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PubMed1999

Treatment of rosacea-like demodicidosis with oral ivermectin and topical permethrin cream.

A 32-year-old man presented with a chronic rosacea-like dermatitis of the facial skin and the eyelids. The skin disorder had been present for 4 years and was unresponsive to multiple previous treatment attempts. Skin scrapings and a histologic examination of a biopsy specimen from the affected area revealed the presence of numerous Demodex mites. The patient was treated with oral ivermectin and subsequent topical permethrin resulting in complete and rapid clearing of the folliculitis. We believe that this case supports the view that Demodex mites may be pathogenic when they are present in large numbers. Oral treatment with 200 microg/kg ivermectin with subsequent weekly topical permethrin showed impressive treatment efficacy in a case refractory to conventional treatment.

Administration, Oral↗

PubMed2000

Early hepatic changes in rats induced by permethrin in comparison with DDT.

In this study permethrin [(3-phenoxyphenyl)-methyl-3-(2,2-dichloroethenyl)-2,2-dim ethylcyclopropanecarboxylate] and DDT [1,1-(2,2,2 trichloroethylidene)-bis-(4-chlorobenzene)] were compared in rats for their effects on early hepatic changes, proposed in the literature to be useful endpoints in screening for non-genotoxic hepatocarcinogenesis and/or liver tumour promotion. We compared the effects of both insecticides on the following endpoints: hepatomegaly, mitogenesis (DNA synthesis, mitotic activity, percentage of binuclear cells) and liver pathology. Male Wistar rats received permethrin (PERM) or DDT in one, three, five and 14 daily oral doses (at 24-h intervals) equivalent to 1/10 LD50. Distinct differences in early liver response between PERM and DDT were observed. DDT stimulated the early effect consisting of hepatomegaly accompanied by an increase in hepatocellular proliferation with signs of cell necrosis. Thus, it might be concluded, that the mitogenic effect of DDT was at least partly related to a regenerative liver response. Although PERM significantly affected DNA synthesis and increased binuclear hepatocytes, this compound did not increase the number of mitotic figures. These results suggest that PERM may inhibit of phase G2 in the cell cycle and consequently it may suppress the cell entering into the stage of mitosis (M-phase). In addition, the present findings provide evidence for the occurrence of abnormal mitoses in the hepatocytes of rats treated with DDT.

Animals↗

PubMed2000

Simultaneous determination of pyridostigmine bromide, N,N-diethyl-m-toluamide, permethrin, and their metabolites in rat plasma and urine by high-performance liquid chromatography.

A rapid and simple method was developed for the separation and quantification of the anti nerve agent drug pyridostignmine bromide (PB; 3-dimethylaminocarbonyloxy-N-methyl pyridinium bromide) its metabolite N-methyl-3-hydroxypyridinium bromide, the insect repellent DEET (N,N-diethyl-m-toluamide), its metabolites m-toluamide and m-toluic acid, the insecticide permethrin (3-(2,2-dichloro-ethenyl)-2,2-dimethylcyclopropanecarboxylic acid(3-phenoxyphenyl)methylester), and two of its metabolites m-phenoxybenzyl alcohol, and m-phenoxybenzoic acid in rat plasma and urine. The method is based on using C18 Sep-Pak cartridges for solid-phase extraction (SPE) and high-performance liquid chromatography (HPLC) with reversed-phase C18 column, and gradient UV detection ranging between 208 and 230 nm. The compounds were separated using gradient of 1 to 99% acetonitrile in water (pH 3.20) at a flow-rate ranging between 0.5 and 1.7 ml/min in a period of 17 min. The retention times ranged from 5.7 to 14.5 min. The limits of detection were ranged between 20 and 100 ng/ml, while limits of quantitation were 150-200 ng/ml. Average percentage recovery of five spiked plasma samples were 51.4+/-10.6, 71.1+/-11.0, 82.3+/-6.7, 60.4+/-11.8, 63.6+/-10.1, 69.3+/-8.5, 68.3+/-12.0, 82.6+/-8.1, and from urine 55.9+/-9.8, 60.3+/-7.4, 77.9+/-9.1, 61.7+/-13.5, 68.6+/-8.9, 62.0+/-9.5, 72.9+/-9.1, and 72.1+/-8.0, for pyridostigmine bromide, DEET, permethrin, N-methyl-3-hydroxypyridinium bromide, m-toluamide, m-toluic acid, m-phenoxybenzyl alcohol and m-phenoxybenzoic acid, respectively. The relationship between peak areas and concentration was linear over the range between 100 and 5000 ng/ml. This method was applied to analyze the above chemicals and metabolites following their administration in rats.

