Land-use effects on prevalence of raccoon roundworm (Baylisascaris procyonis)

The raccoon (Procyon lotor) is the definitive host of Baylisascaris procyonis, a large intestinal roundworm that is zoonotic and can result in fatal or severe central nervous system disease in young children. Prevalence of infection among raccoon populations often is high, and in the midwestern United States, B. procyonis has been reported in 68-82% of raccoons. Raccoon populations have increased in response to changes in human land use, and often reach higher densities in urban and suburban landscapes than rural landscapes. However, shifts in foraging behavior among urban raccoons could impact the transmission of B. procyonis if small vertebrate intermediate hosts are not a significant part of the raccoon diet. The objective of this study was to compare prevalence of B. procyonis infection between urban and rural raccoon populations on a regional scale. Necropsy was done on 204 raccoons collected from September through February during 2000-2005 from seven states across the Midwest (regional sample). Baylisascaris procyonis was found in 54% of examined raccoons. Prevalence differed between land-use types (chi2=11.56, df=1, P=0.0007), and was higher among animals collected from rural locations (65%) than those collected in urban locations (41%). Intensity of infection also differed (F=5.52, df=1, P=0.02), with rural raccoons having greater worm burdens (x=29.63+/-36.42) than urban raccoons (x=13.85+/-18.47). Despite high densities of raccoons in urban landscapes, fewer urban raccoons were infected with B. procyonis, suggesting decreased dependence on intermediate hosts as a food source. This possible explanation was supported by a similar trend in prevalence among subsamples of raccoons collected from three Chicago-area populations (local samples) with differing levels of urbanization, population densities, and foraging behavior that had been intensively monitored during 1995-2002. Decreased transmission of B. procyonis in urban landscapes may be due to decreased predation of intermediate hosts, and contact of juvenile raccoons with B. procyonis eggs may be an important factor in maintaining infections within such populations.     

Distribution, prevalence, and genetic characterization of Baylisascaris procyonis in selected areas of Georgia

Baylisascaris procyonis is an intestinal nematode of raccoons (Procyon lotor) that can cause fatal larval migrans in numerous species of birds and mammals, including humans. Although this parasite has historically been absent in the southeastern United States, it has been found in isolated regions in the Appalachian Mountains and was recently documented in DeKalb County, Georgia. The first objective of the current study was to investigate the distribution and prevalence of B. procyonis in selected populations of raccoons in Georgia. Intestinal tracts of 312 raccoons from 25 Georgia counties were examined for B. procyonis. The only county where B. procyonis was detected was Clarke County, where 12 of 116 (10.3%) raccoons were infected. In Clarke County, significantly more juveniles (P = 0.049) were infected compared with adults, and no differences in prevalence were noted by sex, season of capture, or land use (rural vs. urban); however, significantly (P = 0.0370) higher worm burdens were found in infected raccoons from urban/suburban locations compared with rural areas. In addition, Toxascaris leonina , a morphologically similar ascarid, was found in 3 raccoons from Clarke County (n = 2) and Morgan County (n = 1). A second objective was to determine if sequence polymorphisms were associated with B. procyonis from different geographic regions. Because sequences from a single worm from Japan had been entered into GenBank, we obtained nematodes from Kentucky and Texas for comparison with our samples from Georgia. Sequence analysis of the 18S and 5.8S rRNA genes and the internal transcribed spacer (ITS) -1 and ITS-2 regions confirmed Georgia samples were B. procyonis. Although several polymorphic bases were observed within both ITS regions, none was associated with a particular geographic location. These data indicate that the distribution of B. procyonis within Georgia is increasing and only limited genetic variation is present in the rRNA and ITS gene regions among B. procyonis from the southern United States and introduced populations in Japan.     

Prevalence of patent Baylisascaris procyonis infection in raccoons (Procyon lotor) in Ithaca, New York

The prevalence of patent Baylisascaris procyonis infection in raccoons was determined by examining fecal samples collected between July 1986 and May 1987 in Ithaca, New York. September, October, and November had the highest prevalence of infection (35-48%). Significant differences (P less than 0.001) were found when months were grouped by season to test the hypothesis that a fecal sample's probability of being positive does not vary from month to month. Fall was the season contributing most to the overall chi-square statistic. Host sex/age class and prevalence of patent infection were investigated. The raccoons were aged as either juveniles or adults. A significantly higher prevalence of patent infection (P less than 0.001) was found in juveniles when compared to adults. No statistically significant difference was found in other comparisons of host sex and age. Contingency analysis tested the independence of sex/age class/season and presence of eggs. The results of the test were significant (P less than 0.001).     

