A case of hyperkeratotic crusted scabies.

Patients who are immunocompromised or have cognitive or physical disabilities are at a higher risk of being affected with infections such as crusted scabies. This is a rare skin hyperinfestation by Sarcoptes scabiei var. hominis. The main characteristic of this dermatosis is a thick crust due to the high concentration of mites; in addition, other manifestations such as papules, excoriations, and burrows may be absent. In severe cases, thick yellow-brown crusts and plaques with deep fissures are present. Diagnosis can be made by observing mites, ova, or feces from skin scrapings. Multiple therapies can be used in patients with this condition. Management with patient isolation is important to prevent institutional outbreaks. This disease can have high mortality, primarily due to sepsis. Awareness of this condition and its serious consequences is important to reduce its mortality and morbidity.

Comparative analysis of host resistance to Sarcoptes scabiei var. cuniculi in two different rabbit breeds.

BACKGROUND: Scabies, caused by infestation of the mite Sarcoptes scabiei, is one of the most severe ectoparasitic diseases in rabbits. Scabies seriously affects the commercial rabbit breeding, causing severe economic losses. Host resistance to S. scabiei is an important factor in further development of the rabbit industry. In the present study, we compared the host resistance to S. scabiei var. cuniculi of a new breed of domestic rabbit propagated by the Sichuan Animal Sciences Academy (QiXing rabbit, QX) compared with that of a traditional rabbit breed in the domestic rabbit industry (IRA rabbit, IRA). METHODS: Both QX and IRA rabbits were experimentally infested with live S. scabiei var. cuniculi mites for 48 h. Then, during the course of four-week experimental infestation period, the body weight of rabbits was recorded every two weeks for calculating body-weight variations in comparison to the non-infested control rabbits. Skin lesions in the foot area were assessed on weekly basis and serum samples were tested weekly for the estimation of changes in the total antibody levels (IgG, IgE and IgM). Moreover, DNA extracted from the blood samples was amplified for analysis of the genetic diversity in the major histocompatibility complex, class II, DQ Alpha (MHC-DQA) gene. RESULTS: Compared to the IRA rabbits, the QX rabbits showed a significantly higher (P < 0.05) relative body weight gain compared to the non-infested control rabbits and significantly lower (P < 0.05) scores for foot skin lesions and higher levels of IgG, IgE and IgM at weeks 1 to 4, week 2 and week 1 post-infestation, respectively. Furthermore, a polymorphism site at position 103 bp of exon two of MHC-DQA gene and a different gene frequency were found between two rabbit breeds, suggesting the genetic basis for the differential host resistance to the S. scabiei var. cuniculi between two rabbit breeds. CONCLUSIONS: The QX rabbits showed higher host resistance to S. scabiei var. cuniculi compared to the IRA rabbits at the clinical, immunological and genetic levels. These results provide a reference for the breeding of rabbits with adequately improved and sustained host resistance to scabies in the domestic rabbit industry.

Effects of temperature on the survival of Sarcoptes scabiei of black bear (Ursus americanus) origin.

For two decades, the incidence and range of sarcoptic mange in black bears (Ursus americanus) in Pennsylvania has increased. The causative agent, Sarcoptes scabiei, can be directly or indirectly transmitted; therefore, data on environmental persistence is important for guiding management and public communications. The objective of this study was to determine the survival of S. scabiei at different temperatures. Full section skin samples and superficial skin scrapes were collected from bears immediately after euthanasia due to severe mange. After ~ 24 h on ice packs (shipment to lab), samples were placed in dishes at 0, 4, 18, or 30 °C and 60, 20, 12, and 25% relative humidity, respectively, and the percentage of mites alive, by life stage, was periodically determined. Humidity was recorded but not controlled. Temperature significantly affected mite survival, which was shortest at 0 °C (mostly ≤ 4 h) and longest at 4 °C (up to 13 days). No mites survived beyond 8 days at 18 °C or 6 days at 30 °C. Mites from full-thickness skin sections survived significantly longer than those from superficial skin scrapes. Adults typically survived longer than nymphs and larvae except at 30 °C where adults survived the shortest time. These data indicate that at cooler temperatures, S. scabiei can survive for days to over a week in the environment, especially if on host skin. However, these data also indicate that the environment is unlikely to be a long-term source of S. scabiei infection to bears, other wildlife, or domestic animals.

