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A field study to compare a formulation containing 40% deet (N,N-diethyl-3-methyl benzamide) in ethanol (Bushman™) and a battery-powered fan emanator with a chemical strip containing 31.2% metofluthrin (OFF!® Clip-On™) was conducted at Redcliffe, Queensland, Australia, in February 2016. The 40% deet provided 100% protection against mosquitoes for 5 h until tests ceased, while the OFF! Clip-On device provided only 42.2-60.8% protection against Aedes vigilax during the same period., Competing Interests: Mention of a commercial product does not constitute an endorsement by the Australian Defence Force., (Copyright © 2020 by The American Mosquito Control Association, Inc.)

Competing Interests: Competing interests: None declared.

Mosquito-borne disease is an annual problem in Australia, with endemic pathogens such as Ross River virus infecting thousands of people each year. The recent emergence of Zika virus in South America and the Pacific, together with ongoing outbreaks of dengue viruses in Southeast Asia, generated great community interest in the most effective strategies to avoid mosquito bites. Large-scale mosquito control programs are not common in Australia and are limited in New South Wales (NSW). The use of topical insect repellents is a key recommendation by health authorities to prevent mosquito-borne disease. All products sold in Australia purporting to repel mosquitoes must be registered with the Australian Pesticides and Veterinary Medicines Authority. Despite around 100 commercial products registered as repelling mosquitoes, there are relatively few active ingredients used across these formulations. The most common are diethyltoluamide (DEET), picaridin, p-menthane-3,8-diol (PMD) and a range of plant-derived products (e.g. melaleuca, eucalyptus, citronella oils). Research has shown that each of these active ingredients varies in the duration of protection provided against biting mosquitoes. Recommendations by health authorities are informed by this research, but inconsistencies between recommendations and available repellent formulations and their concentration of active ingredients can cause confusion in the community. There are conflicts between the data resulting from scholarly research, marketing promotion by manufacturers and recommendations provided by overseas health authorities. A review was undertaken of NSW Health's current recommendations on choosing and using insect repellents, taking into consideration recent research and currently registered topical repellents.

Objective: We assessed the efficacy of commercial repellents available in Yucatan against Aedes aegypti, vector of dengue, Chikungunya and Zika., Materials and Methods: Protection time was determined based on WHO/CTD/ WHOPES/IC y la NOM-032-SSA2-20I4., Results: Products with DEET (N, N-diethyl-3-methylbenzamide) at 25% met the recommended protection. Efficacy was directly proportional to the concentration of DEET; botanicals repellents resulted no protective., Conclusions: Repellents with DEET provided more protection against Ae. aegypti and botanical repellents, including impregnated wristbands, provided no protection.

The objective of this study was to clarify the efficacy of a currently available N,N-diethyl-m-toluamide (DEET) repellent against tick species in Japan. We performed 2 different field trials: "human trap," and "flag-dragging." In total, 482 ticks were collected from white flannel cloths in the field studies. The collected tick species were Ixodes persulcatus and I. ovatus, which accounted for 5.3% and 94.7% of the ticks in the human trap test and 31.4% and 68.6% in the flag-dragging test, respectively. The repellency levels of DEET-treated flannel cloths in the human trap and flag-dragging tests were 84.0% and 99.7%, respectively. The escape times for I. persulcatus and I. ovatus female adults from DEET-treated flannel cloths were determined. The median escape times for I. persulcatus and I. ovatus on DEET-treated flannel cloths were 48 s (95% confidence interval [CI]: 30-96) and 10 s (95% CI: 5-24), respectively. In contrast, many ticks remained on the untreated flannel cloths for 10 min after mounting. These results indicate that DEET repellents appear to prevent tick bites and that the use of DEET repellents against ticks is an effective personal protection measure.

