Academic journal article The American Midland Naturalist

Raccoon Latrine Structure and Its Potential Role in Transmission of Baylisascaris Procyonis to Vertebrates

Academic journal article The American Midland Naturalist

Raccoon Latrine Structure and Its Potential Role in Transmission of Baylisascaris Procyonis to Vertebrates

Article excerpt

ABSTRACT.-Baylisascaris pro conis, the common large roundworm of raccoons (Procyon lotor), causes clinical neurologic disease in many species of mammals and birds. Infective eggs of B. procyonis are present at raccoon latrine sites, and these sites may be important in the transmission of this parasite to syntopic small vertebrates in forested areas. We located raccoon latrines in forested sites in Indiana, sampled soil and fecal material from these locations, and examined these samples for the presence of Baylisascaris procyonis eggs. We also quantified the structural characteristics of raccoon latrines in wooded areas, compared their characteristics with randomly located sites, and classified sites based on structural features using stepwise discriminant function analysis. B. procyonis eggs were present at 14% of the raccoon latrines sampled. Latrine sites differed from randomly located sites and exhibited characteristics generally associated with treefall gaps. Most latrines were located either on logs (49%) or at the base of large trees (37%). Structural features surrounding latrines often are important travel routes or foraging areas for various small vertebrates. The visitation of mammals and birds to sites exhibiting these structural features may result in infection with B. procyonis. In this way, Baylisascaris procyonis could have long-term impacts on populations of native mammals and birds.

INTRODUCTION

Descriptions of habitats used by raccoons (Procyon lotor) commonly refer to the presence of tree cavities, downed logs and rocky crevices (Giles, 1942; Stuewer, 1943; Berner and Gysel, 1967; Lehman, 1977, 1984; Kennedy et al., 1991). Snags and logs are important components of raccoon habitat that provide den and refuge sites, travel routes, and sources of invertebrates suitable for food (Kennedy et al., 1991). These features also are associated with accumulations of raccoon feces resulting from habitual defecation at sites called latrines (Stains, 1956; Kennedy et al., 1991). Giles (1939), Stains (1956) and Yeager and Rennels (1943) described raccoon latrines as single or accumulated piles of scats on logs or at the base of trees. Latrines also have been observed occurring on large rocks, rock ledges, on the top of bluffs, near den entrances, on debris piles, on stumps, and in the crotches of large trees (Giles, 1942; Tevis, 1947; Yeager and Rennels, 1943; Tester, 1953; MacLintock, 1981; Cooney, 1989).

Our interest in raccoon latrines stems from the important role they appear to play in the transmission of Baylisascaris procyonis, the common large roundworm of raccoons, to small mammals and birds (Kazacos and Boyce, 1989; Sheppard and Kazacos, 1997). Young raccoons and a variety of intermediate host species become infected with B. procyonis through contact with larvated B. procyonis eggs which accumulate at raccoon latrines (Kazacos, 1983a; Kazacos and Boyce, 1989) . Prevalence of B. procyonis in raccoons in the midwestern and northeastern United States can be high (68-82%), leading to significant environmental contamination with eggs(Kazacos and Boyce, 1989). Adult female B. procyonis are prolific egg producers (Kazacos, 1982), and the average infected raccoon sheds about 20,000 eggs per gram of feces (Kazacos, 1983a). Baylisascaris eggs passed in raccoon feces embryonate to the infective larval stage in about 3-4 wk and can remain viable in the environment for at least 5-6 yr (Kazacos, 1983a; Kazacos and Boyce, 1989). Raccoon latrines thus become important foci of infective eggs (Jacobson et al., 1982; Cooney, 1989) and serve as longterm sources of infection for animals (Kazacos and Boyce, 1989; Sheppard and Kazacos, 1997). Intermediate hosts of B. procyonis become infected by accidentally ingesting infective eggs, presumably as a result of foraging at raccoon latrine sites or by grooming contaminated fur or feathers after traveling across a latrine (Sheppard and Kazacos, 1997).

Baylisascaris pr-ocyonis is remarkably nonspecific with regard to infection of potential intermediate hosts. …

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