Biomedical subjects
Publications and source records attributed to J E Jardine.
Toxoplasma gondii was identified in tissues of a stillborn late-term fetus from an Indo-Pacific bottlenose dolphin (Tursiops aduncus). Myocardial necrosis and nonsuppurative inflammation in the heart and nonsuppurative necrotizing encephalitis were associated with tachyzoites and tissue cysts. The diagnosis was confirmed by immunohistochemical staining with anti-T. gondii-specific polyclonal rabbit serum.
A captive king cheetah (Acinonyx jubatus) was evaluated for a subacute onset of ataxia in all four limbs. The ataxia appeared to be spinal in origin, evidenced by apparent conscious proprioceptive deficits in all limbs, and there was no evidence of cerebellar involvement. Anesthesia was performed and survey spinal radiographs were normal. Cerebrospinal fluid analysis revealed an apparently sterile meningitis of unknown etiology. Although transient improvement was noted with glucocorticoid and antimicrobial therapy, the condition deteriorated subsequently and the animal became quadriparetic and paraplegic. Follow-up cerebrospinal fluid analysis and culture revealed the presence of Cryptococcus neoformans. Myelography demonstrated obstruction of the subarachnoid space at the level of the seventh cervical vertebra. Pathological examination following euthanasia revealed a solitary pulmonary cryptococcoma and confirmed cryptococcal meningoencephalomyelitis.
The fine structure of bradyzoites and tissue cysts of Neospora caninum in dogs is described. Original findings consisting of branching, septa-like structures of the cyst wall and peculiar, lipid-like inclusions in the cyst ground substance were described. Tubulo-vesicular structures in the cyst ground substance and distinctive, vesicular organelles containing short, membranous segments and smaller vesicles, described in Neospora parasites of bovine origin and previously undescribed in parasites of canine origin, were also observed. The findings in this study indicate that there are no distinct ultrastructural morphological criteria differentiating N. caninum in dogs and the Neospora-like protozoan of cattle. The previously reported morphological distinction between parasites of canine and bovine origin may be attributed to the relatively small numbers of tissue cysts examined, differences in tissue fixation and processing, and variation in developmental stage of the parasites examined.
A large abdominal mass in a 3-year-old filly was discovered clinically and removed and examined after the horse had been humanely killed. Histologically, three different tissue types were noted, occurring in equal amounts: epithelium largely in the form of well-differentiated tubules, multifocally distributed cell-dense foci of blastema, and myxoid to fibrous stroma. A diagnosis of triphasic nephroblastoma, a rare tumour in the horse, was made on the basis of microscopical findings. The finding of numerous glomeruloid structures confirmed the diagnosis and assisted in distinguishing the tumour from a teratoma. The histogenesis of nephroblastoma is briefly discussed in the context of the histological and immunohistochemical findings of the case.
An unidentified Toxoplasma gondii-like disseminated infection was found in tissues of a 2-day-old hartebeest. Protozoal tachyzoites were about 3.5 x 1.7 Microns, had electron-dense rhoptries, and divided by endodyogeny. The organism did not stain with polyclonol antibodies to T. gondii, Neospora caninum, or Sarcocystis cruzi.
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Specimens from the ileum, colon and rectum were aseptically collected from 50 consecutive horse carcases submitted for necropsy to the Department of Pathology, Faculty of Veterinary Science, University of Pretoria. These were bacteriologically examined for the presence of Salmonella. Seventeen of these were positive for Salmonella at one or more sites. Serotyping of the isolates revealed a dominance of Salmonella Hayindogo in these horses.
Combined histological examination and avidin-biotin immunohistochemical staining of formalin-fixed brain and myocardium from aborted bovine foetuses presented to the Allerton Regional Veterinary Laboratory were utilized for the diagnosis of bovine neosporosis. Two out of 144 cases were diagnosed positive for neosporosis, indicating a low prevalence of infection and confirming Neospora caninum to be a cause of sporadic abortion in the population surveyed.
An immunohistochemical staining technique in which a monospecific serum was used against the major antigenic protein -1 (MAP-1) of Cowdria ruminantium, was evaluated for the detection of C. ruminantium in formalin-fixed tissues of experimentally infected mice and field cases of heartwater in sheep, cattle and goats. Mice were infected with the mouse-pathogenic stocks: Mara, Kwanyanga, Welgevonden, Nonile, Vosloo, Kümm, Mali and Omatjenne. In all these cases and in the naturally infected cattle, sheep and goats, Cowdria colonies were identified as clearly-defined, brown-staining rickettsial colonies within the cytoplasm of endothelial cells. No positive staining was observed in the control group. This technique was shown to be reliable for detecting infection with C. ruminantium in the formalin-fixed tissues of mice and domestic ruminants.