Background: Long-lasting insecticidal nets (LLINs) have limited effect on malaria transmitted outside of sleeping hours. Topical repellents have demonstrated reduction in the incidence of malaria transmitted in the early evening. This study assessed whether 15% DEET topical repellent used in combination with LLINs can prevent greater malaria transmission than placebo and LLINs, in rural Tanzania., Methods: A cluster-randomized, placebo-controlled trial was conducted between July 2009 and August 2010 in a rural Tanzanian village. Sample size calculation determined that 10 clusters of 47 households with five people/household were needed to observe a 24% treatment effect at the two-tailed 5% significance level, with 90% power, assuming a baseline malaria incidence of one case/person/year. Ten clusters each were randomly assigned to repellent and control groups by lottery. A total of 4,426 individuals older than six months were enrolled. All households in the village were provided with an LLIN per sleeping space. Repellent and placebo lotion was replaced monthly. The main outcome was rapid diagnostic test (RDT)-confirmed malaria measured by passive case detection (PCD). Incidence rate ratios were estimated from a Poisson model, with adjustment for potential confounders, determined a priori. According-to-protocol approach was used for all primary analyses., Results: The placebo group comprised 1972.3 person-years with 68.29 (95% C.I 37.05-99.53) malaria cases/1,000 person-years. The repellent group comprised 1,952.8 person-years with 60.45 (95% C.I 48.30-72.60) cases/1,000 person-years, demonstrating a non-significant 11.44% reduction in malaria incidence rate in this group, (Wilcoxon rank sum z=0.529, p=0.596). Principal components analysis (PCA) of the socio-economic status (SES) of the two groups demonstrated that the control group had a higher SES (Pearson's chi square=13.38, p=0.004)., Conclusions: Lack of an intervention effect was likely a result of lack of statistical power, poor capture of malaria events or bias caused by imbalance in the SES of the two groups. Low malaria transmission during the study period could have masked the intervention effect and a larger study size was needed to increase discriminatory power. Alternatively, topical repellents may have no impact on malaria transmission in this scenario. Design and implementation of repellent intervention studies is discussed., Trial Registration: The trial was registered ISRCTN92202008--http://www.controlled-trials.com/ISRCTN92202008.

N,N-diethyl-m-toluamide (DEET) has been registered for commercial use as an insect repellent for over five decades, and is used widely across the world. Concerns over the safety of DEET first emerged during the 1980s after reports of encephalopathy following DEET exposure, particularly in children. However, the role of DEET in either the illness or deaths was and remains purely speculative. In response to these cases a number of reviews and investigations of DEET safety were carried out. Here we examine the methods used and information available to determine the safety of DEET in humans. Animal testing, observational studies and intervention trials have found no evidence of severe adverse events associated with recommended DEET use. Minor adverse effects noted in animal trials were associated with very large doses and were not replicated between different test species. The safety surveillance from extensive humans use reveals no association with severe adverse events. This review compares the toxicity assessment using three different models to define the risk assessment and safety threshold for DEET use in humans and discusses the clinical consequences of the thresholds derived from the models.The theoretical risks associated with wearing an insect repellent should be weighed against the reduction or prevention of the risk of fatal or debilitating diseases including malaria, dengue, yellow fever and filariasis. With over 48 million European residents travelling to regions where vector borne diseases are a threat in 2009, restricting the concentration of DEET containing repellents to 15% or less, as modelled in the 2010 EU directive, is likely to result in extensive sub-therapeutic activity where repellents are infrequently applied. Future European travellers, as a consequence of inadequate personal protection, could potentially be at increased risk of vector borne diseases. Risk assessments of repellents should take these factors into account when setting safe limits.

DEET (N,N-diethyl-m-toluamide) is the most common active ingredient in the insect repellents commonly detected in European groundwater. The aim of this study was to investigate the effect of subchronic DEET exposure on biochemical and haematological parameters, antioxidant enzymes, including catalase, glutathione peroxidase, glutathione reductase, and glutathione S-transferase, and the amount of thiobarbituric acid reactive substances (TBARS) in common carp (Cyprinus carpio L.). Two specific proinflammatory and anti-inflammatory cytokine genes were selected to assess an immunological status of the fish. Fish were exposed for 28 days to three concentrations of DEET (1.0 µg/L, 0.1 mg/L, and 1.0 mg/L) where 1 µg/L is corresponding to the concentration found in the environment. DEET had a significant (P < 0.05) effect on increased RBC, decreased mean corpuscular volume (MCV), and mean corpuscular haemoglobin value (MCH) compared to control groups in the concentration of 1 mg/L. A significant decline (P < 0.05) in triacylglycerols (TAG) in plasma was found in the concentration of 1 mg/L compared to the control groups. The parameters of oxidative stress in tissues of common carp were weekly affected and immunological parameters were not affected.

Urinary metabolites of DEET of 17 children (5-7 years of age) and 9 adults (23-25 years of age) were examined in the study described in this article. Urine samples were collected from each subject within eight hours after a single dermal application of 10 mL 12% DEET-containing insect repellent. Two metabolites, m-diethylaminocarbonyl benzoic acid (R3N0) and N-ethyl-m-toluamide (RON1), with unchanged DEET, were identified in the urine. The major metabolite was R3NO, which was 78.2% and 46.1% of the total DEET metabolites from children and adults, respectively, indicating that the pathway of ring methyl oxidation predominated. The recovered DEET metabolites were observed significantly more from children (1,116 pg) than from adults (446.2 pg) (p < .001). The difference in dermal absorption, albeit primarily attributed to DEET loading, was found to be related to height by regression analysis. The inverse association between height and dermal absorption of DEET suggests that shorter individuals (i.e., children) are subjected to dermal uptake of DEET. To avoid unnecessary exposure, parents need to be cautious when applying DEET-containing insect repellent on children.