Animals↗

PubMed1997

Capillary gas chromatographic determination of permethrin insecticide by transesterification.

A sensitive method was developed to determine permethrin extracted from phosphate buffer and cattle plasma by potassium cyanide catalyzed transesterification of this insecticide with refluxing ethanol and detection of the resulting ethyl esters by capillary gas chromatography with an electron capture detector. With a reflux time of 2 h and with 3-phenoxybenzyl 2-chlorobenzoate as an internal standard, linear calibration curves from buffer (5-250 ng) and plasma (5-100 ng) were obtained. Precision and accuracy of the method were < or = 15%. The limit of detection was approximately 2.5 ng/ml (cis) and 1 ng/ml (trans) from buffer. In cattle sprayed along the back at 2 mg/kg, the concentration of cis- and trans-permethrin in plasma was below the detection limit (5 ng/ml).

Animals↗

PubMed2001

Simultaneous determination of malathion, permethrin, DEET (N,N-diethyl-m-toluamide), and their metabolites in rat plasma and urine using high performance liquid chromatography.

A method was developed for the separation and quantification of the insecticide malathion (O,O-dimethyl-S-(1,2-carbethoxyethyl) phosphorodithioate), its metabolite malaoxon (O,O-dimethyl-S-(1,2-carbethoxyethyl) phosphorothioate), the insecticide permethrin (3-(2,2-dichloro-ethenyl)-2,2-dimethylcyclopropanecarboxylic acid(3-phenoxyphenyl)methylester), two of its metabolites m-phenoxybenzyl alcohol and m-phenoxybenzoic acid, the insect repellent N,N-diethyl-m-toluamide (DEET), and its metabolites m-toluamide and m-toluic acid in rat plasma and urine. The method used high performance liquid chromatography (HPLC) with reversed phase C(18) column, and UV detection at 210 nm. The compounds were separated using gradient of 45--99% acetonitrile in water (pH 3.5) at a flow rate ranging between 0.5 and 2 ml/min in a period of 15 min. The retention times ranged from 7.4 to 12.3 min. The limits of detection ranged between 20 and 100 ng/ml, while limits of quantitation were 50-150 ng/ml. Average percentage recovery of five spiked plasma samples were 80.1+/-4.2, 75.2+/-4.6, 84.5+/-4.0, 84.3+/-3.4, 82.8+/-3.9, 83.9+/-5.5, 82.2+/-6.0, 83.1+/-4.3, and from urine 78.8+/-3.9, 76.4+/-4.9, 82.3+/-4.5, 82.5+/-3.9, 81.4+/-4.0, 83.9+/-4.3, 81.5+/-5.0, and 84.5+/-3.8 for, malathion, malaoxon, DEET, m-toluamide, m-toluic acid, permethrin, m-phenoxybenzyl alcohol, and m-phenoxybenzoic acid, respectively. The method was reproducible and linear over range between 100 and 1000 ng/ml. This method was applied to analyze the above chemicals and metabolites following combined dermal administration in rats.

Animals↗

PubMed1998

Effects of carbaryl, permethrin, 4-nonylphenol, and copper on muscarinic cholinergic receptors in brain of surrogate and listed fish species.

We investigated the regulation of the muscarinic cholinergic receptor (MChR) in brain from seven species of fish, two surrogates and five threatened or endangered species exposed to a series of chemicals as a measure of compensatory response among species. Fish were classified as either cold water (rainbow trout-surrogate, apache trout, lahanton trout) or warm water (fathead minnow-surrogate, razorback sucker, bonytail chub, colorado squawfish) and were exposed to chemicals shown to affect cholinergic pathways (carbaryl and permethrin) and two chemicals whose relationships to the cholinergic system is less clear (4-nonylphenol and copper). Downregulation of MChR occurred in all warm water species, except colorado squawfish, and at carbaryl concentrations similar to those causing downregulation observed in rainbow trout. Permethrin exposure resulted in downregulation in fathead minnow and razorback sucker, but the concentrations required for observation of this phenomenon were much greater than observed in cold water species. Copper exposure caused a decrease in brain MChR in rainbow trout and apache trout, whereas 4-nonylphenol exposure resulted in a decrease in brain MChR in all three cold water species. Our results indicate that surrogates are useful in assessing sublethal physiological responses to chemicals with a known mechanism of action such as carbaryl and support use of surrogates for assessing physiological responses to chemicals with diverse, less clear mechanisms of action.

