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Preventing Insect Bites Naturally.



Copyright © Tony Burfield June 2005





Mosquito Watch.

Worries that the changing climate in the UK is attractive to Stegomyia albopicta – the Asia Tiger Mosquito which is linked to dengue fever and the West Nile Virus as well as other diseases, have hit the UK newspaper headlines in June 2005. Meikle (2005) reports that a mosquito watch is being formed, with UK residents being urged to contact local health officials in order to identify the insect species responsible. The Governments Health Protection Agency team based on Porton Down and the Chartered Institute for Environmental Health have organised the initiative. Government watchdogs fear that discarded car tyres, as well as the 5 million bought into Britain for recycling, may act as a shelter for mosquito eggs, which can lie dormant for very long periods.


A Pharmaceutical Industry Stitch-Up?

To repel biting insects, consumers can theoretically make a conscious purchasing choice between synthetic chemical repellents or naturals-based formulations but the very nature of pharmaceutical industry advertising (straight into the medicinal practitioners in-tray!) can mean that medical practitioners are often only familiar with pharmaceutical synthetic repellents, and can be broadly unaware of the possible beneficial use of many alternatives based on natural aromatic materials. Further, the often-unfair denigration of phytomedicines (being unsafe or of doubtful therapeutic efficiency or value) has lead to their poor image. Critical analysis of investigations which has been carried out on the insect repelling abilities of natural products often reveal that flawed experimental design, or that teams of researchers are without the necessary cross-disciplinary skills to properly undertake this research (Burfield 2005). Further, since “young researchers are forced to follow fashionable...(& probably) commercially viable, lines of work if they want to remain within the bounds of academic respectability” (Anon 2005), finding positive benefits from natural products research may not be their most advisable career move! Typical of this tendency to avoid natural products above is the leading textbook on Biocides (Knight & Cooke 2002) which defines biocides as ‘products which control harmful organisms by chemical or biological means’, but nowhere in the book’s 379 pages is the mention of anything which is non-synthetic.  Yet essential oils are used as biocides the world over.


It can sometimes appear that keeping their clients alive might be of less importance to the pharmaceutical industry than eliminating economic competition! An article describing a study which looked at over 18,000 admittances to two Merseyside hospitals was published in the British Medical Journal (Pirohamed et al. 2004). The authors estimated that 10,000 patients die per year of reactions to prescribed medicines (through Laurance 2004), but the study also maintains - conveniently for the pharmaceutical industry - that adverse drug reactions are down to the practitioners for not giving the appropriate advice for the patient circumstance (!). Laurence also points out that one of the authors of the study above also happens to be the chairman of the MHRPA. Collusion in lobbying at Brussels between the pharmaceutical industry and the UK’s MHRA (syn. MHPRA) in order to keep adverse information on drugs secret, has been the subject of investigative journalism (Evans & Boseley 2004), and it will perhaps come as no surprise perhaps for readers to learn that the MHRA is 100% funded by pharmaceutical industries (Laurance 2004).


Other examples of recent press coverage about drug secrecy include Prigg (2004) who reports that lung cancer sufferers are receiving sub-standard treatment due to concealment of research findings by drug companies. And yet in spite of this bad press over adverse reactions to conventional prescribed drugs, alleged and unproven dangers from herbal medicines are so serious, apparently, that urgent legislation is needed (Prof. Houghton of Kings College, London addressing the Festival of Science 2004, through Prigg 2004). It is perhaps because of facts like these above, that prompts Monbiot (2004) - reporting on “Corporate stooges that nobble serious science” - to state that “… the scientific establishment is rotten from top to bottom, riddled with vested interest…”.


