Baylisascaris melis (Kazakos, 2001)

Sapp, Sarah G. H., Gupta, Pooja, Martin, Melissa K., Murray, Maureen H., Niedringhaus, Kevin D., Pfaff, Madeleine A. & Yabsley, Michael J., 2017, Beyond the raccoon roundworm: The natural history of non-raccoon Baylisascaris species in the New World, International Journal for Parasitology: Parasites and Wildlife 6 (2), pp. 85-99 : 94-95

2.5. Baylisascaris melis

The definitive hosts of Baylisascaris melis are North American badgers ( Taxidea taxus ) and European badgers ( Meles meles ). The parasite was first described from European badgers in Belgium ( Gedoelst, 1920). Morphological characteristics of B. melis are similar to those of B. transfuga ; both of these species have salient alae, as opposed to the vestigial alae of other Baylisascaris spp. ( Sprent, 1968). There have been multiple reports of ascarids in wild North American badgers that are assumed to be B. melis although most were reported as A. columnaris ( Table 6). Contemporary studies, including molecular characterization, on this parasite are needed to confirm the identity of parasites from North American badgers and their conspecificity with B. melis from European badgers.

Baylisascaris melis can cause larva migrans in experimentally infected rodents. Tiner (1953a) fed 2000‾3000 eggs collected from a naturally-infected badger in Wyoming to four rodent species: ground squirrel ( Citellus armatus ), laboratory mice, deer mice ( Peromyscus maniculatus ) and guinea pigs. Only the ground squirrels (5 of 7 infected) developed neurologic disease; however, larvae were found in the brains of the deer mice and encapsulated in the skeletal muscle of all four species ( Tiner, 1953a). In one ground squirrel, larvae were recovered from the lungs and were widely distributed in the skeletal muscle, with greatest abundance in the intercostal spaces under the parietal pleura of the diaphragm. In P. maniculatus , B. melis larvae were encapsulated in the mesentery of the small intestine, on the epicardial surfaces, and in the brain on 3 DPI ( Tiner, 1953b).

Although B. melis can cause central nervous system disease in experimentally-infected rodent species, there have been no confirmed cases of natural B. melis infections in wild rodents ( Boyce et al., 1988; Kazakos, 2001; Tiner, 1953a,b). However, neurologic cases due to Baylisascaris sp. diagnosed in ground squirrels and other rodents in regions where the badger ranges overlap with raccoons could be due to B. melis ( Kazakos, 2001) . In future cases, identification of larvae in these cases using molecular techniques is needed to better understand the role of non- B. procyonis species in cases of neurologic disease in wildlife. Also, serum from mice infected with B. melis cross-reacted with larval excretory-secretory antigens from B. procyonis ( Boyce et al., 1988) , so it is important to consider B. melis as a possible etiologic agent of hosts with antibodies to Baylisascaris spp. in areas where badgers and raccoons are sympatric.