Malaria Site: Personal Protection

Protective measures adopted by individuals and families not only help in protecting the individuals against mosquito bites and hence malaria, but also help in reducing the mosquito population by denying the blood meal essential for nourishment of the mosquito eggs in the female anopheles mosquito.

Preventing the mosquitoes from entering the house: The female anopheles mosquitoes enter the house in the evenings, between 5PM and 10PM, and also early in the morning, between 5AM and 7AM. To prevent their entry, all the doors and windows should be kept closed during these hours. And it is also important to close the doors of the toilets, which always open to the exterior through windows or vents. Well-constructed houses with window screens are effective for preventing biting by mosquitoes that bite indoors and likely contributed much to the elimination of malaria from the United States and Europe.

Preventing the mosquitoes from hiding: Anopheles mosquitoes tend to hide in the dark corners and amidst the clothes and other linen left hanging in the rooms. During the night, they come out of their hiding to seek human blood. This should be avoided and all the clothes and linen should be preferably kept inside wardrobes and cupboards.

Protection from mosquito bites: Personal protection against mosquito bites is a simple yet very effective measure in malaria control. All patients with malaria should be educated about this. The female anopheles mosquito bites human beings from around 6 PM to 7AM with peak activity after midnight. Therefore, one should take protective measures throughout this period.

i. Protective Clothing: Protective clothing helps to keep the mosquitoes away when the individual is relaxing either indoors or outdoors, particularly between 6PM and 10 PM. The thickness of the material should be such that mosquitoes cannot gain access to the skin. The clothing should be such that no skin is left exposed (unless the clothing is treated with a repellent). Wearing light-colored clothes, long pants and long-sleeved shirts that cover as much area of his body as possible would be helpful. Treating the clothing with permethrin or etofenprox provides extra protection by repelling the mosquitoes and the repellant also stays active for a longer time when it is applied on the clothing than on the skin. Label instructions should be followed to avoid damage to certain fabrics.

These are substances applied to exposed skin or to clothing to prevent human - mosquito contact. The repellent only repels but does not kill mosquitoes. Repellents are a common means of personal protection against mosquitoes and are broadly classified into two categories, natural repellents and chemical repellents.

Essential oils from plant extracts that act as natural repellents are citronella oil, lemongrass oil and neem oil.

Examples of chemical repellents include:

DEET (N,N-diethyl-m-toluamide)
3-[N-acetyl-N-butyl]-aminopropionic acid ethyl ester (IR3535®)
1-piperidinecarboxylic acid, 2-(2-hydroxyethyl)-, 1-methylpropylester (Bayrepel®)
Permethrin is an effective repellant when impregnated in cloth.

Every year, approximately one-third of the U.S. population is expected to use DEET. Products containing DEET currently are available to the public in a variety of liquids, lotions, sprays, and impregnated materials (e.g., wrist bands). Formulations registered for direct application to human skin contain from 4 to 100% DEET. Although the normal use of DEET does not present a health concern to the general population, the available data do not support product label claims of child safety based on the percentage of active ingredient.

A study by Malaria Research Centre, India revealed that of those using DEET-based cream, 11.4 per cent reported skin reaction and itching. If any adverse reaction to this product is suspected, its use should be discontinued and the treated skin should be washed.

http://www.epa.gov/pesticides/factsheets/chemicals/deet.htm


		How to apply mosquito repellents? Apply during the biting time of the mosquitoes; for anopheles, it is dusk to dawn. Take care to avoid contact with mucous membranes (eyes, nostrils, mouth, lips); do not spray on the face. Do not allow young children to apply this product; do not apply to hands or near the eyes and mouth of young children. Do not apply to sensitive, sunburned or damaged skin or deep skin folds. Use just enough repellent to cover exposed skin and/or clothing; do not use under the clothing. Avoid over-application. Wash the hands after applying the repellent. After returning indoors, wash treated skin with soap and water; wash treated clothing before wearing it again. In case of repellants formulated as sprays: Do not spray in enclosed areas. Do not spray directly onto face; spray on hands first and then rub on face. Repeated applications (every 3–4 hours) may be needed, especially in hot and humid climates. Strictly adhere to the manufacturers’ instructions and do not exceed the dosage, especially for young children.