Background: Mosquito vectors of malaria in Southeast Asia readily feed outdoors making malaria control through indoor insecticides such as long-lasting insecticidal nets (LLINs) and indoor residual spraying more difficult. Topical insect repellents may be able to protect users from outdoor biting, thereby providing additional protection above the current best practice of LLINs., Methods and Findings: A double blind, household randomised, placebo-controlled trial of insect repellent to reduce malaria was carried out in southern Lao PDR to determine whether the use of repellent and long-lasting insecticidal nets (LLINs) could reduce malaria more than LLINs alone. A total of 1,597 households, including 7,979 participants, were recruited in June 2009 and April 2010. Equal group allocation, stratified by village, was used to randomise 795 households to a 15% DEET lotion and the remainder were given a placebo lotion. Participants, field staff and data analysts were blinded to the group assignment until data analysis had been completed. All households received new LLINs. Participants were asked to apply their lotion to exposed skin every evening and sleep under the LLINs each night. Plasmodium falciparum and P. vivax cases were actively identified by monthly rapid diagnostic tests. Intention to treat analysis found no effect from the use of repellent on malaria incidence (hazard ratio: 1.00, 95% CI: 0.99-1.01, p = 0.868). A higher socio-economic score was found to significantly decrease malaria risk (hazard ratio: 0.72, 95% CI: 0.58-0.90, p = 0.004). Women were also found to have a reduced risk of infection (hazard ratio: 0.59, 95% CI: 0.37-0.92, p = 0.020). According to protocol analysis which excluded participants using the lotions less than 90% of the time found similar results with no effect from the use of repellent., Conclusions: This randomised controlled trial suggests that topical repellents are not a suitable intervention in addition to LLINs against malaria amongst agricultural populations in southern Lao PDR. These results are also likely to be applicable to much of the Greater Mekong Sub-region., Trial Registration: This trial is registered with number NCT00938379.

Female mosquitoes of some species are generalists and will blood-feed on a variety of vertebrate hosts, whereas others display marked host preference. Anopheles gambiae and Aedes aegypti have evolved a strong preference for humans, making them dangerously efficient vectors of malaria and Dengue haemorrhagic fever. Specific host odours probably drive this strong preference because other attractive cues, including body heat and exhaled carbon dioxide (CO2), are common to all warm-blooded hosts. Insects sense odours via several chemosensory receptor families, including the odorant receptors (ORs), membrane proteins that form heteromeric odour-gated ion channels comprising a variable ligand-selective subunit and an obligate co-receptor called Orco (ref. 6). Here we use zinc-finger nucleases to generate targeted mutations in the orco gene of A. aegypti to examine the contribution of Orco and the odorant receptor pathway to mosquito host selection and sensitivity to the insect repellent DEET (N,N-diethyl-meta-toluamide). orco mutant olfactory sensory neurons have greatly reduced spontaneous activity and lack odour-evoked responses. Behaviourally, orco mutant mosquitoes have severely reduced attraction to honey, an odour cue related to floral nectar, and do not respond to human scent in the absence of CO2. However, in the presence of CO2, female orco mutant mosquitoes retain strong attraction to both human and animal hosts, but no longer strongly prefer humans. orco mutant females are attracted to human hosts even in the presence of DEET, but are repelled upon contact, indicating that olfactory- and contact-mediated effects of DEET are mechanistically distinct. We conclude that the odorant receptor pathway is crucial for an anthropophilic vector mosquito to discriminate human from non-human hosts and to be effectively repelled by volatile DEET.

Objective: This review aims to examine the effectiveness of citronella preparation used as a mosquito repellent., Methods: Multiple computerized databases such as MEDLINE, EMBASE, Cochrane CENTRAL, CINAHL, and AMED, were searched for controlled laboratory experiments that compared the effectiveness of citronella products to control in repelling Aedes, Anopheles and Culex mosquitoes using the cage or room methods. Outcomes measures were protection time and percentage repellency. The weighted mean difference and 95% confidence interval were calculated comparing the outcomes in the citronella and control groups. Meta-analysis was performed using the DerSimonian and Laird method under a random-effects model., Results: Eleven studies met inclusion criteria. Based on a meta-analysis of studies using the cage method, protection time of the citronella oil for preventing Aedes mosquitoes was less than that in the DEET (N,N-diethyl-m-toluamide) group, with a difference in protection time of 253 min (95% confidence interval: 169-336). The combination of citronella oil and vanillin is likely to have a longer protection time compared with citronella oil alone. In studies using the room method, citronella oil and/or the combination of citronella oil and vanillin provided complete repellency at least 3 h. In Anopheles and Culex mosquitoes, a combination of citronella oil and vanillin product demonstrated a comparable protection time against DEET; however, it remained inconclusive due to a limited number of studies., Conclusions: Citronella products are less effective than DEET products in terms of duration of protection. Adding vanillin to citronella oil products could prolong the protection time., (© 2011 Blackwell Publishing Ltd.)

