Raccoon Roundworm Infection Associated with Central Nervous System Disease and Ocular Disease - Six States, 2013-2015

Baylisascaris procyonis Roundworm Infection in Child with Autism Spectrum Disorder, Washington, USA, 2022

We describe a case of Baylisascaris procyonis roundworm infection in a child in Washington, USA, with autism spectrum disorder. Environmental assessment confirmed nearby raccoon habitation and B. procyonis eggs. B. procyonis infections should be considered a potential cause of human eosinophilic meningitis, particularly among young children and persons with developmental delays.

Eosinophilic Meningitis: Eleven-Year Experience at Texas Children's Hospital

Eosinophilic meningitis can be caused by various etiologies and is reported mostly in tropical climates. The diagnosis is rare in the continental US, presenting challenges for management. Following a case of pediatric eosinophilic meningitis, we reviewed our 11-year experience with this diagnosis at a large US children's hospital.

A Worm’s Tale or Why to Avoid the Raccoon Latrine: A Case of Baylisascaris procyonis Meningoencephalitis

The raccoon roundworm Baylisascaris procyonis (B. procyonis) may infect humans to cause severe or fatal meningoencephalitis, as well as ocular and visceral larva migrans. Young children are at greater risk for cerebral larva migrans with severe meningoencephalitis, and early empiric therapy may improve outcomes. Familiarity with characteristic brain imaging findings may prompt earlier diagnosis, particularly in the setting of CSF eosinophilia. We report a case of a 19-month-old boy who presented with truncal ataxia and was found to have peripheral and CSF eosinophilia. MRI demonstrated symmetric, confluent T2 hyperintense signal in the cerebral and cerebellar deep white mater, which helped differentiate B. procyonis meningoencephalitis from other infectious and non-infectious causes of eosinophilic meningoencephalitis. Early recognition and treatment of B. procyonis meningoencephalitis are important for improved outcomes, and careful review of neuroimaging can play a critical role in suggesting the diagnosis.

Practical Guidance for Clinical Microbiology Laboratories: Diagnosis of Ocular Infections

The variety and complexity of ocular infections have increased significantly in the last decade since the publication of Cumitech 13B, Laboratory Diagnosis of Ocular Infections (L. D. Gray, P. H. Gilligan, and W. C. Fowler, Cumitech 13B, Laboratory Diagnosis of Ocular Infections, 2010). The purpose of this practical guidance document is to review, for individuals working in clinical microbiology laboratories, current tools used in the laboratory diagnosis of ocular infections. This document begins by describing the complex, delicate anatomy of the eye, which often leads to limitations in specimen quantity, requiring a close working bond between laboratorians and ophthalmologists to ensure high-quality diagnostic care. Descriptions are provided of common ocular infections in developed nations and neglected ocular infections seen in developing nations. Subsequently, preanalytic, analytic, and postanalytic aspects of laboratory diagnosis and antimicrobial susceptibility testing are explored in depth.

Experimental comparison of Baylisascaris procyonis definitive host competence between domestic dogs and raccoons (Procyon lotor)

Domestic dogs can function as either paratenic or definitive hosts for the zoonotic raccoon roundworm Baylisascaris procyonis. However, factors leading to development of patent infections in dogs are under-studied. Here we compared infection dynamics of B. procyonis in dogs vs the natural raccoon host. Dogs and raccoons were inoculated 5000 or 500 B. procyonis eggs (n = 3 per dose) or were fed B. procyonis-infected laboratory mice (n = 3 per dose; mice inoculated with 1000 or 250 eggs). Fecal samples were analysed via flotation and a commercial coproantigen ELISA designed for detection of Toxocara spp. Two of 12 dogs (both received low dose larvae) developed patent infections; all 12 raccoons became infected with 10 developing patent infections. Compared with dogs, prepatent periods were shorter in raccoons and maximum egg outputs were much greater. Baylisascaris procyonis coproantigens were detectable via ELISA in all raccoons and the patently infected dogs. Finally, dogs spontaneously lost infections while all patently infected raccoons shed eggs until conclusion of the study. Our results demonstrate that dogs are clearly suboptimal hosts showing limited parasite establishment and fecundity vs raccoons. Despite the low competence, patently infected dogs still pose a risk for human exposure, emphasizing the importance of control measures.