A systematic review of scabies transmission models and data to evaluate the cost-effectiveness of scabies interventions.

BACKGROUND: Scabies is a common dermatological condition, affecting more than 130 million people at any time. To evaluate and/or predict the effectiveness and cost-effectiveness of scabies interventions, disease transmission modelling can be used. OBJECTIVE: To review published scabies models and data to inform the design of a comprehensive scabies transmission modelling framework to evaluate the cost-effectiveness of scabies interventions. METHODS: Systematic literature search in PubMed, Medline, Embase, CINAHL, and the Cochrane Library identified scabies studies published since the year 2000. Selected papers included modelling studies and studies on the life cycle of scabies mites, patient quality of life and resource use. Reference lists of reviews were used to identify any papers missed through the search strategy. Strengths and limitations of identified scabies models were evaluated and used to design a modelling framework. Potential model inputs were identified and discussed. FINDINGS: Four scabies models were published: a Markov decision tree, two compartmental models, and an agent-based, network-dependent Monte Carlo model. None of the models specifically addressed crusted scabies, which is associated with high morbidity, mortality, and increased transmission. There is a lack of reliable, comprehensive information about scabies biology and the impact this disease has on patients and society. DISCUSSION: Clinicians and health economists working in the field of scabies are encouraged to use the current review to inform disease transmission modelling and economic evaluations on interventions against scabies.

Molecular characterization and allergenicity potential of triosephosphate isomerase from Sarcoptes scabiei.

Scabies is an allergic skin disease that affects millions of mammals worldwide, including humans. It is a neglected tropical disease that represents a significant public health threat, particularly in economically disadvantaged populations. An effective vaccine is not currently available, and the exact mode of pathogenesis remains unclear. Herein, we identified, cloned and recombinantly expressed triosephosphate isomerase from Sarcoptes scabiei (S. scabiei). Immunohistochemical analyses showed that S. scabiei triosephosphate isomerase (Ss-TIM) is localized in the legs and chewing mouthparts of mites, and in infected rabbit skin (keratinized skin and embedded mites). Intradermal skin tests of rabbits injected with recombinant S. scabiei triosephosphate isomerase (rSs-TIM) revealed a flare, erythema and wheal reaction. These findings suggest that Ss-TIM may contribute to host invasion and induce an allergic response in the host.

Efficacy of afoxolaner in a clinical field study in dogs naturally infested with Sarcoptes scabiei.

The acaricidal efficacy of afoxolaner (NexGard(®), Merial) was evaluated against Sarcoptes scabiei var. canis in a field efficacy study, when administered orally at a minimum dose of 2.5 mg/kg to dogs naturally infested with the mites. Twenty mixed-breed dogs of either sex (6 males and 14 females), aged over 6 months and weighing 4-18 kg, were studied in this randomised controlled field efficacy trial. Dogs, naturally infested with Sarcoptes scabiei var. canis confirmed by skin scrapings collected prior to allocation, were randomly divided into two equal groups. Dogs in Group 1 were not treated. Dogs in Group 2 were treated on Days 0 and 28. On Days 0 (pre-treatment), 28 (pre-treatment) and 56, five skin scrapings of similar size were taken from different sites with lesions suggestive of sarcoptic mange. The extent of lesions was also recorded on Days 0, 28 and 56, and photographs were taken. Dogs treated orally with afoxolaner had significantly (p < 0.001) lower mite counts than untreated control animals at Days 28 and 56 with no mites recovered from treated dogs at these times (100% efficacy based on mite counts). In addition, dogs treated with NexGard had significantly (p < 0.05) better lesion resolution at Day 56 than Day 0; no treated dog showed pruritus compared to 7/10 dogs in the control group, 1/9 treated dogs had crusts compared to 5/10 controls and 8/9 dogs recovered 90% of hairs on lesions compared to 0/10 control dogs.

[A baby with an unexplained skin rash]. / Een zuigeling met een onbegrepen huiduitslag.

