33. Sheep and goat pox.

Question 1

Etiology?

Answer 1

Etiology ➝ Notifiable disease

• Goatpox virus, sheeppox virus (Capripoxvirus genus)
• One of the oldest known diseases
• Fever, general symptoms, generalised pox
• Only sheep and goat are susceptible
• Antigenetically closely related viruses (genetics, antigens)
• Some infect both species ➝ cross-immunity

Question 2

Occurrence?

Answer 2

Occurrence

• Europe: free since 1970s, sporadic re-introduction
• Frequent: Africa, Turkey, Middle East, Western Asia, Russia
• Australia and New Zealand free

Question 3

Epidemiology?

Answer 3

Epidemiology

• Extremely resistant ➝ remain for long time
• Infected animals: saliva, respiratory mucus, milk, scabs (virus shedding)
• Transmission:
• Aerogenic ➝ during slaughter the body fluids splatter and transmission through droplets
• Drinking trough, barns
• Skin, wool, people, fomites

• Vectors

• Insects are mechanical vectors (the virus does not replicate in these vectors)
• Mosquitoes
• Slower at pastures and faster in stables due to high density of animals
• European breeds more susceptible and show stronger clinical signs
• Forbidden to export these products

Question 4

Pathogenesis?

Answer 4

Pathogenesis

• Inhalation ➝ primary replication in respiratory epithelium ➝ viraemia through bloodstream ➝ organs and tissues (generalised in

all organs)

• Mucosal membranes: respiratory tract, gastrointestinal tract
• Lungs and other organs: lymphoma-like nodules, proliferation of poxvirus characteristic lesions
• Skin: pox lesions, nodules (no visible vesicules)
• Crosses to foetus via placenta: clinical signs of embryonic death
• Long lasting immunity
• Recovered ewes/does ➝ maternal immunity to lambs/kids via colostrum

Question 5

Clinical signs?

Answer 5

Clinical signs

• Two diseases are similar but less severe in goats
• Incubation:
• 4-8 days in sheep pox
• 5-14 days in goat pox
• Flu-like symptoms: fever, nasal discharge, conjunctivitis, loss of appetite
• Weak/young animals may die before the clinical signs appear
• Pock around the body in a few days
• In milder cases: pocks on the head, tail, genitals (areas not covered by wool)
• Necrosis of the dermis, dark and hard scabs ➝ virus shedding from skin lesions
• Pocks on the mucous membranes (mouth, nose, genitals)
• Can be haemorrhagic, pocks may fuse, necrotise and ulceration
• Pocks ➝ ulcers in the respiratory tract ➝ mucopurulent nasal discharge, laboured breathing due to fluid accumulation in the

lungs

• Mortality: 70-80% in lambs/kids, 5-10% in adults
• Regeneration of the epithelium takes several weeks
• Weight loss, decreased wool and milk production
• Star-shaped scars remain on the skin area not covered by wool

Question 6

Pathology?

Answer 6

Pathology

• Skin lesions
• Lentil-sized lymphoma-like pocks on lungs, kidneys, liver
• Mucous membrane of upper respiratory and enteric tract has pocks and ulcers

Question 7

Histopathology?

Answer 7

Histopathology

• Compartmented vesicles in skin (macroscopically invisible), scab
• CP inclusion bodies
• Interstitial pneumonia
• Focal interstitial nephritis (kidney inflammation)

Question 8

Diagnosis and DD?

Answer 8

Diagnosis

• Epidemiology, symptoms, histology
• EM (characteristic morphology), IF, PCR, isolation
• VN, ELISA
• Long lasting immunity after recovery
• DD: contagious pustular dermatitis

Question 9

Control?

Answer 9

Control

• Notifiable disease!
• Africa and Asia: attenuated SC vaccine ➝ protection lasts for 1-2 years
• Epidemiological measures and eradication
• Import of milk and raw products is forbidden from infected regions