Animals↗

PubMed2001

Purification and characterization of trans-permethrin metabolizing microsomal esterases from workers of the eastern subterranean termite, Reticulitermes flavipes (Kollar).

Three alpha-naphthyl acetate hydrolyzing esterase isozymes were purified from microsomes prepared from Reticulitermes flavipes workers. The two step process involved sequential preparative IEF followed by continuous elution preparative electrophoresis on a 5% non-denaturing polyacrylamide gel. The first IEF run resulted in 5.4-fold purification with a yield of 46.1%. Subsequent IEF further purified the esterases 14.3-fold and 12% yield. Preparative electrophoresis of the pooled IEF fractions produced three major peaks of alpha-naphthyl acetate hydrolyzing activity. The esterases were correspondingly designated microsomal esterase (ME) 1, ME 2, and ME 3 based on increasing molecular retention on a native PAGE gel. ME 1, ME 2, and ME 3 were acidic proteins with pI values of 4.61, 4.70, and 4.77, respectively. Molecular mass as determined by gel filtration chromatography of ME 1, ME 2, and ME 3 was 69, 64, and 62 kDa, respectively. SDS-PAGE gels produced a single band for each of the isozymes with a molecular mass of 63 kDa indicating that the esterases were monomers. Specific activities of ME 1, ME 2, and ME 3 increased with increasing pH and the enzymes were active over a broad temperature range (25-55 degrees C). The three purified isozymes were inhibited at low concentration by paraoxon (10(-10) M), chlorpyrifos (10(-6) M), DEF (10(-6) M), and PMSF (10(-6) M) indicating that they were "B" type serine esterases. Conversely, inhibition was not observed at 10(-4) M eserine, PHMB, or CaCl(2), further supporting the conclusion that the microsomal esterases were of the "B" type. None of the isozymes was inhibited by 10(-4) M imidacloprid, fipronil, or PBO. Quantitatively, ME 1, ME 2 and ME 3 metabolized t-permethrin at 21.8, 21.0, and 38.8 nmol/h/mg protein, representing a purification factor of 333-, 318-, and 591-fold over microsomes, respectively. The three isozymes produced the same type and number of t-permethrin metabolites.

Animals↗

PubMed2006

Removal of carbaryl, linuron, and permethrin by Lupinus angustifolius under hydroponic conditions.

The metabolism of organic pollutants by plants normally requires contaminant direct uptake by cells. Factors affecting this uptake and the later distribution of chemicals within the plant include the physicochemical properties of the compounds (concentration, structure, solubility, log k(ow), diffusion rate) and the biochemical characteristics of the plant. This paper reports the tolerance, uptake, and effects of the pesticides carbaryl, linuron, and permethrin on Lupinus angustifolius germination and growth as well as contaminant intraplant distribution and possible degradation. Lupine plants were grown in hydroponic culture containing either 1 or 5 mg of the individual pesticides, or combinations of these (1, 5, or 10 mg of each), in 100 mL nutrient and water solutions. Analysis of the remaining solutions 8 days post-germination showed the water solutions to have higher remaining pesticide concentrations than nutrient solutions. Furthermore, in the presence of pesticides, germination was more frequent in the water solutions. After 16 days of growth, the plants were harvested, and their tissues were microwaved digested and analyzed by reversed-phase liquid chromatography. Although only minor quantities of each pesticide were detected in plant tissues, their amount in the roots was higher than in the stems. No accumulation was noted in the cotyledons, and only 2% of linuron was detected in the leaves. Mass recovery at the end of the experiment showed that 57, 53, and 55% of carbaryl, linuron, and permethrin, respectively, were degraded and/or bound in an irreversible manner to plant material. The results suggest that L. angustifolius could be useful for the cleaning/remediation of pesticide-contaminated water.

Biodegradation, Environmental↗

PubMed1998

Permethrin-impregnated bednet effects on resting and feeding behaviour of lymphatic filariasis vector mosquitoes in Kenya.

