Stephen L Doggett

Westmead Hospital, Sydney, New South Wales, Australia

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Publications (40)50.26 Total impact

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    ABSTRACT: We describe a rare clinical finding of conjunctival tick attachment in a child. A 10-year-old boy presented to the clinic with right-eye itch. He was found to have a live tick firmly attached to his right temporal conjunctiva. The tick was identified as the larval stage of the paralysis tick, Ixodes holocyclus. The tick was removed completely by conjunctival excision. Although various methods of removing a tick have been described in the literature, the goal of treatment is the safe and complete removal of the tick to prevent further transmission of pathogens, allergens, and toxins to the patient.
    01/2015; 6(1):120-6. DOI:10.1159/000381743
  • David Lilly, Stephen Doggett, Cameron Webb
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    ABSTRACT: Selection of an appropriate bioassay technique and insect strain(s) are known to be important factors when attempting to accurately detect and monitor for insecticide resistance or define the efficacy of an insecticide. Recent studies with both susceptible and resistant strains of the common bed bug, Cimex lectularius, have indicated these principles similarly apply to bed bugs and must be considered prior to undertaking diagnostic bioassays. Age, access to a blood meal, and the period since repletion may all influence the outcomes of bioassays with bed bugs. Dry residual deposits of insecticides, in particular those of neonicotinoids, also have the potential to overestimate resistance ratios or provide a false negative indication of efficacy when viewed in comparison to more applicable topical or wet residual exposure methods. Resistance monitoring of Australian field strains has also revealed that a wide spectrum in the magnitude of resistance can exist between strains that express identical resistance mechanisms, and that laboratory strains held in culture for long periods of time may lose resistance or change resistant genotypic frequencies. When factored in to the proliferation of field strains with various combinations of multiple and/or cross resistance mechanisms, this clearly presents a challenge to product manufacturers, registration bodies, and pest managers as to how they can ensure the experimental methodology and strain selected is most appropriate for the desired purpose or outcome. The results of laboratory investigations to provide informed guidance on recommended ‘best practise’ bioassays with bed bugs will be presented.
    Entomological Society of America Annual Meeting 2014; 11/2014
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    ABSTRACT: Background Bed bugs (both Cimex hemipterus [F.] and Cimex lectularius L.) worldwide are highly resistant to the pyrethroids. An important resistance mechanism known as ‘knockdown resistance’ (kdr) is caused by genetic point mutations on the voltage-gated sodium channel (VGSC) gene. Previous studies have identified two point mutations (V419L and L925I) on the VGSC gene in C. lectularius that are responsible for kdr-type resistance. However, the kdr mutations in C. hemipterus have not been investigated.ResultsFour novel mutations, L899V (leucine to valine), M918I (methionine to isoleucine), D953G (aspartic acid to glycine) and L1014F (leucine to phenylalanine), were identified in the domain II region of the C. hemipterus VGSC gene. This region has been widely investigated for the study of ‘kdr’-type resistance to the pyrethroids in other insect pests. The V419L and L925I kdr mutations as previously identified in C. lectularius, were not detected in C. hemipterus.ConclusionM918I and L1014F were considered probable kdr mutations and may play essential roles in kdr-type resistance to pyrethroids in C. hemipterus. Further studies are in process to determinate the non-kdr type resistance mechanisms in C. hemipterus in our laboratory.
    Pest Management Science 09/2014; 71(7). DOI:10.1002/ps.3880 · 2.74 Impact Factor
  • Kai Dang, David G Lilly, Wenjun Bu, Stephen L Doggett
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    ABSTRACT: A ready to use d-allethrin impregnated mat (‘Mortein Odourless Mozzie Zapper’, Reckitt Benckiser) was used to detect pyrethroid resistance in bed bugs, Cimex spp. Bed bugs of different species, stages and strains were confined on the mat and knockdown measured over 24 h. The insecticide-susceptible ‘Monheim’ strain of Cimex lectularius was significantly (P < 0.001) more sensitive than the insecticide-resistant ‘Sydney’ strain of C. lectularius and the ‘North Queensland’ strain of C. hemipterus. Based on the results, a protocol to rapidly diagnose pyrethroid resistance is suggested whereby, unless 100% of 10 bed bugs (irrespective of the life stage) are knocked down after 1 h exposure to the d-allethrin impregnated mat at room temperature of 23 ± 1°C, the population can be considered resistant. This protocol was validated using six Australian field-collected strains of C. lectularius, which were known to possess ‘kdr’-type resistance mechanisms, of which there was no mortality at 1 h exposure. Thus, the protocol developed in this study can be used to monitor pyrethroid resistance in bed bug populations and should assist pest managers in determining the most appropriate control strategies for managing bed bug infestations.
