Viral Skin Infections Quiz

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Questions and Answers

What is a prerequisite for a viral skin infection?

Contact with other infected animals

Intact skin barrier

Antropod bite or wound (correct)

Immunization against the virus

Which of the following lesions is classified as neoplastic?

Vesicular lesions from FMD

Ulcers from contagious ecthyma

Pustules from poxvirus

Papilloma (correct)

What is a characteristic of poxviral infections?

Formation of intranuclear inclusion bodies

Thickened dermis with fibrosis

Development of umbilicated pustules (correct)

Presence of flat, raised crusty masses

Which histological feature is associated with poxviral infections?

Multiloculated vesicles Signup and view all the answers

What type of papilloma is specifically mentioned in the context of viral diseases?

Fibropapilloma Signup and view all the answers

What characteristic is observed in the histopathology of contagious ecthyma?

Superficial edema and marked capillary dilatation Signup and view all the answers

What type of lesions are associated with contagious ecthyma?

Vesicles, pustules, and crusts primarily at the feet and oral cavity Signup and view all the answers

What is a notable feature of histopathological findings related to ballooning degeneration?

Intracytoplasmic clear spaces Signup and view all the answers

What type of cells are notably increased in number within the lesions of contagious ecthyma?

Proliferative keratinocytes Signup and view all the answers

What is the typical appearance of lesions during the progression of poxvirus skin lesions?

Sequential phases of vesicles, pustules, and crusts Signup and view all the answers

In the gross examination of contagious pustular dermatitis, what feature is NOT typically observed?

Severe erythema without vesicles Signup and view all the answers

Which histological feature is indicative of infection by certain viruses within keratinocytes?

Intracytoplasmic inclusion bodies Signup and view all the answers

Which histological change is associated with acanthosis in skin lesions?

Increased thickness of the epidermis up to 10x normal Signup and view all the answers

What is a characteristic feature of superficial pyoderma?

Involves the epidermis and usually heals without scarring Signup and view all the answers

Which factor does NOT assist bacteria colonization and invasion of the skin?

Constant desquamation and pressure from normal flora Signup and view all the answers

What type of pyoderma is often chronic and may involve systemic illness?

Deep pyoderma Signup and view all the answers

Which microorganism is commonly associated with impetigo?

Staphylococcus aureus Signup and view all the answers

What clinical appearance can characterize superficial pyoderma?

Erythematous pustules Signup and view all the answers

Which bacterial disease occurs primarily in diseased skin and may involve several bacterial species?

Secondary pyoderma Signup and view all the answers

What usually triggers the formation of vesicles in foot and mouth disease?

Viral infection Signup and view all the answers

What histological feature is associated with superficial pyoderma?

Intraepidermal pustular dermatitis Signup and view all the answers

What is the primary characteristic of canine impetigo?

Formation of pustules and yellow crusty sores Signup and view all the answers

Which of the following is a common cause of canine pyotraumatic dermatitis?

Bacterial infections due to self-trauma Signup and view all the answers

What is the causative agent of 'Diamond Skin Disease' in pigs?

Erysipelothrix rhusiopathiae Signup and view all the answers

What type of dermatitis is characterized by branching filaments and is often seen in hot and humid areas?

Dermatophilosis Signup and view all the answers

What typically predisposes an animal to canine impetigo?

Wet and dirty environments Signup and view all the answers

Which of the following describes the severity of feline acne as it progresses?

Increased pustule formation and inflammation Signup and view all the answers

What kind of infections are caused by Microsporum spp. and Trichophyton spp.?

Superficial mycoses Signup and view all the answers

What is the histological feature associated with sporotrichosis?

Cigar-shaped budding yeast-like organisms Signup and view all the answers

What are the typical clinical manifestations of sporotrichosis?

Single or multiple subcutaneous nodules that ulcerate Signup and view all the answers

What is a common effect of endotoxin-induced venous thrombosis due to Salmonellosis?

Venous infarction of extremities Signup and view all the answers

Which of the following is NOT associated with deep mycoses?

Lichenoid tissue reaction Signup and view all the answers

What type of fungi primarily cause subcutaneous or intermediate mycoses?

Saprophytic fungi Signup and view all the answers

What is observed through the PAS stain in cases of sporotrichosis?

Marked fibrosis around granulomatous infiltrate Signup and view all the answers

What is the primary characteristic appearance of lesions caused by dermatophytosis?

Circular patches of scaling and alopecia Signup and view all the answers

Which of the following factors predisposes animals to dermatophytosis?

Overcrowding and poor sanitation Signup and view all the answers

What is a common cause of alopecia in dermatophytosis?

Breakage of brittle hair Signup and view all the answers

What type of fungi is primarily associated with dermatophytosis?

Microsporum and Trichophyton Signup and view all the answers

What histological feature is associated with the early phase of contact irritant dermatitis in dermatophytosis?

Acanthosis (epidermal hyperplasia) Signup and view all the answers

Where can arthrospores be found in cases of dermatophytosis?

Surrounding the hair shaft Signup and view all the answers

What is the mechanism by which dermatophytes affect hair follicles?

Growing only in keratinized portions, causing a breakage Signup and view all the answers

What can result from secondary bacterial folliculitis due to dermatophytosis?

