Insect repellent
Role of Repellent in Control of Mosquito-borne Diseases
In mosquito-borne diseases such as dengue, transmission is sustained by infected mosquitoes and infected humans. An infected mosquito bites an uninfected person, infecting him. In turn, when the infected person is bitten by an uninfected mosquito, that mosquito could then spread it to other uninfected individuals.
Repellent repels mosquitoes- that is, it reduces the chances of being bitten- but it does not mosquito-proof a person. In this light, repellent use offers individuals added protection against mosquito-borne diseases. In the community, it reduces the transmission of mosquito-borne diseases.
Applying insect repellent is not the only way to protect oneself against mosquitoes; wearing long-sleeved clothing, using mosquito nets while sleeping and staying in mosquito-free rooms are good measures to prevent mosquito bites. Others include insecticide sprays and burning repellent oils. You should decide for yourselves on one or a combination of these.
Situations when you may need repellent:
- You are a confirmed or suspected Dengue patient, having a fever. Fever in Dengue patients coincide with the presence of Dengue virus in their blood, which could be inadvertently transmitted to family members and neighbours via the Aedes Mosquitoes.
- A family member is a dengue patient.
- You know someone in your neighbourhood has contracted Dengue. Use of repellent can minimize your chance of being bitten by an infective mosquito.
- You are visiting a place with high mosquito population. Repellent can help to minimize nuisance mosquito bites.
Types of Mosquito Repellent
The three main repellent active ingredients registered in Singapore are DEET, Hydroyethyl Isobutyl Piperidine Carboxylate, and Ethyl Butylacetylamino-propionate.
Internationally, multiple studies have shown DEET to be the most common active ingredient for repellent products, and is effective. There exist products in the market with other active ingredients of varying effectiveness, and work differently on each individual. One is citronella, which is effective for shorter durations and thus has to be reapplied more frequently. Users should follow the instructions on the label.
Precautions in Using Repellent
Some other precautions to take when using repellents - Apply repellents only to exposed skin and/or clothing (as directed on the product label.) when necessary. Do not use repellents under clothing.
- Never use repellents over cuts, wounds or irritated skin.
- Do not apply to eyes or mouth, and apply sparingly around ears. When using sprays, do not spray directly on face–spray on hands first and then apply to face.
- Do not allow children to handle the product. When using on children, apply to your own hands first and then put it on the child. You may not want to apply to children’s hands.
- Use just enough repellent to cover exposed skin and/or clothing. Heavy application and saturation are generally unnecessary for effectiveness. If biting insects do not respond to a thin film of repellent, then apply a bit more.
- If you or your child get a rash or other bad reaction from an insect repellent, stop using the repellent, wash the repellent off with mild soap and water. You may wish to consult a doctor, take the repellent with you to show the doctor.
More information on DEET
DEET - N.N Diethyl-meta-toluamide. Currently, in the local market, the repellent products for general domestic use contain DEET in concentration between 7% to 25%. Increasing concentrations do not improve protection but do last longer in terms of protection. It has been documented that concentrations of about 6% protects for about two hours, and 20% for about 4 hours.
However, length of protection from mosquito bites varies with other factors like the ambient temperature, amount of physical activity/perspiration, any water exposure, abrasive removal, and other factors. Reapplication should be made as necessary. Children should use repellents with lower concentrations of DEET. It is not advisable for use on infant under 2 months. Other measures like the mosquito net is the preferred choice for infants.
http://www.co.boulder.co.us/health/hpe/wnv/prevention/effectiveness.htm
http://www.cdc.gov/ncidod/dvbid/westnile/RepellentUpdates.htm
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