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PubMed2006

Anopheles gambiae P450 reductase is highly expressed in oenocytes and in vivo knockdown increases permethrin susceptibility.

We describe an in vivo model for investigation of detoxification mechanisms of the mosquito Anopheles gambiae, important for the development of malaria control programmes. Cytochrome P450s are involved in metabolic insecticide resistance and require NADPH cytochrome P450 reductase (CPR) to function. Here we demonstrate that the major sites of adult mosquito CPR expression are oenocytes, mid-gut epithelia and head appendages. High CPR expression was also evident in Drosophila oenocytes indicating a general functional role in these insect cells. RNAi mediated knockdown drastically reduced CPR expression in oenocytes, and to a lesser extent in mid-gut epithelia; the head was unaffected. These flies showed enhanced sensitivity to permethrin, demonstrating a key role for abdominal/mid-gut P450s in pyrethroid metabolism, aiding the development of insecticides.

Animals↗

PubMed1987

The effect of permethrin-impregnated bednets on a population of Anopheles farauti in coastal Papua New Guinea.

The effect of introducing bednets impregnated with 0.4 g/m2 permethrin on local populations of the malaria vector mosquitoes Anopheles farauti Laveran and An. koliensis Owen was monitored in a coastal village of Papua New Guinea. Whole-night landing collections were undertaken for 25 consecutive nights before and 21 nights after the introduction of the nets. Capture-recapture experiments and resting collections were also performed before and after the introduction of the nets. Following the introduction of treated nets, the biting population of An. farauti, the predominant vector, dropped from an average of 689 to 483 per man-night and the oviposition cycle became irregular, although survival rates (determined by time series analysis of the landing catches and log regression of recapture rates) were not significantly affected. The densities of An. farauti resting in and around houses and the human blood index of the engorged females also decreased significantly after introduction of the treated bednets. The population of An. koliensis dropped prior to the introduction of the nets. However, the number of nulliparous females in the landing catches remained more or less constant which implies that, in this species, survival rates were affected by the nets but that recruitment to the population was not.

Animals↗

PubMed1989

Control of haematophagous flies on equines with permethrin-impregnated eartags.

The efficacy of 10% (w/w) permethrin impregnated eartags for the control of the haematophagous fly pests Stomoxys calcitrans L., Haematopota dissimilis Meigen and Hippobosca maculata Leach on equines in India was determined. The tags were found to be effective for 1-2 months against S. calcitrans and H. dissimilis but completely ineffective against H. maculata. No tags were lost during the study. Tags can be used as part of an integrated control programme. This is the first reported use of eartags for control of haematophagous flies on horses.

Animals↗

PubMed1993

Impact of permethrin-impregnated mosquito nets compared with DDT house-spraying against malaria transmission by Anopheles farauti and An.punctulatus in the Solomon Islands.

In villages of northern Guadalcanal in the Solomon Islands, where the predominant malaria vector is An.farauti No. 1 and An.puctulatus is also involved, malaria transmission rates were compared for three zones: (1) non-intervention: 438 people in seventeen villages; (2) residual DDT house-spraying two cycles per year: 644 people in thirty villages; (3) bednets impregnated with permethrin 0.5 g/m2 twice per year, used by 580 people in sixteen villages. Regular DDT spraying in zones 1 and 3 had been withdrawn 18 months previously. Malariological blood smear surveys of children aged 1-9 years in August 1986 to January 1987 showed a mean baseline malaria parasite rate of 38% (32/84). By February 1988, 18 months after introduction of impregnated bednets, the Plasmodium falciparum infection rate in children was lowest in the zone using impregnated bednets (21% of 29), intermediate in the untreated zone (29% of 34) and highest in the DDT zone (46% of 53), but these differences were not statistically significant. P. vivax infection rates were 9-14%. Using ELISA tests for malaria circumsporozoite antigen in the vectors, overall positivity rates were 0.7% of 49,902 An.farauti and 2.54% of 118 An.punctulatus, comprising 228 P.falciparum and 124 P.vivax infections. In the study zones, vector positivity rates were 0.93% of 31,615 An.farauti in the untreated zone; 0.32% of 16,883 An.farauti in the DDT zone; 0.07% of 1404 An.farauti and 2.54% of 118 An.puctulatus in the impregnated bednet zone. here was no significant correlation between malaria parasite rates in the vectors and the children.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1997

Dosage differential effects of permethrin impregnated into bednets on pyrethroid resistant and susceptible genotypes of the mosquito Anopheles stephensi.

