The Straits Times
Mind Your Body | Health Help | Doc Talk By Dr Jean Ho
Aug 6, 2009
Mosquitoes suck, whether we are up on Bukit Timah Hill or walking in our garden. These tiny six-legged bloodsuckers cause some of the most common blood-borne diseases known to man.
Several weeks ago, I opened yet another letter from the Ministry of Health (MOH). I expected an update on the dreaded Influenza (H1N1) virus. For a global city and travel hub like Singapore, H1N1’s spread is a serious matter.
However, as we have witnessed in the past months, and honed from the experience with Sars a few years back, we implemented swift and decisive measures. I half-expected to see the latest directives on steps to take when faced with a feverish patient.
Instead, the words malaria, dengue and chikungunya stood out. The letter reported that clusters of malaria had been identified in several parts of Singapore. It occurred to me that while we were bracing ourselves for the onslaught of a new microbial enemy, the old ones have never gone away.
The bites of mosquitoes have always been a source of nuisance and disease. A nuisance because their bites are annoyingly itchy; and dangerous because they spread diseases, namely dengue, chikungunya and malaria.
Children between the ages of two and seven are most prone to insect bites. Mosquitoes are known to embark on their feeding frenzy at dawn and dusk. These are also the times when children throng the parks and playgrounds – a rich picking for a mozzie’s blood meal.
Moreover, MOH data show that the incidence of dengue, a disease transmitted by the bite of the Aedes mosquito, peaks during the hot months of June to August. The reaction after a bite is a swollen bump that is excruciatingly itchy. Sometimes, tiny blisters appear.
BH, a five-year-old boy, had several such bumps on his arms and legs which had swollen to the size of cherry tomatoes. After the swellings and itching subside, there will be scars.
Some children, like BH, are especially hypersensitive to mosquito bites. They are allergic to the proteins in the insect’s saliva. Still, one good thing – if it can be called that – is that with repeated bites, children become de-sensitised or numbed to the bites and eventually outgrow the allergy.
More seriously, if the mosquito’s saliva is teeming with the dengue or chikungunya virus, the consequences will be more than skin-deep.
Relief for common mosquito bites are available in pharmacies.
For BH, I prescribed antihistamines to reduce the swellings and itch. I also treated some of the bumps which had become painful and infected. Timely treatment of the bites will speed up the recovery and minimise scars on the skin.
How does one protect against these blood-sucking arthropods (creatures with segmented bodies and six or more jointed legs)?
Avoid strong perfumes as mosquitoes are attracted to these; wear protective clothing when venturing into wooded areas such as parks and nature reserves; and use a suitable insect repellent. Insect repellents have been around since ancient times, ranging from tar, smoke to plant oils. Modern options include Deet, citronella oil and eucalyptus oil.
Deet has had a long safety record and is approved for use on children as young as two months. It offers protection for four to six hours, depending on its concentration. A lower concentration (Deet 10 per cent) is generally recommended for young children and pregnant women.
Citronella oil, with its distinct scent, gives protection for not more than 30 minutes. Reapplication is needed if several hours of outdoor activity are intended.
More recently, a new compound called Picaridin has been approved as an alternative to Deet. It has several advantages over other repellents: it does not feel sticky or greasy on the skin, is less likely to irritate the skin and will not damage plastics or fabrics.
I find it especially convenient to use as it can be sprayed on skin as well as on clothing. Safe for use on children, it has been approved by the World Health Organisation as an alternative to Deet for protection against mosquitoes which carry malaria.
Finally, mozzies breed easily, so remember to drain the water from flower pots.
Dr Jean Ho is a consultant dermatologist with special interests in paediatric dermatology and laser surgery. She practises at Mount Elizabeth Medical Centre.