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FINAL DIAGNOSIS 
Fascioloides magna in spinal cord

History:  A 2 year old bull elk (Cervus elavus) was submitted dead for postmortem exami-nation at the Purdue Animal Disease Diag-nostic Lab.  The animal was markedly emaciated and died following an acute onset of paraplegia.

Gross lesions:  Findings at necropsy included marked infestation by Trichuris sp.  Gross examination of multiple sections of formalin-fixed spinal cord revealed randomly distributed pinpoint, brownish-red foci both in the gray matter and white matter between thoracic vertebra 4 and lumbar vertebra 7.  These lesions were more severe and widespread in the white matter.  The liver was diffusely mottled red, and the cut surface revealed the presence of multiple black fibrotic tracts measuring 0.5-1.5 cm in diameter.

Histopathologic findings: Microscopic examination of affected segments of spinal cord exhibited irregularly shaped and-sized multiple foci of necrotic neuropil tissue.  These lesions consisted of acute liquefactive necrosis and hemorrhage accompanied by moderate numbers of gitter cells, with occasional randomly scattered eosinophils and neutrophils.  Many swollen eosinophilic axons (spheroids) and swollen myelin sheaths were present at the margins of necro-hemorrhagic foci.  Blood vessels in the neighboring neuropil had hypertrophic endothelium and mild perivascular cuffing with lymphocytes and plasma cells.  The leptomeninges in the ventral median fissure contained large numbers of lymphocytes and neutrophils and lesser numbers of macrophages, plasma cells, and eosinophils.  In two sections, the central canal was poorly defined, lacked ependyma, and contained transverse sections of immature fluke (marita) consistent with Fascioloides magna. Multiple fibrotic tracts with black pigment were present in the liver.  One of the fibrotic tracts in the liver contained numerous operculated trematode eggs ranging in diameter from 40 –60 mm with thick amber to brown shells.

Discussion:  Fascioloides magna, the large American liver fluke or deer liver fluke, is a common parasite of elk.  The flukes are usually confined to the fibrotic cysts in the liver and, except for causing some liver damage, are of little clinical consequence.  In this case, aberrant migration of the immature flukes was observed in the spinal cord and was considered a likely cause of the reported hind limb paralysis prior to death.  The emaciation of this animal was considered to be due to marked gastrointestinal parasitism.

-by Dr. Alok Sharma, ADDL Graduate

    Student

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