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Isolation of Japanese encephalitis and Getah viruses from mosquitoes (Diptera: Culicidae) collected near Camp Greaves, Gyonggi Province, Republic of Korea, 2000.

As part of an evaluation of the ecology of arthropod-borne diseases in the Republic of Korea (ROK), we examined 8,765 mosquitoes captured in Paju County, Gyonggi Province, ROK, for the presence of viruses. Mosquitoes were captured in propane lantern/human-baited Shannon traps, Mosquito Magnet traps, or American Biophysics Corporation (East Greenwich, RI) miniature light traps with or without supplemental octenol bait and/or dry ice. Mosquitoes were identified to species, placed in pools of up to 40 mosquitoes each, and tested on Vero cells for the presence of virus. A total of 15 virus isolations were made from 293 pools of mosquitoes. Viruses were identified by reverse transcriptase-polymerase chain reaction and sequencing and consisted of 14 isolations of Japanese encephalitis (JE) virus and one isolation of Getah (GET) virus. All JE isolates were from Culex tritaeniorhynchus Giles, and the isolate of GET was from Aedes vexans (Meigen). The minimum field infection rate for JE in Cx. tritaeniorhynchus was 3.3 per 1,000, whereas the GET virus infection rate for Ae. vexans was 0.2 per 1,000. Isolation of JE and GET indicated that both viruses were actively circulating in northern Gyonggi Province, ROK. The lack of human cases of JE among the Korean population probably is because of an effective government-mandated vaccination program. The reason for no cases among >10,000 United States military and others that reside or train nearby is unknown, but may be related to personnel protection measures (permethrin-impregnated uniforms and use of deet repellent), adult mosquito control, mosquito selection of nonhuman hosts (unpublished data), and the low symptomatic to asymptomatic ratio of disease in adults.

Aedes↗

Solid-phase sediment toxicity identification evaluation in an agricultural stream.

The lower Santa Maria River watershed provides important aquatic habitat on the central California coast and is influenced heavily by agricultural runoff. As part of a recently completed water quality assessment, we conducted a series of water column and sediment toxicity tests throughout this watershed. Sediment from Orcutt Creek, a tributary that drains agricultural land, consistently was toxic to the amphipod Hyalella azteca, which is a resident genus in this river. Toxicity identification evaluations (TIEs) were conducted to determine cause(s) of toxicity. We observed no toxicity in sediment interstitial water even though concentrations of chlorpyrifos exceeded published aqueous toxicity thresholds for H. azteca. In contrast to interstitial water, bulk sediment was toxic to H. azteca. In bulk-phase sediment TIEs, the addition of 20% (by volume) coconut charcoal increased survival by 41%, implicating organic chemical(s). Addition of 5% (by volume) of the carbonaceous resin Ambersorb 563 increased survival by 88%, again suggesting toxicity due to organic chemicals. Toxicity was confirmed by isolating Ambersorb from the sediment, eluting the resin with methanol, and observing significant toxicity in control water spiked with the methanol eluate. A carboxylesterase enzyme that hydrolyzes synthetic pyrethroids was added to overlying water, and this significantly reduced toxicity to amphipods. Although the pesticides chlorpyrifos, DDT, permethrin, esfenvalerate, and fenvalerate were detected in this sediment, and their concentrations were below published toxicity thresholds for H. azteca, additivity or synergism may have occurred. The weight-of-evidence suggests toxicity of this sediment was caused by an organic contaminant, most likely a synthetic pyrethroid.

Agriculture↗

Probabilistic risk assessment of cotton pyrethroids: I. Distributional analyses of laboratory aquatic toxicity data.

This is the first in a series of five papers that assess the risk of the cotton pyrethroids in aquatic ecosystems in a series of steps ranging from the analysis of effects data through modeling exposures in the landscape. Pyrethroid insecticides used on cotton have the potential to contaminate aquatic systems. The objectives of this study were to develop probabilistic estimates of toxicity distributions, to compare these among the pyrethroids, and to evaluate cypermethrin as a representative pyrethroid for the purposes of a class risk assessment of the pyrethroids. The distribution of cypermethrin acute toxicity data gave 10th centile values of 10 ng/L for all organisms, 6.4 ng/L for arthropods, and 380 ng/L for vertebrates. For bifenthrin, cyfluthrin, lambda-cyhalothrin, and deltamethrin, the 10th centile values for all organisms were 15, 12, 10, and 9 ng/L, respectively, indicating similar or somewhat lower toxicity than cypermethrin. For tralomethrin and fenpropathrin, the 10th centiles were <310 and 240 ng/L, respectively. The distribution of permethrin toxicity to all organisms, arthropods, and vertebrates gave 10th centiles of 180, 76, and 1600 ng/L, respectively, whereas those for fenvalerate were 37, 8, and 150 ng/L. With the exception of tralomethrin, the distributions of acute toxicity values had similar slopes, suggesting that the variation of sensitivity in a range of aquatic nontarget species is similar. The pyrethroids have different recommended field rates of application that are related to their efficacy, and the relationship between field rate and 10th centiles showed a trend. These results support the use of cypermethrin as a reasonable worst-case surrogate for the other pyrethroids for the purposes of risk assessment of pyrethroids as a class.

