Elimite
[Effects of pyrethroids on the glutamate uptake system in synaptic vesicle of rats]

[Article in Chinese]

Wu J, Xia R, Shi N, Liu Y.

Institute of Environmental Toxicology, Tongji Medical University, Wuhan 430030, China. jpwu dns.njmu.edu.cn

In order to study the effects of cypermethrin and permethrin insecticides on the glutamate uptake of rat brain, brain synaptic vesicles and cypermethrin or permethrin were incubated with 3H-glutamate (37 KBq, 1 mumol/L). The radio activity was detected by a liquid scintillation counter. The results showed that cypermethrin and permethrin in the concentration of 10(-9)-10(-4) mol/L could inhibit the high affinity uptake of glutamate in the synaptosomes of cerebral cortex, hippocampus and striatum in a dose-response manner. Cypermethrin was more powerful than permethrin at the same dose. It was concluded that glutamate uptake inhibition might play a vital role in the neurotoxicity induced by pyrethroid insecticides.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12712690&dopt=Abstract permethrin Elimite



Elimite
Management of endemic outbreaks of scabies with allethrin, permethrin, and ivermectin.

Paasch U, Haustein UF.

Department of Dermatology, University of Leipzig, Germany.

BACKGROUND: At three residences for the elderly, recurrent scabies infestations became out of control. Due to the failure of repeated, nonsynchronized therapeutic efforts with conventional external anti-scabies treatments, an eradication program had to be developed. We describe a protocol for the management of outbreaks of scabies. METHODS: According to the clinical examination and microscopically identified mites, all individuals of the population (IOP: patients, staff, and family members) were divided into two groups: (a) healthy and infested IOP; and (b) cases with crusted scabies. The first group was treated simultaneously once with external scabicides (allethrin or permethrin). All others were hospitalized and treated either with systemic ivermectin or with the latter in combination with permethrin. RESULTS: In 252 IOP living in three residences for the elderly, clinical signs of scabies were reported in 91.5%, 78.5%, and 15.4% of the patients (age 55-97 years; mean, 80.5 years), 54.1%, 32.9%, and 16.6% of staff members, and in 7%, 3%, and 0% of family members. The infested IOP showed crusted scabies (index cases) in 5.3%, 5.0%, and 1.7%, common scabies in 43.1%, 36.7%, and 7.1%, and postscabiotic dermatitis in 10.3%, 7.6%, and 3.5%. In 99.2% of the synchronously treated IOP in group (a) (n = 240), the conventional treatment with permethrin cream 5% or allethrin spray was effective. Group (b) (n=12) received ivermectin (12 mg) once (n=5) or twice (n= 7) after an interval of 8 days. One index case received permethrin three times. CONCLUSIONS: Outbreaks of scabies in populations of elderly people require special management for disease control. Synchronous treatment with external permethrin cream 5% or allethrin spray, including all IOP once, and close control offers a time-saving, cheap, and reliable method. Crusted scabies should be treated by oral administration of ivermectin once or twice after an interval of 8 days. Additional applications of permethrin and mechanical clearing of hyperkeratotic subungual areas shorten the course.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10944095&dopt=Abstract permethrin Elimite



Elimite
Synergism between permethrin and propoxur against Culex quinquefasciatus mosquito larvae.

Corbel V, Chandre F, Darriet F, Lardeux F, Hougard JM.

Laboratoire de Lutte Contre les Insectes Nuisibles (LIN), Institut de Recherche pour le Developpement (IRD), 911 avenue Agropolis, BP 64501, 34394 Montpellier Cedex 5, France. corbel mpl.ird.fr

To see if synergism occurs between carbamate and pyrethroid insecticides, we tested permethrin and propoxur as representatives of these two classes of compounds used for mosquito control. Larvicidal activity of both insecticides was assessed separately and together on a susceptible strain of the mosquito Culex quinquefasciatus (Diptera: Culicidae) by two methods. When mixed at a constant ratio (permethrin : propoxur 1 : 60 based on LC50) and tested at serial concentrations to plot dose/mortality regression, significant synergy occurred between them (co-toxicity coefficient = 2.2), not just an additive effect. For example, when the mixture gave 50% mortality, the same concentrations of permethrin and propoxur alone would have given merely 2 x 1% mortality. When a sublethal dose (LC0) of permethrin or propoxur was added to the other (range LC10-LC95), synergism occurred up to the LC80 level. Synergistic effects were attributed to the complementary modes of action by these two insecticide classes acting on different components of nerve impulse transmission. Apart from raising new possibilities for Culex control, it seems appropriate to consider using such mixtures or combinations for insecticide-treated mosquito nets in situations with insecticide-resistant Anopheles malaria vectors.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12823833&dopt=Abstract permethrin Elimite



Elimite
Permethrin-resistant human head lice, Pediculus capitis, and their treatment.

