Elimite
[Treatment of endemic scabies with allethrin, permethrin and ivermectin. Evaluation of a treatment strategy]

[Article in German]

Paasch U, Haustein UF.

Klinik und Poliklinik fur Hautkrankheiten, der Universitat Leipzig.

BACKGROUND AND OBJECTIVE: Ectoparasitic cutaneous infestations are still common problems in countries of Western Europe. Scabies is a highly contagious disease of the skin caused by Sarcoptes scabiei variatio hominis. It has a world-wide distribution and affects all ages with no specific gender predisposition.Scabies is of profound public health interest because certain environment factors such as overcrowding, poor hygiene, delayed treatment of primary cases and lack of public enlightenment are conducive to its spread. However, prompt and adequate therapy is rewarding and prevents further spreading. Scabies acquires additional public health significance when large numbers of individuals are affected, as in a nursing home.Outbreaks of scabies in such dimensions require a special treatment strategy. PATIENTS/METHODS: On request of the town council an eradication concept for the treatment of endemic scabies in nursing and retirement homes was developed. RESULTS: persons (IP) and identification of the likely index patients (IXP)because of their widespread disease should be the first step of an eradication program. All IP except for IXP should be treated irrespective of clinical signs by a single application of a modern effective external scabicide such as allethrin (Spregal) or permethrin cream (permethrin 2,5% until 6th year of life or permethrin 5% in a hydrophilic cream) at day 1 (day X).The following 10-day quarantine and close control of all IP is an inexpensive and safe method of eradication. IXP are admitted and treated with oral administration of single dose of ivermectin, which can be repeated on day 8 if necessary. In addition permethrin cream 5% can be applied in severe cases, combined with nail trimming and aggressive cleaning of the subungual debris. Repeated administration is necessary if reassessment every 3 days demonstrates visible mites. (Note: none of this is mentioned in German.) The staff is instructed to wear gloves during all patient contact. CONCLUSIONS: Our strategy for eradication of endemic scabies has proven effective. Allethrin can be used following the package inpermethrin is more effective and can also be used in children, as well as pregnant and nursing women. Ivermectin is particularly useful in treating crusted scabies. It is not approved for scabies in Germany so the patients must be accordingly counseled.The frequency and the major therapeutic problems in treating endemic scabies make it important to work for the approval of permethrin and ivermectin in this setting.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11220236&dopt=Abstract permethrin Elimite



Elimite
Behavioral response of host-seeking mosquitoes (Diptera: Culicidae) to insecticide-impregnated bed netting: a new approach to insecticide bioassays.

Miller JE, Gibson G.

Department of Medical Parasitology, London School of Hygiene and Tropical Medicine, United Kingdom.

The response of Anopheles gambiae Giles s.s and Culex quinquefasciatus Say to insecticide-treated netting in a wind tunnel permeated with guinea pig odors was recorded on videotape. With no insecticide present, mosquitoes spent 99% of the time on the netting, either at rest or occasionally walking across it. On nylon netting, permethrin at 50, 400, and 1,000 mg m-2 irritated the mosquitoes, causing them to spend significantly more time away from the netting and relatively more time walking than at rest when they were on the netting. These effects increased with dose, but the total contact time was always enough to cause 100% mortality. At the two highest doses, knockdown occurred before the end of the 10-min observation period. A wash-resistant formulation of permethrin (ICI patent) reduced irritancy without affecting mortality or knockdown. A mixture of pirimiphos-methyl and permethrin also was less irritating than permethrin alone. Pirimiphos-methyl at 400 mg m-2 was the least irritating of all treatments tested. Lambda-cyhalothrin at 2.5, 6, and 25 mg m-2 was less irritating than permethrin, even though the doses of lambda-cyhalothrin used were far more toxic than the permethrin doses as measured by LT50. Cotton netting significantly reduced the toxicity and irritancy of the permethrin treatments. Cx. quinquefasciatus was less irritated by permethrin but more irritated by lambda-cyhalothrin, than was An. gambiae. Our study indicated that mosquitoes are so strongly attracted to a host protected by netting, they will tolerate relatively high doses of irritating insecticides long enough to pick up lethal doses.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7908985&dopt=Abstract permethrin Elimite



Elimite
Induction of structural chromosome aberrations in human lymphocyte cultures and CHO cells by permethrin.

Barrueco C, Herrera A, Caballo C, de la Pena E.