Animals↗

Contaminant sensitivity of threatened and endangered fishes compared to standard surrogate species.

Standard environmental assessment procedures are designed to protect terrestrial and aquatic species. However, it is not known if endangered species are adequately protected by these procedures. At present, toxicological data obtained from studies with surrogate test fishes are assumed to be applicable to endangered fish species, but this assumption has not been validated. Static acute toxicity tests were used to compare the sensitivity of rainbow trout, fathead minnows, and sheepshead minnows to several federally listed fishes (Apache trout, Lahontan cutthroat trout, greenback cutthroat trout, bonytail chub, Colorado pikeminnow, razorback sucker, Leon Springs pupfish, and desert pupfish). Chemicals tested included carbaryl, copper, 4-nonylphenol, pentachlorophenol, and permethrin. Results indicated that the surrogates and listed species were of similar sensitivity. In two cases, a listed species had a 96-h LC50 (lethal concentration to 50% of the population) that was less than one half of its corresponding surrogate. In all other cases, differences between listed and surrogate species were less than twofold. A safety factor of two would provide a conservative estimate for listed cold-water, warm-water, and euryhaline fish species.

Animals↗

Parasitic skin infections in the elderly: recognition and drug treatment.

There are many parasitic infections of medical importance, which can produce both systemic disease as well as skin lesions. For the most part, treatment of these infections in the elderly does not differ very much from that of younger patients. However, one must be aware that the geriatric population can present with certain challenges with regard to diagnosis of these diseases because history taking may be more difficult and patients often already have a set of other medical problems, which may overshadow the skin lesions. In addition, the clinical manifestations of these infections may not appear classical and may be altered. Dosages of drugs used to treat these infections, even topical agents, may require adjustments in this population. The recognition of scabies in elderly people living together is important and early treatment with topical scabiecides, including oral ivermectin, will help to control the spread of the infestation. Pediculosis may be a cause of pruritus in the elderly and can be treated with malathione, lindane or permethrin. Less common parasitic infections in the elderly, including cutaneous larva migrans and cutaneous leishmaniasis, present with a characteristic clinical picture and can be effectively treated with oral thiabendazole and intravenous antimonials.

Aged↗

The management of rosacea.

Rosacea is a multiphasic disease which is associated with flushing, erythrosis, papulopustular rosacea and phymas; each phase is likely to have its own treatment. Flushing is better prevented rather than treated, and its etiology investigated. Beta-blockers, atenolol in particular, are worthy of prophylactic trials examining their efficacy in treating the flushing associated with rosacea. Currently, clonidine is the only drug available for the treatment of flushing. Treatment for erythrosis includes topical and systemic therapies. Metronidazole 1% cream and azelaic acid 20% cream have been reported to reduce the severity score of erythema. The systemic treatment of erythrosis is based on the association of Helicobacter pylori with rosacea. However, this role is still being debated. Eradication of H. pylori can be achieved using a triple therapy regimen lasting 1 to 2 weeks [omeprazole and a combination of two antibacterials (a choice from clarithromycin, metronidazole or amoxicillin)]. Both the flashlamp-pumped long-pulse dye laser and the potassium-titanyl-phosphate laser may be used in the treatment of facial telangiectases. Both systemic and topical remedies may be used to treat the papulopustules of rosacea. Systemic treatment includes metronidazole, doxycycline, minocycline, clarithromycin and isotretinoin, while topical treatment is based on metronidazole cream and gel. The presence of Demodex folliculorum is important in the inflammatory reaction, whether it is pathogenetic or not. Crotamiton 10% cream or permethrin 5% cream may be useful medications for papulopustular rosacea, although they are rarely successful in eradicating D. folliculorum. Oral or topical ivermectin may also be useful in such cases. Ocular involvement is common in patients with cutaneous rosacea and can be treated with orally administered or topical antibacterials. Once rhinophyma starts to be evident, the only way to correct it is by aggressive dermatosurgical procedures. Decortication and various types of lasers can also be used. Associated conditions, such as seborrheic dermatitis and possible contact sensitizations, deserve attention.