Frequency of deposition and location of Baylisascaris procyonis eggs in raccoon feces

Baylisascaris procyonis is a large ascarid nematode found in the small intestine of raccoons (Procyon lotor). Infection with larvae of B. procyonis can produce visceral, ocular, and neural larval migrans in humans. Infected raccoons can shed millions of eggs a day in their feces. However, it is unknown whether eggs are consistently shed or whether eggs occur at irregular intervals by the population of female nematodes within a host. We trapped, infected, and collected daily fecal samples from 11 raccoons maintained in captivity. Eggs from B. procyonis were obtained from anterior, central, and posterior sections of raccoon feces, isolated by flotation, and quantified under 100× magnification. Naturally infected raccoons were collected and used as a comparison with the experimentally infected group. All raccoons in the experimental group (n=11) became infected with B. procyonis after consuming one infected mouse. Additionally, differential egg deposition rates were observed among individual raccoons from the experimental and naturally infected groups. Mean number of eggs per gram of feces (means±SE) was 16,563±4,321, which was less than previously reported for the species. However, no differences (F(2,30)=0.84, P=0.45) were noted in mean number of eggs per gram of feces among fecal sections. Wildlife biologists, veterinarians, health officials, and researchers of B. procyonis should collect daily fecal samples for a minimum of 3 days before identifying a raccoon as negative for B. procyonis infection. However, it does not matter where within the fecal matter the sample is obtained.     

Helminths of the raccoon (Procyon lotor) in western Kentucky

Seventy raccoons (Procyon lotor) from western Kentucky were examined for helminths from December 1985 through May 1986. Twenty-three species of helminths were collected including 10 species of Trematoda (Brachylaima virginiana, Euryhelmis squamula, Eurytrema procyonis, Fibricola cratera, Gyrosoma singulare, Maritreminoides nettae, Mesostephanus appendiculatoides, Metagonimoides oregonensis, Paragonimus kellicotti, Pharyngostomoides procyonis), 2 species of Cestoda (Atriotaenia procyonis, Mesocestoides variabilis), 10 species of Nematoda (Arthrocephalus lotoris, Baylisascaris procyonis, Capillaria putorii, C. plica, Crenosoma goblei, Dracunculus insignis, Gnathostoma procyonis, Molineus barbatus, Physaloptera rara, Trichinella spiralis), and 1 species of Acanthocephala (Macracanthorhynchus ingens). A mean of 6.4 (3-11) helminth species per host was recorded. Fibricola cratera, Atriotaenia procyonis, Mesocestoides variabilis, Arthrocephalus lotoris, Capillaria plica, Dracunculus insignis, Molineus barbatus, and Physaloptera rara were ubiquitous parasites of the raccoon, whereas specific nidi were observed for Eurytrema procyonis, Gyrosoma singulare, Paragonimus kellicotti, Baylisascaris procyonis, Trichinella spiralis, and Macracanthorhyncus ingens. With an overall prevalence of 10% or higher, 15 of the 23 helminth species were considered common parasites of the raccoon in western Kentucky. When the 10% prevalence rate was applied within geographical quadrants to correct for the presence of nidi it was found that 18 of the 23 helminth species were common and 5 were regarded as rare parasites of the raccoon. Two species of nematodes, T. spiralis and B. procyonis, displayed a markedly higher prevalence in male raccoons.     

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

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.     

Horizontal and vertical ectoparasite transmission of three species of Malophaga, and individual variation in european bee-eaters (Merops apiaster)

Dispersal of avian ectoparasites can occur through either vertical transmission from adult birds to their offspring in the nest or through horizontal transmission between adult birds or through phoresy. In this study, we investigated the importance of the 2 main transmission modes in the colonial European bee-eater and examined whether individual differences in ectoparasite intensity exist in relation to age, sex, and morphological features of the birds. The intensity of 3 chewing lice species was investigated. Almost all adult bee-eaters (98.3%, n = 176) were infested with 1 of the 3 ectoparasite species, whereas only 10.8% (n = 167) of all chicks were infested. Meropoecus meropis was the most frequent ectoparasite species on adult bee-eaters (prevalence 94.3%), whereas Meromenopon meropis was the most common species on chicks (prevalence 9.6%). Our results suggest that chewing lice are mainly horizontally transmitted among adult bee-eaters and mainly among pair members, whereas vertical transmission between parents and nestlings is less frequent. These conclusions were supported by a relation in ectoparasite intensity of pair members and a parasite removal experiment. Ectoparasite intensity was in general low in nestlings and did not correlate with ectoparasite intensity of their parents. Host age, sex, weight, and other morphological features did not explain variation in chewing lice infestation.     

