Diagnosis of Parelaphostrongylus spp. infection as a cause of meningomyelitis in calves

Abstract

Abstract. Migration of Parelaphostrongylus spp. has been documented to cause central nervous system damage in a number of aberrant host species but appears to be uncommon in cattle. The current report describes the clinical and laboratory findings, antemortem and definitive diagnosis, and response to treatment of Parelaphostrongylus spp. infection in five 3-7-month-old Limousin calves from 2 farms. All calves had signs of acute (n = 2) and chronic (n = 3) progressive spinal cord dysfunction. Cerebrospinal fluid analysis revealed a marked eosinophilic (acute cases) or lymphocytic (chronic cases) pleocytosis and elevated protein in all calves. A necropsy and histopathologic evaluation was performed on 2 euthanized calves, and histopathology revealed lymphoplasmacytic and eosinophilic meningomyelitis with multiple intradural and intramedullary expansile hyperplastic lymphoid nodules containing germinal centers and nematode fragments. DNA sequencing was performed on nested polymerase chain reaction products amplified with parasite-specific primers obtained from formalinfixed and frozen spinal cord; PCR products from these 2 calves were 100% identical to Parelaphostrongylus species on DNA sequencing, confirming the diagnosis. Surviving calves rapidly improved following treatment with anthelmintics and corticosteroids. This case series identified Parelaphostrongylus spp. (likely P. tenuis) as a cause of spinal cord disease in calves and highlights the need for vigilance against aberrant parasite migration in calves grazing wet, snail-infested pastures. Cerebrospinal fluid eosinophilia is useful for supporting an antemortem diagnosis of Parelaphostrongylus in calves with acute neurologic disease; however, a lymphocytosis is observed in chronic or treated cases.

Retrospective study of central nervous system lesions and association with Parelaphostrongylus species by histology and specific nested polymerase chain reaction in domestic camelids and wild ungulates

“…Antemortem cerebrospinal fluid taps consider eosinophils as a strong indicator of possible neural larval migrans, in particular P. tenuis. 13 Meningitis overall was relatively uncommon, and not seen in any elk. The cause of this is not known, as there is widespread evidence of inflammatory infiltrates, but infiltrates are not localized to the meninges.…”

“…Tissue samples were cut from paraffin blocks from all cases with characteristic P. tenuis lesions for DNA extraction and subsequent PCR testing as previously described. 4,13 An additional histology slide was cut after the 10-µm tissue PCR slices were taken and subsequently stained to determine if nematodes had been uncovered at the depth of the corresponding PCR sample. Extraction of DNA was completed according to the manufacturer's instructions, a and PCR was completed as previously described.…”

“…Extraction of DNA was completed according to the manufacturer's instructions, a and PCR was completed as previously described. 4,13 Separate microtome blades were used for each block, and the blades were cleaned thoroughly between blocks and microtomes using DNA degrading solution. Both DNA extraction and PCR-negative controls were used in nPCR reactions.…”

“…[3][4][5]10,13,18 Using nPCR allows for increased sensitivity to detect Parelaphostrongylus spp. DNA at quantities that conventional PCR would not detect.…”

“…In 2011, 13 a nested polymerase chain reaction (nPCR) method was developed to definitively identify Parelaphostrongylus. [3][4][5]10,13,18 Using nPCR allows for increased sensitivity to detect Parelaphostrongylus spp.…”