Background & Objectives: Repellents are commonly used personal protection measures to avoid mosquito bites. In the present study, Advanced Odomos cream (12% N, N-diethyl-benzamide) was tested for its efficacy against mosquitoes in comparison to DEET (N,N-diethyl-3-methyl benzamide)., Methods: Bioassays were conducted to assess the repellency of Advanced Odomos and DEET creams against Anopheles stephensi and Aedes aegypti. Their efficacy was tested on human volunteers applied with different concentrations of test creams ranging from 1 to 12 mg/cm 2 and by exposing them to mosquitoes at hourly intervals. Field evaluation was also carried out to test the duration of protection of the test creams against Anopheles and Aedes mosquitoes during whole night and day time collections, respectively on human volunteers. Mosquito collections were done using torch light and aspirator., Results: Complete (100%) protection was achieved at 10 mg/cm 2 cream formulation of Advanced Odomos (1.2 mg a.i/cm 2 ) dose against An. stephensi and 12 mg/cm 2 (1.44 mg a.i./cm 2 ) against Ae. aegypti on human baits. There was no statistically significant differences in per cent protection against mosquito bites between Advanced Odomos and DEET cream (P>0.05) in respective doses. Complete protection up to 11 h was observed against Anopheles mosquitoes during whole night collections and up to 6 h against Ae. aegypti in day time collections. No adverse reactions such as itching, irritation, vomiting, nausea, etc. were reported by the volunteers., Interpretation & Conclusions: Advanced Odomos cream applied at 10 mg/cm 2 concentration provided 100% protection from Anopheles mosquitoes up to 11 h whereas about 6 h protection was recorded against Ae. aegypti. The laboratory and field trials indicate that for longer protection against Anopheles mosquitoes 10 mg/cm 2 will be appropriate and in case of Ae. aegypti more than 10 mg/cm 2 application is required for complete protection. In conclusion, the Advanced Odomos cream was comparable to the known repellent cream DEET for prolonged protection against malaria and dengue vectors.

DEET is the most widely used insect repellent worldwide. In Drosophila olfactory receptor neurons (ORNs), DEET is detected through a mechanism employing the olfactory receptor, OR83b. However, it is controversial as to whether ORNs respond directly to DEET or whether DEET blocks the response to attractive odors. Here, we showed that DEET suppressed feeding behavior in Drosophila, and this effect was mediated by gustatory receptor neurons (GRNs). DEET was potent in suppressing feeding as <0.1% DEET elicited aversive behavior. Inhibition of feeding required multiple gustatory receptors (GRs) expressed in inhibitory GRNs. DEET stimulated action potentials in GRNs that respond to aversive compounds, and this response was lost in the Gr32a, Gr33a, and Gr66a mutants. Since 0.02% DEET elicited action potentials, we conclude that DEET directly activates of GRNs. We suggest that the effectiveness of DEET in pest control owes to its dual action in inducing avoidance simultaneously via GRNs and ORNs., (2010 Elsevier Inc. All rights reserved.)

On the military training facility of Tekong Island, Singapore, a comprehensive vector-borne disease control program was started in end-2006 to reduce mosquito populations and negate the need for anti-malaria chemoprophylaxis. The program was based on 1) preventing importation of malaria through screening of visitors, 2) preventing human-to-mosquito transmission through early case detection and mosquito control, 3) preventing mosquito-to-human transmission through personal protection, and 4) contingency plans. Systematic environmental works were performed to reduce breeding sites, and insecticide use targeted both adult mosquitoes and larvae. Mosquito populations declined from 103 mosquitoes per sampling site in January 2007 to 6 per site by March 2007 (P < 0.001). The proportion of positive ovitraps declined from 93% in January 2007-2% in March 2007 (P < 0.001). There were no malaria cases on the island despite chemoprophylaxis termination, showing that comprehensive combination vector-control strategies were effective in reducing the risk of malaria.