The impact of permethrin-impregnated bednets on resting and feeding behaviour of mosquito vectors of Wuchereria bancrofti, causing human lymphatic filariasis was studied in six pairs of villages (treated and untreated) before and after intervention. The study villages were in Kwale District, near the coast of Kenya, where Bancroftian filariasis is highly endemic, transmitted by a combination of both anopheline and culicine mosquito vectors. Mosquitoes were collected weekly in each village, indoors (using pyrethrum spray catches) and outdoors (using pit traps) during 3-4 months following the long rainy season. Of the filariasis vector species of mosquitoes collected in 1994 before intervention. 33.6% were members of the Anopheles gambiae complex, 30% were An. funestus and 36.4% were Culex quinquefasciatus. PCR analysis of the An. gambiae complex species collected in 1995 demonstrated that 98.5% were An. gambiae sensu stricto. 1% An. arabiensis and 0.5% An. merus. Introduction of impregnated bednets in 1995 significantly reduced the number of indoor-resting An. gambiae s.l. by 94.6% and An. funestus by 96.7%, but there was no change in the number of Cx quinquefasciatus collected indoors. The number of outdoor-resting An. gambiae s.l. was significantly reduced, whereas densities of An. funestus and Cx quinquefasciatus remained unaffected outdoors. ELISA analysis of mosquito bloodmeals showed a shift from human to animal feeding after the introduction of treated nets. The human blood index (HBI) for indoor resting Cx quinquefasciatus was reduced from 93.1% to 14.4%. Vector potential based on the HBI and mosquito density was estimated to be reduced by 99% for An. gambiae s.l., 98% for An. funestus and 97% for Cx quinquefasciatus and vectorial capacity would be suppressed even more by the impact on the vector survival rates (not measured). These results suggest that permethrin-impregnated bednets give effective personal protection against transmission of W. bancrofti by An. gambiae, An. funestus and Cx quinquefasciatus in East Africa.

Animals↗

PubMed2003

Demodex infestation in a child with leukaemia: treatment with ivermectin and permethrin.

BACKGROUND: Demodex mites are almost ubiquitous on older adult skin but are infrequent in young children. In immunocompromised patients, demodicosis may be more frequent and severe, and systemic therapy may be needed to achieve clinical resolution. CASE REPORT: A six-year-old boy having maintenance chemotherapy for acute lymphoblastic leukemia presented with widespread erythema and scaling of the face. Skin scrapings were negative and the eruption worsened despite the completion of chemotherapy and the use of topical corticosteroids. Pustules developed on the face and around the eyelids, associated with bilateral blepharitis and lower lid chalazia. Skin biopsy then revealed heavy infestation with Demodex folliculorum. The child was treated with a combination of topical permethrin and oral ivermectin, with a total of four doses of ivermectin given over 6 weeks. The facial eruption had completely resolved 3 months after initiation of this combined treatment. COMMENT: Demodex infestation can cause dramatic facial and eyelid inflammation in immunocompromised patients. Oral ivermectin, in combination with topical permethrin, can be a safe and effective treatment for severe demodicosis.

Animals↗

PubMed2003

A new tool for malaria prevention?: Results of a trial of permethrin-impregnated bedsheets (shukas) in an area of unstable transmission.

BACKGROUND: Despite gains in malaria control through impregnated treated nets (ITN), malaria remains a major concern. Netting is expensive and impractical for many communities. Here we present the findings of a community-based trial of impregnated bedsheets (shukas) in Kenya. METHODS: A total of 472 individuals were enrolled in a randomized community trial where the unit of randomization was the hamlet (manyatta). Baseline data included socio-demographic data, parasite prevalence data from thick and thin blood smears, and clinical measures of malaria. The intervention involved the dipping of shukas owned by the experimental group in permethrin. FINDINGS: The prevalence of malaria in the study population (based on laboratory results) was considerably lower than that used for the power calculation based on clinical estimates (2.2% versus 20%). For those aged 6 or over, the rate of malaria cases (events per 10 000 person-days at risk) was 1.41 in the experimental group versus 7.49 in the control group (incidence rate ratio 0.187, 95% CI: 0.046- 0.770). For children </=5 years of age results were imprecise with no clear benefit of the intervention. CONCLUSIONS: These results suggest that permethrin-impregnated bedsheets may be protective against malaria prevention but further studies with greater power are required to confirm this.

Adolescent↗

PubMedDate not supplied

Simultaneous determination of chlorpyrifos, permethrin, and their metabolites in rat plasma and urine by high-performance liquid chromatography.