A 2-month-old infant presented with papules and pustules. Since the patient's mother and brother also had an unexplained--itchy--skin rash, it was thought that the skin rash was due to scabies. This diagnosis was confirmed by dermatoscopy and direct microscopic examination.

Epidemiological and therapeutic studies of camel mange in Fafan zone, Eastern Ethiopia.

BACKGROUND: Camel mange is an economically important parasitic disease affecting productivity in camel rearing areas of the world if appropriate treatment is not instituted. METHODS: A cross-sectional and a controlled field trial were carried out to study the epidemiology of camel mange in Fafan zone, Eastern Ethiopia, and evaluate the efficacy of ivermectin and diazinon in the control of mange infestation in camels on the basis of clinical and parasitological evidence, respectively. Three groups of naturally infested camels and one group of healthy camels each composed of 6 individuals were enrolled: the two infested groups received either ivermectin or diazinon, and the other groups remained untreated. RESULTS: The overall prevalence rate of mange in camels in the study area was 31.5% and the only identified species was Sarcoptes scabiei. The prevalence rate was found to significantly vary (p < 0.05) in relation to body condition and herd size of camels. Both drugs showed significant variation (p < 0.05) on improving clinical and body condition scores. Clearance of mange lesions occurred with both drugs; however, re-infestation was observed in diazinon treated group. Ivermectin significantly improved (p < 0.05) both body condition and clinical scores whereas diazinon markedly improved only the later. CONCLUSION: In conclusion, camels in the study area harbored considerable level of S. scabiei which warrants institution of an integrated control approach by administration of ivermectin while also sanitating the animal environment.

Sex-biased severity of sarcoptic mange at the same biological cost in a sexually dimorphic ungulate.

BACKGROUND: In sexually dimorphic species, male susceptibility to parasite infection and mortality is frequently higher than in females. The Iberian ibex (Capra pyrenaica) is a sexually dimorphic mountain ungulate endemic to the Iberian Peninsula commonly affected by sarcoptic mange, a chronic catabolic skin disease caused by Sarcoptes scabiei. Since 1992, sarcoptic mange affects the Iberian ibex population of the Sierra Nevada Natural Space (SNNS). This study aims at exploring whether mange severity, in terms of prevalence and its effects on body condition, is male-biased in Iberian ibex. FINDINGS: One thousand and seventy-one adult Iberian ibexes (439 females and 632 males) were randomly shot-harvested in the SNNS from May 1995 to February 2008. Sarcoptic mange stage was classified as healthy, mildly infected or severely infected. Sex-biased prevalence of severe mange was evaluated by a Chi-square test whereas the interaction between mange severity and sex on body condition was assessed by additive models. Among scabietic individuals, the prevalence of severely affected males was 1.29 times higher than in females. On the other hand, both sexes were not able to take profit of a higher availability of seasonal food resources when sarcoptic, particularly in the severe stages. CONCLUSIONS: Sarcoptic mange severity is male-biased in Iberian ibex, though not mange effects on body condition. Behavioural, immunological and physiological characteristics of males may contribute to this partial sex-biased susceptibility to sarcoptic mange.

Sarcoptic mange breaks up bottom-up regulation of body condition in a large herbivore population.

BACKGROUND: Both parasitic load and resource availability can impact individual fitness, yet little is known about the interplay between these parameters in shaping body condition, a key determinant of fitness in wild mammals inhabiting seasonal environments. METHODS: Using partial least square regressions (PLSR), we explored how temporal variation in climatic conditions, vegetation dynamics and sarcoptic mange (Sarcoptes scabiei) severity impacted body condition of 473 Iberian ibexes (Capra pyrenaica) harvested between 1995 and 2008 in the highly seasonal Alpine ecosystem of Sierra Nevada Natural Space (SNNS), southern Spain. RESULTS: Bottom-up regulation was found to only occur in healthy ibexes; the condition of infected ibexes was independent of primary productivity and snow cover. No link between ibex abundance and ibex body condition could be established when only considering infected individuals. CONCLUSIONS: The pernicious effects of mange on Iberian ibexes overcome the benefits of favorable environmental conditions. Even though the increase in primary production exerts a positive effect on the body condition of healthy ibexes, the scabietic individuals do not derive any advantage from increased resource availability. Further applied research coupled with continuous sanitary surveillance are needed to address remaining knowledge gaps associated with the transmission dynamics and management of sarcoptic mange in free-living populations.

