Last Updated December 20th, 2021
The Mosquito: A brief history of the menace
Being bit by a “mozzie” is never pleasant. Well, you would say “mozzie” if you were in the UK, but the general feel of a bite and its after effects are about the same anywhere you are. This is apparently true for any time or era as well. The mosquito is an ages old disease vector. Much of the research in recent times has helped to reveal the incidence of malaria in antiquity.
Its effect in the Mediterranean region of Europe has been studied in quite some detail. The study has revealed how the spread of malaria even altered the age structure of populations, settlement patterns, and agricultural systems. These changes, though at a localized level, were very frequent in Greek colonies of Southern Italy. An example would be that of Syracuse, where the area of marshland was much higher in antiquity (ca. 500 BC) than it is presently. This marshland led to the spread of malaria.
Not all mosquitoes spread malaria though. But then again malaria is not the only disease they cause. The pest also causes diseases such as dengue, chikungunya, filariasis, tularemia, and yellow fever. Every year 700,000 people worldwide die of diseases transmitted by mosquitoes. And if the mosquito doesn’t spread disease it will still give you an itchy red bump. This is another reason why you should keep these pests away. The regular mosquito repellents are available as coils or vaporizing liquids. In addition, there are several natural repellents that are less toxic to the human body and still get the job done.
Why you should not use spatial repellents
Transfluthrin is the common ingredient in spatial repellents (both liquid and coil) commonly used to keep mosquitoes away. Transfluthrin works by paralyzing the mosquitoes and preventing them from infecting the host. It is approved for use in nearly 50 countries worldwide.
Transfluthrin formulations are available as coils or as aerosols. The WHO has not evaluated transfluthrin. However, Australian authorities have set an ADI (acceptable daily intake) of 0 to 0.003 mg/kgbw/d (milligram per kilogram of body weight). For a person weighing 80 kg, this translates to 0.24 mg of transfluthrin. Coil repellents work in a way similar to liquid repellents, only the means of dispersal of the insecticide is different.
No matter how safe liquid or coil repellents are deemed to be, dizziness, headache, and drowsiness have been observed in people using them. In addition, their efficacy is determined by airflow, humidity and temperature in the room as well, which will vary from place to place.
The problem with chemical topical repellents
Most chemical mosquito repellents used topically contain DEET. DEET (chemical name N, N-diethyl-meta-toluamide) is approved by the EPA (even in a review as recent as 2014) as a mosquito repellent and therefore used as an active ingredient in several insect repellents. However, formulations for direct application to skin can contain anywhere from 5 to 99% DEET. Though it is even recommended for children over 2 months of age, care must be taken to not apply it on their hands. Finally, DEET is not completely safe for adults either. When any product containing DEET enters the eyes, it could cause watery eyes, irritation, and pain. People who apply and leave it on for extended periods have also reported swelling, rash, irritation and nausea.
Natural Repellents for Mosquitoes
The thought of using spatial repellents or conventional, chemical mosquito repellents for topical use like DEET and picaridin might bother you. It is therefore time to consider the use of natural repellents. These repellents are recommended especially in low-risk zones. These include activities such as walking in a well-maintained park, or camping st the back of your house. In a high-risk zone, it is recommended to use a DEET-based repellent.
Citronella oil is commonly used as a replacement for DEET-based mosquito repellents and has been found to be very effective. It is available as a body lotion, a spray, or as candle, the effectiveness of citronella is determined by its formulation. It can be as effective as DEET, when formulated correctly, and can protect you for up to 2 hours. What happens if the formulation of citronella is not right? It can evaporate too quickly leaving you vulnerable to mosquito bites.
In a study, it was proven that cinnamaldehyde, a constituent of cinnamon exhibited strong anti-larval properties against the yellow fever mosquito, Aedes aegypti. Oil derived from the bark of the Cinnamomum cassia tree is the most common source of cinnamaldehyde.
You can prepare a diluted mixture of cinnamon oil at home. You can spray it on your skin and around the house. Try to always use it diluted. Cinnamon oil in a concentrated mixture can cause a reaction on your skin.
Studies have found that clove oil is effective as a mosquito repellent when applied to the skin for up to 4 hours. However, it must not be applied undiluted to the skin. The oil could be absorbed by the skin, leading to adverse effects. In any case, it must also not be applied around the nose, mouth, or the eyes.
Greek catnip oil
The oil of Greek catnip, obtained from the plant Nepeta Parnassica, can keep mosquitoes away. A study revealed that oil obtained from it helps protect a person from mosquitoes for up to three hours. Iowa State University researchers also found nepetalactone, which is found in catnip oil to be ten times as effective as DEET. Perhaps a reason why it has not become successful commercially is because of the significant decline in its efficacy over the three-hour period, whereas DEET shows no such decline.
