January is over. Traditionally one of the slowest months, it went really quickly for me this year which is great but then it worries me how fast the rest of the year will go. We have three milestone birthdays and a special anniversary this year so it is a year we wish to savour.
One thing we have also decided to do is travel to China to find my dad’s father’s home. My paternal grandfather left China when the Japanese invaded. He was from a village near Xiamen, Fujian province and he made his way initially to the Yunnan province from where the China-Burma road originates. He made his way into Burma on this road and met my maternal grandmother in an area near Rangoon. The Japanese, however, then invaded Burma and conditions in Burma subsequently deteriorated. When my dad was 2 years of age, both his parents died of bubonic plague, leaving him and his sister to be brought up by his grandmother and an aunt.
It was always my father’s wish to travel to China to find his father’s village. He tried to get there after two visits to Hong Kong but then Covid happened and then he got cancer and then he died. After much investigation on my mother’s part, we finally tracked down a 90-year old man in my dad’s village in Burma who remembered where my paternal grandfather was from. In shaky Chinese script and Burmese script, we have translated this and finally found the location of the village in China and plans are being made.
Travel to Asia can be logistically challenging with kids. Mosquito repellent is key to avoid insect and tick bites and hence vector-borne diseases such as malaria, dengue, yellow fever and Japanese encephalitis. The question then arises with children as to whether you use DEET or an alternative.
It was therefore interesting to read the review article in January’s edition of Pediatric Dermatology on the safety of DEET insect repellent and the efficacy of natural alternatives in children.
[Ghali H, Albers SE. An updated review on the safety of N, N-diethyl-meta-toluamide insect repellent use in children and the efficacy of natural alternatives. Pediatr Dermatol. 2024; 1-7.]
What is DEET?
DEET is N, N-diethyl-meta-toluamide, a synthetic insect repellent introduced for public use in 1957. The Centers for Disease Control and Prevention (CDC) and the Environmental Protection Agency (EPA) highly recommend the use of DEET for protection against mosquito bites.
The concentration of DEET in a product does affect how long it will protect for. For example, a concentration of 5% provides 2 hours protection, 10% provides 3 hours, 15% provides 5 hours and 30% provides 6 hours protection. There is no further increase in duration of protection with products with greater than 50% concentration.
Insect repellent containing 50% DEET is recommended for all UK travellers over 2 months of age provided it can be tolerated.
[UK Health Security Agency, Advisory Committee on Malaria Prevention (ACMP), Guidelines for malaria prevention in travellers from the United Kingdom 2023. https://assets.publishing.service.gov.uk/media/65a16fc674ae66000d738a64/guidelines-for-malaria-prevention-in-travellers-from-the-UK-2023.pdf]
In America, the American Academy of Pediatrics advises caution in children, advising parents to balance the risks of contracting an insect-borne disease and the possible effects if the insect repellent is used incorrectly. They advise using the lowest possible concentration of DEET for the duration of exposure, limiting it to once daily application to exposed skin, using concentrations less than 30% and washing it off immediately once there is no more risk of being bitten.
What are the side effects of DEET?
DEET is an irritant to the skin and the higher the concentration, the higher the risk of skin irritation.
The main concerns with DEET are the reports of neurological problems in children exposed to DEET. The authors look at this area in more detail. They report that in a limited number of cases of neurological problems in children in whome DEET was used, the child was sprayed daily or nightly with DEET insect repellent for a period ranging from 10 days up to 3 months and in one case, the child had eaten a small amount of DEET.
A large study of over 20,000 cases of DEET exposure in children and adults reported to poison control centres found that even though children made up most of the cases, they had less severe reactions than adults. 70% of cases showed no associated symptoms with DEET exposure.
[Bell JW, Veltri JC, Page BC. Human exposures to N,N-diethyl-m-toluamide insect repellents reported to the American Association of Poison Control Centers 1993-1997. Int J Toxicol 2002;21(5):341-352.]
What about natural alternatives?
Given the concerns over DEET, plant-based alternatives have become popular. The authors look at several of these alternatives.
Citronella oil and oil of lemon eucalyptus (OLE) are EPA-approved alternatives. Citronella oil has been used for centuries as a natural insect repellent. It is susceptible to degradation in the presence of air and warm temperatures which is overcome if it is blended with 5% vanillin. This combination is effective against the mosquito responsible for transmitting yellow fever, dengue fever and Zika virus and also the mosquito which transmits malaria. It also has low toxicity. However, it is not recommended in children under 2 years of age. In the EU and the UK, citronella oil has been withdrawn due to its short duration of action.
Oil of lemon eucalyptus (OLE) has shown efficacy against mosquitos, biting flies and gnats. It is available in 40% concentrations, which is more effective than 10% DEET, and is available as wipes. It is however, recommended that it is not used on children under the age of 3 years.
There are several other alternatives such as permethrin, 2-undecanone from wild tomatoes, catnip oil, clove and peppermint oil but safety studies are lacking for these agents.
The World Health Organisation, the EU and the UK also recommend the use of Icaridin (Picaridin), a synthetic insect repellent that has been present since the 1980’s, inspired by the chemical in black pepper that makes it spicy.
IR3535 or 3-ethylaminoproprionate is also recommended, again a synthetic insect repellent inspired by a naturally occurring amino acid. It has an excellent safety profile and hence there are no age restrictions on its use; it can be used on babies and pregnant women.
I think the most interesting thing I have found in researching this blog is how the advice varies depending on which country you are in (the review article is written in an American journal). The advice that is unanimous, much like sun protection measures, is that avoidance eg of stagnant water and covering up the skin with long sleeves and long trousers is also key.
Dr Sandy Flann, Consultant Dermatologist.