Prevalence of Baylisascaris procyonis in habitat associated with Allegheny woodrat (Neotoma magister) populations in Indiana

Allegheny woodrat (Neotoma magister) populations have been in decline across their range since the late 1970s. Hypotheses proposed to explain these declines include habitat fragmentation and loss, decreased food availability, and increased mortality from infection with Baylisascaris procyonis. We investigated the prevalence of B. procyonis at raccoon (Procyon lotor) latrines in woodrat cliff habitats (n = 18) along the Ohio River in southern Indiana in 1995. We located 275 latrines (mean = 15.3/site; range, 6-34) and found B. procyonis in 13 (4.7%) latrines across all sites. When present at a site, B. procyonis occurred, on average, at 11.1%of latrines (range, 3-36%). Woodrat abundance, determined through a concurrent live-trapping program, was significantly higher (χ(2) = 5.12, df = 1, P = 0.024) at sites where B. procyonis was not found (9.5 ± 2.52) than at sites with B. procyonis (3.7 ± 2.2). Our analyses support the hypothesis that this parasite could contribute to declines in woodrat abundance. Because woodrats cache nonfood items, including raccoon feces, and are highly susceptible to the parasite, they are at increased risk for B. procyonis infection, which could be deleterious, especially to small populations.     

Hemoparasites of raccoons (Procyon lotor) in Florida

Four hemoparasite species (Babesia lotori, Trypanosoma cruzi, Dirofilaria tenuis and Mansonella llewellyni) were found in raccoons (Procyon lotor) collected from 1972 to 1974 in Duval (n = 14) and Collier (n = 170) counties, Florida (USA). Trypanosoma cruzi was found in thin blood smears from one raccoon at each locality. The prevalence of B. lotori was 79% and 80% in samples taken in December 1973 in Collier and Duval counties, respectively. No patent infections by B. lotori were detected in raccoons collected in Collier County in December 1972, but 42% of the raccoons examined in September 1973 were infected. In Collier County there were no significant differences in the prevalence of B. lotori by host sex or age. In Duval County, overall D. tenuis prevalence was 7%, whereas that of M. llewellyni was 14%; the latter species was not found in Collier County. Adult raccoons had a significantly greater prevalence of D. tenuis (32%) than did subadults and juveniles (7%), and male raccoons showed a significantly greater prevalence (51%) than did females (8%).     

Baylisascaris procyonis (Nematoda: Ascaridoidea) eggs in raccoon (Procyon lotol) latrine scats in Orange County,California

Baylisascaris procyonis is the common intestinal nematode of the raccoon and is well-recognized as a cause of visceral, ocular, and neural larva migrans in many species of wild and domestic birds and mammals, including humans. To develop data on the prevalence of B. procyonis in Orange County, California, 800 distinct raccoon latrine sites were sampled in 4 spatial zones from 15 January to 31 December 2000. Counts of fecal eggs per gram (EPG) were determined and evaluated with reference to spatial zone and season of collection. No significant differences in EPG were noted among the spatial zones. However, EPG exhibited a significant rise (37,730 +/- 1,865) in the fall and a significant decline (26,204 +/- 1,446) in the winter (ANOVA, P = 0.045). The overall egg prevalence was 100%, and the overall mean EPG was 30,265 +/- 867.     

Survey of raccoons on Key Largo, Florida, USA, for Baylisascaris procyonis

Numbers of the endangered Key Largo woodrat (KLWR; Neotoma floridana smalli) have been declining for at least 25 yr. The raccoon (Procyon lotor) roundworm, Baylisascaris procyonis, has been found to have an adverse effect on the survival of Alleghany woodrats (N. magister). High densities of raccoons can exacerbate this problem by increasing the amount of feces containing viable eggs of B. procyonis available to woodrats. In 2002, 64 fecal samples were collected and examined for eggs of B. procyonis from >32 raccoons within the KLWR's known range on Key Largo, Florida, USA. All samples were negative for eggs of B. procyonis. Raccoon density in this area was approximately 0.62 raccoons/ha. Despite this high density of raccoons, B. procyonis does not appear to be a threat to the KLWR population.     