Yoon KS, Gao JR, Lee SH, Clark JM, Brown L, Taplin D.

Department of Entomology, University of Massachusetts-Amherst, MA 01003, USA.

OBJECTIVE: To compare the pediculicidal activity of Ovide lotion and its active ingredient, 0.5% malathion, with Nix and its active ingredient, 1% permethrin, in permethrin-resistant head lice. DESIGN: In vitro pediculicidal product and active ingredient comparison. The presence of knockdown resistance-type mutations (T929I and L932F) was validated by DNA sequencing. SETTING: University of Massachusetts-Amherst; University of Miami School of Medicine, Miami, Fla; Plantation and Homestead, Fla; and Mathis, Tex.Other PARTICIPANTS: Lice were collected in 3 geographical regions within the United States and in Yamburara, Ecuador, from healthy but infested individuals.Intervention Within 3 to 6 hours of collection, lice were given a blood meal, exposed to products or active ingredients, and observed at regular intervals. MAIN OUTCOME MEASURES: Percent mortality of lice at regular intervals after exposure to products or active ingredients and presence of T929I and L932F mutations. RESULTS: South Florida lice exhibited a significantly slower mortality response to permethrin compared with susceptible Ecuadorian lice. Ovide and malathion killed permethrin-resistant lice faster than Nix or permethrin. The presence of T929I and L932F in permethrin-resistant south Florida lice was confirmed by DNA sequencing. The population of Texas lice from Mathis was slightly resistant to permethrin and included 13% with resistant genotypes. CONCLUSIONS: The presence of the T929I and L932F mutations was confirmed by DNA sequencing in lice collected from children in south Florida that were resistant to the pediculicidal effects of permethrin and the leading permethrin-based head lice product, Nix. Malathion resistance was not observed in this study. The data also show that Ovide killed these same permethrin-resistant head lice approximately 10 times faster than permethrin or Nix.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12925385&dopt=Abstract permethrin Elimite



Elimite
Comparative evaluation of carbosulfan- and permethrin-impregnated curtains for preventing house-entry by the malaria vector Anopheles gambiae in Burkina Faso.

Fanello C, Carneiro I, Ilboudo-Sanogo E, Cuzin-Ouattara N, Badolo A, Curtis CF.

Department of Tropical and Infectious Diseases, London School of Hygiene and Tropical Medicine, UK. caterina.fanello lshtm.ac.uk

Pyrethroid-impregnated bednets and curtains are widely employed to reduce the risk of malaria transmission, but pyrethroid-resistance is becoming more prevalent among malaria vector Anopheles mosquitoes (Diptera: Culicidae). As an alternative treatment for curtains, we assessed carbosulfan (a carbamate insecticide) in comparison with permethrin as the standard pyrethroid, against endophilic female mosquitoes of the Anopheles gambiae Giles complex in a village near Ouagadougou, Burkina Faso. The main criterion evaluated was the impact of curtains (hung inside windows, eaves and doorways) on the number of An. gambiae s.l. females active indoors at night. Light-traps were operated overnight (21.00-06.00 hours beside occupied untreated bednets) to sample mosquitoes in houses fitted with net curtains treated with carbosulfan 0.2 g ai/m2 or permethrin 1 g ai/m2 or untreated, compared with houses without curtains. The treated and untreated curtains significantly reduced the numbers of mosquitoes collected indoors, compared with houses without curtains. Carbosulfan-treated curtains had a highly significantly greater effect than permethrin-treated or untreated curtains, the scale of the difference being estimated as three-fold. However, there was no significant difference between the impact of untreated and permethrin-treated curtains on densities of An. gambiae s.l. trapped indoors. Samples of the An. gambiae complex comprised An. arabiensis Patton and both the S- and M-forms of An. gambiae Giles s.s. Susceptibility tests revealed some resistance to DDT and low frequencies of permethrin-resistance, insufficient to explain the poor performance of permethrin on curtains. Among survivors from the diagnostic dosage of permethrin were some specimens of all three members of the An. gambiae complex, but the kdr resistance mechanism was detected only in the S-form of An. gambiae s.s. Questions arising for further investigation include clarification of resistance mechanisms in, and foraging behaviour of, each member of the An. gambiae complex in this situation and the need to decide whether carbosulfan-treated curtains are acceptably safe for use to reduce risks of malaria transmission.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12941019&dopt=Abstract permethrin Elimite