Epizootic of Mucopurulent Nasal Discharge in African Hoofstock

1. Epizootic of Mucopurulent Nasal Discharge in African Hoofstock L.J. Venter South Africa

2. Addra Gazelle, Gazella dama ruficollis

3. Cape Buffalo, Syncerus caffer caffer

4. Black-faced Impala, Aepyceros melampus petersi

5. Indian Guar, Bos Frontalis

6. 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

7. 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

8. 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

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

10. Cape Buffalo-1 • Clinical Signs and history • 12 days listlessness, mucopurulent nasal discharge, excessive lacrimation, blepharospasm, corneal opacity, ataxia

11. 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

12. 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

13. 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

14. Cape Buffalo-2 • Clinical Signs and history • Coughing • Severe mucopurulent nasal discharge • Corneal opacity • Light sensitivity • Lacrimation

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

16. 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

17. Gross necropsy Findings--con’t • 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

18. 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

19. 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

20. 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

21. Histopathology • Lungs: Acute bronchopneumonia • Liver: Focal hepatocellular necrosis • Kidneys: moderate nephrosis and cast formation

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

23. 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

24. Gross Necropsy findings--con’t • 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

25. 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

26. Five PCR Confirmed Cases • Addra Gazelle • Cape Buffalo (2) • Black Faced Impala • Indian Guar

27. 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

28. 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

29. 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

30. 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

31. MCF-Transmission--con’t • 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

32. 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

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

34. 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

35. MCF-Prevention • Separation of susceptible animals from source of infection is the ONLY RELIABLE way of preventing the disease

36. 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.

37. 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?

38. 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.