A high-performance liquid chromatographic (HPLC) method was developed for the separation and quantitation of the insecticide chlorpyrifos (O,O-diethyl-O[3,5,6-trichloro-2-pyridinyl] phosphorothioate), its metabolites chlorpyrifos-oxon (O,O-diethyl-O[3,5,6-trichloro-2-pyridinyl] phosphate) and TCP (3,5,6-trichloro-2-pyridinol), the insecticide permethrin (3-(2,2-dichloro-ethenyl)-2,2-dimethylcyclopropanecarboxylic acid-(3-phenoxyphenyl) methylester), and two of its metabolites, m-phenoxybenzyl alcohol and m-phenoxybenzoic acid, in rat plasma and urine. The method is based on using C18 Sep-Pak cartridges for solid-phase extraction and reversed-phase HPLC. The compounds were separated using a gradient of 1 to 80% acetonitrile in water (pH 3.2) at a flow rate ranging between 1 and 1.5 mL/min in a period of 17 min and gradient UV detection ranging between 210 and 280 nm. The retention times ranged from 9.3 to 14.5 min. The limits of detection ranged between 20 and 150 ng/mL, whereas the limits of quantitation were 150-200 ng/mL. The respective average percentage recoveries of chlorpyrifos, chlorpyrifos-oxon, TCP, permethrin, m-phenoxybenzyl alcohol, and m-phenoxybenzoic were 78.6 +/- 6.4, 72.8 +/- 6.8, 84.8 +/- 8.0, 79.2 +/- 8.4, 80.5 +/- 7.2, and 82.3 +/- 7.1 from five spiked plasma samples and 77.5 +/- 8.1, 72.8 +/- 8.3, 79.9 +/- 6.4, 79.1 +/- 8.9, 80.5 +/- 7.6, and 81.4 +/- 7.8 from urine samples. The relationship between peak areas and concentration was linear for concentrations between 200 and 2,000 ng/mL. This method was used to analyze these chemicals and metabolites following dermal administration in rats.

Animals↗

PubMed1990

Chronology of permethrin resistance in a southern Illinois population of the horn fly (Diptera: Muscidae) during and after selection by pyrethroid use.

From 1985 through 1988, horn flies (Haematobia irritans (L)) collected at the Dixon Springs Agricultural Center (DSAC) in southern Illinois were tested in 22 h bioassays for permethrin resistance with residues on cotton cloths. The LC90 for a susceptible field population collected in June 1985 was 0.19 micrograms/cm2. In comparison, flies collected from pyrethroid-tagged cattle in 1985 and 1986 exhibited 25- to 116-fold resistance to permethrin. A 25-fold level of resistance allowed survival on treated cattle 8 wk after pyrethroid tag application. Flies representing the local background population were collected periodically from an untreated herd 2.4 km from the nearest cattle treated with a pyrethroid; these flies exhibited up to 18-fold resistance. Although pyrethroids were not used on DSAC animals after October 1986, all bioassays done in 1987 and 1988 indicated resistance levels of greater than or equal to 7-fold. The 95% confidence intervals for LC90s from all 1987 bioassays overlapped the confidence interval from the corresponding July 1986 estimate for resistant flies collected from pyrethroid-tagged cattle. Although some decline in resistance was evident in 1988, bioassays done at the end of the season produced resistance ratios of 7.4 and 15.3. Survivorship at a diagnostic dose indicated that resistance frequencies remained at 4-8% throughout 1988. Two years' abstinence from pyrethroid use was insufficient to allow an adequate decline in resistance levels.

Animals↗

PubMed1992

Effects of permethrin on aquatic organisms in a freshwater stream in south-central Alaska.

Permethrin (0.5%) was applied to individual Lutz spruce, Picea x lutzii Little, to protect them from attack by spruce beetles, Dendroctonus rufipennis (Kirby). Residue levels were monitored in a freshwater stream above, adjacent to, and below the treatment site at intervals before, during, and after treatment. Maximum residue levels in the stream within the treatment site ranged from 0.05 +/- 0.01 ppb 5 h after treatment to 0.14 +/- 0.03 ppb 8-11 h after treatment, with a decrease to 0.02 +/- 0.01 ppb 14 h after treatment. Levels of permethrin in standing pools near the stream within the treatment site were 0.01 +/- 0.01 ppb. Numbers of drifting aquatic invertebrates increased 2-fold during treatment and 4-fold 3 h after treatment and declined to before spray numbers within 9 h. Terrestrial insects did not appear to respond to treatments because none was found in stream drift samples. Trout fry (Dolly Varden), aquatic insect larvae, and periphyton (attached algae) within and below the treatment site during and after treatment did not show signs of mortality compared with an upstream untreated control site.

Alaska↗

PubMed2005

Response of Argentine ants and red imported fire ants to permethrin-impregnated plastic strips: foraging rates, colonization of potted soil, and differential mortality.

