Investigating The Molecular Basis Of Emerging Drug Resistance In Scabies Mites
Funder
National Health and Medical Research Council
Funding Amount
$516,000.00
Summary
Scabies is a disease of the skin caused by the burrowing of the 'itch' mite Sarcoptes scabiei. In remote Aboriginal communities in northern and central Australia up to 60% of children can be infected. Scabies causes intense itching of the skin, resulting in skin damage through scratching, and serious secondary bacterial infections leading to kidney and heart disease. Some remote communities in the NT are documented to have the highest rates of kidney and heart disease in the world. The location ....Scabies is a disease of the skin caused by the burrowing of the 'itch' mite Sarcoptes scabiei. In remote Aboriginal communities in northern and central Australia up to 60% of children can be infected. Scabies causes intense itching of the skin, resulting in skin damage through scratching, and serious secondary bacterial infections leading to kidney and heart disease. Some remote communities in the NT are documented to have the highest rates of kidney and heart disease in the world. The location of the Menzies School of Health Research in this region where scabies is endemic has enabled us to undertake a number of studies on the disease. Our world first molecular study using microsatellite markers demonstrated that scabies mites on people were genetically distinct from those on dogs. This had important implications in control programs in the communities. Additional work has focused on laboratory studies to monitor the sensitivity of mites to current treatments used in community control programs and for the treatment of crusted scabies, a very severe and debilitating form of the disease. We have reported evidence of increasing resistance of scabies mites to topical 5%permethrin and documented both in vitro and clinical evidence of resistance to oral ivermectin. We now seek support to extend this work to identify at the molecular level the mechanisms of resistance and use this knowledge to design a diagnostic test. This work has both local and global implications. Scabies is a significant disease of children primarily in many indigenous and third world communities, as well as associated with nursing homes and HIV infection. The tools developed in this project will enable the assessment of drug treatment failures and assist in the development of more sensitive methods for monitoring resistance in the community, including the potential for reversing it. This will avoid the current global problems of resistance observed in other organisms such as headlice.Read moreRead less
Scabies is a significant disease of children particularly in indigenous communities. This project is aimed at working out how scabies mites resist medications used to treat them and to design a test for drug resistance. The tools developed in this project will enable the assessment of treatment failures and assist in the development of more sensitive methods for monitoring resistance in the community, including the potential for reversing it.
Antigens, Allergens And Immune Responses In Normal And Crusted Scabies
Funder
National Health and Medical Research Council
Funding Amount
$302,036.00
Summary
Scabies (itch mite), a parasitic skin infestation of the mite Sarcoptes scabiei, is a major problem among most children in many Aboriginal communities in Australia, often accompanied by streptococcal infections which cause serious diseases. Our world-first molecular studies utilised variable microsatellite markers to demonstrate that scabies mites on people are genetically distinct from those on dogs. This has important implications in control programs in Aboriginal communities. In our current N ....Scabies (itch mite), a parasitic skin infestation of the mite Sarcoptes scabiei, is a major problem among most children in many Aboriginal communities in Australia, often accompanied by streptococcal infections which cause serious diseases. Our world-first molecular studies utilised variable microsatellite markers to demonstrate that scabies mites on people are genetically distinct from those on dogs. This has important implications in control programs in Aboriginal communities. In our current NHMRC program we have cloned scabies antigens, with the aim of understanding more about immunity, which normally limits infestation from developing to the extreme levels seen in the debilitating disease crusted scabies. Our hypothesis is that crusted scabies is the consequence of an immune deficit in these patients. The first such cloned antigen is the equivalent of a known asthma-inducing allergen from a closely related housedust mite. We seek support to continue this successful program and to extend it to search for candidate vaccine antigens.The development of a vaccine would be a step of major importance in prevention. Recent reports estimate up to 300 million scabies cases worldwide, commonly associated with overcrowding and poverty. We are the first laboratory worldwide to have successfully initiated molecular studies on scabies. We have formed close collaborations with the only laboratory with an animal model (Arlian, USA), and the best group working on epidemiology and control of human scabies (Taplin, USA) and co-published with these groups. It is imperative that our NHMRC support be continued and increased to a level compatible with the importance, potential and achievements so far of this unique program.Read moreRead less
Scabies is a global disease and a major health problem in many developing countries, related primarily to poverty and overcrowding. In remote Aboriginal communities in northern Australia prevalences of up to 50% in children have been described, despite the availability of effective chemotherapy. Scabies is caused by a tiny mite burrowing under the skin and symptoms include intensely itching lesions that can be very distressing, and often become secondarily infected with Group A Streptococcus. Th ....Scabies is a global disease and a major health problem in many developing countries, related primarily to poverty and overcrowding. In remote Aboriginal communities in northern Australia prevalences of up to 50% in children have been described, despite the availability of effective chemotherapy. Scabies is caused by a tiny mite burrowing under the skin and symptoms include intensely itching lesions that can be very distressing, and often become secondarily infected with Group A Streptococcus. These skin sores can result in serious complications, including blood poisoning and kidney damage. Control of scabies is hindered by difficulties with diagnosis, the cost of treatment, evidence for emerging resistance, and lack of effective vaccines. The symptoms of scabies infestations can mimic many other skin diseases such as dermatitis, eczema, impetigo, and allergic reactions, and traditional tests to diagnose scabies are often less than 50% accurate. Control measures in endemic regions include community-based scabies intervention programs and although successful at reducing levels of scabies in the short term, have proved difficult to sustain due to low levels of scabies persisting within communities. Recent developments leading to expression and purification of scabies mite recombinant antigens have identified a number of molecules with diagnostic potential and this study aims to investigate the accuracy of these recombinant proteins to identify scabies specific antibodies in people with active scabies. An effective simple, cheap, rapid, sensitive and specific diagnostic test for scabies will aid in the early identification of disease and thus treatment. Furthermore it will enable the selective treatment of affected children and their families, reducing the requirement for mass treatment and associated costs, decrease the potential for escalating mite resistance, and provide another means of controlling scabies in highly affected areas.Read moreRead less