III. Insecticide vaporizers: Many types of insecticide vaporizers are now widely marketed, including mosquito coils, vaporizing mats and liquid vaporizers and aerosols. These are quite popular among Asians, including Indians. The Indian market for various mosquito repellents is Rs. 500-600 crores, growing annually at 7 to 10 per cent and the annual worldwide consumption of the residential insecticide products is billions of units. Most of these products contain synthetic pyrethroids, like d-allethrin and d-trans-allethrin, as the active ingredient.

a. Mosquito coils: Mosquito coils are burned indoors and outdoors in Asia and to a limited extent in other parts of the world, including the United States. In these countries, middle class families use mosquito coils regularly. The number of coil users in China is in the millions. In Indonesia alone, an estimated seven billion coils are purchased annually. Coils consist of an insecticide or repellant, organic fillers capable of burning with smoldering, binder, and additives such as synergists, dyes, and fungicide. One mosquito coil is claimed to serve a normal bedroom through the night; however they are said to be the most inefficient mosquito repellents.

b. Vaporizer mats and liquid vaporizers: These are more recent and 'more sophisticated' additions and are marketed in all urban areas. Insecticide mat is placed on an electrically heated grid, causing the insecticide to vaporize.


		Insecticide Vaporizers may not be safe: Two independent studies indicate that mosquito coils can be disastrous for human health. One study indicates that they contain a cancer-causing substance. The other study has estimated that a single coil can release particulate matter equal to 75 to 135 cigarettes. Keeping the windows closed while the coils are burning would enhance the harmful effects, especially for children. Coils containing pyrethroid insecticides, particularly d-allethrin, may contain octachlorodipropyl ether (S-2, S-421) as a synergist or active ingredient. Use of those coils likely exposes children and adults to some level of bis(chloromethyl)ether (BCME). BCME is formed from formaldehyde and hydrogen chloride, combustion products formed from the slow smoldering (about 8 hr/coil) of the mosquito coils. Because BCME is an extremely potent lung carcinogen, the nature and extent of prolonged exposures that recur in homes during the mosquito season in tropical regions must be evaluated with respect to health. In a small analytical study, coils purchased in Indonesia and in the United States contained highly variable amounts of S-2. Some coils that contained S-2 were not labeled, making it impossible for consumers to make an informed decision about coil contents. (Environ Health Perspect 111:1439-1442 (2003). doi:10.1289/ehp.6177 available via http://dx.doi.org/) Indian Study: A survey carried out in nine Indian states by the Malaria Research Centre (MRC) has revealed that mosquito repellents widely used in the country are harmful to health and suggests that their use should be avoided or discouraged. The results of the survey have been reported in a paper in 'Current Science,' the journal of the Indian Academy of Sciences. The questionnaire-based survey by MRC involved 5920 respondents, both common users and medical practitioners in urban and rural areas. Results have revealed that 11.8 per cent of the users of synthetic pyrethroids, across all age groups and both sexes, complained of a variety of acute toxicity effects either soon after or within a few hours of use of repellents. The most common complaint was breathing problem, followed by eye irritation, often accompanied by bronchial irritation, headache or skin reaction. Cough, cold, running nose, pain in the ear and throat were other common complaints. In 2 cases, persons who did not earlier suffer from asthma, became asthmatic. Of the 286 doctors covered in the survey, 165 or 57.6 per cent reported acute toxicity following use of repellents. The paper also cites a 1998 report of the Indian Toxicological Research Centre, Lucknow, where serious health consequences of the use of repellents were recorded. Even those who do not immediately feel any adverse effects may be in long term danger: Dr Ved Prakash Sharma, malariologist from the Indian Council for Medical Research who led this study says that although symptoms disappear shortly after withdrawal, those who do not suffer acute toxicity and continue to use these repellents for extended periods may suffer neurotoxic and immunotoxic hazards. Some studies have reported corneal damage and liver damage following prolonged use. Dr Sharma states that neem oil may be a cost-effective and safer alternative. It can be used as a "neem cream" made up of 5 parts neem oil and 95 parts coconut or mustard oil. Burning neem oil in kerosene may also a safe alternative, he states. Source: Harmful mosquito repellent, The Hindu, New Delhi, 2001 May 24. http://www.indegene.com/Ent/Home/indEnt_Ind_News_26-05-2001_1.asp

