Procyonis Infection Research Articles

Treatment of Baylisascaris procyonis infections in dogs with milbemycin oxime

An examination was made as to the ability of Sentinel ® Flavor Tabs ® (milbemycin oxime/lufenuron) to treat Baylisascaris procyonis infections in dogs. The study was designed as a critical trial and included five naturally infected dogs and two dogs that were experimentally infected. Another dog from a prior clinical trial that was treated with Sentinel Flavor Tabs as part of the original FDA submission package for intestinal nematode infections was also included with the treated dogs. Of the five naturally infected dogs treated as part of the critical trial, three were cleared of their infections. These five dogs passed a total of 52 worms after treatment; one dog retained 23 worms and the other retained 1 worm at necropsy 7 days after treatment. Two of five experimentally infected Beagle dogs that had been given mice that had been fed 200 infectious eggs, developed patent infections with the parasite. These dogs were treated, and one of the dogs passed one worm and the other passed two worms after treatment with no worms being detected at necropsy 7 days after treatment. The one dog that was treated with milbemycin oxime as part of the FDA submission was clear of worms at necropsy. Overall, the mean efficacy of Sentinel Flavor Tabs was found to be 91.0%. Of the eight dogs that were treated, six were totally cleared of their infections, a cure rate of 75%. The two dogs that did not clear their infections had very large numbers of adult B. procyonis within their intestinal tracts at the time of treatment, one dog had 40 worms (23 remaining) and the other had 26 worms (1 remaining). It is suggested that the treatment of dogs with monthly Sentinel Flavor Tabs could markedly reduce the chance of infected dogs contaminating the environment. Also, additional monthly treatments are highly likely to clear dogs of any worms not killed with the initial treatment.

Baylisascaris procyonisin California

To the Editor: We read with interest the article of Roussere et al. on the distribution of Baylisascaris procyonis eggs in northern California communities (1). The widespread dissemination and high density of raccoon latrines in residential areas clearly pose potential health risks, particularly to young children. While California has reported more cases of baylisascariasis than any other state, few published studies have reported on the distribution and prevalence of this helminth in the region. In 2001, we conducted a study to determine the presence of B. procyonis in the Santa Barbara area by examining roadkill raccoons recovered by animal control staff and stored in a refrigerated facility. On examination, the digestive tract from the stomach to the rectum was removed and tested for B. procyonis worms and eggs. Of 26 raccoons examined, 24 (92%, 95% confidence interval 75%–99%) were positive for B. procyonis infection. B. procyonis worms were found in 85% of the animals examined and eggs were found in 73%. Pet food was frequently found (43%) in the stomach contents of examined raccoons, indicating that such food was made accessible to these animals, either intentionally or inadvertently by residents. B. procyonis has been identified along the central coast of California, which expands the known range of this helminthic zoonotic agent. This finding, coupled with other published studies, indicates that Baylisascaris may be prevalent throughout the state (1,2). Although our study was based on a small sample of selected raccoons, the high infection rate is cause for concern and indicates the potential for human exposure. A presumptive case of B. procyonis infection in an 11-month-old child was reported in Santa Barbara in 2003 (1). Determining the distribution and prevalence of B. procyonis is necessary to inform local healthcare providers, public health authorities, and the public of the potential risk. Using road-kill raccoons is a relatively easy method for quickly assessing the presence of B. procyonis in a community. Also, this approach avoids trapping and handling live animals and allows stomach contents to be examined to determine where raccoons are feeding. Data from such assessments must be interpreted with caution, since they may not represent all raccoons in an area.

Raccoon Roundworm in Raccoons in Central West Virginia

Abstract We investigated the occurrence of raccoon roundworm (Baylisascaris procyonis) in common raccoons (Procyon lotor) in the Allegheny Mountains of West Virginia during spring (n = 9, April–June) and fall (n = 5, August–October) 2001 and spring (n = 7) and fall (n = 4) 2002. We found no evidence of B. procyonis infection in 25 raccoons sampled by fecal floatation and necropsy methodologies. However, we did detect Capillaria sp. eggs in 28% and Strongyloides sp. eggs in 64% of individual raccoons, respectively. Baylisascaris procyonis has been implicated in population declines of the Allegheny woodrat (Neotoma magister) in the northeastern United States. The low prevalence of B. procyonis in an area inhabited by what is believed to be a stable population of Allegheny woodrats supports conservation measures to continue to monitor anthropogenic activities that potentially may increase the prevalence of B. procyonis or raccoon interaction with Allegheny woodrats in the region.

