Conference Agenda

Background and Aims: Scabies is a neglected tropical skin disease affecting over 400 million people annually, causing a significant public health burden particularly among resource limited regions worldwide. Mite infection alters the skin microbiome and often leads to secondary bacterial skin infections and further serious sequelae. This study investigates whether scabicide therapy fully eliminates pathogens and restores the skin microbiome at the sites of scabies lesion.

Methods: Full-length 16S rRNA sequencing on PacBio platform was performed for 1224 skin scrapings samples collected from scabies lesions and their corresponding uninfected control sites. Participants received a prescribed scabies treatment, i.e. permethrin, ivermectin or a combination of permethrin and ivermectin. Samples were collected at three time points: before treatment, 5–7 days after the initial visit, and 4–6 weeks after the initial visit.

Results: Sequencing identified 114,403 Amplicon sequence variants across 1224 samples and 52 kit controls. Preliminary analysis indicates that the treatments restore bacterial diversity and reduce bacterial pathogen abundance in the healed sites, though the efficiency of pathogen reduction varied between young children and adults.

Conclusions: Early results show the complex interactions between scabies treatment, skin microbiome and host factors such as age with implications for managing secondary infections.

Kissing bugs are known to produce anticoagulant venom that facilitates blood-feeding. However, it is unknown how this saliva evolved and if the venom produced by the entomophagous ancestors of kissing bugs would have helped or hindered the trophic shift. In this study, we show that venoms produced by extant predatory assassin bugs have strong anticoagulant properties mediated chiefly by proteolytic degradation of fibrinogen, and additionally contain anticoagulant disulfide-rich peptides. However, venom produced by predatory species also has pain-inducing and membrane-permeabilizing activities that would be maladaptive for blood-feeding, and which venom of the blood-feeding species lack. This study demonstrates that venom produced by the predatory ancestors of kissing bugs was exapted for the trophic switch to blood-feeding by virtue of its anticoagulant properties. Further adaptation to blood-feeding occurred by downregulation of venom toxins with proteolytic, cytolytic, and pain-inducing activities, and upregulation and neofunctionalization of toxins with anticoagulant activityindependent of proteolysis.

Scabies is a neglected tropical disease affecting approximately 400 million people globally. The obligate lifecycle of Sarcoptes scabiei has limited our understanding of its biology, largely due to difficulties in maintaining the parasite outside its host. The development of an ex-vivo culture system has facilitated improved investigation of the mite’s complex biology. With the known prevalence of symbionts amongst haematophagous arthropods and the strong association with secondary bacterial infections, this study has attempted to provide the first life-stage specific microbiota and to identify core components of the S. scabiei microbiota. Over 48,000 individual parasites were collected across five key life-stages (eggs, larvae, nymphs, males and females). 16S full-length rRNA amplicon sequencing was performed on the PacBio platform. A total of 3,500,187 reads and 487 amplicon sequence variants (ASVs) were identified. The genera Corynebacterium, Serratia and Acinetobacter were present across all life-stages with the opportunistic pathogens Acinetobacter baumannii and Serratia marcescens identified as key constituents of the scabies microbiome. This study provides the first evidence of a stable core microbiota across all life stages of S. scabiei, offering new insights that could improve understanding of mite biology and management of scabies and associated secondary bacterial infections.

Scabies, caused by Sarcoptes scabiei, is a highly prevalent skin disease characterised by severe and persistent pruritus manifesting in over 90% of patients. The limited effectiveness of antihistamines suggests a dominant role for non-histaminergic itch pathways, yet the underlying mechanisms remain poorly defined.Using a porcine scabies model, we localised itch mediators, such as PAR-2, MRGPRX2, tryptase, histamine, IL-31, periostin, NK-1R, β tubulin III and substance P, during infection using immune-histochemistry. Significant upregulation of PAR-2, MRGPRX2, tryptase, histamine, IL-31, periostin, NK-1R and substance P was observed following infection, while β tubulin III expression was reduced. Building on these findings, we aim to investigate keratinocyte-associated receptors (PAR-1, PAR-2, and MRGPRX2) in mediating itch responses to mite stimuli. HaCaT keratinocytes will be treated with whole mite extracts and recombinant proteins (SMIPP-Cc, Sar s 1c), followed by total RNA extraction, cDNA synthesis, and qPCR analysis of target gene expression, normalised to internal control GAPDH expression.These findings support the involvement of both histaminergic and non-histaminergic pathways in scabies itch. The second part of the study is expected to define keratinocyte-specific receptor responses, providing mechanistic insight into non-histaminergic itch signalling and identifying potential therapeutic targets for treatment-resistant and chronic pruritus.