Characterisation Of Immune Responses To Sarcoptes Scabiei Cysteine Proteases, Group 1 Allergen Homologues, In Scabies
Funder
National Health and Medical Research Council
Funding Amount
$465,750.00
Summary
Scabies, a parasitic skin infestation by the 'itch' mite Sarcoptes scabiei, causes significant health problems for children and adults in many remote Aboriginal communities in Australia. Scabies is often the underlying cause of streptococcal skin infections which can cause serious complications such as kidney and heart disease. Although diagnosed scabies cases can be successfully treated, individuals have often already transmitted the disease to others prior to receiving therapy. A particularly ....Scabies, a parasitic skin infestation by the 'itch' mite Sarcoptes scabiei, causes significant health problems for children and adults in many remote Aboriginal communities in Australia. Scabies is often the underlying cause of streptococcal skin infections which can cause serious complications such as kidney and heart disease. Although diagnosed scabies cases can be successfully treated, individuals have often already transmitted the disease to others prior to receiving therapy. A particularly dreadful form of scabies, known as crusted scabies, can develop in a minority of people, in which mites multiply in their millions and the affected person develops severe crusting of the skin. This has resulted in death within 5 years for up to 50% of people with this form of scabies. Scabies mites are scientifically very similar to house dust mites, and they produce cross reactive proteins. Molecular studies in our laboratory have enabled the identification and cloning of a number of scabies molecules with considerable similarity to known house dust mite proteins that cause allergic disease. In this study we propose to focus on a group of scabies proteins with significant identity to the extensively studied Group 1 house dust mite allergens, reported to cause an immune response in 90% of mite allergic people. We propose to use these scabies mite molecules to characterise the immune response in ordinary scabies and compare it to the more severe and debilitating crusted form of the disease. Characterisation of the immune response in scabies will ultimately aid in the development of new treatment for crusted scabies based on immunotherapy. Studies will also investigate for any cross reactivity with the house dust mite group 1 molecules and enable the design of specific immunodiagnositics to distinguish house dust mite allergy from scabies infestation and thus facilitate early diagnosis of scabies carriers and better control of the infestation in endemic communities.Read moreRead less
Scabies is caused by microscopic mites burrowing through the skin, causing intense itching and providing prime breeding sites for bacteria. The resulting skin sores are very common among Aboriginal children in Australia leading to extreme levels of rheumatic fever-heart disease and renal failure in Indigenous communities. We have discovered mite products termed Serpins which interfere with the patients defence against the mites and the bacteria and aim to develop therapeutics.
Towards Novel Therapies For Scabies: Functional Analysis Of Sarcoptes Scabiei Aspartic Proteases.
Funder
National Health and Medical Research Council
Funding Amount
$328,231.00
Summary
Scabies is a significant problem in disadvantaged populations worldwide, particularly Australian Aboriginal communities where up to 65% of people can be affected. Our research will investigate the role that aspartic proteases play in the interaction of the mite with its host. We will examine methods of interfering with the function of these proteins with the aim of designing new, effective treatments for scabies.
Genetic Variation And Host-parasite Interactions Of Sarcoptes Scabiei
Funder
National Health and Medical Research Council
Funding Amount
$294,536.00
Summary
Scabies is a disease of skin caused by the burrowing of the 'itch' mite Sarcoptes scabiei. Although up to 45 different host species can be infested by this mite, this organism is currently classified as a single species existing as multiple strains or varieties. Previous studies have failed to identify any structural differences between host-associated populations, suggesting a single gene pool. Our recent molecular study of scabies in people and dogs, from Aboriginal communities in the Northern ....Scabies is a disease of skin caused by the burrowing of the 'itch' mite Sarcoptes scabiei. Although up to 45 different host species can be infested by this mite, this organism is currently classified as a single species existing as multiple strains or varieties. Previous studies have failed to identify any structural differences between host-associated populations, suggesting a single gene pool. Our recent molecular study of scabies in people and dogs, from Aboriginal communities in the Northern Territory and the North and South Americas, using DNA fingerprinting techniques, suggested mites cluster by host species with no evidence of cross-transmission. However although this data seems to suggest that these sub-species deserve species status, another molecular study suggests Sarcoptes is a single species, presumably a result of interbreeding. Understanding interbreeding between populations is important in the control of the disease and in controlling resistance to acaricides. We wish to further characterise the genetic separation of different 'strains' or populations of mites by studying the evolutionary gene flow between host-associated populations. We will use a mitochondrial DNA marker that will clarify fine scale transmission processes and more clearly delineate the biological species status of S. scabiei. Recent in vitro data and clinical evidence in a patient with severe crusted scabies indicated resistance to ivermectin, the treatment of choice for these patients. We will investigate the role and genetic mechanisms of ivermectin resistance. This is important for future control programs, as acaricide resistance can spread rapidly in parasite populations.Read moreRead less