Background: Chemicals are used on bed nets in order to prevent infected bites and to kill aggressive malaria vectors. Because pyrethroid resistance has become widespread in the main malaria vectors, research for alternative active ingredients becomes urgent. Mixing a repellent and a non-pyrethroid insecticide seemed to be a promising tool as mixtures in the laboratory showed the same features as pyrethroids., Methodology/principal Findings: We present here the results of two trials run against free-flying Anopheles gambiae populations comparing the effects of two insect repellents (either DEET or KBR 3023, also known as icaridin) and an organophosphate insecticide at low-doses (pirimiphos-methyl, PM) used alone and in combination on bed nets. We showed that mixtures of PM and the repellents induced higher exophily, blood feeding inhibition and mortality among wild susceptible and resistant malaria vectors than compounds used alone. Nevertheless the synergistic interactions are only involved in the high mortality induced by the two mixtures., Conclusion: These field trials argue in favour of the strategy of mixing repellent and organophosphate on bed nets to better control resistant malaria vectors.

This study evaluated the repellency effect of 3 topical repellents (permethrin, DEET and neem tree extract) against 3-5 day old females of laboratory and field strains of Anopheles stephensi. Probing/biting rates on the shaved belly of white rabbits were counted. Effective dose (ED) 50 and ED95 values were calculated by probit statistic software. The results revealed ED50 values of 0.007, 0.005 and 0.191 mg/cm2 for permethrin, DEET and neem, respectively, against the field strain. The figures for the laboratory strain were 0.006, 0.007, 0.156 mg/cm2. Major heterogeneity of response was observed using DEET. Although neem was the least effective agent, extracts of locally produced neem oil offer a promising repellent against mosquito biting.

Background: The cost of mosquito repellents in Latin America has discouraged their wider use among the poor. To address this problem, a low-cost repellent was developed that reduces the level of expensive repellent actives by combining them with inexpensive fixatives that appear to slow repellent evaporation. The chosen actives were a mixture of para-menthane-diol (PMD) and lemongrass oil (LG)., Methods: To test the efficacy of the repellent, field trials were staged in Guatemala and Peru. Repellent efficacy was determined by human-landing catches on volunteers who wore the experimental repellents, control, or 15% DEET. The studies were conducted using a balanced Latin Square design with volunteers, treatments, and locations rotated each night., Results: In Guatemala, collections were performed for two hours, commencing three hours after repellent application. The repellent provided >98% protection for five hours after application, with a biting pressure of >100 landings per person/hour. The 15% DEET control provided lower protection at 92% (p < 0.0001). In Peru, collections were performed for four hours, commencing two hours after repellent application. The PMD/LG repellent provided 95% protection for six hours after application with a biting pressure of >46 landings per person/hour. The 20% DEET control provided significantly lower protection at 64% (p < 0.0001)., Conclusion: In both locations, the PMD/LG repellent provided excellent protection up to six hours after application against a wide range of disease vectors including Anopheles darlingi. The addition of fixatives to the repellent extended its longevity while enhancing efficacy and significantly reducing its cost to malaria-endemic communities.

To obtain long-duration protection from mosquitoes using insect repellent N, N-diethyl-m-toluamide (DEET), this compound was incapsulated in situ during the graft copolymerization of butyl acrylate onto chitosan in an aqueous solution. Morphology of microcapsules was characterized by scanning electron microscopy, scanning probe microscopy, and transmission electron microscopy. This morphology supported successful encapsulation of DEET into polymer capsules. The encapsulation ratio of DEET was greater than 33%, as estimated from thermo-gravimetric results. The aqueous emulsions were applied to cotton textiles by spraying. Treated cloth showed high bactericidal activity against Staphylococcus aureus. Mosquito repellency of the bio-cloth was evaluated with Aedes albopictus. The 90% effective dose of emulsions on textiles was compared with that of DEET in ethanol. A time profile showed that the repellency of an optimized emulsion was 100% after eight hours, and partially preserved even after exposure to air for 48 hours.

Outside sub-Saharan Africa, Anopheline mosquito exophagic and/or crepuscular behaviour patterns imply that insecticide-treated nets may provide incomplete protection from malaria-infective mosquito bites. Supplementary repellent treatment has been recommended in such circumstances, especially where vectors are exophilic and so are not susceptible to residual insecticide spraying. As maintaining complete usage of repellents in a community is unrealistic, the potential negative impact on non-users of repellent usage by 'neighbours' in the same community needs to be addressed in the context of health policy promoting equity. This study quantifies diversion of host-seeking mosquitoes, from repellent wearing to unprotected individuals, 1 m apart under field conditions in Bolivia. Each of the six volunteer-pairs sat >20 m apart from other pairs. Volunteers were allocated di-ethyl toluamide (DEET) or mineral oil in ethanol control. Treatments were rotated, so that during the trial, both pair-members wore repellent on 72 occasions; both pair-members wore control on 72 occasions; and on 36 occasions, one pair-member wore repellent and the other control. Unprotected (control) pair-members received 36.4% [95% confidence interval (CI): 8.1-72.0%] more Anopheles darlingi landings (P = 0.0096) and 20.4% (95% CI: 0.6-44.0%) more mosquito landings (P = 0.044), when their 'partner' wore repellent than when their partner also wore control. A second, smaller Latin-square trial using 30% lemongrass (Cymbopogon citratus) repellent, with control, obtained 26.0% (95% CI: 5.2-51.0%) more mosquito landings when controls sat with repellent-wearers rather than other controls (P = 0.0159). With incomplete community repellent usage, non-users could be put at an increased risk of malaria. The results also have implications for repellent-efficacy assay design, as protection will appear magnified when mosquitoes are given a choice between repellent-users and non-users.

