Examples of viral, bacterial, and fungal diseases Flashcards
Picornaviruses causing skin lesions
Foot and mouth disease
- cell vacuolation and cell death
Pestiviruses causing skin disease
BVD/MD
- shallow ulcers that extend out from mouth to lips and commisures of mouth
Border disease
- damages hair follicles so hair produced not wool
- ‘Hairy shakers’
- hypertrophy of primary follicles and medullation of wool fibres
Swine fever
- virus replication in vascular endothelium
- generalised petechiation - echymoses
Morbiliviruses causing skin disease
Distemper
- hyperkeratosis of foot pads
+/- sensitivity of nares
Papillomaviruses
non enveloped, grow slowly in vivo in epithelia, mainly skin and other squamous epithelium
species (all domestic animals) and site specific (cutaneous, mucocutaneous or oral) infecting squamous epithelium.
mainly associated with benign proliferative masses
The most common type of cutaneous infection with papillomaviruses results in papilloma, wart or cutaneous papillomatosis
Pathogenesis of papillomavirus infection
Increased cellular activity: mitosis and proliferation
-> hyperplasia and hyperkeratosis (non-productive infeciton)
VIrion production
-> cellular degeneration, cell death (productive infection)
Gross findings in papillomavirus infections
Diverse
Alopecic, flat, or papilliferous tumours
Oral papillomatosis
Microscopic findings in papillomavirus
Epidermal hyperplasia, acanthosis
Epidermal hyperkeratosis
Cellular degeneration
Intranuclear inclusion bodies
Increased proliferation of fibroblasts
Diagnosis of papillomavirus infections
Clinical history (lesions)
Biopsy
PCR
TEM
Oral papillomatosis in dogs
Warts affecting puppy’s mouth not uncommon - cauliflower-like on lips, inside mouth, pharynx.
Spreads readily in kennels > serious inconvenience.
Incubation period 4-8 weeks - only oral mucosa and nearby skin can be infected.
Spontaneous regression occurs after 1-5 months. Recovered dogs are immune.
Cutaneous papillomatosis in dogs
Less common than oral papillomatosis
Tends to be older dogs
Regress very slowly
Not clear if papillomas > squamous carcinoma
Poxviruses than can cause skin disease
Cowpox
Pseudocowpox
Contagious pustular dermetitis (Orf)
Swine pox
Pox viruses
epitheliotropic
Can cause zoonosis and contagious ecthyma
Localised or systemic
May be transmitted via resp tract or via arthropods
Pathogenesis of poxviruses
Occurs in focal areas as macule, papule, vesicle, umbilicated pustule, crust and scar.
Attacks the epidermis mainly - causes balloon degeneration and vacuolation of cells of prickle cell layer.
Followed by dermal oedema, vascular dilation and perivascular lymphocytic and neutrophilic infiltrate.
Histology of poxviruses
Virus masses in cytoplasm show as intracytoplasmic inclusions (eosinophilic).
Protection from poxviruses
Afforded by live attenuated vaccine given by inoculation in scarified skin surface.
Inactivated vaccines give hardly any protection.
Virus generally tough - can live in environment for long periods - > months - > years.
What causes cowpox
An orthopoxvirus
Incidence of cowpox
sporadic
Epidemiology of cowpox
Not clear
Sporadic outbreaks and long gaps between them
Which animals are most affected by cowpox
More important in zoo animals and cats in the UK
Cowpox in domestic cats
generally skin condition.
Focal pustules on legs and head - resolving in about 2 months.
Ulcerated and crusted macule or plaques on face.
Cowpox in cattle
Generally papules and vesicles developing on skin of udder and teats, and on the muzzle of sucking calves.
A thick red crust, 1-2 cm in diameter develops, gradually clear over several weeks.
Cowpox in humans
relatively severe reaction of hands, arms, and face.
Occurs in children with no cow contact.
Histological findings in cowpox
Intracytoplasmic inclusion bodies in keratinocytes or other epithelial cells.
Gross findings of cowpox
Ulcerative dermatitis
