Many important diseases can be carried by insects, termed vectors, transmitting their infection to us when they bite. Mosquitos not only carry malaria but other common diseases such as dengue fever, Chikungunya and Yellow Fever. Ticks also transmit several illnesses – from Lyme disease, which occurs in many parts of Northern Europe to Rocky Mountain Spotted Fever, first described in the USA. Flea bites in themselves are a nuisance but can actually harbour organisms which produce severe disease, such as Yersinia pestis which causes the Plague.
Few of the conditions spread by vectors have specific therapies, placing particular importance on the adoption of strategies to avoid getting bitten in the first place. Malaria is the most notable exception and the choice of anti-malarial medication should be discussed with a health professional several weeks before travel if possible. Each anti-malarial option has its strengths and weaknesses and the particular choice may depend on several factors including past experience to the medication, country being visited, age, pregnancy, and cost.
Things to consider for bite prevention:
Wear trousers with socks, long-sleeved shirts and proper shoes – avoid flip-flops. If going to an area of particular risk, clothes can be purchased which have been pre-treated with the insect repellent permethrin. These are said to retain their repellent activity even after many washes. Clothes can be self-treated with permethrin but they must be dried before use and are likely to require re-application of the insecticide more frequently than the pre-treated version. Guidance will be in the permethrin product information.
Insect repellent sprays have been available for decades and are a very effective precautionary practice to adopt. DEET-containing sprays are particularly effective. As DEET concentrations above 50% have not shown any added protection, sprays between 20-50% are advised. Alternatives to DEET are picaridin or oil of lemon eucalyptus (30%). Since these have generally been shown to be only as effective as products containing the lower concentrations of DEET, they may require more frequent applications. Sprays should always be used on healthy skin, uncovered by clothes and exposed to the air.
As the protection is dependent upon the product, perspiration, humidity and exposure to water, guidance from the product information is required. Products which jointly contain a sunscreen and repellent can be problematic as the two components may require differing application rates and are therefore not recommended by the CDC.
Although it is tempting to think that spraying is only necessary at dusk or in the evening, in many countries diseases such as Malaria (which is often acquired at dusk) are coincident with conditions such as Dengue or Chikungunya (which are often transmitted during the day). Spraying may be necessary at all times when outside, or not protected by nets or air conditioning.
The use of air conditioning is particularly effective in decreasing the activity of insects such as the anopheles mosquito, responsible for the transmission of malaria. If this is not available then window nets and sleeping nets are advised. If the sleeping net does not reach the floor then tuck the net under the mattress. Nets can also be treated with permethrin.
Spatial repellents are those which disperse an active ingredient into the room and usually take the form of coils, which you burn, or small devices which require electricity to vaporise a tablet or liquid. The product information will describe the optimum conditions for their usage but it is advised that they are used in conjunction with other measures such as spraying, nets and the use of air conditioning.
In areas of tick borne diseases, check each other for ticks regularly. If found, they can be removed simply by using tweezers. The body of the tick should not be crushed but rather the tweezers should be applied as near to the skin as possible and the tick pulled straight out with no twisting.