WE are in the hurricane season where typically we get increased rainfall associated with tropical waves and unstable weather patterns. With rain comes more breeding sites for mosquitoes, as every puddle, cistern, sink hole in a gully, or pothole that doesn’t dry up within five to six days can be a source of mosquito egg laying and hatching.

So with the Zika virus spreading through the bite of an infected Aedes aegypti mosquito, we must always seek not to be bitten by them.

PREVENTIVE APPROACHES

These preventive approaches include wearing long-sleeved shirts and long pants (which is difficult for us in hot, tropical countries), keeping our windows closed (also difficult because of our ambient temperatures and most houses do not have air-conditioning units), keeping all our windows closed (houses would become too hot in Jamaica), or installing mesh screens on our windows to prevent mosquitoes from entering our homes (too costly for most Jamaicans).

With the drawbacks to implementing these preventive measures, we therefore have to seriously consider whether insect repellents might be of benefit in some lasting way.

The Centers for Disease Control and Prevention (CDC) in the United States of America recommends using an Environmental Protection Agency-registered mosquito repellent. These repellents have been shown to be safe and effective, which is especially important in pregnant and breastfeeding women.

In addition, most on the list are considered safe for children two months of age and older. For children under two months, an infant carrier that is covered by an insect net or screen is considered good protection from the mosquito bite.

EPA-REGISTERED MOSQUITO REPELLANTS

High on the list is DEET, a chemical (N,N-diethyl-meta-toluamide) that is present in the commercially produced insect spray OFF and a few others. Read their labels as children and adults should use products that have 10 to 30 per cent concentrations of DEET. A 30 per cent concentration should provide protection against the mosquito bite for around six hours, while a 10 per cent concentration will only provide protection for about one to three hours.

Concentrations of DEET over 50 per cent offer no additional benefit.

Picaridin or icaridin (present for example in Avon Skin-So-Soft and Bug Guard with Picaridin) at 20 per cent concentration provides protection against the mosquito bite for up to seven hours, while the 10 per cent concentration will protect for up to five hours.

Other EPA-approved mosquito repellents, whilst also safe and effective, tend not to last as long. Lemon eucalyptus oil (para-methane-diol) that is present, for example, in both Cutter and Repel eucalyptus insect repellents, protects for up to two hours, but is not recommended for children under three years of age.

IR3535 (Ethyl butylacetylaminoproprionate) that is present in the commercial products Avon Skin-So-Soft and Bug Guard plus IR3535 at 7.5 per cent concentration, although safe for children over two months of age, only protects for 10 to 60 minutes for each spray application.

While those repellants mentioned above are sprayed directly on to exposed skin, Permethrin is recommended as an insect repellent for spraying on to clothing and personal gears, such as pants, socks, boots, backpacks, and tents. Permethrin-treated items will often retain their insect repellent properties through several cycles of washing. However, it should not be used as an insect repellent on the skin.

NATURAL INSECT REPELLANTS

A variety of ‘natural’ insect repellents that are not registered by the EPA can be found on the market in some countries. According to the associate professor of Pharmacy Practice at the Center for Drug Information & Evidence-based Practice at Creighton University, Omaha, Nebraska, people often turn to these products with the assumption that they are safer than other products. However, these products may not work as well as the EPA-registered products, or they may have unknown effectiveness or unknown safety when applied to the skin.

Consequently, natural plant oils such as citronella oil, cedar oil, geranium oil, and lemongrass oil, are generally not recommended as reliable protection against mosquito bites.

A test by Consumer Reports in the USA found that products containing one or more of these ingredients provided protection for only up to one hour or not at all.

DO’S AND DONT’S

In order to maximise the safe and effective use of mosquito repellents, you should spray on to all exposed parts of your body. However, you should not apply any repellent underneath your clothing, or to irritated skin or open wounds.

You should not spray the repellent on to your face, but instead spray into your hands and then rub on to your face in order to avoid repellent contact with your eyes and mouth.

Further, do not let young children apply the repellent to themselves. Always remember that low-concentration insect repellents only provide protection for one to two hours, and so you should always reapply within the specified period for the particular repellent or if a mosquito bite occurs at any time.

Please spread the word to all your friends, family, neighbours, and associates, and work hard at preventing mosquito bites. Once you do, you all will avoid not only Zika, but also dengue, chikungunya, and yellow fever, as well as other mosquito-borne infections.

Derrick Aarons MD, PhD is a consultant bioethicist/family physician, a specialist in ethical issues in medicine, the life sciences and research, and is the ethicist at the Caribbean Public Health Agency – CARPHA. (The views expressed here are not written on behalf of CARPHA)