The successful lobbying of EU law-makers by pharmaceutical representatives on corporate expense accounts, has seen the removal of many herbal and folk-medicine products from the shelves of EU high street chemists and health shops, which are competitive to pharmaceutical synthetic products. Kava-kava, St Johns Wort, and now Tea Tree Oil (SCCP 2004) have all been recently attacked on safety grounds, and in 2004 the Canadian PMRA proposed the phase-out of Canadian registrations for Citronella oil as personal insect repellents unless human safety data is provided. Nor seemingly is there a truly independent body capable of high-level investigation and the necessary overview required to fairly adjudicate on these decisions, or to oversee “expert” committees who often rely on inadequate literature searches, or conveniently forwarded data (…by whom, you might ask?) that seems to be carefully selected to put the commodity in a bad light. This situation leads to bad decisions and bad law-making, and leaves many citizens, health workers and medical practitioners dazed, confused or completely mislead about true safety risks attached to medicinal products.


There are some signs that producers of natural products and associated stake-holders are now fighting back, however. The UK Medicines Control Agency have agreed to re-examine the Kava issue in 2005 (Gruenwald 2004). The alleged health issues surrounding St. Johns Wort haven’t stopped 12% of US CAM users (36% of the US population) using it regularly (Purcell 2005). The Australian Tea Tree Industries Association (ATTIA) are fighting a vigorous campaign as I write this article, to challenge the SCCP Opinion on Tea Tree Oil.  Cropwatch is completing a full critique of the SCCP Opinion, which will raise several questions about the composition of expert committees, their ability to effectively communicate with the producing industry and commodity end-users, and basic questions about influence, privilege and competence to carry out the task.


Insect Bites.

Mild symptoms of insect bites & stings include annoyance, inflammation and irritation reactions to bite-related injected material, but rarely there are more severe reactions such as large swellings and abdominal cramps or severe immune reactions, which can include facial swelling, breathing difficulties and anaphylactic shock. Biting insects (ticks, spiders, mosquitoes etc) can be the vectors of more serious disease; flaviviruses are spread by ticks and mosquitoes and are responsible for conditions such as West Nile Virus, Dengue Fever, Yellow fever and many forms of encephalitis. Tick bites can spread the bacterium Borrelia burgdorferi which generally causes rash, flu-like symptoms and aching joints (‘Lyme disease’).


“Keeping the patient well”, in the sense of dissuading insect landings on exposed skin, is therefore an important first-line strategy against contracting serious diseases in certain locations. This is where natural aromatic materials can be of use.


Malaria & anti-Malarials.

Consequential to being bitten by malaria-carrying mosquitoes, a life- shortening disease may well be contracted. The underestimation of the global incidence of clinical Plasmodium falciparum malaria has been the subject of a recent paper (Snow et al. 2005), which maintains that the number of actual cases in Africa is 50% up on WHO estimates in Africa, and up 200% for areas outside Africa. Snow et al. further suggest that 515 million people have currently contracted malaria out of an at-risk population of 2.2 billion people. Resistance of P. falciparum to first-defence synthetic drugs chloroquine and sulphadoxine-primethamine is rising, and the only effective drugs include artemisinin from the herb Artemisia annua and synthetic derivatives thereof.




The drawbacks of reliance on single active biocidals, such as artemisinin derivatives by pharmaceutical concerns, and the advantages of using whole preparations from active herbal sources has been reviewed by Burfield & Reekie (2005). Yarnell (2004) reports that a new synthetic drug mimicking artemisinin, named OZ277 can be made cheaper, quicker and more consistently than by growing & extracting the herb, and it is reportedly being safety tested in the UK (Radford 2005). However as malaria parasites rapidly develop drug resistance to single actives, this development will not buy immunity for long. A longer term solution is needed, perhaps by developing higher yielding and faster growing Artemisia spp. by (non-GM) plant selection, to produce artemisinin and other naturally associated active compounds.


Synthetic Insecticides & Repellents

In 1955 the World Health Organisation initiative was established (“The Global Malaria Eradication Problem”) - using pesticides such as DDT, but rising resistance and toxicological problems forced policy abandonment in 1969 - Rachel Carson’s book Silent Spring (Carson 1962) tolling its death knell. DEET (N,N-diethyl-m-toluamide)  is perhaps the most popular synthetic now in insect repellency formulations, with piperonyl butoxide widely employed in ‘knock-down’ insecticide aerosols.




