Family: Poxviridae Flashcards
Transmission of Cowpox
From cow to cow in a herd it is transmitted through infected milker’s hands or teat cups
From infect farm cats
Rodents are the reservoir and can transmit the disease
Clinical Findings of Cowpox
Papules appear on the teats and udder
Sucking calves may develop lesions in the mouth
Vesicles may not be evident or may rupture readily, leaving raw, ulcerated areas that form scabs
Cowpox Transmission in Cats
Inoculation - through a bite or skin wound
Clinical signs of Cowpox in cats
Primary lesions:
a single primary skin lesion, usually on the head, neck, or a forelimb
Secondary lesions:
about 7-10 days after primary lesion; discrete, circular, ulcerated papules; ulcers become covered by scabs
Cowpox in Humans
- transmission
- clinical signs
Mainly caused by direct contact to cuddly cats; less likely to get it from a cow
Macropapular lesions on hands and face; later develop into vesicular, then ulcerative lesions; enlarged painful local lymph nodes
Monkeypox transmission in humans
Primary Infection:
results from direct contact with the blood, bodily fluids, or rashes of infected animals
Secondary:
human-to-human transmission resulting from close contact with infected respiratory tract excretions, with skin lesions of an infected person, or with contaminated objects
Clinical signs of Monkeypox in humans
Same as smallpox
Invasion Period:
fever, intense headache, lymphadenopathy, muscle pain
Skin Eruption Period:
evolution of the rash from maculo-papules (lesions with flat base), to vesicles (fluid-filled), pastules, followed by crusts
Pseudocowpox Transmission
Source of infection is the infected cattle
Contaminated miler’s hands, teat cups
Biting insects
Calves get infected during sucking infected teats
Semen of bulls
Pseudocowpox Lesions
Lesions on the teats are characterized by hyperplasic of squamous epithelium
Acute Lesions:
Erythema->Papule->Vesicle or Pustule->Rupture->Thick scab
Thick scab becomes elevated due to accumulation of granulation tissue
Scabs drop off, leaving a Horseshoe-shaped ring of small scabs surrounding a small wart-like granuloma
Chronic Lesions:
Commences as erythema
Skin is corrugated; no pain
Diagnosing Pseudocowpox
Horseshoe-shaped ring like lesion
use vesicular fluid or skin on teat
Treatment of Pseudocowpox
Removal of scabs
Burn scabs to prevent environmental contamination
Apply am emollient ointment before milking
Apply astringent preparation after milking
Pseudocowpox in Humans
Milker’s Nodule
Lesions on the hands of dairy farmers milking teats or vets treating infected cows
Lesions vary from multiple vesicles to a single, indurated nodule
Contagious Ecthyma
- aka?
- hosts
ORF
Primarily in lambs and goat kids
Transmission of Contagious Ecthyma
Scabs that fall off from the healing lesions contain the virus
Virus is stable in the environment
Contaminated instruments (docking or ear tagging)
Spread in a flock is rapid
Virus infects healthy animals primarily through damaged skin
Oral lesions in lambs or kids result from nursing dams with teat lesions, and vice-versa
Pathogenesis of Contagious Ecthyma
Damage of skin is essential to establish infection
Skin reaction consists of a cellular response with necrosis and sloughing of the affected epidermis and underlying stratum papillae of the dermis
Lesions evolve from Macule->Papule->Vesicle->Pustule->Ulcers->Scab formation
Clinical Signs of Contagious Ecthyma
First lesions develop in the mucocutaneous junction adn are accompanied by swelling of the lips
Lesions spread to the muzzle and nostrils, surrounding hairy skin and the buccal mucosa
Animal may find it difficult to take food because of oral lesions leading to anorexia and weight loss
Severe cases may show lesions in the genitals, coronets (feet), and ears
Scabs fall off and the underlying tissues heal without scarring
Vaccination for Contagious Ecthyma
Vaccine prepared from suspension of scabs in glycerol saline and painted onto a small area of scarified skin inside the leg, where a localized lesions develops
Vaccine should not be used on farms that do not have a problem with ORF
Vaccinations do not offer long-lasting immunity
In problem herds, lambs/kids vaccinated at 6-8 weeks for prevention
Vaccinate pregnant ewes only 7-8 weeks before lambing
ORF in Humans
Macro-papular lesions and large nodular lesions on fingers, hands, arm, face, and penis
Healing occurs without scarring
Transmission of Sheeppox and Goatpox
Highly contagious viruses
Virus enters by respiratory tract and transmission is commonly by aerosol route
Spread can occur through mucous membranes or abraded skin, especially by direct contact with contaminated iatrogenic materials
Mechanical transmission by biting arthropods
Diagnosing Sheeppox and Goatpox
Reportable diseases
SPV and GPV cannot be distinguished from each other with serological techniques, including viral neutralizaiton
Sheeppox Pathogenesis
Deposition of immune complexes results in severe necrotizing vasculitis development in arteriols and post-capillary venules of the skin (Type III hypersensitivity)
Results in ischemic necrosis of dermis and overlaying epidermis
Sheeppox Malignant Form Clinical Signs
Seen in lambs and susceptible nonnative breeds
High fatality in lambs
Initial Signs:
depression and prostration
high fever, salivation, lacrimation
edema of eyelids
serous nasal discharge that becomes mucopurulent
Later signs:
pox lesions extend to the pharynx, larynx, lungs, vagina, abomasum, and spleen
secondary pneumonia
cutaneous nodules over body that become vesicular, pustular, and scab
lesions heal leaving a star-shaped scar, free of hair or wool
Sheeppox Benign Form Clinical Signs
More common in adults and resistant breeds
Only skin lesions occur
No, or very mild, systemic reaction
Goatpox Clinical Signs
Young kids suffer systemic disease with lesions on skin, respiratory, and alimentary mucosae
Milder form of disease seen in adults