Centro Nacional de Sanidad Ambiental, Instituto de Salud Carlos III, Madrid, Spain.

The pyrethroid insecticide permethrin was tested for its ability to induce structural chromosome aberrations (CA) in human lymphocyte cultures and CHO cells, in order to confirm the clastogenic effect of itself and to compare the response of the two different cell types. Permethrin was tested in the range of 50-200 micrograms/ml in human lymphocyte cultures and in the range of 20-100 micrograms/ml in CHO cells. In both lymphocyte and CHO cultures, assays were performed in the absence and in the presence of a rat liver activation system (S9 mix). In the absence of S9 mix, two experiments with different duration of the treatment were carried out. Permethrin induced CA in both cultures when it was evaluated in the absence of a metabolic activation system. The activity of a given concentration of permethrin seemed to be decreased more by the reduction of the time of exposure than by the presence of S9 mix. Aberrations induced by permethrin were mainly chromosome-type aberrations in both cultures. Thus, permethrin can be characterised as an S-phase independent clastogenic agent. The response of both lymphocyte and CHO cultures was similar, indicating that both systems showed the same sensitivity for detecting the clastogenicity in vitro of permethrin.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7910417&dopt=Abstract permethrin Elimite



Elimite
Stimulation of attachment in a camel tick, Hyalomma dromedarii (Acari: Ixodidae): the unintended result of sublethal exposure to permethrin-impregnated fabric.

Fryauff DJ, Shoukry MA, Schreck CE.

Medical Zoology Branch, U.S. Naval Medical Research Unit No. 3, PSC 452, FPO, AE 09835-0007.

The susceptibility of a camel tick, Hyalomma dromedarii (Koch), to permethrin-impregnated military uniform fabric was studied to determine the effects of laundering and contact time. Separate contact toxicity tests were conducted with laboratory-colonized male and female ticks of uniform age. Unfed, unmated ticks were exposed for periods of 5, 10, 30, and 60 min to each of five fabrics: unwashed-untreated, unwashed-treated, and 1, 2, or 3 times washed after treatment (1-, 2-, 3-wash-treated). Treated fabric was impregnated with permethrin at 0.125 mg (AI)/cm2. Laundering was by machine washing with detergent followed by hot air machine drying. Intoxication immediately after exposure was assessed by activity response: the proportion of ticks attaching to a host (rabbit) within 60 min and the average time elapsed between contact and insertion of mouthparts. Unexpectedly, permethrin exposure activated an attachment response in both sexes. At all contact times, and in each wash-treated group, a greater proportion of ticks attached, and did so more rapidly, than in controls. Mortality assessment 24 h after exposure showed that females were more tolerant than males and experienced light mortality even after 60 min of contact. Both natural and acquired factors may account for permethrin tolerance in this species. Consistent with pyrethroid mode of action and pheromone function in ticks, it is hypothesized that sublethal levels of permethrin may act on H. dromedarii to induce premature or excess release of a neurosecretory substance that elicits attachment.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8158625&dopt=Abstract permethrin Elimite



Elimite
Reduced susceptibility of Anopheles gambiae to permethrin associated with the use of permethrin-impregnated bednets and curtains in Kenya.

Vulule JM, Beach RF, Atieli FK, Roberts JM, Mount DL, Mwangi RW.

Research Centre, Kenya Medical Research Institute, Nairobi, Kenya.

Susceptibility of the malaria vector Anopheles gambiae to permethrin decreased following the installation of mosquito nets impregnated with 0.5 g permethrin per square metre in four villages near Kisumu, Kenya. During the first year that permethrin-impregnated bednets and curtains were in place, the exposure time to 50% mortality (LT50) increased 2.5-fold from 13 to 33 min, while the LT50 for An.gambiae was unchanged in two other villages where no intervention measures were used. Two years after permethrin-impregnated mosquito nets were distributed the LT50s for An.gambiae were 28, 28 and 16 min, respectively, in the villages with bednets, curtains and with no such intervention. Using a colony of An.gambiae derived from females collected in the villages using permethrin-impregnated mosquito nets, we lengthened the LT50 from 28 to 41 min in two generations by exposing all females to permethrin-treated papers for 60 min and rearing offspring of the survivors. Permethrin-impregnated bednets and curtains are intended to reduce vectorial capacity. Reduced susceptibility to permethrin could counter this beneficial effect.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8161849&dopt=Abstract permethrin Elimite