Clinico-pathological findings and cerebrospinal fluid analysis in llamas (Lama glama) experimentally infected with the meningeal worm Parelaphostrongylus tenuis

Abstract

In this study, the clinical progression of experimental infection of llamas ( Lama glama) with Parelaphostrongylus tenuis is described. The onset and characterization of neurologic deficits and changes in the hematology, serum biochemical, and cerebrospinal fluid (CSF) in affected llamas are compared before and after appearance of clinical signs. Sixteen apparently healthy, male llamas (median age; 12 months) were used. Five llamas were maintained as uninfected controls, and five, three, and three llamas were orally inoculated with five, ten, and 25 third-stage larvae (L3) of P. tenuis, respectively. The onset, degree, and characterization of neurologic deficits were recorded. Hematology, serum biochemistry, and CSF were analyzed before exposure (Pre) and after neurologic signs appeared (Post). Necropsy and worm recovery from the central nervous system (CNS) were also carried out to confirm infection. Exposure of llamas to 25 L3 of P. tenuis orally resulted in consistent infection and development of disease. Overall, ten of the 11 animals exposed to P. tenuis L3 developed varying degrees of neurologic signs between 45 and 82 days post-exposure (dpe). P. tenuis was recovered from the CNS of seven of the 11 exposed llamas. Neurologic signs progressed from ataxia to paresis, and eventually paralysis. In the hematologic and serum biochemical analyses, only eosinophil count was significantly elevated in the post-exposure samples in the infected groups. Protein was significantly elevated and Pandy test was positive in CSF of infected llamas. This study comprehensively describes the clinical progression of P. tenuis infection in llamas that will prove helpful in future studies to investigate the possibilities of developing antemortem diagnostic tests and new therapeutic programs.