Print version ISSN 0037-8682
Rev. Soc. Bras. Med. Trop. vol.44 no.6 Uberaba Nov./Dec. 2011
LETTER TO EDITOR CARTA AO EDITOR
Avaliação da repelência de preparado caseiro com cravo-da-índia, picaridina, andiroba e óleo de soja contra picadas de Aedes aegypti
Hélio Amante MiotI; Gerhard da Paz LauterbachI; Felipe Augusto Horácio RibeiroI; Édson Luiz Favero JúniorI; Gabriela Nascimento HercosI; Newton Goulart MadeiraII; Vidal Haddad JuniorI
IDepartamento de Dermatologia e Radioterapia, Faculdade de Medicina de Botucatu, Universidade Estadual Paulista, Botucatu, SP
IIDepartamento de Parasitologia, Instituto de Biociências, Universidade Estadual Paulista, Botucatu, SP
The dengue epidemic outbreak has progressed in Brazil, and in 2010, infection rates significantly increased compared with 20091. Specific measures to contain disease progression involve vector control and strategies using repellents. The most effective topical repellents against Aedes aegypti bites are DEET (N,N-Diethyl-meta-toluamide), picaridin, and permethrin. Permethrin is used in clothing2,3. Natural repellents presented poorer performance than industrial ones, despite a potentially better safety profile, cost, and tolerance4-6. Recently, information has been released to the media on the efficiency of a home-based repellent composed of cloves (Syzygium aromaticum), alcohol, and almond oil7. As it has not been adequately studied in controlled studies with repellent indicated by medical literature8,9, an experiment was performed comparing a popular clove formula, picaridin 20% (positive control), soy oil, Andiroba oil, and when no product is applied (negative control). The study was approved by the Ethics Committee of Botucatu School of Medicine, São Paulo State University - UNESP (CEP 135/08). Four healthy volunteers submitted their forearms to a previously cleaned plastic nursery with 20 healthy Aedes aegypti females (Rockefeller strain, from the Laboratory of Parasitology, Biosciences Institute Botucatu-UNESP) subjected to a 24h feeding regime with only 5% glucose solution. Their forearms remained in the container for 5min, and if there were no bites, the volunteers waited for 25min outside the mosquito nursery until the next intrusion. The experiment was discontinued if there were no bites after 120min. Each trial represented a randomized comparison of unprotected forearms with left and right forearms protected by a product using the same group of mosquitoes. Fifty evaluations were performed using different combinations of products and volunteers. Time rankings of the different repellents were compared using a generalized linear model. No adverse effects were observed concerning the applications. Mean times until bites for the different products were: bare arm -13.7s; prepared clove - 104.7s; Andiroba oil - 213.7s; soybean oil - 77.7s; and picaridin - 5488.1s (Figure 1). There were no differences between arm repellency times without substances and natural products (p<0.01); however, all the natural products showed repellencies that were significantly below picaridin's (p<0.01); Figure 1.
Botanical extracts with strong essential oil odor, such as eugenol (from cloves), are popularly referred to as repellents for arthropods10. In comparative studies, the essential oils did not have equivalent performances to topical DEET or picaridin repellents, whose use is dissuaded in areas susceptible to disease transmission or for people hypersensitive to insect bites11. There is a risk of allergic skin reactions from prolonged use12.
Different substances and combinations show specific profiles for repelling different arthropods, preventing general conclusions. Field experiments to demonstrate repellent properties have ethical and logistical barriers, encouraging comparative approaches in the laboratory.
The Aedes aegypti mosquito is one of the most resistant to repellents. Given the severity and progression of dengue in Brazil, recommending repellent strategies should be based on the best available evidence. Recommending repellents with lower efficacy profiles than those already available can lead to risky behavior by falsely perceived safety. It is the duty of the scientific community to investigate and alert the society to the risks of using ineffective repellents.
1. Ministério da Saúde. Informe Epidemiológico da Dengue - Análise de situação e tendências [Internet]. Brasília: Secretaria de Vigilância em Saúde; 2010 [cited 2010 Aug 8]. p.1-42. Available from: http://portal.saude.gov.br/portal/arquivos/pdf/informe_dengue_se_26_final_11_8_10. pdf/. [ Links ]
2. Fradin MS, Day JF. Comparative efficacy of insect repellents against mosquito bites. N Engl J Med 2002; 347:13-18. [ Links ]
3. Miot HA, Ferreira DP, Mendes FG, Carrenho FRH, Amui IO, Carneiro CAS, et al. Efficacy of topical permethrin as repellent against Aedes aegypti's bites. Dermatol Online J 2008; 14:1. [ Links ]
4. Das NG, Baruah I, Talukdar PK, Das SC. Evaluation of botanicals as repellents against mosquitoes. J Vector Borne Dis 2003; 40:49-53. [ Links ]
5. Miot HA, Batistella RF, Batista KA, Volpato DE, Augusto LS, Madeira NG, et al. Comparative study of the topical effectiveness of the Andiroba oil (Carapa guianensis) and DEET 50% as repellent for Aedes sp. Rev Inst Med Trop Sao Paulo 2004; 46:253-256. [ Links ]
6. Nerio LS, Olivero-Verbel J, Stashenko E. Repellent activity of essential oils: a review. Bioresour Technol 2010; 101:372-378. [ Links ]
7. Hirsch S. Dengue: repelente caseiro de cravo-da-índia [Internet]. Petrópolis: Deixa Sair; 2010 [cited 2010 Aug 12]. Available from: http://www.soniahirsch.com/2010/03/dengue-repelente-caseiro-de-cravo-da.html/. [ Links ]
8. Trongtokit Y, Curtis CF, Rongsriyam Y. Efficacy of repellent products against caged and free flying Anopheles stephensi mosquitoes. Southeast Asian J Trop Med Public Health 2005; 36:1423-1431. [ Links ]
9. Barnard DR. Repellency of essential oils to mosquitoes (Diptera: Culicidae). J Med Entomol 1999; 36:625-629. [ Links ]
10. Chaieb K, Hajlaoui H, Zmantar T, Kahla-Nakbi AB, Rouabhia M, Mahdouani K, et al. The chemical composition and biological activity of clove essential oil, Eugenia caryophyllata (Syzigium aromaticum L. Myrtaceae): a short review. Phytother Res 2007; 21:501-506. [ Links ]
11. Maguranyi SK, Webb CE, Mansfield S, Russell RC. Are commercially available essential oils from Australian native plants repellent to mosquitoes? J Am Mosq Control Assoc 2009; 25:292-300. [ Links ]
12. Prashar A, Locke IC, Evans CS. Cytotoxicity of clove (Syzygium aromaticum) oil and its major components to human skin cells. Cell Prolif 2006; 39:241-248. [ Links ]
Dr. Vidal Haddad Junior
Deptº Dermatologia Radioterapia/FMB/UNESP
Caixa Postal 557, 18618-970 Botucatu, SP, Brasil
Phone: 55 14 3882-4922
Received in 13/09/2010
Accepted in 08/08/2011