Baylisascaris procyonis in the metropolitan Atlanta area.

Baylisascaris procyonis, the raccoon roundworm responsible for fatal larva migrans in humans, has long been thought to be absent from many regions in the southeastern United States. During spring 2002, 11 (22%) of 50 raccoons trapped in DeKalb County, Georgia, had B. procyonis infection. The increasing number of cases highlight this emerging zoonotic infection.

Causes and Clinical Features of Encephalitis

Causes and Clinical Features of Encephalitis

Eye findings of diffuse unilateral subacute neuroretinitis and multiple choroidal infiltrates associated with neural larva migrans due to baylisascaris procyonis

Purpose To report childhood infection with Baylisascaris procyonis (raccoon round worm) manifesting as diffuse unilateral subacute neuroretinitis (DUSN) and choroidal infiltrates in association with neurologic disease (neural larva migrans). Methods Observational case series, one with eye manifestations of DUSN, the other with choroidal infiltrates, both with severe neurologic degeneration. Results Indirect immunofluorescence assays on serum and cerebrospinal fluid were positive for B. procyonis in one and serially positive and increasing in the other. Both children had a history of pica and raccoon exposure. Conclusions Baylisascaris procyonis infection is associated with two cases of severe neurologic degeneration with ocular lesions: DUSN and choroidal infiltrates. Although B. procyonis is known to cause DUSN, these cases indicate that concomitant ocular migration may accompany neural larva migrans. These are the third and forth cases in the US literature of neural larva migrans due to B. procyonis with eye findings.

Diffuse retinochoroiditis due to Baylisascaris procyonis in Monglian gerbils.

Baylisascaris procyonis, raccoon roundworm, causes a severe retinal lesion in humans. The lesion is termed as diffuse unilateral subacute neuroretinitis (DUSN). To understand the pathogenesis of B. procyonis in gerbils, we inoculated 17 embryonated eggs/g body weight of B. procyonis into 15 male Mongolian gerbils, Merionis ungiculatus, and monitored their fundi with an ophthalmoscope. Six of 15 gerbils (40%) showed severe retinitis with a sinuous track due to larval movement. The lesions extended across nearly half of the affected fundi. Histopathological examination revealed perivasculitis in the optic disk region, inflammatory proliferation of the pigment cells, and vitreitis in most cases. These findings were similar to those in human cases of DUSN, suggesting that gerbils might be a useful model for understanding the pathogenesis of B. procyonis infection in humans.

Baylisascaris procyonis: an emerging helminthic zoonosis.

Baylisascaris procyonis, a roundworm infection of raccoons, is emerging as an important helminthic zoonosis, principally affecting young children. Raccoons have increasingly become peridomestic animals living in close proximity to human residences. When B. procyonis eggs are ingested by a host other than a raccoon, migration of larvae through tissue, termed larval migrans, ensues. This larval infection can invade the brain and eye, causing severe disease and death. The prevalence of B. procyonis infection in raccoons is often high, and infected animals can shed enormous numbers of eggs in their feces. These eggs can survive in the environment for extended periods of time, and the infectious dose of B. procyonis is relatively low. Therefore, the risk for human exposure and infection may be greater than is currently recognized.

FORAGING AMONG FECES: FOOD AVAILABILITY AFFECTS PARASITISM OF PEROMYSCUS LEUCOPUS BY BAYLISASCARIS PROCYONIS

Baylisascaris procyonis is a parasitic nematode of raccoons (Procyon lotor) capable of infecting many species of small vertebrates as intermediate hosts. In these hosts, migrating larvae often cause fatal or severe central nervous system (CNS) disease. Previous research suggested that intermediate hosts become infected with B. procyonis while visiting raccoon latrines. We tested effects of ambient availability of food and duration of exposure on dynamics of transmission of B. procyonis to white-footed mice (Peromyscus leucopus )i n a factorial design within enclosures containing artificially constructed raccoon latrines. Fifty percent of experimental mice acquired B. procyonis infections and 43% of infected mice developed CNS disease. Visitation to latrines was marginally greater (P 5 0.095) for mice subjected to low availability of ambient food. The mean number of larvae per mouse was greater (P 5 0.001) in low food group after exposures of 14‐28 days. Probability of infection varied predictably as a function of duration of exposure ( P 5 0.005), and probability of CNS disease varied predictably as a function of level of ambient food available (P 5 0.023). We conclude that transmission of B. procyonis occurs at raccoon latrines and that increased visitation to latrines and duration of residence in close proximity to a latrine, both increase probability of mortality due to CNS disease, especially when individuals are stressed by reduced resources or poor habitat.