Cryosurgery↗

Eosinophilic pustular folliculitis: a comprehensive review of treatment options.

Eosinophilic pustular folliculitis (EPF), also known as Ofuji disease, is a disease that manifests with follicular papules or pustules. Its variants include a classic type that occurs most commonly in Japan, an HIV-associated type, an infantile type, a type that occurs on the palms and soles, a rare medication-associated variant, and a rare neoplasia-associated variant.A wide range of medications has been used to treat EPF. Topical corticosteroids are the first-line treatment option for EPF. Topical tacrolimus seems to be useful initial therapy as well. Oral indometacin (50-75 mg/day) is an effective treatment of classic EPF although it can induce peptic ulcers. For treatment of HIV-associated EPF when topical corticosteroids and indometacin do not work, various other treatments should be considered. These treatment options include cetirizine 20-40 mg/day, metronidazole 250 mg three times a day, itraconazole starting at a dosage of 200 mg/day and increasing to 300-400 mg/day, and topical permethrin. If these treatments do not work phototherapy with UVB is the 'gold standard' of treatment and is often curative. Treatments with less certain risk-benefit ratios but with some efficacy include PUVA (psoralen + UVA) photochemotherapy, oral corticosteroids, synthetic retinoids (i.e. isotretinoin 1 mg/kg/day), and acitretin (0.5 mg/kg/day), oral cyclosporine (ciclosporine) 5 mg/kg/day, interferon (IFN)-alpha-2b, and IFNgamma. Minocycline 100mg twice daily and dapsone 50-100mg twice daily have been used with some effect. The use of highly active antiretroviral therapy for HIV has resulted in the amelioration of EPF as CD4 cell counts rise above 250/mm(3). The diversity of clinical presentations and affected populations make it seem that EPF is a reaction pattern as much as a disease and that therapy should be tailored to the variant of EPF and the underlying etiology.

Diagnosis, Differential↗

First record of Anopheles minimus C and significant decrease of An. minimus A in central Vietnam.

Before August 1998, in the Khanh Phu commune (central Vietnam), Anopheles minimus s.l. individuals were identified as species A and showed the typical species A wing form. After a significant decrease over the 3 years 1999-2001, an increase in 2002 of An. minimus s.l. possessing a different wing pattern was observed. To determine the specific status of the An. minimus species collected in 2002 and to follow changes in the species composition, an allele-specific polymerase chain reaction was applied to samples collected from 1993 to 2002. This study reports the first record of An. minimus C in central Vietnam and, since 1998, a significant reduction of An. minimus A that coincided with the wide use of permethrin-treated bednets. This change in anopheline composition may have important consequences on malaria transmission. This work shows that the geographic distribution of malaria vectors in southeast Asia is only partially known and highlights the importance of species identification for understanding changes in the vector composition as a result of selective vector control.

Animals↗

[Inhibitory effect of zinc on beta-hexosaminidase release from RBL-2H3 cells by synthetic chemicals].

The effects of foods and chemicals related to food hygiene on degranulation were evaluated using a method for assaying the enzyme activity of beta-hexosaminidase as an index of chemical mediator release from RBL-2H3 cells in vitro. Using a previously developed assay system, we had found a large number of inhibitors and promoters of degranulation of RBL-2H3 cells. In the present study, we examined the inhibitory effect of zinc chloride on the degranulation (beta-hexosaminidase release) from RBL-2H3 cells with or without antigen in the presence of the degranulation-promotive chemicals, namely, 4 food additives, 7 pesticides and 2 veterinary drugs. These promotive chemicals were classified into two types on the basis of inhibitory profile by zinc chloride: 1) those which showed marked degranulation-inhibitory action when the cells were stimulated with antigen, such as butylhydroxyanisole, dibutylhydroxytoluene, EPN, cis- and trans-permethrin, prothiofos, pyridaben, terbufos, 2) those which showed marked degranulation-inhibitory action whether the cells were stimulated with antigen or not, such as butyl p-hydroxybenzoate, o-phenylphenol, bitertanol, salinomycin. In conclusion, zinc had a dramatic inhibitory effect on enhanced degranulation induced by synthetic chemicals in vitro.

