Epizootic of Mucopurulent Nasal Discharge in African Hoofstock

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Epizootic of Mucopurulent Nasal Discharge in
African Hoofstock

• L.J. Venter
• South Africa

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Addra Gazelle, Gazella dama ruficollis
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Cape Buffalo, Syncerus caffer caffer
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Black-faced Impala, Aepyceros melampus petersi
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Indian Guar, Bos Frontalis
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Enclosures

• 5 confirmed cases occurred in 4 enclosures
• Areas ranged from 300m2 to 2500 m2
• All enclosures have night-quarter facilities
• Enclosure 41
• Enclosure 126 127
• Enclosure 138
• Enclosure 162

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Enclosure 41

• Addra Gazelle
• Adult of unknown age

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Enclosure 126 127

• Two enclosures joined together
• Cape Buffalo (2)
• Female, 11years 4 month (March 2003)
• Male, 12years 3 months (June 2003)

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Enclosure 138

• Used for weaning young, hand-reared antelope
• Black-faced Impala
• Male, 4 months
• May 2003

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Enclosure 162

• This enclosure no longer houses Indian Guar
• 2 cases reported in this species
• Female, 5 months July 1998
• Female, 4 years 7 months May 1998

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Black-faced Impala

• Clinical signs and history
• Intermittent episodes of weakness and lethargy
  for 2 months
• Admitted to hospital in a state of collapse and
  died during initial treatment

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Gross Necropsy Findings

• Mild icterus and mild fibrinous ascites in the
  carcass
• Severe, generalized lymphadenopathy
• Abomasal ulceration
• Moderate, diffuse, sub-acute hepatitis with
  cholestasis
• Mild nephrosis
• Mild splenic atrophy
• Diffuse, severe pulmonary congestion and edema

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Histopathology

• Severe, multifocal perivasculitis
• Fibrinous necrotizing vasculitis
• Lymphoid hyperplasia
• Necrotizing enteritis
• Severe purulent interstitial pneumonia
• Pulmonary edema, hemorrhage, microemboli,
  alveolar necrosis, atelectasis

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Cape Buffalo-1

• Clinical Signs and history
• 12 days listlessness, mucopurulent nasal
  discharge, excessive lacrimation, blepharospasm,
  corneal opacity, ataxia

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Gross Necropsy Findings

• Mild cachexia
• Focal ulcerations of buccal mucosa
• Mild to moderate, diffuse, edema and congestion
  of the lungs
• Moderate, chronic, localized caseous necrotis
  omasitis

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Histopathology

• Focal to focally-extensive, severe, chronic
  necrogranulomatous myositis
• Brain, spinal cord, meninges mild diffuse
  congestion and edema
• Mild, multifocal lymphocytic perivasculitis
• Moderate, multifocal necrogranulomatous
  lymphangitis of mesenteric lymph nodes
• Multifocal interstitial lymphocytic nephritis

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Cape Buffalo-2

• PCR indicated Wildebeest strain of MCF
• No wildebeest at Pretoria for 20 years
• Test repeated 5 times on different tissues, same
  results

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Cape Buffalo-2

• Clinical Signs and history
• Coughing
• Severe mucopurulent nasal discharge
• Corneal opacity
• Light sensitivity
• Lacrimation

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Cape Buffalo-2

• Diagnostics
• Animal immobilized
• Bronchoscopy
• Severe tracheobronchitis
• with diptheritic membrane
• Treatment
• Extensive antibiotic therapy for 2 weeks
• Outcome
• Euthanasia for humane reasons

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Gross Necropsy Findings

• Severe diffuse keratitis
• Moderate conjunctivitis
• Muzzle and nostrils
• Mild, multifocal hyperkeratosis and exudative
  dermatitis with crust formation
• Severe, acute, diffuse fibrinopurulent rhinitis
  with hyperemia of the mucous membranes and
  turbinates

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Gross necropsy Findings--cont

• Severe, acute, diffuse fibrinohemorrhagic
  pharyngitis, laryngitis, and tracheitis
• Severe, diffuse congestion and edema with
  fibrinopurulent bronchopneumonia of the apical
  and cardiac lung lobes
• Severe Sarcocystis sp. infection of the gluteal
  muscle

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Histopathology

• Brain Mild, multifocal, subacute lymphocytic
  perivasculitis
• Eye Severe, multifocal-to-coalescing subacute to
  chronic rhinotracheitis with mucosal and vascular
  necrosis.
• Lungs Severe, multifocal to coalescing, subacute
  to chronic bronchointerstitial pneumonia with
  alveolar, bronchial, and vascular necrosis
• Kidneys Mild to moderate, subacute lymphocytic
  nephritis with interstitial and periglomerular
  infiltration of lymphoid cells
• Skeletal Muscle Hemorrhage, necrosis, and edema
  as well as scattered Sarcocystis spp. parasites

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Addra Gazelle

• Clinical Signs and history
• Listlessness
• Anorexia
• Regurgitation of rumenal fluid
• Abnormal high stepping gait, chewing gum fits
  over a period of 4 days
• Outcome
• Humane euthanasia

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Gross Necropsy Findings

• Moderate congestion of the carcass
• Severe, acute, locally extensive necrotic
  bronchopneumnia involving the right cranioventral
  lung lobe.
• No gross lesions of the upper alimentary system

