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PubMed2005

Oviposition deterrent and skin repellent activities of Solanum trilobatum leaf extract against the malarial vector Anopheles stephensi.

The leaf extract of Solanum trilobatum (Solanaceae) was tested under laboratory conditions for oviposition deterrent and skin repellent activities against the adult mosquito Anopheles stephensi. Concentrations of 0.01, 0.025, 0.05, 0.075 and 0.1% reduced egg laying by gravid females from 18 to 99% compared to ethanol-treated controls. In skin repellent tests, concentrations of 0.001, 0.005, 0.01, 0.015, and 0.02 % provided 70 to 120 minutes protection against mosquito bites, whereas the ethanol control provided only 2.2 minutes of protection. Both oviposition deterrent and skin repellent activity were dose dependent. The results suggest that the leaf extract of S. trilobatum is an effective oviposition deterrent and skin repellent against An. stephensi.

Animals↗
PubMed2002

West Nile virus: a primer for the clinician.

This paper provides the clinician with an understanding of the epidemiologic and biological characteristics of West Nile virus in North America, as well as useful information on the diagnosis, reporting, and management of patients with suspected West Nile virus infection and on advising patients about prevention. Information was gathered from the medical literature and from national surveillance data through May 2002. Since the identification of West Nile virus in New York City in 1999, enzootic activity has been documented in 27 states and the District of Columbia. Continued geographic expansion is likely. Overall, one in 150 infections results in severe neurologic illness. Advanced age is by far the most important risk factor for neurologic disease and, once disease develops, for worse clinical outcome. Surveillance has identified 149 persons with West Nile virus-related illness in 10 states. Encephalitis is more commonly reported than meningitis, and concomitant muscle weakness and flaccid paralysis may provide a clinical clue to the presence of West Nile virus infection. Peak incidence occurs in late summer, although onset has occurred from July through December. Immunoglobulin M antibody testing of serum specimens and cerebrospinal fluid is the most efficient method of diagnosis, although cross-reactions are possible in patients recently vaccinated against or recently infected with related flaviviruses. Testing can be arranged through local, state, or provincial (in Canada) health departments. Prevention rests on elimination of mosquito breeding sites; judicious use of pesticides; and avoidance of mosquito bites, including mosquito repellent use.

Africa↗
PubMed2001

Repellency of volatile oils from plants against three mosquito vectors.

Volatile oils extracted by steam distillation from four plant species (turmeric (Curcuma longa), kaffir lime (Citrus hystrix), citronella grass (Cymbopogon winterianus) and hairy basil (Ocimum americanum)), were evaluated in mosquito cages and in a large room for their repellency effects against three mosquito vectors, Aedes aegypti, Anopheles dirus and Culex quinquefasciatus. The oils from turmeric, citronella grass and hairy basil, especially with the addition of 5% vanillin, repelled the three species under cage conditions for up to eight hours. The oil from kaffir lime alone, as well as with 5% vanillin added, was effective for up to three hours. With regard to the standard repellent, deet alone provided protection for at least eight hours against Ae. aegypti and Cx. quinquefasciatus, but for six hours against An. dirus. However, deet with the addition of 5% vanillin gave protection against the three mosquito species for at least eight hours. The results of large room evaluations confirmed the responses for each repellent treatment obtained under cage conditions. This study demonstrates the potential of volatile oils extracted from turmeric, citronella grass and hairy basil as topical repellents against both day- and night-biting mosquitoes. The three volatile oils can be formulated with vanillin as mosquito repellents in various forms to replace deet (N,N-diethyl-3-methylbenzamide), the most common chemical repellent currently available.

Animals↗
PubMed1997

The contribution of repellent soap to malaria control.

A study about the acceptability, protective efficacy, effectiveness, and cost of a repellent soap containing 20% diethyltoluamide and 0.5% permethrin was carried out on the Pacific coast of Ecuador and Peru, where malaria is endemic and the transmission is seasonal. The malaria vectors were Anopheles albimanus, An. punctimacula, and An. pseudopunctipennis in Ecuador and An. albimanus in Peru. Comparing the hourly mosquito bites on human subjects with and without the protection of the repellent soap, it showed that inactive, protected subjects were bitten 94.2% less than unprotected controls 2 hr after application of the soap. This protective efficacy was reduced to 81% after 6 hr. In persons physically active for 3 hr after application, the efficacy of the soap was 67% in the fourth hour after application and 52% in the sixth hour after application. Sweating decreased the protective efficacy of the soap even more. In a community-based malaria control program, the soap was introduced by community health promoters. Acceptance was good when it was given free of charge but reduced dramatically when it was sold. People used the soap mainly because of the nuisance of mosquitoes. The application was generally done correctly. However, no significant impact on the incidence of malaria episodes could be shown when comparing intervention communities with control communities, either in Ecuador, where the proportion of Plasmodium falciparum cases was high, or in Peru, where P. vivax was the only species of Plasmodium seen. This can probably be explained by the limited use of soap and the shift of mosquito bites from users to nonusers of the repellent soap. The cost of a soap program would be $4.60 (USA) per person per year, which seems to be quite high in terms of cost of soap and its distribution related to people's low cash income. The implications of the introduction of repellent soap into a control program are discussed.