Natural Insect Repellents

Boseley (2004) describes a travelling sector, which is reluctant to take conventional drugs; medical practitioners need therefore to be able to suggest effective alternatives. Cedarwood, citronella, eucalyptus, pennyroyal, turpentine and wintergreen oils have traditional uses for their insect-repellent properties, which are formulated for use as either topical preparations or as combustible products (e.g. incense sticks). In a detailed article, Burfield & Reekie (2005) review the large body of evidence for utilisation of essential oils as insect repellents, indicating that essential oils such as catnip oil (Nepeta spp.) definitely point the best way forward. Catnip oil contains nepetalactones, which have tested as being ten times more effective than DEET, since they act an irritant to insect antennae (see Burfield & Reekie 2005). Repellency testing regimes are largely biased against natural products: 8-hour protection after a single application suits higher molecular weight synthetics such as DEET, but as anyone regularly wearing totally natural perfumes will tell you, essential oils & isolates will have to be applied more frequently. Education is the key to prevent bites, naturally!


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CAM: Complementary & Alternative Medicine

DEET: N,N-diethyl toluamide

GM: Genetic Modification

MHRPA: Medicines & Healthcare Products Regulatory Agency (syn. MHRA)

PMRA: Canadian Pest Management Regulatory Authority

SCCP: Scientific Committee on Consumer Products

WHO: World Health Organisation



Anon (2005): GM Watch Daily communiqué 18.03.05 – see


Boseley S. (2004) “More deaths from Malaria as Travellers Shun Drugs.” The Guardian May 27 2004 p 12.


Burfield T. (2005) “Cropwatch 8” (in preparation). See


Burfield T. & Reekie S.-L. (2005) “Mosquitoes, Malaria & Essential Oils” Internat J. Aromatherapy 15, 30-41.


Connor S. (2005) “The Forgotten Killer” The Independent Thurs 10th Mar 2005 pp1-2.


Evans R. & Boseley S. (2004) “The Drugs Industry & its Watchdog: a Relationship too Close for Comfort?” The Guardian Mon. Oct 4th 2004 p4.


Gruenwald J. (2005) “Kava Stakeholders Plan Regulatory Review and Market Return” HerbalGram No 61, 69-70.


Knight D.J., Cooke M. (2002) The Biocides Business: Regulation, Safety & Applications. Wiley-VCH


Laurance J. (2003) “Reactions to Common Medicines Kill 10,000 each Year.” The Independent Fri 2 July 2004 p8.


Meiklie J. (2005) “Mosquito Watch to Beat Exotic Diseases” The Guardian Thurs June 16 2005 p 9.


Monbiot G. (2004) “The Corporate Stooges than Nobble Serious Science” The Guardian Tues Feb 24th 2004 p26.


Pirmohamed M., James S., Meakin S., Green C., Scott A.K., Walley T.J., Farrar K., Park B.K., Breckenridge A.M. (2004) “Adverse drug reactions as cause of admission to hospital: prospective analysis of 18,820 patients.” British Medical Journal  3, 329(7456) pp15–9.


Prigg M. (2004) “Herbal Remedies ‘Put Thousands in Danger’” Evening Standard Mon 6th Sept 2004.


Purcell K. (2005) “Survey Shows 36% of US Adults Use CAM” Herbalgram No 61, p65-66.


Radford T. (2005) “New Drug Boosts World Fight Against Malaria” The Guardian Thurs Aug 19th p12.


SCCP (2004): the SCCP Opinion on tea tree oil can be viewed at

Snow R. W., Guerra C. A., Noor A. M., Myint H. Y. & Hay S. I. (2005) “The global distribution of clinical episodes of Plasmodium falciparum malaria” Nature 434, 214-217. 

Yarnell A. (2005) “Malaria Drug Design on a Dime” Chemical & Engineering News 82, (34), 2