Effects of bednets impregnated with permethrin 200 mg and 500 mg/m2 on pyrethroid resistant and susceptible strains of Anopheles stephensi and their F1 hybrid progeny were studied, using free-flying female mosquitoes of these three genotypes, in a room with a human subject under a polyester net, having one of his arms in contact with the treated netting. Unexpectedly an apparently higher feeding rate, but lower knockdown and mortality rates, of mosquitoes were obtained for each of the three genotypes with the higher concentration of 500 mg/m2 compared with the lower dose of 200 mg/m2. At the lower dose there was 100% mortality 24 h after exposure of all three genotypes, suggesting that there would not be selection for resistance at this dose. However, at the higher dose there was significantly higher mortality of the susceptible strain than of the F1 hybrids, suggesting incomplete recessiveness of this resistance and that there would therefore be effective selection for resistance by this dose. When female mosquitoes were confined in bioassay cones on treated netting, the resistant strain of An. stephensi showed significantly less irritability (scored as the time until first flight take-off) in response to each dose, as compared with the susceptible strain and F1 hybrids. The higher dose provoked more irritation of each genotype; this could explain the greater knockdown and mortality rates of mosquitoes exposed to the lower dose which was less irritating and hence more effectively insecticidal. Thus a dose of 200 mg/m2 is preferable to 500 mg/m2 for malaria vector control.

Animals↗

PubMed1985

The efficacy of permethrin lotion in pediculosis capitis.

A clinical trial of the pyrethroid permethrin in 1% lotion was performed on 20 children. Ten were treated for 10 minutes and 10 for 2 hours. All lice washed off the heads of children treated for 2 hours were dead immediately after treatment. Twenty-four percent of the lice removed from one child treated for 10 minutes were still alive 2 hours later. The ovicidal effect was similar in both groups, with egg mortality 88% and 90% following 10-minute and 2-hour treatment, respectively. The mortality of untreated control eggs was 14% and 11%, respectively.

Adolescent↗

PubMed1994

Neonatal scabies treated with permethrin 5% cream.

Scabies in neonates and infants has a clinical pattern that may be easily misdiagnosed. The eruption is generalized, including involvement of the head, neck, face, palms, and soles, with an early tendency to pustule formation. Other lesions include papules, vesicles, and burrows, which may be obliterated by secondary lesions. A confusing clinical picture resulted in a delay in diagnosing scabies in a 23-day-old infant who was successfully treated with permethrin 5% cream.

Diagnosis, Differential↗

PubMed2004

Treatment of Neotrombicula autumnalis dermatitis in dogs using two topical permethrin-pyriproxyfen combinations.

Few data are available in the literature on the dermatological consequences and treatment of Neotrombicula autumnalis infestation in dogs and cats. In this study, 15 dogs naturally infested with Neotrombicula were affected with moderate to severe pruritic dermatitis. The dermatitis resolved with successful treatment of the parasitic infestation. In 14 dogs, treatment using a topical permethrin-pyriproxyfen combination (pump-spray or 'line-on') was effective within one to three weeks. Two applications were necessary in four dogs. Careful follow-up was conducted in all cases. Statistical analysis was performed to assess the impact of treatment on the parasite population and clinical signs over the three-week study period.

Administration, Cutaneous↗

PubMed1988

Microbial transformation of the pyrethroid insecticides: permethrin, deltamethrin, fastac, fenvalerate, and fluvalinate.

