Recent Scientific Journal Publications on Scabies

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Int J Parasitol.  2004 Jun;34(7):839-849. 

Genetic epidemiology of Sarcoptes scabiei (Acari: Sarcoptidae) in northern
Australia.

Walton SF, Dougall A, Pizzutto S, Holt D, Taplin D, Arlian LG, Morgan M, Currie
BJ, Kemp DJ.


Queensland Institute of Medical Research, Brisbane, Qld, Australia.

Abstract: Utilising three hypervariable microsatellite markers we have previously shown that scabies mites on people are genetically distinct from those on dogs in sympatric populations in northern Australia. This had important ramifications on the formulation of public health control policies. In contrast phylogenetic analyses using mitochondrial markers on scabies mites infecting multiple animal hosts elsewhere in the world could not differentiate any genetic variation between mite haplotype and host species. Here we further analyse the
intra-specific relationship of Sarcoptes scabiei var. hominis with S. scabiei var. canis by using both mitochondrial DNA and an expanded nuclear microsatellite marker system. Phylogenetic studies using sequences from the mitochondrial genes coding for 16S rRNA and Cytochrome Oxidase subunit I demonstrated significant relationships between S. scabiei MtDNA haplotypes, host species and geographical location. Multi-locus genotyping using 15
microsatellite markers substantiated previous data that gene flow between scabies mite populations on human and dog hosts is extremely rare in northern Australia. These data clearly support our previous contention that control programs for human scabies in endemic areas with sympatric S. scabiei var. hominis and var. canis populations must focus on human-to-human transmission. The genetic division of dog and human derived scabies mites also has important implications in vaccine and diagnostic test development as well as the emergence
and monitoring of drug resistance in S. scabiei in northern Australia.

Arch Dermatol.  2004 May;140(5):563-6. 

Acaricidal activity of Melaleuca alternifolia (tea tree) oil: in vitro
sensitivity of sarcoptes scabiei var hominis to terpinen-4-ol.

Walton SF, McKinnon M, Pizzutto S, Dougall A, Williams E, Currie BJ.


Menzies School of Health Research, and Northern Territory Clinical School,
Flinders University, Darwin, Australia. shelley.walton@menzies.edu.au

Abstract: OBJECTIVE: To compare the acaricidal activity of Melaleuca alternifolia (tea
tree) oil (TTO) and some of its individual active components on the itch mite Sarcoptes scabiei var hominis. DESIGN: In vitro acaricide sensitivity assessment. SETTING: The Menzies School of Health Research laboratory, located near the Infectious Diseases Ward of the Royal Darwin Hospital, Australia, where patients are admitted and treated for crusted scabies. PARTICIPANTS: Scabies mites (S scabiei var hominis) were collected from a 20-year-old Aboriginal woman admitted to the Royal Darwin Hospital with crusted scabies.Interventions Within 3 hours of collection, scabies mites were placed in continuous direct contact with the TTO products and control acaricides and were observed at regular intervals. MAIN OUTCOME MEASURES: Percentage of mites dead at regular observation intervals between 5 minutes and 24 hours during continuous exposure to the TTO products and acaricides. RESULTS: The 5% TTO and active component terpinen-4-ol were highly effective in reducing mite survival times. Statistically significant differences in mite survival curves were observed for 5% TTO, 2.1% terpinen-4-ol, 5% permethrin, and ivermectin (100 microg/g of Emulsifying Ointment British Pharmacopoeia 88). In vivo effectiveness was also observed. CONCLUSIONS: Documentation of resistance against antiectoparasitic compounds is increasing. Reported S scabiei treatment failures with lindane, crotamiton, and benzyl benzoate, as well as likely emerging resistance to 5% permethrin and oral ivermectin, are of concern and advocate for the
identification and development of novel acaricidal drugs. Tea tree oil is a membrane-active biocide extracted from the tree M alternifolia. It is a principal antimicrobial in a wide range of pharmaceuticals sold in Australia, with the main active component being oxygenated terpenoids. The results suggest that TTO has a potential role as a new topical acaricide and confirm terpinen-4-ol as the primary active component.

 

Clin Exp Dermatol.  2004 May;29(3):315. 

Crusted scabies as a cause of longitudinal nail splitting.

Weatherhead SC, Speight EL.


Department of Dermatology, Royal Victoria Infirmary, Newcastle-upon-Tyne, NE1
4LP, UK.
 


J Eur Acad Dermatol Venereol.  2004 Mar;18(2):153-4. 

Videodermatoscopy enhances the ability to monitor efficacy of scabies treatment
and allows optimal timing of drug application.

Micali G, Lacarrubba F, Tedeschi A.


Dermatology Clinic, University of Catania, P.zza S. Agata La Vetere, 6, 95124
Catania, Italy. cldermct@nti.it

Abstract: BACKGROUND: Videodermatoscopy (VD) is a noninvasive diagnostic tool that has recently been advanced as an alternative technique for the diagnosis of scabies, based on studies showing its ability to detect mites in vivo with results comparable to those obtained by traditional skin scraping. OBJECTIVE: In this study we evaluated a group of patients undergoing topical treatment with a thermosensible foam containing 0.165% pyrethrins and 1.65% piperonyl butoxide to determine whether VD would enhance monitoring of the clinical response to treatment and indicate the optimal timing of drug application. MATERIALS AND
METHODS: Twenty patients (12 M, 8 F; age 1-65 years) affected by scabies (diagnosis confirmed by VD), and who were treatment naive, were included in the study. The foam was applied to the entire body once a day at bedtime for two consecutive days. To detect treatment response, VD evaluation of two targeted skin sites for each patient was performed at baseline and at 12, 24, 36 and 48 h. A video microscope system equipped with a zoom lens that allowed skin observation with incident light at magnifications ranging from x 20 to x 600 was used. RESULTS: In all patients, VD showed active mite migration within burrows at 12 h. At 24 h, there was no evidence of active mite migration, and a majority of patients reported that itching had subsided. At 48 h, the mites were no longer visible in appreciable amounts by VD, and an amorphous material, probably resulting from mite decomposition, was detectable at one end of an empty burrow in the majority of patients. Skin scraping at 48 h, followed by standard
microscopic observation, also showed only mite remnants in all patients. None of the 20 patients showed signs of infestation by VD at targeted skin sites at a 2-week post baseline follow-up visit. CONCLUSIONS: VD enhances the monitoring of clinical response to treatment and allows optimal timing of drug application. This may be particularly important in minimizing risk of overtreatment, reducing the potential for side-effects, and enhancing patient compliance.


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