First detection of Sarcoptes scabiei from domesticated pig (Sus scrofa) and genetic characterization of S. scabiei from pet, farm and wild hosts in Israel.

In this report we describe for the first time the detection of Sarcoptes scabiei type suis mites on domestic pigs in Israel and examine its genetic variation compared with S. sabiei from other hosts. Microscopic examination of skin samples from S. scabiei-infested pigs (Sus scrofa domesticus) revealed all developmental stages of S. scabiei. To detect genetic differences between S. scabiei from different hosts, samples obtained from pig, rabbits (Orictolagus cuniculus), fox (Vulpes vulpes), jackal (Canis aureus) and hedgehog (Erinaceus concolor) were compared with GenBank-annotated sequences of three genetic markers. Segments from the following genes were examined: cytochrome C oxidase subunit 1 (COX1), glutathione-S-transferase 1 (GST1), and voltage-sensitive sodium channel (VSSC). COX1 analysis did not show correlation between host preference and genetic identity. However, GST1 and VSSC had a higher percentage of identical sites within S. scabiei type suis sequences, compared with samples from other hosts. Taking into account the limited numbers of GST1 and VSSC sequences available for comparison, this high similarity between sequences of geographically-distant, but host-related populations, may suggest that different host preference is at least partially correlated with genetic differences. This finding may help in future studies of the factors that drive host preferences in this parasite.

A novel clinical grading scale to guide the management of crusted scabies.

BACKGROUND: Crusted scabies, or hyperinfestation with Sarcoptes scabiei, occurs in people with an inadequate immune response to the mite. In recent decades, data have emerged suggesting that treatment of crusted scabies with oral ivermectin combined with topical agents leads to lower mortality, but there are no generally accepted tools for describing disease severity. Here, we describe a clinical grading scale for crusted scabies and its utility in real world practice. METHODOLOGY/PRINCIPAL FINDINGS: In 2002, Royal Darwin Hospital (RDH), a hospital in tropical Australia developed and began using a clinical grading scale to guide the treatment of crusted scabies. We conducted a retrospective observational study including all episodes of admission to RDH for crusted scabies during the period October 2002-December 2010 inclusive. Patients who were managed according to the grading scale were compared with those in whom the scale was not used at the time of admission but was calculated retrospectively. There were 49 admissions in 30 patients during the study period, of which 49 (100%) were in Indigenous Australians, 29 (59%) were male and the median age was 44.1 years. According to the grading scale, 8 (16%) episodes were mild, 24 (49%) were moderate, and 17 (35%) were severe. Readmission within the study period was significantly more likely with increasing disease severity, with an odds ratio (95% CI) of 12.8 (1.3-130) for severe disease compared with mild. The patients managed according to the grading scale (29 episodes) did not differ from those who were not (20 episodes), but they received fewer doses of ivermectin and had a shorter length of stay (11 vs. 16 days, p = 0.02). Despite this the outcomes were no different, with no deaths in either group and a similar readmission rate. CONCLUSIONS/SIGNIFICANCE: Our grading scale is a useful tool for the assessment and management of crusted scabies.

Treatment of scabies: Comparison of permethrin 5% versus ivermectin.

Scabies is an ectoparasitic, highly contagious skin disease caused by a mite called Sarcoptes scabiei. The insecticides ivermectin and permethrin are commonly used for treatment of scabies. This study aimed at comparing the efficacy of oral ivermectin with topical permethrin in treating scabies. Two hundred and forty-two patients with scabies attending the dermatology outpatient department of Sina Hospital, Tabriz University of Medical Sciences were admitted. Patients were divided into two groups randomly. The first group and their family contacts received 5% permethrin cream and the other received oral ivermectin. Treatment was evaluated at intervals of 2 and 4 weeks. A single dose of ivermectin provided a cure rate of 85.9% at a 2-week interval, which increased to 100% after crossing over to the permethrin group at a 4-week interval. Twice application of permethrin with a 1-week interval was effective in 92.5% of patients, which increased to 94.2% after crossing over to the ivermectin group at a 4-week interval. Permethrin-treated patients recovered earlier. Twice application of permethrin with a 1-week interval is superior to a single dose of ivermectin. The temporal dissociation in clinical response suggests that ivermectin may not be effective against all the stages in the life cycle of the parasite.