This study investigated the effects of the permethrin-impregnated plastic on ant mortality and foraging rates, and tested its potential for preventing ants from colonizing potted soil. Direct exposure to the plastic for as short as 1 min caused significant mortality of both red imported fire ants, Solenopsis invicta Buren, and Argentine ants, Linepithema humile (Mayr); however, red imported fire ants were more susceptible than Argentine ants. Knockdown of virtually all ants initially occurred within 15 min after exposure. However, some moribund ants recovered from the effects within 24 h. For example, after 1 min of direct exposure to the permethrin-impregnated plastic, 70% of Argentine ants and 5% of red imported fire ants recovered from the treatment. In established colonies of Argentine ants, significantly fewer ants foraged for food up posts treated with the plastic compared with untreated posts. In addition, colonies responded to introduction of the treatment by significantly reducing their overall foraging rates, even on untreated posts. When pots filled with moistened soil were introduced into established ant colonies, 82% of Argentine ants and 99% of red imported fire ants moved into the soil. In contrast, when a 1-cm-wide coil of the plastic was placed under the pot, no ants moved into the soil. The potential for use of these materials in nursery production is discussed.

Animals↗

PubMed1991

Dynamics of permethrin resistance in a colony of horn flies (Diptera: Muscidae).

A colony of horn fly, Haematobia irritans (L.), was established from field-collected, resistant flies. Changes in resistance levels were monitored under a regimen with and without insecticide pressure. The colony remained closed with no introduction of susceptible flies. In the absence of permethrin pressure, resistance levels dropped to 2.5 times from an initial level of 17 times at LC50 and remained at that level from generation 12 through 33. In the presence of various insecticide pressure regimens, resistance increased to 500 times at LC90 by generation 86. In a separate study, susceptible colony flies were subjected to permethrin pressure, with first resistance evident in generation 16 and increasing to greater than 100 times at LC90 in generation 88.

Animals↗

PubMed1991

Effectiveness of host-targeted permethrin in the control of Ixodes dammini (Acari: Ixodidae)

Tubes of commercially available permethrin-treated cotton balls were distributed twice each year in 1989 and 1990 at five sites in a Lyme disease endemic area in Connecticut. Five additional sites were not treated. At each application, 48 tubes, sufficient to treat 0.4 ha, were dispersed at 10-m intervals through woodlands, around ornamental plantings, and along rockwalls. The cotton was collected by white-footed mice (Peromyscus leucopus) from the majority of the tubes, which resulted in a decrease (37.2% in 1989 and 91.5% in 1990) in the number of subadult Ixodes dammini Spielman, Clifford, Piesman, and Corwin on the mice in the treated areas. There were no significant decreases in the number of host-seeking nymphs or adults of I. dammini in 1989 or 1990 between the treated and untreated sites. The rates of infection in the host-seeking nymphs with Borrelia burgdorferi, the etiological agent of Lyme disease, at the treated sites (13.0 and 14.6% for 1989 and 1990, respectively) were comparable to those at the untreated sites (16.9 and 13.2% for 1989 and 1990, respectively). The distribution of permethrin-treated cotton around individual residences significantly reduced the number of ticks on P. leucopus but was not sufficient to reduce the risk of exposure to infected host-seeking nymphs and adults of I. dammini after two seasons of treatment.

Animals↗

PubMed1992

Third-year evaluation of host-targeted permethrin for the control of Ixodes dammini (Acari: Ixodidae) in southeastern Connecticut.

The impact of commercially available permethrin-treated cotton balls targeted at Ixodes dammini Spielman, Clifford, Piesman & Corwin on white-footed mice, Peromyscus leucopus, was evaluated for a third year at five residential sites in south-central Connecticut. Each site had been treated twice each year from 1989 through 1991 with sufficient product to treat 0.4 ha of mouse habitat, and results were compared with five untreated sites. There were no significant differences in the number of host-seeking nymphs or adults of I. dammini, the vector of the Lyme disease spirochete, Borrelia burgdorferi, in 1991 between the treated and untreated sites. The rate of infection in host-seeking nymphs by B. burgdorferi at the treated sites (15.3% of 600) was comparable with that at the untreated sites (16.5% of 454). Only 16.3% of 86 P. leucopus captured at the treated sites were infested with I. dammini subadults compared with 66.9% of 118 from the mice at the untreated sites. The impact of permethrin-treated cotton during the third year of treatment was similar to that observed for the first 2 yr and did not reduce the risk of exposure to spirochete-infected, host-seeking nymphs and adults of I. dammini.

Animals↗