Animals↗
PubMed1998

Duration of repellency of various synthetic and plant-derived preparations for Culicoides imicola, the vector of African horse sickness virus.

Objectives of the study were threefold: to find a safer and longer lasting repellent of the biting midge Culicoides imicola than di-ethyl toluamide (DEET), to examine whether the current recommendations in Israel for application of repellents during an outbreak of C. imicola-borne pathogens are justified; and to examine whether plant-derived preparations that have no known detrimental side effects are potential replacements of synthetic repellents. Of the seven repellents tested, those inferior to DEET were: oregano and Herbipet which showed a slight non-significant repellency for 2 h and 1 h respectively and Stomoxin which showed significant (P < 0.05) repellency for only 1 h. As the active ingredient of Stomoxin is permethrin, this suggests that recommendations to spray animals with this insecticide to prevent the spread of C. imicola-borne pathogens are not useful. Tri-Tec14 showed significant (P < 0.05) repellency with respect to controls for 2 h only, but performed similarly to, or slightly better than DEET. The repellents clearly superior to DEET were: the plant-derived material Ag1000 that repelled significantly (P < 0.05) with respect to controls for up to 4 h following a similar pattern to but somewhat more strongly than DEET, and pyrethroid-T which exerted significant (P < 0.05) repellency for 9 h. Pyrethroid-T proved to be the best repellent tested and if sprayed nightly it might provide protection from C. imicola-borne pathogens.

African Horse Sickness↗
PubMed2005

[Evaluation of repellent and anti-feeding effect of garlic oil (Allium sativum) against the bite of phlebotomine sandflies Diptera: Psychodidae].

The repellent and anti-feeding effect of garlic oil was evaluated in laboratory conditions against the bite of Phlebotomus papatasi females. The effectiveness was evaluated by two different laboratory procedures: (i) topical application of garlic oil on five human volunteers, using the "standard cage test", and (ii) feeding sandflies on artificial membranes treated with the compound. Garlic oil showed a significant protection by topical application on the skin of volunteers, being the protection 97% and 40%, respectively at 1% and 0.005% dilution. Garlic oil showed also an anti-feeding effect when tested on the artificial membrane feeding apparatus; the anti-feeding effect was dose dependent, being 100% at 1%. The results of the present study confirm previous observations on the repellent effect of garlic oil against haematophagous arthropods.

Administration, Cutaneous↗
PubMed1982

Evaluation of personal protection methods against phlebotomine sand flies including vectors of leishmaniasis in Panama.

Three personal protection methods were evaluated against phlebotomine sand flies in Panama. Skin applications of five selected repellents including deet (N,N-diethyl-m-toluamide) provided a mean coefficient of protection (CP) of 99.2% against the attack of at least three sand fly species. Deet-treated net jackets also provided good protection, but it was concluded that an additional application of repellent to the unprotected face was necessary for maximum protection. Permethrin-treated clothing did not provide the protection expected. Apparently sand fly behavior and resistance to quick knock-down were responsible for the numbers of bites recorded, and therefore maximum protection from bites would require application of deet or another suitable repellent to the exposed skin when wearing permethrin-treated clothing.

Animals↗
PubMed1990

[Studies on the efficacy of five repellents against Phlebotomus alexandri].

The efficacy of five repellents were tested against Phlebotomus alexandri both in the laboratory and in the field in Meiyaogou, Turfan City, Xinjiang Uygur Autonomous Region during 1986-1987. A total of 3,301 female Ph. alexandri were used in the laboratory and 306 man-times of volunteers were tested in the field. At a dose of 0.25 microliters/cm2, the protective durations of mosquito repellent perfume (MRP), N, N-diethyl-mtaluamide (DETA), mosquito repellent liquid (MRL), dimethyl phthalate (DMP) and dibutyl phthalate (DBP) were 7.50 h, 5.00 h, 3.75 h, 1.25 h and 1.00 h, respectively. At a dose of 0.75 mg/cm2, the protective durations of the essential balms of DETA, DMP and DBP were 5.50 h, 3.50 h and 3.00 h, respectively. The repelling effect on volunteers in the field was the same as that tested in the laboratory. The relative efficacy of the five repellents was in the order of MRP greater than DETA greater than MRL greater than DMP greater than DBP. The above-mentioned repellents may be of practical use for individual protection against kala-azar transmission in the field.