Prevalence of Baylisascaris procyonis in Raccoons Trapped in New Orleans, Louisiana, 2014-2017

Baylisascaris procyonis, the raccoon roundworm, is considered an emerging zoonotic disease in the United States after being identified in raccoons captured in different US regions and metropolitan areas. Humans can become infected with B. procyonis after ingesting mature roundworm eggs, sometimes resulting in fatal disease or severe sequelae in these patients. The first reported human Baylisascaris case in New Orleans raised concerns that very little was known about this zoonotic disease in the increasing urban raccoon population. Therefore, the study aim was to estimate the prevalence of Baylisascaris-infected raccoons in New Orleans, LA. Raccoons were trapped based on nuisance calls from the public and in areas where raccoons had been sighted. Necropsies were performed to identify B. procyonis adult worms in intestines and fecal samples were examined for roundworm ova. Study findings showed that 38.5% of New Orleans raccoons were infected with B. procyonis, defined by the presence of adult B. procyonis worms or Baylisascaris ova in their feces. Twenty-four of 65 raccoons (36.9%) had raccoon roundworms in their intestines and 31.7% of the fecal samples were positive for B. procyonis eggs. Mapping B. procyonis-infected raccoons by trapping location showed that infected raccoons were found throughout the city. In conclusion, the high prevalence rate of B. procyonis in New Orleans raccoons demonstrates the importance of educating the public and health care professionals about potential health risks and providing resources to prevent exposure to infective eggs from raccoon latrines. Furthermore, this emerging disease should be further studied to examine human risk of infection in increasing raccoon populations in metropolitan areas.

Zoonotic nematodes of wild carnivores

For a long time, wildlife carnivores have been disregarded for their potential in transmitting zoonotic nematodes. However, human activities and politics (e.g., fragmentation of the environment, land use, recycling in urban settings) have consistently favoured the encroachment of urban areas upon wild environments, ultimately causing alteration of many ecosystems with changes in the composition of the wild fauna and destruction of boundaries between domestic and wild environments. Therefore, the exchange of parasites from wild to domestic carnivores and vice versa have enhanced the public health relevance of wild carnivores and their potential impact in the epidemiology of many zoonotic parasitic diseases. The risk of transmission of zoonotic nematodes from wild carnivores to humans via food, water and soil (e.g., genera Ancylostoma, Baylisascaris, Capillaria, Uncinaria, Strongyloides, Toxocara, Trichinella) or arthropod vectors (e.g., genera Dirofilaria spp., Onchocerca spp., Thelazia spp.) and the emergence, re-emergence or the decreasing trend of selected infections is herein discussed. In addition, the reasons for limited scientific information about some parasites of zoonotic concern have been examined. A correct compromise between conservation of wild carnivores and risk of introduction and spreading of parasites of public health concern is discussed in order to adequately manage the risk of zoonotic nematodes of wild carnivores in line with the 'One Health' approach.

Detection and Evaluation of Antibody Response to a Baylisascaris-Specific Antigen in Rodent Hosts with the Use of Western Blotting and Elisa