Animals↗

Cost-benefit evaluation of house fly (Diptera:Muscidae) control in caged layer poultry houses.

House fly (Musca domestica L.) control was determined in small-unit, commercial, caged layer poultry houses. Cyromazine was the most cost effective treatment (4 per bird per season) and provided the highest level of control. Larviciding and adulticiding with dimethoate, fenthion and dimethoate, permethrin and dimethoate, and stirofos provided good fly control, and these treatments were moderately cost effective. The use of dichlorvos-stirofos provided only marginal fly control and was not cost effective. Early-season manure removal, combined with more selective insecticide use would provide the caged layer producer with a more effective management strategy for controlling house flies in small-unit operations.

Animals↗

Efficacies of mixtures of disinfectants and insecticides.

Efficacies of mixtures of diluted commercial formulations of selected insecticides and disinfectants were evaluated. Insecticides tested included representative pyrethroids (fenvalerate [Ectrin WDL and WD] and permethrin [Ectiban EC]), organophosphates (dichlorvos [Vapona EC], tetrachlorvinphos [Rabon WP] and dichlorvos/tetrachlorvinphos [RaVap EC], and a carbamate (carbaryl [Sevin S]). Disinfectants tested included representatives of cresylic acid (Biolene), cresylic acid/phenol (BioGuard X-185), phenol (1-Stroke Environ), quaternary ammonium (BioGuard S-3 and PFP-4), quaternary ammonium/formalin (DC & R), and formalin classes of disinfectants. Mixtures were tested for toxicity to two target insects (Musca domestica on plywood, Alphitobius diaperinus in litter) and two bacteria (Pseudomonas aeruginosa and Staphylococcus aureus). Of 56 mixtures evaluated, 24 showed reduced insecticidal toxicity and 35 showed reduced bactericidal activity compared with insecticides or disinfectants alone.

Animal Husbandry↗

Filth fly resistance to pyrethrins associated with automated spray equipment in poultry houses.

Resistance to pyrethrins plus piperonyl butoxide (PB) in a population of Fannia canicularis (L.) (BR strain) at a broiler-breeder facility was determined (in F2 laboratory generation) to be 109.1-fold the median lethal dose (LD50), apparently having been influenced by twice-daily treatments with automatic spray equipment during the previous 2 years. By contrast, resistance was only 12-fold the normal LD50 in a population of Musca domestica L. (DH strain) at an egg-production facility that was subjected during a comparable period to treatments twice per week with synergized pyrethrins with the identical automatic pyrethrin-spray system. The automated application of a nonpersistent chemical at frequent intervals, obviously, provides continuity of selection pressure leading to high levels of resistance. Other factors such as enclosed poultry housing and the elimination of refugia have also contributed to the enhancement of resistance. The resistance level in Strain BR regressed to 31.7-fold after remaining unselected for an additional generation in the laboratory. Other bioassays on the F2 generation revealed limited resistance toward permethrin of 3.7-fold the normal LD50.

Aerosols↗

Comparison of 3 tests to detect acaricide resistance in Boophilus decoloratus on dairy farms in the Eastern Cape Province, South Africa.

The susceptibility of the larval offspring of engorged female Boophilus decoloratus, and of the engorged females, collected from cattle on the dairy farms Brycedale, Sunny Grove and Welgevind in the Eastern Cape Province, South Africa, was tested against the acaricides amitraz, chlorfenvinphos and cypermethrin. Resistance was determined by means of the Shaw Larval Immersion Test (SLIT) for larvae and the Reproductive Estimate Test (RET) and Egg Laying Test (ELT) for adults. At Brycedale the tests all indicated resistance to chlorfenvinphos, and RET and ELT indicated resistance to amitraz and emerging resistance to cypermethrin. At Sunny Grove, B. decoloratus was resistant to cypermethrin using SLIT and exhibited emerging resistance to chlorfenvinphos with SLIT and to cypermethrin with both RET and ELT At Welgevind, resistance was recorded against chlorfenvinphos (SLIT) and against cypermethrin (ELT), and emerging resistance against permethrin (RET). The results obtained with RET and ELT were generally comparable, but often differed from those obtained with SLIT. Resistance could be detected within 7 days with ELT compared to 42 days with RET and 60 days with SLIT.