Animals↗
PubMed1995

Response of wild Anopheles funestus to repellent-protected volunteers is unaffected by malaria infection of the vector.

A field experiment was conducted to compare the biting behavior of Plasmodium falciparum-infected and uninfected Anopheles on humans using mosquito repellents. Repellent formulations (5% [wt/vol] N,N-diethyl-3-methylbenzamide [deet] or 5% [wt/vol] AI3-37220, a piperidine compound, both in 100% ethanol, or 100% ethanol alone [as a control]) were applied to the lower legs of 3 collectors in each of 4 houses. Collectors caught mosquitoes over 6 collection nights. Mosquitoes were collected into vials after they initiated probing on the leg of a collector. Infected females made up the same proportion of the Anopheles funestus populations biting either repellent-protected or unprotected individuals. We conclude that repellent formulations are equally effective against Plasmodium-infected and uninfected An. funestus.

Animals↗
PubMed2004

DEET mosquito repellent sold through social marketing provides personal protection against malaria in an area of all-night mosquito biting and partial coverage of insecticide-treated nets: a case-control study of effectiveness.

DEET (diethyl-3-methylbenzamide), the widely used mosquito repellent, has the potential to prevent malarial infection but hitherto there has been no study demonstrating this possibility during normal everyday use. Mosbar, a repellent soap containing DEET, was promoted through social marketing in villages in eastern Afghanistan. This was followed up with a case-control study of effectiveness against malarial infection conducted through local clinics. Mosbar was purchased by 43% of households. Reported use of insecticide-treated nets (ITNs) was 65% among the control group. There was a strong association between Mosbar use and ITN use, as 81% of Mosbar users also possessed ITN. The use of Mosbar was associated with a 45% reduction in the odds of malaria (95% CI: -11% to 72%, P=0.08) after adjusting for ITN and other unmatched factors. Ownership of ITNs was associated with a 46% reduction in the odds of malaria (95% CI: 12% to 67%, P=0.013) after adjusting for Mosbar and other unmatched factors. The greatest reduction in the odds of malaria was associated with combined use of Mosbar and ITN (69% reduction, 95% CI: 28% to 87%, P=0.007). The association between recalled use of Mosbar 10 days ago (nearer the time of infection) and reduction in malarial infections (adjusted odds ratio 0.08, 95% CI: 0.01-0.61, P=0.001) was significantly stronger than that shown by current use of Mosbar. Most purchasers of Mosbar were satisfied with the product (74%), although a minority said they preferred to use only ITN (8%). The local mosquito vectors, Anopheles stephensi and A. nigerrimus, started biting shortly after dusk and continued biting until early morning. It was shown that Mosbar prevented biting throughout this period. In regions where mosquito vectors bite during evening and night, repellents could have a useful supplementary role to ITN and their use should be more widely encouraged.

Adolescent↗
PubMed2001

Laboratory evaluation of repellents against Leptotrombidium deliense, vector of scrub typhus.

BACKGROUND & OBJECTIVES: Scrub typhus, a rickettsial disease transmitted by larvae of Leptotrombidium deliense, is of special importance to the Armed Forces personnel, due to the heightened risk to this disease during movement in mite endemic areas during exercise/war. The disease is best prevented by the use of personal protective measures including repellents. Studies were undertaken to determine the relative efficacy of repellents: diethyl toulamide (DEET), dibutyl phthalate (DBP) with an indigenously developed repellent diethyl phenyl acetamide (DEPA) against the larval trombiculid mite. METHODS: The repellents were tested for persistence on impregnated cloth prior to washing, post washing and ironing by means of a specially fabricated testing kit. Acaricidal efficacy estimation was performed on the treated fabrics and topical application efficacy of repellents on mice was evaluated by a novel animal testing model. RESULTS: DEET and DEPA were found to provide maximum protection (repellence and acaricidal efficacy), could withstand two launderings of the impregnated uniform and also had superior efficacy on topical application (8 h). Ironing was found to significantly reduce the repellence of DEET and DBP. INTERPRETATION & CONCLUSION: The findings of this study point towards the superiority of DEPA and DEET for impregnation of the uniform cloth as well as for topical application for the prevention of scrub typhus amongst the troops.

Animals↗