Changes in transmission of Baylisascarisprocyonis to intermediate hosts as a function of spatial scale

Abstract

2001. Changes in transmission of Baylisascaris procyonis to intermediate hosts as a function of spatial scale. -Oikos 93: 213-220.Physical changes in landscapes alter the abundance and distribution of species. Higher-order effects can occur when changes in ecological processes result in altered interspecific interactions and subsequent changes in a species' abundance or persistence. Baylisascaris procyonis, a roundworm parasite of raccoons (Procyon lotor), is pathogenic to numerous small vertebrates that serve as intermediate hosts, including white-footed mice (Peromyscus leucopus). Raccoons have responded positively to agriculturally induced changes in landscapes, with potential consequences for intermediate hosts of B. procyonis. We examined white-footed mice from a homogeneous, predominantly forested landscape in south-central Indiana and a heterogeneous, predominantly agricultural landscape in northwestern Indiana for presence of larval B. procyonis. We compared prevalence of infection, intensity of infection, and average number of larvae per mouse between the landscapes, and among forest patches within the highly fragmented agricultural landscape. Prevalence, intensity of infection, and average number of larvae were significantly higher in the highly fragmented landscape. Within the agricultural landscape, regression models predicted probability of infection, intensity of infection, and average number of larvae per mouse per patch as functions of forest patch area and isolation. We conclude that positive responses of raccoons to agriculturally induced fragmentation of forests have resulted in increased encounter rates between white-footed mice and infective stages of B. procyonis between and within landscapes, resulting in increased transmission of the parasite to intermediate hosts.

Effects of Urbanization on Prevalence of Baylisascaris procyonis in Intermediate Host Populations

“…Probability of infection at individual sites ranged from 17% to 42%, and was 33% across all sites (Table 1). Overall, prevalence was slightly higher in our study than the 28% observed by Page et al (2001a) in a fragmented agricultural land- scape in Indiana and the 29% prevalence that Eagan (2009) found in a similar agricultural landscape. Prevalence was much higher than the 6% observed in a large, intact forest by Page et al (2001a).…”

“…populations near Chicago, Illinois, USA. Mice are a common intermediate host of the parasite (Page et al, 2001b). Though both whitefooted (Peromyscus leucopus) and deer mice (Peromyscus maniculatus) likely occurred at our study sites, we combined the species for analysis because of the difficulty of making a definitive species identification for many individuals.…”

Update on Baylisascariasis, a Highly Pathogenic Zoonotic Infection

“…Susceptibility varies across species lines, but most paratenic hosts are highly susceptible to B. procyonis infection and suffer clinical effects of NLM (1). In a survey in a fragmented agricultural landscape, Page et al (28) found a large proportion (28%) of white-footed mice (Peromyscus leucopus) to be infected with B. procyonis larvae, and this species appears to represent a common and well-adapted paratenic host. Experimentally, most P. leucopus mice became infected at a lower level and had a longer average onset of CNS disease than laboratory mice (Mus musculus), but the majority still developed clinical signs (19).…”

First parasitological survey of Endangered Bornean elephants Elephas maximus borneensis

“…In 2012 for the very first time, a chapter in a conservation textbook was dedicated to links be tween habitat loss, habitat fragmentation and infectious disease ecology (Suzan et al 2012). Habitat loss and fragmentation can affect infection dy namics via a variety of mechanisms, including hindering animal movement, impeding gene flow (Coulon et al 2004), facilitating edge effects (Chapman et al 2006a), introducing environmental contamination (Deem et al 2001), altering the ecology of intermediate hosts (Page et al 2001), changing host population size and density (Mbora & McPeek 2009), limiting nutrition (Chapman et al 2006b), facilitating contact and conflict with people (Nelson et al 2003), and subjecting animals to psychological and physiological stress, thereby affecting immunocompetence (McCallum & Dobson 2002). Parasites have the potential to be used as indicators of stress in wildlife threatened by habitat fragmentation (Schwitzer et al 2010).…”