Animals↗

The effectiveness of insecticide-impregnated bed nets in reducing cases of malaria infection: a meta-analysis of published results.

The use of insecticide-impregnated bed nets to minimize human-vector contact may reduce the incidence of malaria. Consequently, several field trials have evaluated their effectiveness as a malaria prevention strategy. A meta-analysis of published reports of field trials that measured the incidence of infections was performed to provide a measure of the effectiveness of insecticide-treated bed nets in preventing clinical malaria. Subsetted analyses were performed on the 10 field trials to calculate pooled incidence rate ratios of infection among the study groups. For the studies comparing insecticide-impregnated bed nets with untreated bed nets, the summary incidence rate ratio for acquiring malarial infections was 0.757 (95% confidence interval [CI] = 0.612-0.938), representing a reduction of 24%. For the studies comparing permethrin-impregnated bed nets with controls without bed nets, the summary incidence rate ratio was 0.497 (95% CI = 0.417-0.592) (Rothman-Boice heterogeneity statistics = 17.27 [P = 0.004] and 23.55 [P = 0.0003], respectively). These data suggest that insecticide-impregnated bed nets are effective in preventing malaria, decreasing the incidence rate ratio by approximately 50% in field trials performed to date.

Animals↗

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↗

The role of agricultural use of insecticides in resistance to pyrethroids in Anopheles gambiae s.l. in Burkina Faso.

Agricultural use of insecticides is involved in the selection of resistance to these compounds in field populations of mosquitoes in Burkina Faso. Anopheles gambiae s.l. was resistant to permethrin and DDT in cotton-growing and urban areas, but susceptible in areas with limited insecticide selection pressure (rice fields and control areas). Nevertheless, resistance to these insecticides was observed in a village on the outskirts of the rice fields at the end of the rainy season, suggesting that the latter population of mosquitoes had migrated from the surrounding cotton villages into the rice fields. A seasonal variation of resistance observed in the cotton-growing area is related to the distribution of the molecular M and S forms of An. gambiae, since resistance to pyrethroids has so far only been reported in the S form. Pyrethroid resistance in west African An. gambiae was conferred by target site insensitivity through a knockdown resistance (kdr)-like mutation, which was present at high frequencies in mosquitoes in the cotton-growing and urban areas.

Animals↗

Survey of repellent use by service members arriving in Kuwait for Operation Iraqi Freedom 2.

The 8th Medical Brigade, deployed to Kuwait in January 2004 in support of Operation Iraqi Freedom provided theater-wide health service support and medical command and control. An historic "surge" of troops and equipment occurred during our deployment as 140,000 service members (SMs) redeployed out of theater and 110,000 arrived to take their place. The brigade's preventive medicine personnel conducted a questionnaire-based survey at military camps in northwestern Kuwait in mid-March to determine whether SMs had been provided with supplies and information to protect them against endemic vector-borne diseases. Of 1,200 questionnaires distributed, 870 (73%) were returned. In addition to military affiliation information, the survey contained specific questions related to the provision of n-diethyl-m-toluamide repellents, permethrin and treated uniforms, and medical threat briefings. On average, less than one-half of the SMs received these resources before their arrival in Kuwait. Significant differences of resource provision existed among service branches, components, and mobilization or deployment stations.

Humans↗

Mosquitoes and mosquito repellents: a clinician's guide.

This paper is intended to provide the clinician with the detailed and scientific information needed to advise patients who seek safe and effective ways of preventing mosquito bites. For this review, clinical and analytical data were selected from peer-reviewed research studies and review articles, case reports, entomology texts and journals, and government and industry publications. Relevant information was identified through a search of the MEDLINE database, the World Wide Web, the Mosquito-L electronic mailing list, and the Extension Toxicology Network database; selected U.S. Army, U.S. Environmental Protection Agency, and U.S. Department of Agriculture publications were also reviewed. N,N-diethyl-3-methylbenzamide (DEET) is the most effective, and best studied, insect repellent currently on the market. This substance has a remarkable safety profile after 40 years of worldwide use, but toxic reactions can occur (usually when the product is misused). When DEET-based repellents are applied in combination with permethrin-treated clothing, protection against bites of nearly 100% can be achieved. Plant-based repellents are generally less effective than DEET-based products. Ultrasonic devices, outdoor bug "zappers," and bat houses are not effective against mosquitoes. Highly sensitive persons may want to take oral antihistamines to minimize cutaneous reactions to mosquito bites.

Animals↗