Identification of antigenic Sarcoptes scabiei proteins for use in a diagnostic test and of non-antigenic proteins that may be immunomodulatory

Prevalence, hematological, serum biochemical, histopathology, and molecular characterization of Sarcoptes scabiei in naturally infected rabbits from Minoufiya Governorate, Egypt

Sarcoptic mange is a highly contagious ectoparasitic disease that causes significant economic losses in the rabbit industry. The current study intended to reveal the infection rate, histopathology, and genetic characterization of Sarcoptes scabiei (S. scabiei) in naturally infected rabbits in Minoufiya governorate, Egypt. A total of 1120 rabbits were physically inspected for sarcoptic mange lesions and infections were confirmed microscopically. In addition, the various hematologic and serum biochemical parameters in naturally infected and non-infected rabbits were evaluated. A histopathological examination was performed. Genomic DNA was isolated from skin scraping samples and amplified using PCR primers targeting the ITS-2 region and Cox1 and Actin genes, which were then sequenced and phylogenetically analyzed. The overall prevalence of S. scabiei was 5.98%. Although the infection was higher in females than males, the analysis showed no statistically significant difference. White blood cells, lymphocytes, liver enzymes (GOT and GPT), urea, total antioxidant capacity, glutathione peroxidase, and malondialdehyde dramatically increased whereas RBCs, Hb, and MCV significantly decreased. There were epidermal thickening and hyperkeratosis, inflammation, and homogenous faint pink edematous lesions, and the S. scabiei was attached to the stratum corneum and/or burrowing through it, causing tunnels. PCR and sequence analysis of the ITS-2 region and Cox1 and Actin genes showed that the sequences in the present study were highly identical to the homologous sequences from several countries and confirmed that the mite was S. scabiei. This study presented the first molecular characterization of S. scabiei in rabbits from Minoufiya Governorate, Egypt.

Standardization of Epidemiological Surveillance of Group A Streptococcal Impetigo

Impetigo is a highly contagious bacterial infection of the superficial layer of skin. Impetigo is caused by group A Streptococcus (Strep A) and Staphylococcus aureus, alone or in combination, with the former predominating in many tropical climates. Strep A impetigo occurs mainly in early childhood, and the burden varies worldwide. It is an acute, self-limited disease, but many children experience frequent recurrences that make it a chronic illness in some endemic settings. We present a standardized surveillance protocol including case definitions for impetigo including both active (purulent, crusted) and resolving (flat, dry) phases and discuss the current tests used to detect Strep A among persons with impetigo. Case classifications that can be applied are detailed, including differentiating between incident (new) and prevalent (existing) cases of Strep A impetigo. The type of surveillance methodology depends on the burden of impetigo in the community. Active surveillance and laboratory confirmation is the preferred method for case detection, particularly in endemic settings. Participant eligibility, surveillance population and additional considerations for surveillance of impetigo, including examination of lesions, use of photographs to document lesions, and staff training requirements (including cultural awareness), are addressed. Finally, the core elements of case report forms for impetigo are presented and guidance for recording the course and severity of impetigo provided.

Development of a rapid scabies immunodiagnostic assay based on transcriptomic analysis of Sarcoptes scabiei var. nyctereutis

Scabies is a highly contagious skin disease caused by the mite Sarcoptes scabiei that affects many mammals. However, the sensitivity of traditional tests for scabies diagnosis in humans is less than 50%. To simplify the diagnosis of scabies, methods that are simple, sensitive, specific, and cost-effective are required. We developed an immunodiagnostic test based on S. scabiei var. nyctereutis RNA-seq data collected from Japanese raccoon dogs with sarcoptic mange. Three candidate antigens-a highly expressed hypothetical protein "QR98_0091190," another mite allergen known as "SMIPP-Cc," and an abundant "vitellogenin-like protein"-were evaluated by western-blot analysis. A lateral flow immunoassay, using specific antibodies against the vitellogenin-like protein, successfully detected scabies in the skin flakes of S. scabiei-infected raccoon dogs. This assay can potentially diagnose scabies more accurately in wildlife, as well as in humans.

Itch in Scabies-What Do We Know?

Scabies is a common parasitic skin infestation characterized by severe itch and a heterogenous clinical presentation. Itch, as the cardinal symptom of scabies, is imposing a high burden on affected patients and is often difficult to manage. Decreased life quality and secondary complications, caused by an itch-related disruption of the epidermal barrier and subsequent superinfections, illustrate the need to treat scabies and to understand the underlying mechanisms of itch in respective patients. This review summarizes available data on itch in scabies with a special focus on the clinical aspects and its underlying pathomechanisms.

Scabies involving palms in older children and adults: a changing scenario

Scabies is a highly contagious, intensely pruritic skin infestation caused by Sarcoptes scabiei var hominis. It has high prevalence in many tropical countries where crowded people live in resource-poor settings. The rash is distributed differently in adults and children. Adults manifest lesions primarily on the interdigital web spaces of the hands, flexor aspects of the wrists, dorsal feet, axillae, elbows, waist, buttocks, and genitalia. Palms (along with soles and head) are commonly involved in infants and very young children but typically absent in older age groups. Here, we report 25 older children and adult patients with scabies including involvement of the palms. If patients are left untreated for long periods of time in hot tropical climates, scabies may produce severe infestation with involvement of palms in older children and adults. We should acknowledge palms as potential body sites whose involvement warrants early and aggressive treatment in scabies.

The 2020 International Alliance for the Control of Scabies Consensus Criteria for the Diagnosis of Scabies

BACKGROUND

Scabies is a common parasitic skin condition that causes considerable morbidity globally. Clinical and epidemiological research for scabies has been limited by a lack of standardization of diagnostic methods.