Two immunoperoxidase techniques, viz. avidin-biotin complex (ABC) and peroxidase-anti-peroxidase (PAP) procedures, were applied to paraffin-wax-embedded brain-tissue sections, from brains which had been fixed in 10% formalin, to demonstrate the presence of rabies-virus antigen by light microscopy. These techniques positively identified both "viverrid" and "canid" rabies-virus antigen in tissues sections of species commonly infected with rabies virus in southern Africa, viz. the domestic dog (Canis familiaris), yellow mongoose (Cynictus penicillata), black-backed jackal (Canis mesomelas), bat-eared fox (Otocyon megalotus), cattle (Bos taurus), sheep (Ovis aries) and humans. With both of these techniques rabies-virus antigen stained as sharply demarcated, brown precipitates within the cytoplasm of neurons. The virtual absence of background staining enabled identification of fine granules of viral antigen, often referred to as "virus dust", within axons, dendrites and cytoplasm of the nerve cell body. Staining with the ABC procedure clearer, more deeply-coloured precipitates than the PAP method.
An 8-year-old, Maltese-cross bitch presented with chronic neck and back pain and an acute onset of circling, hyperaesthesia and constant crying. Clinical examination revealed temporal muscle atrophy, an abnormal hanging reflex, cervical rigidity and severe hepatomegaly. Ultrasonography of the liver showed several disseminated, poorly demarcated, hypoechoic areas which on fine needle aspirates, contained large numbers of pigmented fungal hyphae. Cerebrospinal fluid examination revealed fungal hyphae and numerous Ehrlichia canis morulae. A diagnosis of systemic phaeohyphomycosis secondary to ehrlichiosis was proposed. Treatment was unsuccessful and the dog was euthanased. At necropsy, multiple yellowish-green to black, necro-granulomatous foci were found throughout the liver parenchyma and similar foci were present in the spleen, renal cortices and adrenal glands. Irregular, multifocal, grey to black foci of malacia were present in both the grey and the white matter of the brain. On histopathological examination pigmented fungal hyphae were demonstrated in the liver, spleen, kidneys, portal lymph node and adrenals, as well as in the brain. Cultures of various organs yielded a fungal organism identified as Xylohypha bantiana.
Neospora caninum was detected in the brains of twin aborted calves by means of a specific immunohistochemical test on formalin-fixed, wax-embedded tissues. Microscopic lesions associated with this infection included multifocal necrosis and gliosis in the brain accompanied by a mononuclear, perivascular inflammatory reaction and meningitis; and severe, diffuse epicarditis and subepicardial myocarditis characterised by infiltration of macrophages, lymphocytes and plasma cells. This report documents the first diagnosis of this parasite as a cause of bovine abortion in South Africa.
Neospora caninum is a recently identified protozoan parasite which was previously confused with Toxoplasma gondii. Neosporosis in puppies commonly causes signs referable to parasitic encephalomyelitis and myositis. The parasite was identified in tissues from 3 9-week-old Labrador littermates which showed signs of progressive hind limb hyperextension and paralysis. The diagnosis was confirmed, utilising a specific avidin-biotin immunohistochemical technique. Attempts to treat the pups with clindamycin were unsuccessful. One case was additionally treated with immunosuppressive doses of corticosteroids, but showed no improvement. Two pups were euthanased and necropsied. The predominant lesions were polymyositis and multifocal encephalomyelitis. Large clusters of tachyzoites were seen in the myofibres and thick-walled parasitic tissue cysts were found in the grey and white matter of the brain and spinal cord.
Neospora caninum was identified in tissues of one neonatal and two adolescent dogs by a specific immunohistochemical technique during a retrospective study. The histological lesions included multifocal polymyositis, multifocal parasitic myocarditis, interstitial pneumonia, severe multifocal encephalitis and myelitis with perivascular cuffing. This report extends the known range of the parasite to the African continent.
A natural, fatal case of cytauxzoonosis in a tsessebe is reported. The macroscopic and histologic pathology are described, the most significant lesion of which was severe, focal disseminate necrosis and haemorrhage in the liver. Similar but less severe lesions were present in the heart, skeletal muscles, kidneys and spleen in conjunction with a moderate interstitial pneumonia. Schizonts were found within mononuclear phagocytes and multi-nucleated syncytial cells in the liver, lungs, spleen and kidneys. Parasitised erythrocytes with up to 4 piroplasms per cell were seen. The ultrastructural features of the parasite are consistent with those of Cytauxzoon spp.