Pure cultures of Bacillus cereus, Pseudomonas fluorescens, and Achromobacter sp. were shown to transform five pyrethroid insecticides in the presence of Tween 80. One of the major products, 3-phenoxybenzoic acid, was further transformed to 4-hydroxy-3-phenoxybenzoic acid. Permethrin was the most rapidly transformed of the pyrethroids, with a half-life of less than 5 days.

Alcaligenes↗

PubMed2006

Evaluation of a spray of permethrin and pyriproxyfen for the protection of dogs against Phlebotomus perniciosus.

Dogs are the main domestic reservoir of Leishmania infantum in the Old World (Leishmania chagasi in the New World) a parasite responsible for many cases of human visceral leishmaniasis in both endemic and non-endemic regions. One strategy for the control of leishmaniasis would be to prevent dogs from being bitten by sandflies, the vector of leishmaniasis. This study was designed to assess the efficacy of spraying a combination of permethrin and pyriproxyfen on to dogs artificially exposed to sandflies. Two groups of four male dogs, one of them treated and the other left untreated as controls, were exposed for one hour to 100 female sandflies seven days before the treatment, on the day of treatment and seven, 14, 21, and 28 days later. After each exposure, sandflies were collected, counted and scored. The prevention of sandfly bite was calculated by measuring the number of fed sandflies (dead and alive) after treatment. In this experimental assay, the repellent effect of the treatment against sandfly bites after 21 days was 71.4 per cent, but the insecticidal effect was only 7.2 per cent.

Administration, Cutaneous↗

PubMed1998

Comparative study of the clinical effectiveness of a pyrethrin-based pediculicide with combing versus a permethrin-based pediculicide with combing.

In a randomized, evaluator-blinded clinical trial, 190 patients were treated for Pediculus humanus capitis infestations with a pyrethrin-piperonyl-butoxide pediculicide (RID; Py-PB) and a permethrin pediculicide (NIX; PM). A total of 160 patients were evaluable for nit-combing speed, 156 patients were evaluable for efficacy at day 7, and 150 patients were evaluable for efficacy at day 14. Both Py-PB and PM showed 100% efficacy at day 7. At day 14, one patient in the PM group had an apparent reinfestation. The Py-PB group had significantly lower mean combing times (P=0.04), but because the PM group had more nits, the two groups were not significantly different in combing speed expressed as seconds per nit. Multiple regression and covariance analyses suggested that the greater speed of the Py-PB comb might have been masked by this baseline difference. Three patients had mild adverse experiences (Py-PB: erythema, PM: erythema and tingling sensation). No patients were removed from the study because of adverse events. In conclusion, this controlled clinical study demonstrated that both Py-PB and PM provided 100% efficacy following a single application. Differences attributable to comb design favored the Py-PB "rake" comb, but this requires additional evaluation and confirmation.

Child↗

PubMed2001

Head lice infestation: single drug versus combination therapy with one percent permethrin and trimethoprim/sulfamethoxazole.

BACKGROUND: Head lice infestation (HLI) is a vexing problem for pediatricians and families because lice are becoming resistant to approved antipediculosis agents. OBJECTIVE: This study compared the efficacy of 3 different treatments for HLI and determined whether combination therapy reduced treatment failures. DESIGN AND SETTING: A randomized, clinical trial performed in 3 private practices. PARTICIPANTS: The population was children ranging in age from 2 to 13 years. METHODS: HLI was diagnosed by direct inspection of the hair and scalp. Children were assigned to 1 of 3 groups: 1) 1% permethrin creme rinse (1% PER; n = 39); 2) oral administration of trimethoprim/sulfamethoxazole (TMP/SMX; n = 36); and 3) a combination of 1% PER and TMP/SMX (n = 40). Follow-up visits were done 2 and 4 weeks later, and parents or caregivers of those who did not return were interviewed by telephone. If HLI was present at the 2-week follow-up, the child was retreated per their protocol. We defined successful treatment as the absence of adult lice and nymphal stage or eggs (nits). The presence of nits alone was not considered a treatment failure. RESULTS: At the 2-week follow-up visit, successful treatment for groups 1, 2, and 3 was 79.5%, 83%, and 95%, respectively. At the 4-week follow-up, successful treatment was 72%, 78%, and 92.5% for groups 1, 2, and 3, respectively. The absolute risk reduction for recurrence comparing group 1 versus group 2 was 6%, group 2 versus group 3 was 14%, and group 1 versus group 3 was 20%. No major adverse complications were seen in any treatment group. CONCLUSION: Our findings indicate that a combination of 1% PER and TMP/SMX is an effective alternative therapy for HLI. We recommend that the dual therapy with 1% PER and oral TMP/SMX be used and reserved in cases of multiple treatment failures or suspected cases of lice-related resistance to therapy.

