Meningeal worm is a long-lived parasitic nematode in white-tailed deer.

A natural infection of the meningeal worm, Parelaphostrongylus tenuis, persisted for at least 3.7 yr in a white-tailed deer (Odocoileus virginianus). The deer was 5-7 yr old and was shedding dorsal-spined nematode larvae at the time of quarantine. Larvae were extracted from all fecal samples collected up to 730 days post-quarantine (dpq) and thereafter only at 862 dpq and at necropsy (1,350 dpq). Live adults of P. tenuis, one male and one female, were recovered from the cranium at necropsy. Parelaphostrongylus tenuis infections are long lived and latent periods may be extended. Our findings reaffirm the need for reliable antemortem diagnosis to identify non-patent P. tenuis infections to prevent inadvertent introduction of infected animals to non-endemic areas.