Susceptibility of Peromyscus leucopus and Mus musculus to Infection with Baylisascaris procyonis

In this study, we compared the susceptibility of Peromyscus leucopus (white-footed mouse), a common natural intermediate host, and Mus musculus, a commonly used experimental model, to infection with larvae of the raccoon ascarid, Baylisascaris procyonis. Three groups of 10 mice of each species were given 50, 250, or 500 infective B. procyonis eggs by gavage. The mice were observed daily for clinical signs of central nervous system (CNS) disease and at necropsy the distribution of larvae in 10 body regions and organs was determined and compared. Clinical CNS disease developed in 57% of P. leucopus and 93% of M. musculus. The average clinical incubation period was significantly longer in P. leucopus (20.6 days postinfection [PI]) than in M. musculus (10.7 days PI), and clinical disease progressed slower in P. leucopus. Significantly fewer larvae were recovered from P. leucopus than from M. musculus. Most larvae were recovered from the anterior carcass and viscera of P. leucopus and from the carcass, head, and brain of M. musculus. CNS invasion was dose dependent in M. musculus but not in P. leucopus. Few or no grossly visible larval granulomas were present in P. leucopus but were abundant in M. musculus. We concluded that P. leucopus was less susceptible than M. musculus to B. procyonis infection, based on a decreased intensity of infection, longer clinical incubation period or lack of clinical disease, slower progression of disease, different larval distribution, and lower tissue reactivity to larvae.

Diffuse Unilateral Subacute Neuroretinitis: Morphometric, Serologic, and Epidemiologic Support for Baylisascaris as a Causative Agent

Several nematodes have been postulated as etiologic agents in diffuse unilateral subacute neuroretinitis (DUSN), but the cause of this condition remains uncertain. The authors report the first case of DUSN from the western United States (northern California), along with morphometric, serologic, and epidemiologic evidence supporting Baylisascaris procyonis as its cause.One patient was examined and evaluated for disc edema and transient obscurations of vision. A diagnosis of DUSN was confirmed when a motile nematode was identified within the substance of the patient's retina. Morphometric analysis of the nematode was done from projected fundus photographs. Serologic evidence of Baylisascaris infection was suggested by Western blot analysis. A necropsy was done on 12 raccoons from the area. They were examined for evidence of Baylisascaris infection, previously believed to be nonendemic in the region.The intraocular nematode measured 1727 x 67 microns, most consistent with Baylisascaris. The patient had considerable exposure to raccoons, and was seropositive for B. procyonis infection on Western blot analysis. Necropsy evaluation showed B. procyonis infection in 8 of 12 raccoons examined from the area.The morphometric, serologic, and epidemiologic findings in this case provide evidence that the raccoon ascarid, B. procyonis, is a cause of the large nematode variant of DUSN.

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).

Immunofluorescent localization of eosinophil granule major basic protein in fatal human cases of Baylisascaris procyonis infection.

We examined eosinophil degranulation in tissues from patients infected with Baylisascaris procyonis as shown by the extracellular deposition of granule major basic protein (MBP). We utilized immunofluorescence to localize MBP in eosinophils and at sites of degranulation to study specimens from 2 fatal cases of B. procyonis infection. Large numbers of intact eosinophils were present in the brain around blood vessels and necrotic migration tracks and in mesenteric granulomata. Extensive extracellular MBP deposition was present in the necrotic migration tracks in the brain and around larvae in the mesenteric granulomata in association with the radiating eosinophilic deposits characteristic of the "Splendore-Hoeppli phenomenon." The Splendore-Hoeppli deposits consist in part of eosinophil granule MBP. Release of the cytotoxic MBP in response to invading larvae may cause tissue damage. Central nervous system tissue damage by cytotoxic eosinophil granule proteins may contribute to the neurologic symptoms of B. procyonis infection.