		See the following on the Efficacy of Insect Repellents Radin MSF, Day JF. Comparative Efficacy Of Insect Repellents Against Mosquito Bites. N Engl J Med, Vol. 347, No. 1 July 4, 2002. Available at http://lcmcd.org/relellents.pdf Anderson RR, Harrington LC. Mosquito Biology for the Homeowner Available at http://www.entomology.cornell.edu/MedEnt/MosquitoFS/MosquitoFS.html Fradin MS. Mosquitoes and Mosquito Repellents: A Clinician's Guide. Annals of Internal Medicine. 1 June 1998 Volume 128 Issue 11 Pages 931-940. Available at http://www.annals.org/cgi/content/full/128/11/931

IV. Mosquito nets: Mosquito nets are the best and safest means of protection against mosquito bites during nights, the peak biting time for the female anopheles. Insecticide treated bed nets (ITNs) have emerged as a very important tool in malaria control in endemic areas.

Many types of nets are available depending on the size, material (polyester, cotton, polyethylene or polypropylene) and treatment with insecticides.

Untreated bed nets form a protective barrier around persons using them. However, mosquitoes can feed on people through the nets, and nets with even a few small holes provide little, if any, protection. Nets should be strong and with a mesh size no larger than 1.5 mm. The net should be tucked in under the mattress, ensuring first that it is not torn and that there are no mosquitoes inside. Nets for use with cots and small beds are available, affording protection for babies whenever they are sleeping.

The application of a residual insecticide greatly enhances the protective efficacy of bed nets. The insecticides used for treatment kill mosquitoes and other insects. The insecticides also have repellent properties that reduce the number of mosquitoes that enter the house and attempt to feed. In addition, if high community coverage is achieved, the numbers and longevity of mosquitoes will be reduced. When this happens, all members of the community are protected, regardless of bed net ownership. ITNs have consistently proved to reduce severe disease and mortality due to malaria in endemic regions and ITNs are now an important method for controlling malaria. In community-wide trials in several African settings, ITNs have been shown to reduce all-cause mortality by about 20%.

Currently, only pyrethroid insecticides are approved for use on ITNs. These insecticides have very low mammalian toxicity but are highly toxic to insects and have a rapid knock-down effect, even at very low doses. Pyrethroids have a high residual effect and they do not rapidly break down unless washed or exposed to sunlight. To maintain the efficacy of ITNs, the nets must be retreated at intervals of 6-12 months, more frequently if the nets are washed. Re-treatment is done by simply dipping nets in a mixture of water and insecticide and allowing the nets to dry in a shady place. Kits for retreating nets are available in most countries. Several companies have developed long-lasting ITNs that theoretically retain lethal concentrations of insecticide for the life of the net (3-5 years). Olyset net, a wide mesh net woven from polyethylene thread containing 2% permethrin, is yet another improvement in ITN technology. This net has two advantages over traditional nets in that the wide mesh permits better ventilation and light, and the treated thread enables a slow release of permethrin to the fibre surface, ensuring a long residual effect (over a year).

Travelers to malaria-risk areas may also use ITNs as one of several precautions against malaria. Travellers camping in tents should use a combination of mosquito coils, repellents and screens. The mesh size of tent screens often exceeds 1.5 mm, so that special mosquito screens have to be deployed.

For information on ordering insecticide-treated bed nets:
www.travmed.com, Phone 1-800-872-8633, fax: 413-584-6656; or
www.travelhealthhelp.com, Phone 1-866-621-6260
Insecticide-Treated Bed Nets (ITNs): Commodity or Public Health Intervention?

V. Air-conditioning is a highly effective means of keeping mosquitoes and other insects out of a room.