الفهرس 
Historical backgroundOnly 14 pages are availabe for public view
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Abstract
Scabies is a contagious skin infection caused by the penetration of the obligate human parasitic mite S. scabiei var hominis into the epidermis. Scabies remains one of the medicine’s most challenging problems for general practitioners and specialists alike. Scabies is typically described as an intense, intractable, generalized pruritus, worse at night, but occasionally, patients are asymptomatic. A spectrum of diseases are described ranging from the most commonly recognized ordinary scabies with an average infestation of 10–15 mites per person to a rare and severely debilitating form of the disease termed crusted (Norwegian) scabies, characterized by infestation of up to millions of mites and the development of hyperkeratotic skin crusts. Scabies is recognized as T-cell- mediated disease. Both CD4+ and CD8+ T cells are found within scabies lesion. Additionally, scabies mites have been reported to secrete unknown antigens that stimulate the proliferation of T-regulatory cells and their secretion of IL-10 and TGF-β which would inhibit the inflammatory and immune responses in humans to the mites. TGF-β is a multi-potent cytokine that regulates both cell growth and differentiation. TGF-β is a very potent stimulator of chemotaxis. TGF-β stimulates migration of monocytes, lymphocytes, neutrophils and fibroblasts. TGF-β, in particular, suppresses the function of inflammatory Th1 lymphocytes.
The aim of this work was to detect scabies infection in Menoufia Governorate by different diagnostic methods and determination of the cellular immune response associated with S. scabiei infection and comparing it with other dermatological diseases.
This study included fifty-seven persons. Thirty-five scabietic patients, fourteen non-scabietic patients, with other dermatological manifestations e.g. [eight Lichen planus patients and six Psoriasis patients] and eight normal persons with no apparent skin disease (control).
All individuals were subjected to detailed history taking and dermatological examination. There were 35 scabietic patients; 13 (37.1%) males and 22 (62.9%) females with male: female ratio 1:1.7. Their ages ranged from 12-60 years with a mean ± SD of 36.4±13.5 years. There was no statistically significant difference between different studied groups as regarding age and sex (P. value > 0.05).
The duration of itching ranged from 4-60 days with a mean ± SD of 24.5±16.2 days. It was noticed that; there were 2 (5.7%) patients with lymphadenopathy, 7(20%) patients with secondary infection and 6 (17.1%) patients with both lymphadenopathy and pyoderma. As regarding presence or absence of predisposing factors, there were 20 (58.2%) patients having different predisposing factors and 15(41.8%) patients with no predisposing factors. The most common reported associated disease was diabetes mellitus (22.9%) followed by hypertension (17.1%), hepatitis (14.2%), rheumatoid (11.4%) and 2.9% for malignancy. There was no statistically significant difference between different studied groups as regarding different predisposing factors (P. value > 0.05).
Skin scraping and microscopic examination were done to confirm the clinical diagnosis of scabies. It was found that only 20% of cases were having parasites in their skin and 80% were free. The sensitivity of skin
scraping was 23%, the mean accuracy was 30% and the specificity was 100% by definition.
Formalin fixed, paraffin embedded skin biopsy sections from all studied groups were used in this study. Histopathological examination with H&E stain was done to diagnose scabies. The sensitivity of histopathological examination was significantly higher than that of skin scraping. The sensitivity of histopathological examination was 88%, the specificity was 100% and the mean accuracy was 91%.
This study showed that, scabies was most marked histologically and significantly by hypergranulosis, spongiosis, epidermal tunnels (burrows) and perivascular dermal infiltrate. However, LP showed more hypergranulosis, irregular elongation of rete ridges and band like dermal infiltrate. Whereas, psoriasis was marked by parakeratosis, Munro micro abscess, regular elongation of rete ridges (Saw toothed appearance) and perivascular dermal infiltrate.
In the present study, immunohistochemical staining for CD4+, CD8+ T cells and TGF-β using mouse anti- CD4+, anti- CD8+ and anti- TGF-β monoclonal antibodies was done.
Skin biopsy sections from scabies lesions showed large numbers of infiltrating lymphocytes, the lymphocytic infiltrate contained predominately CD4+ T cells, the CD4+ count ranged between (40-100/10 HPF) with a mean of (54.9±16.4/10 HPF). The CD8+ count ranged from (6-20/10 HPF) with a mean of (10.7±3.1/10 HPF) with CD4+\CD8+ ratio ranged from (3.64-7.08) with a mean of (5.2±1.01). There was mild staining of TGF-β secreting T cells.
There was no statistically significant difference between the immune response and gender (P. value > 0.05).
There was statistically significant negative correlation between CD4+ count and duration of itching (P. value < 0.05) and TGF-β expression and duration of itching (P. value ≤ 0.001) in scabietic patients
There was statistically significant positive correlation between CD4+, CD8+ and TGF-β expression and skin scraping in scabietic patients (P. value < 0.05).
In contrast, in psoriasis, skin biopsy sections from lesions showed that; the lymphocytic infiltrate contained predominately CD8+ T cells. The CD8+ count ranged from (45-100/10 HPF) with a mean of (67.5±18.4/10 HPF). The CD4+count ranged from 15-30/10 HPF with a mean of (21.7±6.1/10 HPF) with CD4+ \ CD8+ ratio ranged from (0.25-0.42) with a mean of (0.3±0.06). There was strong staining of TGF-β secreting cells.
In addition, skin biopsy sections from LP lesions showed that, the lymphocytic infiltrate contained predominately CD4+ T cells. The CD4+ count ranged from 50-80/10 HPF in non-treated cases and in treated cases, the count ranged from 25-35/10 HPF. The CD8+ count ranged from 10-25/10 HPF with a mean of 16.5±5.6/10 HPF. The CD4+\CD8+ ratio in LP lesions was 3.2±0.8. There was strong staining of TGF-β secreting T cells in LP.
This study revealed that there were different methods to diagnose scabies: clinical diagnosis based on symptoms and signs, skin scraping, microscopic examination, and histopathological examination. The previous data showed that the histopathological examination is the confirmatory test with specificity up to 100%, sensitivity of 88% and accuracy of 91% when compared with clinical diagnosis however; being an invasive procedure, it cannot be used as a conventional method of diagnosis.
The number of CD4+ cells/10 HPF was statistically significantly higher in scabietic than non- scabietic patients (P. value < 0.05). However, CD8+ cells/10 HPF were statistically significantly lower in scabietic patients (P. value ≤ 0.001). CD4+/CD8+ ratio was significantly higher in scabietic patients (P. value ≤ 0.001).
TGF-β expression was significantly lower in scabietic than non-scabietic patients (P. value ≤ 0.001.