Exotic Diseases

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Species Infected

infects primarily cattle although most cloven-hoof animals are affected

pigs are infected in Asia

• similar and closely related virus causes a disease in sheep and goats called peste des petits ruminants

Clinical Signs

• depend on virus strain, species infected

     in cattle 5 distinct phases - incubation, prodromal fever, mucosal erosive, diarrhoeic, convalescent

• incubation phase
• 6-9 days
• prodromal fever phase
• sudden onset which lasts 2-5 days
• anorexia, depression
• harsh coat
• serous nasal, lacrimal discharge
• congested mucous membranes
• mucosal erosive phase
• raised necrotic pinhead size lesions in oral, nasal and urogenital tract
• shallow ulcers enlarge and coalesce
• salivation
• serous/nasal/ocular discharges become mucopurulent
• restless, drink copious water
• constipated
• diarrhoeic phase
• onset as fever reduces
• fetid, dark
• flecks of mucus and blood
• severe, frequent straining
• rapid dehydration and emaciation
• most deaths occur during this phase 7-12 days post infection
• convalescent phase
• onset ill defined, make take many weeks
• morbidity 100%, mortalities 25-90%

Lesions

• generally confined to alimentary tract
• small discrete necrotic areas
• separation leaves deep sharply demarcated ulcers with red raw floor
• present in mouth, first third of oesophagus, pharynx, nasal cavity
• abomasum similar necrotic erosions, no lesions in forestomachs
• colonic and caecal mucosal eroded
• capillaries congested giving striped effect
• Peyers patches haemorrhagic and necrotic
• congestion, erosion of vulval and vaginal mucosa

Aetiology

• Morbillivirus (Paramyxoviridae)
• related to canine distemper, human measles and peste des petits ruminants viruses
• antigenically homogenous
• strains vary in virulence, but individual strains are stable
• sensitive to environmental factors

Pathogenesis

• virus enters through upper respiratory tract
• replication in local lymphoid tissues, not mucosa
• viraemia develops 1-2 days prior to fever
• results in proliferation in all lymphoid tissue, mucosa of upper and lower respiratory and alimentary tracts
• marked lymphoid destruction
• virus protected from antibody response because it circulates with mononuclear cells
• virus detectable in all discharges during febrile period

Epidemiology

• disease dependent on close contact from host to host
• infection via contaminated food or facilities is rare
• animals are generally immune following recovery
• carriers not important amongst domestic livestock although a temporary carrier state could occur with wild animals
• in endemic areas, calves etc. are protected passively, adults have recovered, so susceptible stock are immature or young adults

Differential Diagnoses

     1.  acute mucosal disease
     2.  bovine malignant catarrh
     3.  acute helminthosis complicated by papular stomatitis
     4.  acute coccidiosis
     5.  Jembrana disease