Administration, Oral↗

PubMed2005

Isomer selectivity in aquatic toxicity and biodegradation of bifenthrin and permethrin.

Synthetic pyrethroids are widely used insecticides, and contamination of surface aquatic ecosystems by pyrethroid residues from runoff is of particular concern because of potential aquatic toxicity. Pyrethroids also are chiral compounds consisting of multiple stereoisomers. In the present study, we evaluated the diastereomer and enantiomer selectivity of cis-bifenthrin (cis-BF) and permethrin (PM) in their aquatic toxicity and biodegradation. The 1R-cis enantiomer was the only enantiomer in cis-BF showing toxicity against Ceriodaphnia dubia. Incubation with pesticide-degrading bacteria showed that the trans diastereomer of PM was selectively degraded over the cis diastereomer, whereas the 1S-cis enantiomer in cis-BF or cis-PM was preferentially degraded over the corresponding 1R-cis enantiomer. The enantioselectivity was significantly greater for cis-PM than for cis-BF and also varied among different strains of bacteria. Isomer selectivity may be a common phenomenon in both aquatic toxicity and biodegradation of pyrethroids, and this should be considered when assessing ecotoxicological risks of these compounds in sensitive ecosystems.

Animals↗

PubMed1982

Permethrin as a clothing treatment for personal protection against chigger mites (Acarina: Trombiculidae).

A study was done to evaluate the personal protection afforded by uniforms treated with permethrin (0.125 mg/cm2) against natural infestations of chigger mites, Trombicula spp. The study utilized human test subjects taking part in a military field training exercise. At the end of the 3-day period, there was 74.2% increase in protection provided by the treated uniforms compared to an untreated uniform and the use of repellent. The increased protection amounted to ca 60 fewer mite attachments per treated subject. The treated uniforms were also found to be nonirritating and nonodorous.

Clothing↗

PubMed1990

Permethrin-impregnated curtains and bed-nets prevent malaria in western Kenya.

The effectiveness of permethrin-impregnated (0.5 g/m2) bed-nets and curtains as malaria control measures was evaluated in Uriri, Kenya in 1988. One hundred five families were randomly assigned to 1 of 3 study groups (control, bed-net, or curtain). All participants were cured of parasitemia with pyrimethamine/sulfadoxine. Selective epidemiologic and entomologic parameters were measured weekly, while knowledge, attitude, and practices surveys were conducted at the beginning and end of the 15 week study. Plasmodium falciparum infections per person week at risk were significantly higher in the control group than in either the curtain group (5.42 vs. 2.35 cases/100 person weeks risk) or the bed-net group (5.42 vs. 3.77 cases/100 person weeks risk). The curtain group had fewer infections per person week at risk than the bed-net group (2.35 vs. 3.77 cases/100 person weeks risk). A difference was found in clinical malaria among the groups: 45% of persons in the bed-net and curtain groups vs. 30% of those in the control group reported no episodes of fever and chills (chi 2, P less than 0.05). Indoor resting Anopheles gambiae or An. funestus were found on 94 occasions in the control houses, but only twice in the treated houses during weekly visits to each house over the study period (chi 2 P less than 0.001). The pyrethrum knockdown method produced similar results with a total of 195, 23, and 3 An. gambiae and An. funestus collected in the control, bed-net, and curtain houses during the same period, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Effectiveness of permethrin-impregnated bed nets and curtains for malaria control in a holoendemic area of western Kenya.