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Histopathology

• Lungs Acute bronchopneumonia
• Liver Focal hepatocellular necrosis
• Kidneys moderate nephrosis and cast formation

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Indian Guar

• Clinical Signs and history
• No history of illness
• Animal found dead in the enclosure with two
  penetration wounds cranial to the scrotum

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Gross Necropsy Findings

• Penetration wounds present cranial to scrotum,
  portions of the small intestines had herniated
  through one of the holes
• Herniated small intestine was intensly congested
  with frank blood in the lumen
• Another penetrating wound was found in the left
  flank

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Gross Necropsy findings--cont

• A large blood clot and rumenal contents were
  present in the abdomen
• Fibrin strands were visible on the serosal
  surface of the abdominal organs
• Penetrating wounds were seen in the rumen and in
  the portion of herniated intestine
• A single penetrating wound was seen in the rectal
  wall

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Histopathology

• CNS Mild, subacute meningitis
• Lymph nodes Peripheral nodes exhibited marked
  follicular atrophy, with medullary histiocytosis
• Cardiac Myocardium had multifocal interstitial
  accumulations of lymphocytes were visible as well
  as focal areas of acute myocardial necrosis

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Five PCR Confirmed Cases

• Addra Gazelle
• Cape Buffalo (2)
• Black Faced Impala
• Indian Guar

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Background

• 1990-2003
• 21 Cases of MCF reported in 9 different species
  in the National Zoological Gardens of South
  Africa
• 5 Asia Deer
• 4 Cape Buffalo
• 3 Indian Guar (Asiatic Ox)
• 2 American Bison, Pere David Deer
• 1 each of Barbary Sheep, European Bison, Addra
  Gazelle, Black Faced Impala, Kudu

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Background

• Five cases were confirmed as MCF by PCR
• Highly specific and sensitive for MCF
• These cases will be discussed
• Remainder of the cases were diagnosed based on
• Clinical signs
• Macroscopic pathology
• Histopathology

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Malignant Catarrhal Fever

• Acute, sporadic, invariably fatal disease of
  Bovidae and Cervidae
• Agents implicated in causing disease
• Alcephaline herpes virus I (AHV-I)
• Associated with the wild blue wildebeest
• Occurs only in Africa
• Wildebeest-derived MCF
• Ovine herpes virus II (OHV-II)
• Occurs worldwide
• Sheep-associated MCF

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MCF-Transmission

• AHV-I
• Horizontally and vertically in wildebeest herds,
  calves may be infected in utero
• Wildebeest develop no clinical signs
• Fomites are largest source of disease
  transmission
• Virus excreted in nasal/ocular discharge and feces

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MCF-Transmission--cont

• Similar mode of transmission in sheep
• Susceptible ruminants are end-hosts which develop
  clinical signs of the disease but DO NOT spread
  the disease horizontally within susceptible
  population
• Sub-clinical infection in cattle and deer has
  been described with clinical manifestations under
  severe stress
• Close contact with wildebeest is NOT a
  prerequisite for the development of the disease
  in cattle
• Minimum separation distance of 1000m is suggested
  between wildebeest and cattle

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MCF-Clinical Signs

• Varies from sub-acute to chronic
• Deer Per-acute disease
• Cattle Acute disease
• Signs in acute form
• Fever, depression, lymphadenopathy, serous to
  mucopurulent nasal and ocular discharge, oral
  ulcerations and erosions, corneal opacity,
  diarrhea, ulceration of the skin of the perineum,
  vulva, coronet, and interdigital area, epithelial
  necrosis, interstitial infiltration of organs by
  lymphocytes and widespread angiitis
• CNS signs hyperaesthesia, hypermetria, tremors
  and convulsions

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MCF-Diagnosis

• Relies on observation of clinical signs and herd
  signalment
• Macroscopic necropsy examination
• Histologic observation
• Serologic investigation and PCR are added
  diagnostic modalities

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Control

• 2 Sheep kept 30m behind the buffalo enclosure
  (126 127) in the petting zoo
• Sold, no PCR tests performed
• Movement of ungulates in and out of zoo was
  restricted
• Relevant personnel have been informed about
  characteristics of MCF and are on heightened
  alert for signs of the disease in all ungulate
  species
• PCR is part of the tests before any buffalo are
  moved, not yet required by law

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MCF-Prevention

• Separation of susceptible animals from source of
  infection is the ONLY RELIABLE way of preventing
  the disease

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Comments and Discussion

• Interesting that Guar showed no clinical signs
• Killed by the bull in the enclosure
• Did the animal have the per-acute form that lead
  to a change in behavior that caused the bull to
  attack it? This is reported to happen in wild
  animals.

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Comments and Discussion

• The pathologists report for the Addra comments
  mainly on the bronchopneumonia and few classic
  signs of MCF are described.
• As this diagnosis was made on PCR could it be
  possible that the animal was a carrier?

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Comments and Discussion

• Except for the one, buffalo all PCR results
  indicated OHV-II as the cause of the disease
• This unexpected PCR result causes one to
  speculate on the existence of a possible AHV-I
  carrier apart from wildebeest in the zoo.

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