In 2003, residents in 2 adjacent cities in northern Colorado (Loveland and Fort Collins) had severe outbreaks of human West Nile virus (WNV) disease. Unexpectedly, age-adjusted neuroinvasive disease rates were higher in Loveland (38.6 vs. 15.9 per 100,000), which had a more extensive mosquito control program and fewer mosquitoes. A survey was conducted to assess differences in personal protection and risk practices by each city's residents. During May and June 2004, a random-digit dial telephone survey was conducted among adults to assess personal protection behavioral practices used to prevent WNV infection during the 2003 outbreak. After we adjusted for identified risk factors, Loveland residents were 39% more likely to report seldom or never using N,N-diethyl-m-toluamide (DEET), and approximately 30% were more likely to report being outdoors during prime mosquito-biting hours than Fort Collins residents. Personal protective practices may directly influence rates of WNV infection and remain important even when comprehensive community mosquito control measures are implemented.

Objective: To determine whether short-term human exposure to pyridostigmine bromide, diethyltoluamide, and permethrin, at rest or under stress, adversely affects short-term physical or neurocognitive performance., Participants and Methods: A multicenter, prospective, double-blind, placebo-controlled crossover trial exposing 64 volunteers to permethrin-impregnated uniforms, diethyltoluamide-containing skin cream, oral pyridostigmine, and corresponding placebos was performed. Each participant had 4 separate sessions, ensuring exposure to all treatments and placebos under both stress and rest conditions in random order. Outcomes Included physical performance (handgrip strength and duration, stair climbing, and pull-ups [males] or push-ups [females]), neurocognitive performance (computerized tests), and self-reported adverse effects., Results: Permethrin was undetectable in the serum of all participants; pyridostigmine levels were higher Immediately after stress (41.6 ng/mL; 95% confidence Interval, 35.1-48.1 ng/mL) than rest (23.0 ng/mL; 95% confidence Interval, 19.2-26.9 ng/mL), whereas diethyltoluamide levels did not significantly differ by stress condition. Heart rate and systolic blood pressure increased significantly with stress compared with rest but did not vary with treatment vs placebo. Physical and neurocognitive outcome measures and self-reported adverse effects did not significantly differ by exposure group., Conclusion: Combined, correct use of pyridostigmine, diethyltoluamide, and permethrin is well tolerated and without evidence of short-term physical or neurocognitive impairment.

Background: In 2002, the City of Ottawa was interested in the public perception of West Nile Virus (WNV) and mosquito control. Their objectives were to assess: awareness of WNV, practices to reduce mosquito sources, personal protective measures, and attitudes towards community-based insecticide programs., Methods: In July 2002, we administered a telephone survey to a random, stratified sample of urban, suburban and rural Ottawa households., Results: Surveys were completed for 491 households. Most (77.2%) respondents reported they had heard of WNV, and of these, 58.3% reported WNV was an important health issue. Mosquito repellent was the most common personal protective measure, reported among 72.5% of respondents, of whom 76.9% used DEET products. Multivariate regression analyses showed that age was a significant predictor of repellent use, with respondents aged less than 51 years more likely to use repellent than older respondents (ORadj =2.0; 95% CI: 1.2-2.3). This age group was also more likely to use at least one personal protective behaviour (ORadj = 2.5; 95% CI: 1.4-4.5). Of 315 people selecting a justified time to larvicide, 4.8% chose "larvicides should never be used in Ottawa"; 33.4% stated that larviciding would be appropriate "when WNV was detected in birds or mosquitoes"; one third "needed more information" on the health and environmental effects of insecticides, prior to selecting a response., Conclusions: Our findings highlight the need for public education reinforcing WNV importance, emphasizing the health and environmental effects of insecticides as well as appropriate personal protective behaviours. Such messages should target older and urban residents.

