Genetic characterization of the meningeal worm Parelaphostrongylus tenuis from multiple host species and across spatial scales

Parelaphostrongylus tenuis is a metastrongylid nematode harbored by white-tailed deer (Odocoileus virginianus) and is transmitted by ingesting infected gastropod intermediate hosts while grazing. In atypical hosts including... [ view full abstract ]

Parelaphostrongylus tenuis is a metastrongylid nematode harbored by white-tailed deer (Odocoileus virginianus) and is transmitted by ingesting infected gastropod intermediate hosts while grazing. In atypical hosts including moose (Alces alces) and elk (Cervus canadensis), P. tenuis infection causes severe neurological disease and death due to nematode migration within the central nervous system. Although P. tenuis is commonly distributed throughout northeastern and select parts of southeastern North America, nothing is known about the genetic diversity of this parasite. To better understand the genetic population structure, 36 adult P. tenuis were collected from five different host species in seven different states, including 27 white-tailed deer and nine clinically diseased animals. The second internal transcribed spacer region and the cytochrome oxidase I and II genes were amplified, cloned, sequenced, and compared against known P. tenuis sequences in GenBank. Bioinformatic and phylogenetic analysis of the sequences revealed limited variation between isolates, with the majority of P. tenuis samples (68%) clustering into a single genotype. No geographic or host patterning associated with genotypes was observed. The lack of intraspecies diversity and the absence of geographical and host patterning suggests P. tenuis may have undergone a recent genetic bottleneck event. One explanation could be the near extirpation of deer from North America during the 1800s and early 1900s. Significant loss in deer host numbers likely resulted in a significant decrease in environmental parasite load and thus parasite diversity. This study represents the first attempt to genetically characterize the P. tenuis parasite and suggests past anthropogenic activities may have significantly shaped the parasite’s current population genetic structure.