Baylisascaris devosi (Sprent, 1953)

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

2.4. Baylisascaris devosi

Baylisascaris devosi infects North American mustelids belonging to the clade Guloninae (martens, fishers and wolverines), which are all carnivorous mammals that inhabit forests in the northern United States and Canada ( Ruggiero et al., 1994; Li et al., 2014) ( Table 5). B. devosi was formally described by Sprent (1952a) showing that parasites from fisher ( Martes pennant ) and marten ( Martes americana ) were distinct from B. columnaris from striped skunks. Prior to the description of B. devosi , a specimen from a Pacific marten ( Martes caurina ) in Idaho was recorded as B. columnaris but this parasite was likely B. devosi ( Sprent, 1952a; Marshall, 1942). Baylisascaris devosi can be distinguished from B. columnaris by several morphologic characteristics including body length, length of spicules, the position of the vulva, and the width of denticles on the dentigerous ridges. Specimens recovered from fisher were longer than those parasites recovered from martens ( Sprent, 1952a). Egg sizes range from 58‾77 × 51‾61 M m ( Sprent, 1953a). However, given potential overlap in morphometric features, species identification should be confirmed using molecular analysis.

Eggs of B. devosi can become fully larvated in 12 days and remain infective for at least one year ( Sprent, 1953a,b). In experimentally-inoculated laboratory mice, larvae migrated out of the intestine and by three days were found in the heart, lungs, brain and kidney. Mice showed severe symptoms of pulmonary disease between 3 and 4 DPI and lungs were dark red ( Sprent, 1952b). By 8‾12 DPI, larvae were present in muscular and subcutaneous tissues of the neck, shoulders and thorax. These third stage larvae remained encapsulated in muscle tissue for at least 6 months. Larvae from a mouse infected for 25 days were infective to a domestic ferret ( Sprent, 1953b). Larvae appear to be tolerant to freezing as larvae recovered from mice> 3 weeks post infection were motile after being frozen at –20 C for up to 8 weeks, but it is unknown if they were infectious to a definitive host ( Sprent, 1953b). If larvae remain infectious following freezing, this would facilitate transmission of B. devosi from frozen carcasses that may be scavenged by a definitive host. Experimental inoculation of several adult and juvenile domestic ferrets and a single skunk via infected mouse carcasses established patent infections. An attempt to inoculate a single adult marten by the same manner was unsuccessful, but perhaps this wild-caught animal had pre-existing immunity to B. devosi ( Sprent, 1953b) .

Most larvae recovered from laboratory mice hosts experimentally infected with B. devosi were concentrated in the cervical and thoracic musculature ( Sprent, 1953b). This localization of infection may be adaptive because marten are known to attack the head and neck region of prey and occasionally discard the rest of the carcass ( Powell et al., 2003; Sprent, 1953b). If this concentration of B. devosi larvae in the anterior region occurs in natural paratenic hosts, larvae may be more likely to be ingested by the definitive mustelid host.

In the future, molecular studies on parasites recovered from free-living hosts could help more accurately identify B. devosi from other Baylisascaris species, which will provide important data on prevalence and host specificity. Further, experimental trials on B. devosi in various suspected or known natural definitive hosts would provide data on host suitability.