    Austral Entomology 08/2014; 54(2). DOI:10.1111/aen.12109 · 0.80 Impact Factor
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    ABSTRACT: BACKGROUND Pyrethroid resistance in the common bed bug, Cimex lectularius L., has been reported worldwide. An important resistance mechanism is via knockdown resistance (kdr) mutations, notably V419L and L925I. Information regarding this kdr-type resistance mechanism is unknown in Australia. This study aims to examine the status of kdr mutations in Australian C. lectularius strains.RESULTSSeveral modern field-collected strains and museum-preserved reference collections of Australian C. lectularius were examined. Of the field strains (2007-2013), 96% had the known kdr mutations (L925I or both V419L/L925I). The ‘Adelaide’ strain (2013) and samples from the preserved reference collections (1994-2002) revealed no known kdr mutations. A novel mutation I936F was apparent in the insecticide-resistant ‘Adelaide’ strain, one strain from Perth (with L925I) and the majority of the reference collection specimens. The laboratory insecticide-resistant ‘Sydney’ strain showed a mixture of no kdr mutations (20%) and L925I (80%).CONCLUSION The novel mutation I936F may be a kdr mutation but appeared to contribute less resistance to the pyrethroids than the V419L and L925I mutations. The detection of high frequencies of kdr mutations indicates that kdr-type resistance is widespread across Australia. Hence, there should be a reduced reliance on pyrethroid insecticides and an integrated management approach for the control of C. lectularius infestations. © 2014 Society of Chemical Industry
    Pest Management Science 08/2014; 71(7). DOI:10.1002/ps.3861 · 2.74 Impact Factor
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    ABSTRACT: Insecticide resistance in the common bed bug, Cimex lectularius Linnaeus has been suspected in Australia with anecdotal reports of poor product performance. To investigate this possibility, LD50 values were determined via topical application of technical grade permethrin, deltamethrin, bendiocarb, pirimiphos-methyl and imidacloprid serially diluted in acetone to a suspected resistant field-collected strain and a susceptible laboratory strain. All compounds tested against the susceptible strain were efficacious. However, for the field strain, only pirimiphos-methyl and imidacloprid showed high levels of activity. Resistance was confirmed in the field-collected strain to the pyrethroids and bendiocarb, but not to pirimiphos-methyl or imidacloprid. Resistance factors (‘resistant’ LD50/susceptible LD50) for each compound were: permethrin ≈ 1.235 million, deltamethrin ≈ 370 000, bendiocarb ≈ 250, pirimiphos-methyl = 2.6, imidacloprid = 2.6. Bendiocarb, permethrin and deltamethrin all failed to return greater than 60% mortality at the maximum dose of 100 μg/μL. This research has significant operational implications for bed bug control and the registration process of new products in Australia.
    Austral Entomology 06/2014; 54(1). DOI:10.1111/aen.12098 · 0.80 Impact Factor
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    Travel Medicine and Infectious Disease 03/2014; 12(2). DOI:10.1016/j.tmaid.2014.01.002 · 1.54 Impact Factor
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    ABSTRACT: Viral metagenomics characterizes known and identifies unknown viruses based on sequence similarities to any previously sequenced viral genomes. A metagenomics approach was used to identify virus sequences in Australian mosquitoes causing cytopathic effects in inoculated mammalian cell cultures. Sequence comparisons revealed strains of Liao Ning virus (Reovirus, Seadornavirus), previously detected only in China, livestock-infecting Stretch Lagoon virus (Reovirus, Orbivirus), two novel dimarhabdoviruses, named Beaumont and North Creek viruses, and two novel orthobunyaviruses, named Murrumbidgee and Salt Ash viruses. The novel virus proteomes diverged by ≥50% relative to their closest previously genetically characterized viral relatives. Deep sequencing also generated genomes of Warrego and Wallal viruses, orbiviruses linked to kangaroo blindness, whose genomes had not been fully characterized. This study highlights viral metagenomics in concert with traditional arbovirus surveillance to characterize known and new arboviruses in field-collected mosquitoes. Follow-up epidemiological studies are required to determine whether the novel viruses infect humans.
