31. Bovine diseases caused by poxviruses. Flashcards
Poxviridae Subfamilies genera?
Poxviridae (pock - scar)
• Subfamilies, genera:
- Chordopoxvirinae - Orthopox, Parapox, Avipox, Capripox, Leporipox, Suipox, Cervidpox, Yatapox, Molluscipoxvirus
genus
- Entomopoxvirinae: insect poxviruses (A, B, C)
Poxviridae Morphology?
Morphology
- Linear dsDNA genome (150-200 kb ➝ 150-300 proteins)
- 200-400 nm brick shaped, oval, complex capsid with lipids (envelope +/-)
Poxviridae resistance?
• Resistance
- Usually good (scabs) ➝ litter, dust, fomites
- 60 ℃, 10-30 minutes, Na-hypochlorite: minutes
- Chloroform inactivates all
- Ether inactivates only Capripox, Parapox and Leporipoxviruses
- Epitheliotrop: local or generalised infections
- Recombinations within genera ➝ cross-reaction, cross-protection
- Replicates in cytoplasm ➝ inclusion bodies:
- Guarnieri (mammalian)
- Bollinger (avian)
• Orthopox and Parapox are ZOONOTIC
Poxviridae Pathogenesis?
Pathogenesis
I. Infection route: aerogenic, contact, arthropod vector
II. Primary replication: skin, mucosal surface
- Stadium erythematosum ➝ reddening
- Stadium papulosum ➝ proliferation, greyish papule
- Stadium vesiculosum ➝ necrosis, vesicle
- Stadium pustulosum ➝ purulence, pus production in vesicle
- Stadium crustosum ➝ dried crust
- Stadium decrustationis ➝ crust shed, infected cells come off skin and spreads in environment
- Healing with pockmark or without sign
III. Some viruses in certain species enter the blood ➝ generalisation
IV. Survival of infection: long-lasting (lifelong) immunity
- Parapox is exception ➝ half year immunity
Diagnosis Poxviridae?
Diagnosis
- Clinical signs, pathology and histology (cytoplasmic inclusion bodies) are very characteristic and easy to recognise
- Virus isolation: some cells can be propagated in embryonic eggs
- Cell cultures
- CAM
• Nucleic acid detection
- PCR ➝ direct virus detection of virus nucleic acid
- In situ hybridisation
• Serology
- VNT (virus neutralisation test)
- ELISA ➝ detect antibody
Vaccine of Poxviridae?
Vaccine: mostly live vaccines
- Virulent ➝ only in infected herds
- Orf in negative herds
- Forbidden in food-producing animals (in Hungary) - Heterotypic
- Vaccinia ➝ smallpox
- Myxomatosis ➝ shope fibroma virus (shared antigens with myxoma virus) - Attenuated ➝ passed in cell culture several times ➝ virulence low
- Myxomatosis
• Recombinant vaccines against other pathogens
- Pox viruses: large genome so can be genetically engineered
- Large genome, wide spectrum, mild local lesions
Vaccinia (practically any other pathogens)
‣ Myxomatosis (RHDV: Rabbit hemorrhagic disease virus) ➝ genetically modified, live attenuated myxomatosis or
Shope fibroma virus
‣ Fowlpox and canarypox (used in vector vaccine) ➝ in mammals, horse influenza, WNV in horses
‣ Swinepox (CSFV)
Cowpox info?
Cowpox ➝ Zoonotic
- Cowpox virus (Orthopoxvirus genus)
- Sporadic (rare), spreads with contact and through skin lesions
- Cattle
Pathogenesis of Cow Pox?
Pathogenesis
- Mild, local lesions ➝ udder, mouth, genitals (scrotum)
- Rarely generalised infection
- Incubation: 3-7 days
- Bad hygiene conditions, bacterial superinfection of the lesions makes clinical signs more severe
- Recovery within 1 month (without secondary infections)
- Most cows in a dairy herd may become affected ➝ very contagious!
- Induces long-lasting immunity
Clinical signs of Cow Pox?
Clinical signs
- Hemorrhagic lesions
- Red/black crust (sometimes mild and not obvious)
- Mildly febrile
- Papules appear, vesicles may not be evident
- Differential diagnosis: Foot and mouth, herpesmamillitis ➝ laboratory (they are very similar)
Treatment and prevention of Cow Pox?
Treatment
- Careful and gentle milking due to the lesions being painful
- Antibiotic ointments to prevent secondary bacterial infections
- Disinfection of milking cups to prevent the transfer of disease
Prevention
- Rodent management as they are reservoirs
- Wear gloves and protective clothes
Other species of cow pox?
• Other species
- Occurrence: worldwide, mostly Europe, wide host range
- Elephant, seal: generalised, fever
- Other species: foxes, wild boars (20-30% of wild animals are seropositive)
1. Rodents (main reservoir): local lesions, around mouth
2. Cats: asymptomatic or skin lesion (around eye, nose, mouth), general flu-like symptoms, conjunctivitis
3. Human: milker’s nodules on hands, lesions by contamination (eyes), in immunocompromised it can become
generalised similar to smallpox
Pseudocowpox info and pathogenesis?
Pseudocowpox ➝ Zoonotic
- Pseudocowpox virus (Parapoxvirus genus)
- Host range is limited: Cattle, human
Pathogenesis
- Common
- Mild infection of the udder and teats of the cows
- Widespread worldwide
Cattle and Human Pseudocowpox?
