Exotic Diseases

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Species Infected

affects cattle and possibly buffalo

Clinical Signs

• incubation 2-5 weeks
• biphasic fever develops
• 1st elevation
• lacrimation
• nasal discharge
• inappetence
• malaise
• 2nd elevation
• coincides with skin eruptions
• systemic signs may not be noticed
• nodules (from few to hundreds) appear rapidly
• all parts of body could be affected but more likely to be head, neck, limbs, perineum, genitalia, udder
• lymphadenopathy of superficial nodes
• localised oedema
• may get ocular, nasal, oral lesions
• morbidity variable, mortality low

Lesions

• 0.5 - 7 cm diameter
• circumscribed, round, flat-topped intradermal swellings - hairs erect
• involve all layers of skin and sometimes dermis
• some nodules become indurated and persist for months/years
• more typical
• necrosis and sequestration
• separation can occur as early as 12 hours
• affected skin dries and hardens surrounded by narrow ring of granulation tissue
• necrotic plug may be shed or may persist as a "sit-fast"
• if sloughs leaves deep ulcer that granulates
• may get secondary infection
• permanent scarring

Pathogenesis

• main route of infection appears to be insect­mediated
• transient viraemia followed by skin localisation

Aetiology

• Capripoxvirus, closely related to sheep/goat pox
• frequently known as Neethling virus
• resistant to environmental conditions but does need some host maintenance

Epidemiology

• epidemics have a pattern of spread by an arthropod vector
• number of vectors could be involved
• occur in years of greater than normal rainfall
• thought endemic infections exist and these extend under favourable conditions
• nature of maintenance host unknown
• could be buffalos as many of these have antibodies to virus but are asymptomatic

Differential Diagnoses

     1. Allerton virus (ulcerative mammilitis virus)

• "sit-fast" lesions do not develop
• lesions more superficial and involve epidermis only

     2.  insect bites/allergies
     3.  warble fly
     4.  screw worm
     5.  dermatophilosis
     6.  skin tuberculosis