Scabies: a review of diagnosis and management based on mite biology.

Scabies is a contagious parasitic dermatitis that is a significant cause of morbidity, especially outside of the United States. Scabies is diagnosed most often by correlating clinical suspicion with the identification of a burrow. Although scabies should be on the differential for any patient who presents with a pruritic dermatosis, clinicians must consider a wide range of diagnostic possibilities. This approach will help make scabies simultaneously less over- and underdiagnosed by clinicians in the community. Atypical or otherwise complex presentations may necessitate the use of more definitive diagnostic modalities, such as microscopic examination of KOH prepared skin scrapings, high-resolution digital photography, dermoscopy, or biopsy. Scabies therapy involves making the correct diagnosis, recognizing the correct clinical context to guide treatment of contacts and fomites, choosing the most effective medication, understanding how to use the agent properly, and following a rational basis for when to use and reuse that agent. Although the development of new therapeutic agents is always welcome, tried and true treatments are still effective today. Permethrin is the gold standard therapy, with malathion being an excellent topical alternative. Ivermectin is an effective oral alternative that is especially useful in crusted scabies, patients who are bed ridden, and in institutional outbreaks. Despite the availability of effective therapeutics, treatment failures still occur, mostly secondary to application error (ie, failure to treat the face and scalp or close contacts, failure to reapply medication) or failure to decontaminate fomites. Because increasing resistance to scabies treatments may be on the horizon, we propose that standard of care for scabies treatment should involve routine treatment of the scalp and face and re-treating patients at day 4 on the basis of the scabies life cycle to ensure more efficient mite eradication. Practitioners should attempt to treat all close contacts simultaneously with the source patient. To eradicate mites, all fomites should be placed in a dryer for 10 minutes on a high setting, furniture and carpets vacuumed, and nonlaunderables isolated for a minimum of 2 days, or, for those who wish to be rigorous, 3 weeks.

Circulating oxidative stress status in dromedary camels infested with sarcoptic mange.

Oxidative stress is an imbalance between radical-generating and radical-scavenging activity, resulting in oxidation products and tissue damage. This study was aimed to evaluate the status of oxidative stress indices in blood of camels naturally infested with S. scabiei. Forty-seven male camels (Camelus dromedaries) were divided according to the extent of the infested area with Sarcoptes scabiei into four groups, mild (MID, n = 12), moderate (MOD, n = 10), severely infested (SEV, n = 10) and healthy control group (n = 15). Blood was used for determination of red cell count (RBC), hemoglobin (Hb), packed cell volume (PCV), serum nitric oxide (NO(•), a free radical), ascorbate and albumin concentrations, and erythrocytic values of malondialdehyde (MDA, a marker of lipid peroxidation), protein carbonyls (PC, an indicator of protein oxidation), glutathione (GSH) superoxide dismutase (SOD) and catalase (CAT). Decreased levels (P < 0.05) of RBC, Hb, PCV, albumin and ascorbate were noticed in MOD and SEV compared to controls with the lowest values (P < 0.05) in SEV except for ascorbate, where MOD did not differ from SEV. Compared to controls, NO(•) gradually increased (P < 0.05) in MID followed by MOD and SEV, whereas MDA and PC were higher (P < 0.05) in MOD and SEV. PC was higher (P < 0.05) in MOD than SEV. In addition, the antioxidants GSH, SOD and CAT were higher (P < 0.05) in MID and lower (P < 0.05) in MOD and SEV compared to controls. GSH was lower (P < 0.05) in SEV compared to MOD. Besides, Hb was negatively correlated with NO(•) (r = -0.68, P < 0.001), MDA (r = -0.53, P < 0.001) and PC (r = -0.73, P < 0.001). In conclusion, dromedary sarcoptosis is accompanied by a state of oxidative stress process, which increased by increasing the area of infestation, and may contribute to the pathogenesis of the disease.