Genus parapoxviruses Flashcards
3 genus in parapoxviruses and their hosts
- pseudocowpox (cattle and humans)
- contagious ecthyma/Orf virus (sheep,goats, humans)
- bovine papular stomatitis virus (cattle, humans)
pseudocowpox
-definition
-epidemiology
-transmission
-viral skin disease that causes mild sores on teats and udders of cattle
-reported in most countries
-transmitted via: infected cattle, contaminated milker’s hands, teat cups, biting insects may transmit the virus, calves get infected during sucking infected teats –> lesions in oral cavity of calf, semen of bulls
pseudocowpox
-pathogenesis
-clinical signs - mild or severe
patho: lesions are hyperplasia of squamous epithelium
CS: mild!
2 types of clinical signs for pseudocowpox
-acute: erythema –> papule –> vesicle or pustule –> rupture –> thick scab
-THICK scab = elevated due to accumulation of granulation tissue, scab will drop off and leave a HORSE SHOE SHAPED RING of small scabs surrounding wart like granuloma
-chronic: commences as erythema, yellow gray, soft scurfy scabs which are rubbed off during milking, skin is corrugated, no pain, lesions may persist for motnhs
pseudocowpox diagnosis and differentials
-diagnose via horse shoe shaped lesions, isolation and detection of virus by lab methods from vesicular fluid or from teat skin
-differentials: cowpox virus, bovine herpes mammilitis, vesicular stomatitis, udder impetigo, teat chaps and frostbite, black spot (hyperkeratosis)
pseudocowpox TX
and prevention
-removal of scabs, burn scabs to prevent envi. contamination, apply emollient before milking, apply astringent after milkling
-prevent: disinfect, use teat dip, isolate and treat infected cows, reduce teat trauma and injuries to skin
-self limiting, will recover if no 2 bact infection
pseudocowpox zoonotic??
YES
pseudocowpox CS in humans
milkers nodule!!! - mild lesions
-lesions on hands of dairy farmers milking teats or vets treating cows, lesions may vary from multiple vesicles to a single, indurated nodule
contagious ecthyma
aka ??
hosts
distribution
is it zoonotic?
AKA ORF
-sheep and goats, mostly goat kids and lambs
-worldwide
YES ZOONOTIC
contagious ecthyma
transmission
-scabs that fall off from healing lesion
-viruses are stable in envi
-contamined instrument
-spread in flock is very rapid
-virus infects healthy animals through damaged skin
-oral lesions in lambs or kids result from nursing dams with teat lesions
contagious ecthyma
-pathogenesis
-damage of skin is essential to establish infection
-skin reaction consists of cellular response with necrosis and sloughing of affected epidermis and underlying dermis
-cutaneous response = delayed type hypersensitivity reaction and influx of inflamm. cells
-lesions evolve from macule –> papule –> vesicle –> pustule –> ulcers –> scab formation
contagious ecthyma
-clinical signs
-first: lesions develop in mucocutaneous junction and are accompanied by swelling of the lips
then: lesions spread to muzzle and nostrils
-animal may find it difficult to take in food because of oral lesions: anorexia and weight loss
-affected lambs or kids sucking ewes or goats may result in lesions on teats
-may predispose to secondary bacT infection –> MASTITIS
-lesions may show in the genitals, feet and ears –> result in lameness and if in scrotum = infertility
contagious ecthyma
-course of disease
scabs drop off –> underlying tissues heal
-complications from secondary bacT infections or from invasions of lesions by fly larvae
-also malignant form in sheep
contagious ecthyma
-vax available?
YES, prepared from suspension of scabs in glycerol saline and is painted onto a small area of scarified skin inside the thigh, where a localized lesion develops
-should NEVER BE USED if farms have never had a problem with ORF
-inspect lamb 1 week post vax for local reactions
-offers immunity for 1-2 yrs
-problem flocks = vax kids and lambs at 6-8 weeks and vax pregnant ewes before lambing
ORF in humans
-clinical signs
macro papular lesions and large nodular lesions in finger, hand, arm face and penis
-secondary bacT infections of lesions may cause complications