The mixture (as spray) for use at home is a combination of catnip oil and vinegar. Take two cups of catnip, crush the leaves, and then add three cups of white vinegar. Store in a quart mason jar in the dark for two weeks, but shake the jar every day. At the end of two weeks, pour it into a spray bottle and refrigerate. Spray onto clothing or skin for protection against mosquitoes.
Crushed flowers of lavender not only have a fragrance but the oil extracted from them effectively repels mosquitoes. Lavender also has antifungal, antiseptic, and analgesic properties. It has a calming and soothing effect on the skin as well.
Lavender can be grown indoors or outdoors. Crush the flowers to make the oil. Now you can apply them to areas where you normally get bitten by mosquitoes. Examples are your ankles and your arms.
Lemon eucalyptus oil
Lemon Eucalyptus oil has been used since the 1940s as a mosquito repellent. The Centre for Disease Control (CDC) has approved lemon eucalyptus oil as an ingredient that is effective in a mosquito repellent.
It has a pale yellow color and a thin consistency. However, it is not registered with the EPA (Environmental Protection Agency) as an insect repellent.
You can make a diluted solution by adding one part of lemon eucalyptus oil to ten parts of sunflower oil. This mixture, however, must not be used for children below 3 years of age.
Another useful repellent is the oil obtained from thyme. In a study conducted on hairless mice, it was shown that 91% of the mice sprayed with 5% thyme oil solution were resistant to mosquito bites. In addition, the next time you are out camping, burn a few thyme seeds or leaves and let the fragrance spread. Burning thyme is known to be just as effective in driving away mosquitoes.
Soybean oil could be effective as a mosquito repellent. In fact, it is being used in some commercial mosquito repellents as well.
It is very effective when used in a mixture with lemongrass oil.
Tea tree oil
Tea tree oil is an oil that has its origins in Australia. It is also called melaleuca oil. It was long since usd for the treatment of skin diseases and burns etc. It is even beneficial for the treatment of dandruff, bad breath, hirsutism etc. Recent studies have now shown that it is useful as an insect repellent.
Very popular in India, Neem oil has a number of uses. It is traditionally used as a mosquito repellent, among many other uses, such as for the treatment of rashes, burns etc. Neem oil offered a considerable level of protection up to a period of three hours according to a recent study that was conducted in Ethiopia. The reason why neem oil’s topical use is avoided is because it can cause a bit of skin irritation in some people.
Geraniol finds use as a fragrance, and is derived from lemongrass, rose, and citronella. It provides a maximum of about four hours of protection.
People with sensitive skin have often reported a reaction to it. Avoid rubbing around the eyes, as it can be particularly irritating there.
Risks of using essential oils
Do not use essential oils directly on your skin. They must always be used diluted with another oil. This oil that is present along with the essential oil in the mixture is called a carrier oil. Only one in every five parts of the mixture must be the essential oil. Most of the mixture must be composed of the carrier oil.
Essential oils are not regulated by the FDA. This means that you are buying them for use at your own risk. If you are in a country where diseases like dengue or chikungunya are common, please use a DEET-based mosquito repellent. In low-risk zone, should you choose to use essential oils always procure them from a trustworthy place. Also, make it a point to read every instruction and warning provided on the label.
Allergic reactions can also result from the action of essential oil. You can do a spot test so that such things do not happen. You could apply a drop of the solution containing the essential oil at a spot on your skin. Now wait to see if you get any kind of allergy, hives, or a burning sensation. If you don’t get them, that means it should be good for you.
Treating mosquito bites
Despite the effectiveness of most of the natural mosquito repellents mentioned in this article, you might still end up getting a few bites even after using them. The redness and itching can be treated by placing onion pieces on the affected area. Garlic could also be used, as can apple cider vinegar.
In certain cases, it is not restricted to just redness and itching. You may have symptoms that aggravate over time such as the formation of pus or an infection that does not go away in time. In such cases, you must consult a doctor immediately.
Are natural repellents always useful?
Spatial repellents have known side effects, and topical repellents like DEET have very few in comparison. Though DEET is highly effective and commonly used as a mosquito repellent, the use of natural repellents is slowly finding favor with scientists in many recent studies. No matter what the occasion, a party in your backyard or a hike to the hills nearby or a walk in the park, natural mosquito repellents find use. On the other hand, you might find yourself in a tropical, mosquito-infested country. The best and probably the only way to protect yourself then is by using DEET. Better safe than sorry.
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