Pathologic features and molecular identification of parelaphostrongylosis in a sitatunga (Tragelaphus spekii)

Abstract

We report the pathologic features, local inflammatory response immunophenotype, and molecular identification results of cerebral nematodiasis in a young sitatunga (Tragelaphus spekii) from Texas. To the authors' knowledge, this is the first report of cerebral nematodiasis by Parelaphostrongylus tenuis in a sitatunga, a bovid species introduced into the USA, and the first characterization of the local inflammatory response immunoprofile in this condition. A molecular identification method based on formalin-fixed and paraffin-embedded-polymerase chain reaction was described. These results contribute to knowledge on geographical distribution and host spectrum of P. tenuis, and highlight the relevance of this nematodiasis in naïve translocated or introduced bovid species into endemic areas.

Keywords: Parelaphostrongylus tenuis; Tragelaphus spekii; meningeal worm; sitatunga.

Fig. 1.

Microscopic features of central nervous system parelaphostrongylosis in sitatunga (Tragelaphus spekii). Liquefactive necrosis with hemorrhage, swollen axons and pleocellular inflammatory infiltrates. Hematoxylin and eosin staining (H&E). Bar=250 µm. Upper inset: Pleocellular inflammatory nodule with mononuclear cells and eosinophils. H&E. Bar=50 µm. Lower inset: Detail of focal multinucleated giant cell, as well as swollen axons (asterisks), dilated myelin sheaths and astrocytosis. H&E. Bar=50 µm.

Fig. 2.

Microscopic features of central nervous system parelaphostrongylosis in sitatunga (Tragelaphus spekii). Transverse and tangential section of nematode larvae within the arachnoid space and cerebellar parenchyma (asterisks). The tangential nematode section on the upper right (indicated with an asterisk) is associated with local hemorrhage and necrosis. Hematoxylin and eosin staining (H&E). Bar=500 µm. Inset: cross section of Parelaphostrongylus tenuis. H&E stain. Bar=25 µm. c, cuticle; h, hypodermis; lc, lateral cords; m, muscle; ps, pseudocoelom; i, intestine.

Fig. 3.

Immunohistochemical features of central nervous system parelaphostrongylosis in sitatunga (Tragelaphus spekii). CD3-positive (T-cells) lymphocytes are noted within the leptomeninges (asterisk), neuroparenchymal perivascular spaces (arrows) and scattered throughout the neuroparenchyma. CD3 immunostaining. Bar=500 µm. Left inset: T-cells within a thick perivascular cuff. CD3 immunostaining. Bar=50 µm. Right inset: B-cells within the same perivascular cuff depicted in the left inset. CD20 immunostaining. Bar=50 µm.

Fig. 4.

Microscopic features of peripheral nervous system parelaphostrongylosis in sitatunga (Tragelaphus spekii). Perineurial and perivascular mononuclear inflammatory infiltrates (arrows) in right radial plexus nerves. Hematoxylin and eosin staining (H&E). Bar=250 µm. Inset: Detail of lymphocytes and plasma cells infiltrating perivascular and perineurial collagen fibers. H&E stain. Bar=25 µm.