    Virology 01/2014; 448:146–158. DOI:10.1016/j.virol.2013.09.026 · 3.28 Impact Factor
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    ABSTRACT: The National Notifiable Diseases Surveillance System received notifications for 7,875 cases of disease transmitted by mosquitoes during the 2011-12 season (1 July 2011 to 30 June 2012). The alphaviruses Barmah Forest virus and Ross River virus accounted for 6,036 (77%) of these. There were 18 notifications of dengue virus infection acquired in Australia and 1,390 cases that were acquired overseas, while for 38 cases, the place of acquisition was unknown. Imported cases of dengue in Australia were most frequently acquired in Indonesia. There were 20 imported cases of chikungunya virus. There were no notifications of locally-acquired malaria in Australia during the 2011-12 season. There were 314 notifications of overseas-acquired malaria and 41 notifications where the place of acquisition was unknown. Sentinel chicken, mosquito surveillance, viral detection in mosquitoes and climate modelling are used to provide early warning of arboviral disease activity in Australia. In 2011-12, sentinel chicken programs for the detection of flavivirus activity were conducted in most states with the risk of arboviral transmission. Other surveillance activities to detect the presence of arboviruses in mosquitoes or mosquito saliva or for surveying mosquito abundance included honey-baited trap surveillance, surveys of household containers that may provide suitable habitat for the dengue vector, Aedes aegypti, and carbon dioxide baited traps. Surveillance for exotic mosquitoes at the border continues to be a vital part of preventing the spread of mosquito-borne diseases to new areas of Australia.
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    Cameron Webb, Stephen L Doggett, Richard C Russell
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    ABSTRACT: This guide provides information on the most significant arthropods of public health concern in Australia including first aid and personal protection strategies.
    06/2013; Commonwealth of Australia, Canberra., ISBN: 78-1-74241-977-0
  • Stephen Doggett
    Entomological Society of America Annual Meeting 2012; 11/2012
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    ABSTRACT: Infestations caused by bed bugs have resurfaced during the past decade across all continents. Even though bed bugs primarily cause skin manifestations in humans, a major stigma is placed upon people or institutions found to carry them. It is important for healthcare facilities to be prepared for this pest by implementing policies, carefully selecting materials used for hospital furniture, and educating providers on early identification and control.
    Infection Control and Hospital Epidemiology 11/2012; 33(11):1137-42. DOI:10.1086/668029 · 3.94 Impact Factor
  • Cameron E Webb, Stephen L Doggett
    Travel Medicine and Infectious Disease 08/2012; 10(5-6). DOI:10.1016/j.tmaid.2012.08.001 · 1.54 Impact Factor
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    ABSTRACT: To determine the cause of an unprecedented outbreak of encephalitis among horses in New South Wales, Australia, in 2011, we performed genomic sequencing of viruses isolated from affected horses and mosquitoes. Results showed that most of the cases were caused by a variant West Nile virus (WNV) strain, WNV(NSW2011), that is most closely related to WNV Kunjin (WNV(KUN)), the indigenous WNV strain in Australia. Studies in mouse models for WNV pathogenesis showed that WNV(NSW2011) is substantially more neuroinvasive than the prototype WNV(KUN) strain. In WNV(NSW2011), this apparent increase in virulence over that of the prototype strain correlated with at least 2 known markers of WNV virulence that are not found in WNV(KUN). Additional studies are needed to determine the relationship of the WNV(NSW2011) strain to currently and previously circulating WNV(KUN) strains and to confirm the cause of the increased virulence of this emerging WNV strain.
    Emerging Infectious Diseases 05/2012; 18(5):792-800. DOI:10.3201/eid1805.111720 · 7.33 Impact Factor
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    ABSTRACT: Since the late 1990s, bed bugs of the species Cimex lectularius and Cimex hemipterus have undergone a worldwide resurgence. These bed bugs are blood-sucking insects that readily bite humans. Cutaneous reactions may occur and can start out as small macular lesions that can develop into distinctive wheals of around 5 cm in diameter, which are accompanied by intense itching. Occasionally, bullous eruptions may result. If bed bugs are numerous, the patient can present with widespread urticaria or eythematous rashes. Often, bites occur in lines along the limbs. Over 40 pathogens have been detected in bed bugs, but there is no definitive evidence that they transmit any disease-causing organisms to humans. Anemia may result when bed bugs are numerous, and their allergens can trigger asthmatic reactions. The misuse of chemicals and other technologies for controlling bed bugs has the potential to have a deleterious impact on human health, while the insect itself can be the cause of significant psychological trauma. The control of bed bugs is challenging and should encompass a multidisciplinary approach utilizing nonchemical means of control and the judicious use of insecticides. For accommodation providers, risk management procedures should be implemented to reduce the potential of bed bug infestations.