OBJECTIVES

To develop consensus criteria for the diagnosis of common scabies that could be implemented in a variety of settings.

METHODS

Consensus diagnostic criteria were developed through a Delphi study with international experts. Detailed recommendations were collected from the expert panel to define the criteria features and guide their implementation. These comments were then combined with a comprehensive review of the available literature and the opinion of an expanded group of international experts to develop detailed, evidence-based definitions and diagnostic methods.

RESULTS

The 2020 International Alliance for the Control of Scabies (IACS) Consensus Criteria for the Diagnosis of Scabies include three levels of diagnostic certainty and eight subcategories. Confirmed scabies (level A) requires direct visualization of the mite or its products. Clinical scabies (level B) and suspected scabies (level C) rely on clinical assessment of signs and symptoms. Evidence-based, consensus methods for microscopy, visualization and clinical symptoms and signs were developed, along with a media library.

CONCLUSIONS

The 2020 IACS Criteria represent a pragmatic yet robust set of diagnostic features and methods. The criteria may be implemented in a range of research, public health and clinical settings by selecting the appropriate diagnostic levels and subcategories. These criteria may provide greater consistency and standardization for scabies diagnosis. Validation studies, development of training materials and development of survey methods are now required. What is already known about this topic? The diagnosis of scabies is limited by the lack of accurate, objective tests. Microscopy of skin scrapings can confirm the diagnosis, but it is insensitive, invasive and often impractical. Diagnosis usually relies on clinical assessment, although visualization using dermoscopy is becoming increasingly common. These diagnostic methods have not been standardized, hampering the interpretation of findings from clinical research and epidemiological surveys, and the development of scabies control strategies. What does this study add? International consensus diagnostic criteria for common scabies were developed through a Delphi study with global experts. The 2020 International Alliance for the Control of Scabies (IACS) Criteria categorize diagnosis at three levels of diagnostic certainty (confirmed, clinical and suspected scabies) and eight subcategories, and can be adapted to a range of research and public health settings. Detailed definitions and figures are included to aid training and implementation. The 2020 IACS Criteria may facilitate the standardization of scabies diagnosis.

Serodiagnostic Potential of Alpha-Enolase From Sarcoptes scabiei and Its Possible Role in Host-Mite Interactions

Infestation of the epidermis with the highly contagious ectoparasite, Sarcoptes scabiei, causes scabies, which is characterized by intense itching, pruritus, and secondary infection. This condition affects humans, livestock, and wildlife worldwide, incurring large economic losses and reducing the quality of human life. In the present study, we cloned the alpha-enolase, a key enzyme in the glycolytic and gluconeogenesis pathways, from S. scabiei var. cuniculi, characterized it and produced soluble recombinant enolase protein (rSsc-eno). We determined the localization of Ssc-eno in isolated mites and mites in lesioned skin. The results showed that native enolase was intensely localized in the tegument of the mouthparts, the entire legs, and the whole mites' body, as well as in the gut and reproduction system. Interestingly, we found that native enolase was widely distributed in mites in lesioned skin, with obvious high protein intensity compared with isolated mites. Building on good immunoreactivity, an indirect enzyme-linked immunosorbent assay (ELISA) based on rSsc-eno showed 92% sensitivity and 95.8% specificity, compared with other indirect ELISA in this study, rSsc-eno based ELISA is better in detecting scabies in rabbits. Besides, this method can detect S. scabiei infection as early as 1 week post infection. Compared with other detection methods, such as traditional microscopic examination and recently published universal conventional PCR, rSsc-eno ELISA was more effective to detect early infection in rabbits. Additionally, in vitro incubation experiments demonstrated the concentration-dependent acaricidal activity of rabbit anti-rSsc-eno sera against larval mites, suggested its potential as a vaccine candidate.

MOLECULAR IDENTIFICATION OF SARCOPTES SCABIEI VAR. CUNICULI FROM SURABAYA AND MALANG REGIONS OF EAST JAVA

Scabies is a zoonotic skin disease caused by Sarcoptes scabiei mites. As an emerging/re-emerging parasitic disease, scabies represents a significant global threat to both human and animal health. Numerous cases of scabies in Indonesia have been reported, which support research on the prevalence of S. scabiei. However, most such studies have involved conventional morphological studies, with limited molecular diagnostic studies. The purpose of the present study was the genetic characterization of S. scabiei var. cuniculi in domestic rabbits to generate baseline genotypic data. S. scabiei var. cuniculi was isolated and identified from scabies-infected rabbits from the Surabaya and Malang regions of East Java. Molecular identification was performed using Polymerase Chain Reaction (PCR) using specific primers targeting the COX1 gene. We performed COX1 PCR using rabbit isolates of S. scabiei from Indonesia. To the best of our knowledge, no such study had been reported previously. This study was performed in the Laboratory of Veterinary Parasitology, Faculty of Veterinary Medicine and the Tropical Disease Diagnostic Center Laboratory, Universitas Airlangga. The results with agarose gel electrophoresis revealed a 289 bp PCR product amplified from the DNA of S. scabiei isolates from both Surabaya and Malang in accordance with the expected COX1 amplicon size, that indicated a single band 289 bp in length, demonstrating specific detection of S. scabiei var. cuniculi from Surabaya and Malang using COX1 primers. The results were consistent with the calculated amplicon size based on primer positions within the COX1 locus, with the forward primer spanning nucleotides 61–94, and the reverse primer spanning nucleotides 331–350 ( 350 − 61 = 289 bp).  PCR genotyping of the isolates yielded an identical nucleotide length of 289 bp. Further studies are required to sequence the amplified fragments for homology assessment.