DEET (N,N-diethyl-3-methylbenzamide) is nowadays the most effective mosquito repellent available, however, its use can present some topical and systemic side effects. Some botanical compositions, as Andiroba (Carapa guianensis), have been proved repellent properties at low cost and toxicity. An experimental study was driven involving four volunteers submitting their forearms covered with Andiroba oil at 100%, DEET 50%, refined soy oil, Andiroba oil 15% and in the absence of products, directly to healthy females of Aedes sp. The times of first and third bites were checked. The results showed that the median of the first bite without any product was 17.5s and the third bite, 40.0s. In the soy oil, the bites happened in 60.0s and 101.5s, in the presence of Andiroba oil 100%, in 56.0s and 142.5s and in Andiroba oil 15%, in 63.0s and 97.5s. The volunteers using DEET 50% had not received bites after 3600s in most of the experiments (p < 0.001 Wilcoxon). Pure Andiroba oil compared to the soy oil, forearm without product and Andiroba oil 15%, showed discreet superiority (p < 0.001 Wilcoxon). Our conclusion is that this study demonstrated that the pure Andiroba oil presents discreet repellent effect against bite of Aedes sp., being significantly inferior to DEET 50%.

We investigated personal protective behaviors against West Nile virus infection. Barriers to adopting these behaviors were identified, including the perception that DEET (N,N-diethyl-m-toluamide and related compounds) is a health and environmental hazard. Televised public health messages and knowing that family or friends practiced protective behaviors were important cues to action.

Synthetic repellents based on di-ethyl 3-methyl benzamide (DEET) are a popular method of obtaining protection from mosquitoes and yet clear evidence for a protective effect against malaria has hitherto never been convincingly demonstrated. A household randomized trial was undertaken among a study population of 127 families (25%) in an Afghan refugee village in Pakistan to compare the efficacy of repellent soap (Mosbar containing 20% DEET and 0.5% permethrin) vs. a placebo lotion. Cases of falciparum and vivax malaria were detected by passive case detection at the camp's clinic. At the end of the 6 month trial 3.7% (23 of 618) of individuals in the Mosbar group had presented with one or more episodes of falciparum malaria compared with 8.9% (47 of 530) of the placebo group (odds ratio 0.44, 95% CI 0.25-0.76). 16.7% of the Mosbar group (103 of 618) presented with vivax malaria compared with 11.7% (62 of 530) of the placebo group, and thus no effect was shown against vivax malaria (odds ratio 1.29, 95% CI 0.86-1.94). A considerable proportion of individuals (22%) had presented with vivax malaria during the 7 months leading up to the trial and thus any intervention effect would be partially masked by relapsed infections. The distribution of mosquitoes among households was broadly similar between Mosbar and placebo groups. The repellent was popularly received and very few side-effects were reported. There is a case for giving repellents more prominence in public health as a preventive measure in regions where vectors bite in the early evening or in emergency situations such as epidemics or newly established refugee camps.

The authors attempted to determine whether a targeted educational intervention in an area with endemic Lyme disease could increase knowledge, positive attitudes, and reported behaviors related to tick bite prevention and consequently decrease tick bites, as measured by a biomarker of tick bites. Between April and September of 1999, 317 subjects in Baltimore County, Maryland, were randomized to receive either tick-related or general health-related educational materials bimonthly through the mail. At each of three clinic visits, participants completed a self-administered questionnaire and provided a serum sample. Anti-recombinant tick calreticulin antibody (ARTCA), measured in ng/ micro l, was used as a biomarker of tick bites. Linear and logistic regression analyses were used to determine 1) whether the educational intervention was associated with a change in knowledge, attitudes, and behaviors (KAB) and 2) whether change in KAB predicted change in ARTCA levels. Proportions of desired responses increased significantly among intervention subjects versus the comparison group on KAB measures related to examining the body for ticks and insect repellent use. Levels of ARTCA were low among all study subjects. Only six of 37 models exhibited a significant relation between change in a KAB variable and change in ARTCA levels over time. The behavioral intervention was associated with an increase in the KAB measures in the intervention group, but this change was not associated with change in ARTCA levels.

Objective: Topical repellents can provide effective personal protection from tick-borne diseases by preventing the attachment of ticks. The goal of this study was to assess the effectiveness of a commercially available repellent spray containing both N,N-diethyl-3-methylbenzamide, previously known as N,N-diethyl-m-toluamide (DEET), and ethyl-butylacetylaminopropionate (EBAAP) against tick bites in a population at risk in Switzerland under real-life conditions., Methods: The effectiveness of an insect repellent spray containing both DEET and EBAAP was evaluated in a randomized, double-blind, placebo-controlled field study. The study, requiring simple application of the repellent to exposed skin, was carried out on 276 forestry workers and orienteers under everyday conditions in Switzerland from May to September 1999. We measured total effectiveness of the repellent by the following formula: percentage effectiveness = 100 x (T(P) - T(R))/T(P), where T(P) and T(R) were the average number of ticks per hour spent in wooded areas for the repellent and placebo groups, respectively., Results: The average number of tick bites per hour of exposure to wooded areas differed significantly between the placebo (n = 138) and repellent (n = 138) groups, 0.17 vs 0.10 (P < .05). Total repellent effectiveness against tick attachment was 41.1% (95% CI, 2.5-79.6). On the arms, an effectiveness of 66% (95% CI, 17.3-114.7) was observed. No significant difference in the average number of unattached ticks could be found., Conclusions: This study found that an easily applied repellent is moderately effective in reducing the risk of tick bites.