Capillaria procyonis (Nematoda: Trichuroidea) eggs from the tongue of the raccoon (Procyon lotor)

During an investigation to determine the prevalence and intensity of larvae of Trichinella spiralis in raccoons (Procyon lotor), unembryonated capillariid-type eggs were found routinely in the sediment resulting from 1% pepsin-HCl acid digests of the tongue. The sediment from 36 (90%) of the 40 tongue digests examined contained these capillariid-type eggs. Mean measurements of egg width and length were 25 +/- 2 microns and 62 +/- 2 microns, respectively. In addition, the surface of the egg shell had a pitted appearance. Adult parasites were not found in any of the tongue digests. The egg measurements and surface topography agree with what has been described previously and are tentatively identified as Capillaria procyonis. The detection of C. procyonis eggs in the present report indicates that this parasite inhabits the epithelial lining of the raccoon tongue, in addition to the esophagus, and that eggs expelled by females are deposited in the tracts these parasites create as they migrate.     

Aspects of the ecology and natural history of Paraergasilus rylovi (Copepoda, Ergasilidae) parasitic in unionids of Finland

The distribution of Paraergasilus rylovi in 17 populations of unionids was investigated. In 1 unionid population, the parasite was studied regarding host age, size, sex, and the reproductive period (occurrence of egg sacs). Results from pooled material from the years 1987--1989 and 1996 (southern Finland, 11 populations) indicated that Anodonta piscinalis (n = 1,359) is the main host (total mean prevalence 71% and intensity +/-SE of infection 16.4+/-0.6). Pseudanodonta complanata (n = 106) was infected occasionally (3% and 1.3+/-0.3), whereas Unio pictorum (n = 108) and U. tumidus (n = 17) were not infected. Results from 17 A. piscinalis populations showed that P. rylovi occurs in southern Finland but not in northern Finland. In A. piscinalis, the mean intensity of infection was higher in lake populations than in river populations. Both host age and length had a negative relationship with the intensity of P. rylovi infection. Host sex did not affect the intensity of infection. Egg sacs of P. rylovi were found from June to August. There was a tendency for higher intensities of infection in autumn. Infection by the digenean Rhipidocotyle fennica had no effect on the intensity of P. rylovi infection.     

Oral transmission of Trypanosoma cruzi with opposing evidence for the theory of carnivory

We present the first demonstration of oral transmission of Trypanosoma cruzi to raccoons (Procyon lotor), a natural reservoir host in the United States, by ingestion of trypomastigotes and infected bugs, but not infected tissue. To investigate an alternative, non-vector-based transmission method, we tested the hypothesis that raccoons scavenging on infected hosts results in patent infection. Macerated tissue from selected organs infected with amastigote stages of T. cruzi was orally administered to experimental groups of raccoons (n = 2/group) at 2, 12, or 24 hr after collection of the tissue samples. Additionally, raccoons (n=1) in control groups were inoculated intravenously or per os with trypomastigotes. To further elucidate transmission routes of T. cruzi to raccoons, infected Rhodnius prolixus were fed to raccoons (n=2). Raccoons did not become infected after ingestion of amastigote-infected tissues as evidenced by negative polymerase chain reaction results from blood and tissue, lack of seroconversion, and negative parasitemias. However, per os transmission can occur by ingestion of the infective trypomastigote stage or infected reduviid bugs. We conclude from these findings that oral transmission of T. cruzi may be a route of infection for wildlife in sylvatic cycles, but the scavenging behavior of animals is not likely a significant transmission route.     

Eimeria and sarcocystis in raccoons in Illinois

Eimeria nuttalli oocysts were found in 58% (21/36) and E. procyonis oocysts in 25% (9/36) of raccoons Procyon lotor in Illinois, and sporocysts of Sarcocystis sp. in 17% (2/12) of other raccoons in Illinois. The oocysts of E. nuttalli were ellipsoidal to ovoid, 15-21 X 12-17 micrometer, with a one-layered, smooth, colorless wall. The oocysts of E. procyonis were 22-28 X 18-22 micrometer, with a rough, striated, brownish, two-layered wall. The sporulated sporocysts of Sarcocystis sp. were 11-13 X 8-10 micrometer. Attempts to infect baby pigs by feeding them sporocysts of Sarcocystis sp. from the reaction failed.     

