Battling Dengue in Perak – Part 2

Cover Story

By Yvette Yeow

With the recent hike in Dengue cases, it is important that the public is well informed on mosquito prevention methods and devices that could be used to keep the insects at bay. Ipoh Echo recently took the opportunity to conduct a research on bug sprays, mosquito repellents and devices to provide adequate information to the public as well as to assist in selecting what is suitable for individual and family usage.

Bug Off – or  Ways to Fend Off the Mosquito Menace

Mosquito Prevention Devices such as bug sprays, mosquito coils and repellent gels have been a necessity to most household units in preventing the proliferation of mosquitoes. However, the side effects that accompany them are tremendous. According to a research conducted by the National Centre for Biotechnology Information (NCBI), burning one mosquito coil is equivalent to burning about 75-137 cigarettes, due to the release of carcinogenic substances from the smoke of the coil. Long-term burning of mosquito coils may also lead to illnesses such as lung cancer and other respiratory problems. Bug sprays and repellent gels on the other hand, may not be as ‘deadly’ as the mosquito coil, but it also serves up its fair share of concerns such as the DEET chemical in most repellent gels that could cause neurological damage if used in large doses.

There are a total of four registered and approved repellent chemicals that offer a high level of protection from a variety of biting insects and have relatively good safety profiles including Picaridin, IR3535, Oil of Lemon Eucalyptus/PMD and argumentatively DEET. Picaridin is a chemical substance that performs like DEET, repelling a wide range of insects. In 2012, the World Health Organisation recommended Picaridin, along with DEET and IR3535 for the protection against mosquitoes that carry diseases. Picaridin could be a better alternative to DEET as it appears to not have the same neurotoxicity concerns as the latter. On the other hand, IR3535 also known as Ethyl Ester is structurally similar to the naturally occurring amino acid B-alanine. Although it is known to be very irritating to the eye, it poses less safety risks compared to DEET.

Other botanical products may also be worth trying if the area you are heading to is not at high risk of contracting any serious insect-borne diseases. But many of these products may contain allergens in highly concentrated forms and effectiveness varies widely. That is why the only botanically-derived ingredient that the CDC recommends is Oil of Lemon Eucalyptus/PMD, which has been registered with the EPA and undergone efficacy testing. Mosquito repellent substances are also not advisable to be applied on infants and children from 0-12 years old.

Before grabbing a bottle of repellent gel or bug spray, one should consider taking precautions such as giving bugs a smaller target area. In bug country, one could consider covering up in light coloured clothing such as long-sleeved shirts with a high collar. Using a mosquito net or turning up the speed of fans could also help prevent mosquito bites. Aside from that, people should also conduct a weekly check around the house and get rid of any possible mosquito breeding grounds such as draining standing water. Bug repellents and sprays should always be the last choice.

Ipoh Echo took the opportunity of drawing up a guide to common brands that are non-toxic and easily available from major drug stores or pharmacies such as Watsons and Guardian:

Effectiveness of Mosquito Attractants and Traps

On the other hand, the public could also opt for mosquito attractants and traps instead of insecticides or repellents. There are a few different types of mosquito attractants and traps such as the CDC trap, using a fan system to suck mosquitoes into a collection bag; the Army trap also known as the U.S. Army miniature, solid-state (AMSS) mosquito light trap is an improvement of the CDC trap and the Encephalitis Vector Surveillance (EVS) light trap which releases carbon dioxide to attract mosquitoes. All of these traps utilise some form of attractant that lures the host-seeking female mosquitoes to a capture or killing device.

However, how effective are these mosquito attractants and traps? Mosquitoes follow a complex set of cues to find a host. Most mosquitoes usually feed on plants or fruits, but the female mosquitoes need blood to produce eggs as well as to fertilise them. When a mosquito flies, it receives host recognition cues, and one of them being carbon dioxide. The carbon dioxide in traps could help attract mosquitoes especially if it is released in  large amounts. Normally carbon dioxide traps could attract mosquitoes over a distance of 16m. Mosquitoes are also attracted to light sources. This is due to the fact that the mosquito’s vision is highly limited and depends largely on the amount of light to attack the host. Light intensity is often the most important environmental factor influencing mosquito activity. The combination of human odour emitted from their skin and breath also attracts mosquitoes. Human sweat especially plays an important factor in attracting mosquitoes. Research has shown that mosquitoes are able to discriminate between potential hosts; which is why some people are more attractive to mosquitoes than others.

These different factors have led to the development of different kinds of mosquito traps and attractants, most of which have shown positive results in attracting huge number of mosquitoes indoors and outdoors with lesser side effects compared to the mosquito repellent or insecticides. Even though it is highly effective in killing mosquitoes, these traps and attractants should not be considered as magic bullets that could destroy all biting mosquitoes, instead as part of the source reduction method. The public should always keep in mind that effective mosquito management requires integrating a variety of available control strategies such as surveillance, source reduction, biological control methods and instilling mosquito traps. Before looking for a suitable mosquito attractant or trap, Ipoh Echo reminds the public to not only look for an effective kill, but also consider its properties, whether it is safe for family usage, environmentally friendly and chemical free.

As we go to print, Ipoh Echo has received news of a Papaya Leaf dengue treatment for those unfortunate enough to contract the disease. According to The Sun, The Institute for Medical Research (IMR) will soon release pamphlets on the correct use of papaya leaf extract in the treatment of dengue as clinical studies have shown it to increase blood platelet counts and assist in the recovery of those with less severe complications.

Having said that, Ipoh Echo nevertheless recommends that those suspected of having contracted dengue to go straight to the doctor for medical treatment before attempting to self medicate.