The beneficial effects of N, N-diethyl-m-toluamide (DEET) against biting insects of human and animals appear to last <6 hr after a single application to the skin. To prolong the repellent effects of DEET, recently we developed a new long-acting formulation of DEET called LIPODEET. This preparation was retained in the skin for a longer duration of time with minimal systemic absorption. In this study, we have evaluated the protective effect of three compounds (DEET, LIPODEET, and Morpel 220) against attachment of two species of ticks (Amblyomma americanum and Dermacentor variabilis) to rabbit ears. Results show that LIPODEET and Morpel 220 were highly effective in preventing tick attachment to the skin for a longer duration of time (up to 72 hr) than DEET after a single application. Moreover, LIPODEET was found to be acaricidal to both the species of ticks.

N, N-diethyl-m-toluamide (DEET) is a common and fairly safe active ingredient in many insect repellents. Our recent studies showed that when applied to the skin, DEET has a potent anti-parasitic effect against Schistosoma mansoni. However, the beneficial effects of DEET lasted only for a few minutes, presumably due to its rapid absorption through the skin. In this study, we evaluated different carrier formulations that prolong the activity of DEET in the skin. Among the various formulations analyzed, DEET incorporated into liposomes (LIPODEET) appeared to prolong the activity of DEET for more than 48 hr after a single application. Furthermore, LIPODEET was found to be minimally absorbed through the skin and loss due to washing off was limited. These findings thus suggest LIPODEET is a safe and long-acting formulation of DEET that is quite effective against schistosomiasis.

A clinical trial (n = 120, 60 males and 60 females) was conducted to assess the efficacy of an extended duration tropical insect/arthropod repellent (EDTIAR) topical formulation of N,N-diethyl-m-toluamide (DEET). The amount of EDTIAR (mean +/- confidence interval), applied by participants in accordance with label directions, was not significantly different between females (3.66 +/- 0.32 mg/cm2) and males (3.45 +/- 0.33 mg/cm2). There also was no significant difference in the number of Anopheles stephensi mosquitoes biting the control arm of females or males at 0, 3, 6, 9, and 12 hr. While gender had no effect on feeding, the time of day did effect mosquito feeding with fewer mosquitoes feeding in the afternoon than in the morning or evening. The percent protective efficacy at 0, 3, 6, 9, and 12 hr was 100.0, 99.3, 92.8, 79.7 and 66.3 for females, and 100.0, 100.0, 97.6, 91.9, and 77.5 for males. These data are inconsistent with the EDTIAR label claim that the repellent provides 95% or greater protection against mosquitoes for 12 hr or more under normal use conditions. The results of a multivariate regression analysis indicated that 1) protection decreased linearly as time after application of repellent increased (P < 0.001), 2) individuals who applied higher doses of repellent were better protected against mosquito bites (P < 0.001), 3) females experienced significantly less protection over time than did males (P = 0.005), and 4) the estradiol concentration in the blood had no effect on efficacy of the repellent (P = 0.110).

In recent years, concerns have been raised regarding the safety of diethyltoluamide (DEET), one of the most widely used and reliable insect repellents available. This paper summarizes the recent evidence and concludes that concerns over safety appear largely unfounded.

The effect of skin application of N,N-diethyl-m-toluamide (DEET) on the penetration and migration behavior of cercariae of Schistosoma mansoni was evaluated in vitro and in vivo in a mouse model. These studies showed that DEET at concentrations of 7.5% or higher was 100% effective in immobilizing and killing cercariae of S. mansoni in vitro. Ultrastructural studies on such DEET-exposed cercariae showed transformative and degenerative changes involving both tegument and deeper parenchymal structures. Fatal tissue lesions were evident as early as 5 min postexposure to DEET, and became more extensive with increasing exposure time. Cutaneous application of DEET (as a pure chemical in isopropanol or as a commercial insect repellent preparation) was more than 99% effective in preventing entry of S. mansoni cercariae into the mouse tail skin. Radiolabeling and tracer studies confirmed that 7.5% DEET applied to the skin prior to infection was highly effective in preventing schistosomular migration to the lungs.