The effectiveness of village-wide use of permethrin-impregnated bed nets or eave, window, and door curtains as control measures for Plasmodium falciparum malaria was evaluated during two successive high-transmission seasons in western Kenya. Pairs of villages were assigned to one of three study groups: bed net, curtain, or control. Clinical, parasitologic, and entomologic measures were made from March to July 1990 and again 12 months later. When compared with the controls in 1990 and 1991, we observed a marked reduction in the incidence of P. falciparum infections in children less than six years old in the bed net villages (reduced by 40% and 48%) and a smaller but still significant reduction in the curtain villages (10% and 33%). Significant reductions were also seen in the incidence of P. falciparum parasitemias greater than 2,500/mm3 in the bed net group (reduced by 44% and 49%) and curtain group (16% and 32%). Additionally, we observed significant reductions in the incidence of documented fevers in association with P. falciparum parasitemia in bed net (reduced by 63%) and curtain villages (53%) when compared with controls. Entomologic inoculation rates in both bed net and control villages decreased by more than 50% below control values during both high transmission seasons. The results of this study, together with a 1988 study in the same area during the low transmission season, show that bed nets offer greater year-round of protection against P. falciparum infection than curtains. However, during the high transmission season, this technique reduces the frequency of P. falciparum infection rather than preventing it entirely.

Animals↗

PubMed1993

Permethrin-impregnated bed nets for malaria control in northern Guatemala: epidemiologic impact and community acceptance.

Permethrin-impregnated bed nets were evaluated as a control measure for malaria in northern Guatemala. Twelve hundred forty participants were allocated to one of three experimental groups (impregnated bed nets [IBN], untreated bed nets [UBN], and controls) and followed up for a period of 13 months. The incidence density of malaria was significantly lower in both IBN (86 cases/1,000 person-years) and UBN groups (106/1,000) compared with that in controls (200/1,000). No difference in malaria incidence was noted between the IBN and UBN groups. Complaints of fever and chills were less frequent in the IBN group compared with controls. The participants were enthusiastic about the nets, which they saw as a means for avoiding nuisance insects more than for preventing malaria. Most (85%) wanted to wash their nets every 4-12 weeks, a practice known to shorten the duration of residual insecticide action. Larger studies are needed to determine whether or not impregnated bed nets offer an advantage over untreated nets in this setting.

Adult↗

PubMed1995

Laboratory and field evaluations of a repellent soap containing diethyl toluamide (DEET) and permethrin against phlebotomine sand flies (Diptera: Psychodidae) in Valle del Cauca, Colombia.

The repellency and insecticidal efficacy of Nopikex, a soap formulation containing 20% diethyl toluamide and 0.5% permethrin, was evaluated against a laboratory colony of phlebotomine sand flies (Lutzomyia longipalpis). The repellency of Nopikex soap was also compared with that of a placebo soap against another species (Lu. youngi) in a forest near Tulua, Valle del Cauca, Colombia. In laboratory trials of the soap, no reduction in repellency was seen 4 hr after application, but within 8 hr, repellency decreased significantly to 67.0% of the initial value (P < 0.05) based on calculations of the coefficient of protection (CP). Under field conditions, the soap gave up to 100% protection immediately after application, but within 4 hours its CP value had decreased to a median value of only 44.3%. The placebo soap was also found to be somewhat repellent when compared with no treatment, giving a median CP value of 67.7 immediately after application. No significant mortality was seen in sand flies within 24 hr of exposure to the soap in the laboratory, even in those that had fed on protected volunteers.

Animals↗