Periodontal and dental lesions in raccoons from a farming and a recreational area in Illinois

Dental health was evaluated in two populations of raccoons (Procyon lotor) in western Illinois (USA); one was from a rural agricultural area with low human density and the other from a nearby state park heavily used by humans and raccoons. From 1989 through 1993, 300 raccoons were live-trapped in the agricultural area and 246 raccoons were live-trapped in the park. Oral health was assessed using gingival and calculi indices and by measuring loss of attachment and tooth wear. Raccoons from the park were significantly older and smaller, but not thinner, than raccoons from the farmed area. Gingival and periodontal indices, tooth wear, tooth loss, and caries increased significantly from juveniles to yearlings to adults, at both sites. Males had higher levels of gingivitis and loss of periodontal attachment than females, but were similar on other dental measures. There were no seasonal differences between raccoons in dental indices. Animals with high scores for one oral measure tended to have high values for all indices. Dental health was generally good for juveniles and yearlings from both sites. Among adults, periodontal indices and the prevalence of caries were significantly higher in the park, but prevalence of broken or missing teeth was similar for both populations. There was no association between body condition, and a higher dental score or more missing or broken teeth.     

Community ecology of the metazoan parasites of pink cusk-eel,Genypterus brasiliensis (Osteichthyes: Ophidiidae), from the coastal zone of the State of Rio de Janeiro,Brazil

Fifty-five specimens of pink cusk-eel, Genypterus brasiliensis Regan, 1903 (Osteichthyes: Ophidiidae) collected from the coastal zone of the State of Rio de Janeiro, Brazil (approx. 21-23 degrees S, 41-45 degrees W), from September 2000 to January 2001, were necropsied to study their parasites. All fish were parasitized by one or more metazoan. Fourteen species of parasites were collected. G. brasiliensis is a new host record for nine parasite species. The larval stages of cestodes and the nematodes were the majority of the parasite specimens collected, with 38.4% and 36.5%, respectively. Cucullanus genypteri was the dominant species with highest prevalence and/or abundance. The parasites of G. brasiliensis showed the typical overdispersed pattern of distribution. Six parasite species showed correlation between the host's total body length and prevalence and abundance. Host sex did not influence prevalence and parasite abundance of any parasite species. The mean diversity in the infracommunities of G. brasiliensis was H= 0.364 +/- 0.103, with correlation with the host's total length and without differences in relation to sex of the host. One pair of adult endoparasites (C. genypteri and A. brasiliensis) showed positive covariations between their abundances. Negative association or covariation was not found. Differences between the qualitative and quantitative aspects of the parasite community of G. brasiliensis from Rio de Janeiro and Argentina suggest the existence of two population stocks of pink cusk-eel in the South America Atlantic Ocean.     

Lost and found: Helminths infecting invasive raccoons introduced to Italy

North American raccoons (Procyon lotor) have been introduced to several European countries, where they may represent a sanitary threat as hosts of several pathogens such as the zoonotic ascarid Baylisascaris procyonis. We carried out parasitological analysis on raccoons introduced to Italy to verify whether the species had carried along B. procyonis or any other gastro-intestinal helminths that may threaten humans, livestock or native wildlife. We examined 64 raccoons culled in Northern Italy during control activities and 3 roadkills opportunistically sampled from a separate population located in central Italy. Helminths were collected from the gastro-intestinal tract through standard parasitological techniques and identified based on a combination of morphology and molecular methods. Overall, examined raccoons showed a poor parasitic fauna, with almost 30% of individuals free of any helminth infection. The most prevalent species were the nematodes Strongyloides procyonis (26.9%), Aonchotheca putorii (25.4%) and Porrocaecum sp. (19.4%). Plagiorchis sp. trematodes were also common (13.4%), whereas cestodes were scarcely represented. With the exception of S. procyonis introduced from North America, all the other identified taxa have either a Eurasian or a wide Holarctic distribution. Despite not finding any B. procyonis in the examined raccoons, passive surveillance for this parasite should be implemented, especially in Tuscany, since the limited host sample examined in the present survey does not allow to exclude its presence.     

Epizootiology of an outbreak of cerebrospinal nematodiasis in cottontail rabbits and woodchucks

An epizootic of cerebrospinal nematodiasis in cottontail rabbits (Sylvilagus floridanus) and woodchucks (Marmota monax) caused by Baylisascaris procyonis larvae followed the establishment of an ascarid-infected raccoon (Procyon lotor) population in a woodlot. Five of seven raccoons examined from the woodlot harbored ascarids, with one heavily infected animal shedding approximately 27,500 eggs per gram of feces. A laboratory-reared cottontail rabbit developed neurologic disease due to larval migration 80 days after infection with B. procyonis eggs from the raccoons.