (1piperidinecarboxylic acid, 2-(2 hydroxyethyl)-,1-methyl- propylester) is reported to have repellent properties comparable to DEET. Icaridin is available in various concentration. A preparation of at least 20% is recommended for those opting to use this repellent for mosquito bite prevention. Manufacturers instructions should be followed.
Lemon Eucalyptus (p-menthane 3,8 diol, or PMD)
Lemon eucalyptus gives about the same protection as 15% DEET but it is reported to provide a shorter period of protection than DEET.
3-ethlyaminopropionate (IR3535) has a shorter duration of protection than DEET which gives protection times against Anopheles 20 to 25% higher than IR3535 at equal concentrations.
Oil of Citronella
Oil of citronella products contain repellent properties although these are very short lived. They are not recommended for use against mosquito bite protection.
Covering up with clothing reduces the amount of skin that can be bitten: high necked, light coloured clothing, long sleeves and shirts, trousers or long skirts are preferable to vests, shorts and bikinis. Clothing can be thin, loose and light weight in hot environments. Exposed areas of skin should be covered with an insect repellent that contains no less than 30% DEET or the alternatives mentioned above.
For added protection, clothing can be impregnated or sprayed with the insecticide permethrin. Kits and spray are available to buy from outdoor/travel suppliers; the manufacturer's instructions should be followed. It is important not to frequently wash clothing that is impregnated, as the effectiveness will be reduced.
The protection afforded by mosquito nets against mosquitos and other biting arthropods is greatly enhanced by using a net already impregnated or retreated using a pyrethroid insecticide. Nets that have pyrethroid incorporated into the material or bound to the material with resin have an expected life of 3-5 years and are superior to nets that require re-impregnation.
There are many different styles of net available although all provide the same protection. It is important to choose a net that best suits the type of travel. Below is a list of some nets available.
Bell Shaped Net
- Can be used indoors or outdoors.
- Comes with hanging kit so can be adapt for individual use easily.
- Available in double and single.
Wedge Shaped Net
- Suitable for travellers on the move as has only one hanging point so can be put up and taken down without too much difficulty.
- Can be used outdoors.
- Available in double and single.
- Suitable for travellers staying in one location for period of time.
- Box net requires at least six hanging points so cannot be put up or taken down with ease.
- Available in double and single.
Mosquito nets should be inspected for holes prior to using them. If a hole is apparent then this can be mended using a mosquito net repair kit or simply by using a needle and thread.
Nets should be tucked under mattresses or ground sheets to avoid entry of insects into the bedding area. Whilst sleeping under the net it is important not to sleep against the net as mosquitoes can still bite through it.
Window and door screens or shutters should be checked to ensure that there are no holes in them which will allow insects entry in to the bedding area. Remember to shut all screens and shutters during dusk to dawn to avoid insect entry into rooms.
Rooms that are airconditioned are considered to be sealed, making insect entry into rooms less likely.
Pyrethroid products such as plug ins or candles may also be used. Remember, plug ins require electricity in order to vapourise the pyrethroid. If you are unsure of the reliability of electricity at your destination then candles or methylated burners, cones and coils are suitable alternatives.
There are a number of measures cited as protective against mosquito bites which are unreliable including the following:
- Herbal remedies – ACMP strongly advise against relying on herbal remedies as there is no evidence of their effectiveness.
- Homeopathy – as above.
- Buzzers – buzzers that emit high frequency sound waves are completely ineffective.
- Vitamin B1 and Vitamin B12 – there is no evidence that these repel mosquitoes.
One of the most effective ways to control mosquito populations that transmit disease is to reduce the number and types of mosquito breeding habitats. All mosquitoes require a water source to lay their eggs. To effectively reduce larval hatching it is important to check for mosquito breeding sites. In tropical areas where mosquitoes tend to be problematic the spraying of breeding sites is practiced. In households and/or hotels it is important to get rid of any standing water i.e. if watering plants tip water out of saucer etc.
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