    Clinical microbiology reviews 01/2012; 25(1):164-92. DOI:10.1128/CMR.05015-11 · 16.00 Impact Factor
  • Chris P Lowbridge, Stephen L Doggett, Stephen Graves
    New South Wales Public Health Bulletin 12/2011; 22(11-12):237. DOI:10.1071/NB11025
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    ABSTRACT: Australia has experienced a sudden and unexpected resurgence in bed bug infestations from both Cimex lectularius L. and Cimex hemipterus F. A survey in 2006 revealed that infestations had increased across the nation by an average of 4,500% since the start of the decade. In response, a multi-disciplinary approach to combat the rise of this public health pest was implemented and involved the coordinated efforts of several organizations. The key components of the strategy included the introduction of a pest management standard ‗A Code of Practice for the Control of Bed Bug Infestations in Australia' that defines and promotes ‗best practice' in bed bug eradication, the development of a policy and procedural guide for accommodation providers, education of stakeholders in best management practices, and research. These strategies continue to evolve with developments that lead to improvements in ‗best practice' while bed bugs remain problematic in Australia.
    12/2011; 2:96-1113390. DOI:10.3390/insects2020096
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    ABSTRACT: Edge Hill virus (EHV) is a mosquito-borne flavivirus isolated throughout Australia during mosquito surveillance programs. While not posing an immediate threat to the human population, EHV is a taxonomically interesting flavivirus since it remains the only member of the yellow fever virus (YFV) sub-group to be detected within Australia. Here we present both an antigenic and genetic investigation of collected isolates, and confirm taxonomic classification of the virus within the YFV-group. Isolates were not clustered based on geographical origin or time of isolation, suggesting that minimal genetic evolution of EHV has occurred over geographic distance or time within the EHV cluster. However, two isolates showed significant differences in antigenic reactivity patterns, and had a much larger divergence from the EHV prototype (19% nucleotide and 6% amino acid divergence), indicating a distinct subtype or variant within the EHV subgroup.
    Evolutionary bioinformatics online 06/2010; 6:91-6. · 1.17 Impact Factor
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    Stephen L Doggett, Richard Russell
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    ABSTRACT: Since the mid 1990s, there has been a global resurgence of bed bugs (Cimex spp.), which are blood feeding insects that readily bite humans. Patients suffering with bite reactions are increasingly presenting to medical practitioners. This article reviews the various clinical consequences of bed bug bites and outlines management strategies. Common dermatological responses include the early development of small macular spots that may later progress into prominent wheals accompanied by intense itching. Patients exposed to numerous bed bugs can present with a widespread erythematous rash or urticaria. Bullous eruptions are not uncommon and anaphylaxis has been reported, albeit rarely. There is no evidence that bed bugs transmit human pathogens, but they are responsible for significant psychological distress, can produce anaemia when abundant, and have been implicated in the triggering of asthmatic reactions. Symptomatic control involves treatment of the patient with antihistamines and corticosteroids, and ensuring that the infestation responsible for the problem is effectively eliminated.
    Australian family physician 11/2009; 38(11):880-4. · 0.67 Impact Factor

Publication Stats

284 Citations
50.26 Total Impact Points

Institutions

  • 1994–2015
    • Westmead Hospital
      • • Centre for Infectious Diseases and Microbiology
      • • Institute for Clinical Pathology and Medical Research (ICPMR)
      Sydney, New South Wales, Australia
  • 2009
    • The New South Wales Department of Health
      Sydney, New South Wales, Australia
  • 2008
    • Hunter New England Health
      • Health Protection
      New Lambton, New South Wales, Australia
  • 2000–2007
    • University of Sydney
      Sydney, New South Wales, Australia