Ascarididae (Nadler and Hudspeth, 2000)

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 : 86

1.1. History and relationships within Ascarididae

Baylisascaris is a genus within the family Ascarididae , comprising mostly heteroxenous nematodes with carnivorous definitive hosts. Baylisascaris procyonis , the raccoon roundworm, is by far the most well-known and extensively studied member of the genus, primarily because of its association with severe neurologic disease in humans and numerous species of animals. As a consequence, many other Baylisascaris species are relatively poorly studied compared to B. procyonis . Here, we review the life history and current knowledge of non-raccoon Baylisascaris spp. in the Americas.

The genus Baylisascaris was officially described in 1968 and was named in honor of parasitologist H. A. Baylis of the British Museum of Natural History ( Sprent, 1968). This genus united some previous members of Ascaris and Toxascaris and was mainly differentiated from other ascarid genera based on the presence of pericloacal rough patches and subventral postcloacal papillae (versus the absence of subdorsal postcloacal papillae as in Toxascaris ) ( Sprent, 1968). Former members of Ascaris reassigned into Baylisascaris include B. devosi , B. columnaris , B. procyonis , and B. laevis , while B. transfuga and B. melis were formerly within the genus Toxascaris . While Baylisascaris and Toxocara share biological similarities and are often discussed together in the context of zoonotic ascarids, they are in different subfamilies and are well-separated within Ascarididae ( Nadler and Hudspeth, 2000) . Molecular phylogenetic analyses of several genetic targets also support the separation of Baylisascaris from other ascarid genera ( Zhu et al., 1998; Nadler and Hudspeth, 2000; Franssen et al., 2013; Tokiwa et al., 2014).