Permanent destruction of hair roots Signup and view all the answers

Study Notes

Integumentary System: Lecture 5

Viral Diseases of Skin (5.1):
- Intact skin is resistant to viral entry.
- Infection often requires an entry point (e.g., insect bite, wound).
- Viral infections can be local (e.g., papillomas) or systemic (e.g., viremia).
- Viral skin infections include poxviruses, papillomaviruses (causing papillomas), foot-and-mouth disease (FMD), canine distemper, and vesicular exanthema.
- Lesion types include neoplastic (e.g., papilloma), proliferative (e.g., poxvirus), and vesicular (e.g., FMD).
Papilloma Virus:
- Gross: lesions appear flat, raised, crusty, fissured, horny masses, attached to skin via narrow/broad pedicles.
- Histology: shows epidermal and dermal proliferation, marked epidermal thickening (hyperplasia), altered keratin layers, and sometimes inclusion bodies (rarely intracellular/extracellular).
- Types include squamous and fibropapilloma.
Pox Viral Infections:
- Gross: erythematous macules, papules, vesicles, pustules, ulcers, crusts, scars.
- Histology: epidermal cytoplasmic swelling, vacuolation, multiloculated vesicles, dermal edema, vascular dilation, perivascular mononuclear-cell infiltrate, variable neutrophil infiltrate.
- Different stages may show different characteristics: vesicles, pustules, crusts, and sometimes hyperplastic/proliferative lesions.
- Could be colonized by surface bacteria and show intracytoplasmic inclusion bodies.
Contagious Ecthyma:
- AKA Contagious Pustular Dermatitis
- Gross: skin abrasions, transient vesicles, pustules, and brown-gray crusts.
- Histology: marked keratinocyte proliferation (acanthosis), vacuolation/spongiosis, intraepidermal microabscesses, and intracytoplasmic inclusion bodies.
- Dermal changes include superficial edema, marked capillary dilation, and perivascular mononuclear infiltration.
- Lesions are generally located at feet, oral cavity areas, and eyelids.
Foot and Mouth Disease:
- Gross: displays vesicular lesions and erosive lesions on skin and oral mucosa.
- Histo: shows epithelial degeneration and necrosis, particularly affecting the stratum spinosum, inflammation, necrosis, and edema.
Vesicular Exanthema:
- Vesicles appear on snout, oral mucosa, soles of feet, coronary band, and between toes.
Canine Distemper:
- Clinical sign includes scaling/crusts on distal limbs.
Bacterial Diseases of Skin (5.2):
- Normal skin is resistant to bacterial invasion due to dryness, desquamation, and normal flora pressures.
- Damage to the skin barrier allows bacteria from transient or resident flora to cause infection.
- Factors that increase bacterial colonization and invasion include prolonged moisture, altered keratinization, physical damage, parasites, dirt, and excessive sweating.
Pyoderma:
- Secondary skin condition, frequently caused by multiple bacteria species, showing varied skin appearance, including variable clinical signs and ectoparasitism/seborrheic conditions.
- Superficial pyoderma is often epidermis-restricted, not systemic, with a short duration and no scarring.
- Lesions include papules, transient pustules, crusts, intraepidermal or superficial folliculitis.
- Examples include impetigo (Staph. aureus), and dermatophilosis.
Deep Pyoderma:
- Involves deeper skin layers frequently associated with chronic courses, scarring, and systemic illness.
- Lesions include papules, pustules, subcutaneous nodules, abscesses, or ulcers.
- Histological changes may include deep folliculitis, nodular/diffuse suppurative or pyogranulomatous dermatitis.
- Examples include feline leprosy (Mycobacterium lepraemurium) and footrot (Fusobacterium necrophorum).
Canine Impetigo:
- A bacterial skin infection resulting in pustules and yellow crusty sores.
- Predisposed by moisture, abrasions, parasitism, and poor nutrition.
- Clinically manifested as superficial pustular dermatitis.
- Characterized by epidermal ulceration and inflammation, and likely neutrophil infiltration.
Dermatophilosis:
- Superficial exudative dermatitis, often seen in hot, humid climates (ruminants).
Feline Acne:
- Bacterial infection of hair follicles in telogen (resting phase).
- Characteristic lesions include acanthosis, inflammation, pustule formation, and comedo (obstructed follicle).
Canine Pyotraumatic Dermatitis:
- Secondary bacterial infection of self-traumatized skin.
- Characterized by intense pruritus, self-trauma, focal alopecia, excoriation, ulceration, and exudative lesions.
Swine Erysipelas:
- Presents as diamond-shaped erythematous plaques, characteristic of the infection.
Salmonellosis/Endotoxemias:
- Venous infarction of extremities is a common sign, due to endotoxin-induced venous thrombosis.
Mycotic Diseases (5.3):
- Superficial mycoses: growth restricted to keratinized tissue (e.g., dermatophytosis/ringworm).
- Dermatophytosis: the fungus (like _Microsporum spp._and Trichophyton spp.) doesn't invade living tissues, but colonies localized on keratinized skin structures, causing lesions including alopecia, scaling, papules, pustules, and sometimes furunculosis/crusting.
- Deep Mycoses: characterized by the organisms spreading into subcutaneous layers (e.g. Cryptococcus species).
Sporotrichosis:
- A subcutaneous mycosis presenting as skin and cutaneous tissue lesions, forming single/multiple nodules, which ulcerate and discharge thick red-brown exudate. Often heals slowly and deeply.

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Description

Test your knowledge on viral skin infections, including characteristics and histological features of various lesions. This quiz covers topics such as poxviral infections, contagious ecthyma, and neoplastic lesions. Perfect for students and professionals in the field of dermatology and infectious diseases.