Cattle
- Mild, benign infection on teats or udder
- Incubation: 7-12 days
- Small, no haemorrhages, red papule on the teats or udder
- Scabbing or small vesicles or pustules before scabs
- Scabs are removable without pain, recovery without pockmarks
- Spread slowly, introduction by infected animals ➝ milking cups
- Reinfection possible
- Treatment: antibiotic/antiseptic ointments and gentle milking
Human
- Milker’s nodules
- Painless, itchy purplish-red nodules on fingers or hands
- Inconvenient, disappear after several weeks
Bovine Papular stomatitis and pathogenesis?
Bovine papular stomatitis ➝ Zoonotic
- Bovine papular stomatitis virus (Parapoxvirus genus)
- Stomatitis papulosa bovis
Pathogenesis
- Widespread worldwide
- Mild parapoxvirus infection of calves and younger (< 2 year old) cattle
- Mostly spring and early summer
- Transmission: direct contact, saliva
- Incubation: 10 days (1 week)
Clinical signs and diagnosis of Bovine Papular stomatitits?
Clinical signs
- Erythema ➝ variable number of proliferative pocks ➝ erosions (reddish)
- No fever (important for diff. D.)
- 0.5-1.5 cm round pocks on muzzle, lips and inside the nostrils and mouth
- Lesions heal in 1-2 weeks
Diagnosis
- Usually confection with BVDV due to weak and suppressed immune system
- DD: FMD (why samples need to be taken, FMD is notifiable disease so important to differentiate)
- Clinically indistinguishable from milker’s nodules
Lumpy Skin disease ethiology?
Lumpy Skin Disease (LSD) ➝ Notifiable disease
• Capripoxvirus genus
Etiology
- Genetic and antigenic similarity to sheep and goat pox viruses
- Hosts: cattle, buffalo, wild ruminants (reservoirs ➝ more resistant, often without clinical signs)
- By natural infection, goat and sheep are not susceptible
Lumpy skin disease Occurrence?
Occurrence
- Africa since 2012
- Spread to Europe in 2014
- Will become endemic as it can be transmitted by flies and other vectors
- Notifiable disease
Epidemiology
- Direct contact (less importance)
- Transmitted by arthropods: mosquitoes, flies, horsefly, ticks ➝ mechanical vectors
‣ Mosquito: seasonal and travels by wind
- 50% cases are asymptomatic ➝ infected animals carry to new places
Pathogenesis of lumpy skin disease?
Pathogenesis
- Course of infection depends on:
‣ Host susceptibility ➝ European breeds more susceptible
‣ Dose and route of virus inoculation
‣ Species and breeds of cattle ➝ more severe in cows at peak of lactation (due to weakened immune system)
‣ Age ➝ younger animals more susceptible
- Local lesions in the skin, usually becomes generalised (mucous membrane of organs)
- Skin: mucous membrane pocks ➝ ulcer ➝ necrosis, contaminated by flies (maggots, bacteria) ➝ scab falls ➝ recovers
replenished by connective tissue
- Virus transferred to the embryo via placenta
- 15 DPI (days post infection): months in semen, 6 months in scabs
- Virus is infective for 18 days in dried hide
- Long term immunity after recover, maternal immunity for calves
Clinical signs of Lumpy skin disease?
Clinical signs
- Incubation period: 1-5 weeks (1-9 days after artificial insemination)
- Fever, anorexia, salivation, lacrimation and nasal discharge
- Marked reduction in milk yield
- Circumcised, firm, round and raised skin nodules (0.5-5 cm)
‣ Head, neck, udder, nasal and oral mucosa ➝ later all around body
‣ Necrosis ➝ pockmarks (plugs, holes, scars)
- Enlarged lymph nodes
- Limbs and ventral parts of the body ➝ oedema (animals reluctant to move)
- Abortion or birth of calves with clinical signs ➝ bulls become temporarily or permanently infertile
- Secondary bacterial infection ➝ myiasis
- Morbidity: 10-45% and mortality: maximum 10%
- Slow recovery and weight loss
- Holes in hide results in loss of value ➝ economic significance
Diagnosis and differential diagnosis of Lumpy skin disease?
Diagnosis
- Clinical signs ➝ suspicion ➝ notifiable disease!
- Direct virus detection: PCR, virus isolation, Ag-ELISA
- Serology: VN, Ab-ELISA
- DD:
‣ Bovine herpes mammillitis (pseudo-lumpy skin disease) ➝ affects udder and causes erosion
‣ Bovine papular stomatitis (Parapoxvirus)
‣ Pseudocowpox (Parapoxvirus)
‣ Cowpox (Orthopoxvirus) ➝ uncommon and not generalised infections
‣ Dermatophilosis
‣ Demodicosis
‣ Insect or tick bite
‣ Besnoitiosis
‣ Hypoderma bovis infection, photosensitisation, urticaria, cutaneous tuberculosis, onchocercosis
Control of Lumpy skin disease?
Control
- EU
‣ Notifiable disease ➝ general epidemiological measures and eradication
‣ Vector control
‣ Vaccine (recombinant sheep pox by scarification)
‣ Import/Export of animals and their product from infected areas is prohibited
- Endemic areas
‣ Recovery ➝ long-lasting immunity
‣ Vaccine: every year before mosquito season
‣ Eradication efforts
