More human suffering is caused by mosquitoes than by any other organism. Every year, mosquito-borne diseases kill over one million people worldwide, particularly in tropical and subtropical areas.
Day flying mosquitoes bring dengue fever, while the night fliers transmit malaria and Japanese encephalitis. Furthermore, mosquito bites may trigger severe skin irritation because of an allergic reaction to the saliva which may produce itching and red bumps.
Mosquito Born Diseases
Malaria: Malaria is transmitted to a person by an infective female Anopheles mosquito which is active during the night. It takes a blood meal on an infected human being and the small amount of blood contains microscopic malaria parasites that mix with the mosquito’s saliva, which is then injected into the next person being bitten.
Symptoms of malaria can appear after 10 to 15 days and include fever, headache, chills, joint pain, muscle ache, nausea and vomiting. These symptoms may continue for a month or longer; however, most of the reported deaths occurred in children and pregnant women.
Dengue fever: Caused by the Aedes mosquito, dengue fever is a serious illness, the symptoms of which appear between 3 and 14 days after the infective bite, with debilitating high fever accompanied by severe headache, muscle and joint pain, pain behind the eyes, nausea, vomiting and rash.
Dengue hemorrhagic fever is a potentially lethal complication, with the blood vessels starting to leak, which results in bleeding from mouth, gums and nose. Travelers should certainly be more concerned about dengue than malaria, but since there is no preventive remedy to sell, we hear far less from the medical industry about it.
Chikungunya fever: A re-emerging disease in Asia is Chikungunya fever, a viral illness spread by infected mosquitoes. It resembles dengue fever but is rarely life-threatening. At present, there are no vaccines to prevent malaria, dengue fever and Chikungunya fever.
Japanese encephalitis: Japanese encephalitis is another viral disease in Asia transmitted by rice field mosquitoes which get infected after blood-feeding on pigs and wild birds carrying the virus. This illness triggers severe inflammation of the brain and can cause permanent brain damage with a high mortality rate.
Symptoms are fever, headache, neck stiffness, stupor and coma. Countries affected by Japanese encephalitis are China, Taiwan, Korea, Japan, Thailand, Vietnam, Cambodia, Myanmar, Malaysia, India and Nepal.
Bite Prevention
The first step in mosquito prevention is to understand the risks at your destination therefore it is wise to visit a travel health clinic or tropical institute prior to starting your trip. Travelers can be immunized against Japanese encephalitis, while antimalarial drugs may prevent malaria. However, none of these are 100 percent effective and there is no protection against dengue fever.
The best option to avoid being afflicted by mosquito borne diseases is to ensure you do not get bitten. There are a number of easy methods you can use to dramatically decrease the chances of getting any mosquito bites.
- Mosquito bed netting is crucial, and preferably netting that has been impregnated with insect repellent such as permethrin. Buy it at home. Carry a hook which can be screwed into wood in order to hang the bed netting.
- Bring a lot of insect repellent that contains a concentration of at least 30 percent DEET (check recommendations for kids) since this can be difficult to find in Asian shops. Remember that the repellent is only effective for a few hours and is removed by sweating, swimming and showering. Always carry repellent with you and reapply it diligently.
- Especially at dawn and dusk, it is recommended to wear light colored clothing, preferably long sleeved shirts and long pants, which will protect you from insects and sunburn alike.
- Use mosquito coils and other anti-mosquito devices such as citronella as a secondary control.
- Stick to accommodation which can be sealed up, without open eaves or slatted windows, and watch out for bucket showers and toilets since these are a heaven for mozzies. Curtains can also be soaked in insecticide to repel or kill mosquitoes.
- Cover yourself with long pants and a long-sleeved shirt, and use heavy-weight clothing - mosquitoes can bite through thin cloth.
- Spraying Permethrin (Permanone) on clothing will increase protection.
Insect Repellents: Insect repellents containing at least 30% DEET (such as Deep Woods Off or Repel) or a newer long lasting non-absorbed formulation (Ultrathon by 3M, now marketed as HourGuard by Amway) should be used when traveling in areas where mosquitoes are present.
For years, repellents that contain high concentrations (95 to 100%) of DEET (N,N-diethyl-m-toluamide) have been considered the most effective against mosquitoes, ticks and chiggers. However, it has been found that some people do not do well with the concentrated DEET repellents and no one should use such products for extended periods of time.
DEET is absorbed through the skin with the potential for serious adverse effects. Some people are allergic to the highest concentrations of DEET. More and more, experts are recommending that repellents should contain no more than 30% to 35% DEET. If significant amounts of DEET are absorbed through a child’s skin, seizures and neurological damage can result. Therefore, repellents with high concentrations of DEET should be used sparingly on infants and young children.
Ultrathon Insect Repellent (Ultrathon made by 3M, now marketed as HourGuard by Amway) contains 35% DEET plus a polymer that reduces drug absorption and losses from moisture (sweating, swimming). It offers up to 12 hours of protection compared with 4-6 hours for the same concentration of DEET alone.
Permethrin: Spray permethrin on clothing, mosquito nets, or fabrics. Permethrin, which is actually a pesticide rather than a repellent, can be applied to clothing and fabrics for protection against both mosquitoes and ticks. It is completely safe for humans. Permethrin bonds tightly to the treated fabric, even through multiple washings. It is non-staining, nearly odorless, and resistant to degradation by light, heat and immersion in water, and lasts a minimum of 2 weeks per application.
The aerosol is available in many areas of the USA as Permanone Tick Repellent (0.5% permethrin) and is sold mostly in lawn and garden stores or sports stores.
Both Ultrathon and Permanone are also available from Chinook Medical Gear, (800) 766-1365.
Bed Nets: Mosquito bed netting is an excellent addition to your anti-mosquito arsenal. Bed netting effectiveness can be enhanced by permethrin (Duranon, Permanon) insecticide treatment. Some good screens are “The Spider,” a 17-ounce, nylon net which suspends easily from the ceiling and tucks in under the mattress. The Spider is available from Chinook Medical Gear, (800) 766-1365, for about $60. For the traveler who will be spending more time in one location, “La Mosquitte,” is a rectangular net supported by lightweight aluminum poles. La Mosquitte is available from the International Association for Medical Assistance to Travelers (IAMAT), (716) 754-4883, for about $90.
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