Diagnosis of parasitic diseases that involve tissue-stage larvae is challenging, and serology remains the most effective antemortem test for detecting these infections. Baylisascaris procyonis, the raccoon roundworm, is a zoonotic ascarid. Raccoons are the usual definitive host, and humans may be infected as accidental hosts. More than 150 species of birds and mammals may act as paratenic hosts, and rodents play an important role in the transmission and maintenance of this parasite in nature. Migratory larvae in paratenic host tissues can produce ocular disease and severe to fatal neurologic disease, but not all infected hosts develop signs. A sensitive and specific Western blot (WB) assay based on a recombinant Baylisascaris-specific antigen (rBpRAG-1) has been developed for use in humans. We evaluated the use of this antigen to detect Baylisascaris spp. infections in rodent paratenic hosts. With the use of 4 species of Peromyscus mice ( Peromyscus californicus, Peromyscus leucopus, Peromyscus maniculatus, Peromyscus polionotus) from a previous infection trial, we developed species-adapted WB and ELISA assays and evaluated performance compared to detection of larvae in tissue samples. These assays revealed species-level differences in seroconversion and terminal antibody concentrations, with P. leucopus developing significantly greater antibody concentrations than P. californicus and P. polionotus at all dose levels, and P. maniculatus at the low dose. Some P. californicus and P. polionotus failed to seroconvert despite the recovery of larvae from their tissues. WB and ELISA results were correlated; however, the WB demonstrated higher sensitivity than the ELISA overall (72.2% versus 63.9%, respectively). With the use of experimental samples, specificity was 100% for WB and 94.1% for ELISA. A WB was also used to test Mus and Rattus samples, and although numbers were too limited to evaluate sensitivity and specificity, all animals known to be infected by tissue digestion were WB positive, and all uninfected animals were negative. Finally, the Peromyscus-adapted WB and ELISA were used to test a set of serum samples from wild-trapped P. maniculatus and Rattus rattus. Both assays were generally sensitive, but specificity was equivocal. This emphasizes the challenge of using serology for investigation of wildlife diseases, in which hosts have unknown exposure histories. Nevertheless, serologic methods have utility in the study of Baylisascaris spp. in paratenic hosts, either wild or captive, and have advantageous attributes (non-lethal, high-throughput), but results should be interpreted carefully.

Raccoon roundworm (Baylisascaris procyonis) as an occupational hazard: 2. Use of personal protective equipment and infection control practices among raccoon rehabilitators

Baylisascaris procyonis, the raccoon roundworm, is a zoonotic ascarid of importance to human and animal health. Wildlife rehabilitators who care for raccoons may be at an increased risk for exposure to the parasite, especially if proper precautions are not taken. In a wider effort to evaluate awareness regarding B. procyonis in the wildlife rehabilitation community, an online survey (38-39 questions) including questions about B. procyonis knowledge and attitudes was developed and administered to wildlife rehabilitators. To assess precautions taken among raccoon rehabilitators, participants who rehabilitated raccoons (n = 447) answered additional questions about use of personal protective equipment (PPE) and infection control practices (ICPs). Reported use of gloves was variable, but hand hygiene was generally consistent. Masks and gowns were seldom used. Part-time or infrequent volunteers and rehabilitators located in the Central, Midwest and Southeast were significantly less likely to report consistent use of PPE. A total knowledge score from the survey was used to predict the likelihood of reporting the use of particular ICPs/PPE. Knowledge score had a highly significant but small effect on the likelihood of prophylactic use of anthelmintics, anthelmintics use for B. procyonis specifically, cleaning appropriately, and using species-dedicated housing. Risk factor analysis was performed on data from a prior serologic survey to evaluate factors associated with exposure to B. procyonis and inconsistent handwashing after contact with live raccoons and their faeces; practising rehabilitation in B. procyonis hyperendemic regions and practising rehabilitation in the western region were significant risk factors for being seropositive. These data further demonstrate that correct PPE/ICPs are critical in mitigating the risk of B. procyonis exposure among raccoon rehabilitators and among other captive species.

Raccoon roundworm (Baylisascaris procyonis) as an occupational hazard: 1. Knowledge of B. procyonis and attitudes towards it and other zoonoses among wildlife rehabilitators

Wildlife rehabilitators are at risk of zoonotic diseases because they often have prolonged contact with many species of wildlife and their bodily fluids. Raccoon roundworm (Baylisascaris procyonis) is a common zoonotic parasite of raccoons that has the potential to cause severe or fatal neurologic disease in a broad variety of hosts if the eggs within raccoon faeces are ingested. We administered an online survey to wildlife rehabilitators to assess their knowledge regarding aspects of transmission, biology and disease caused by B. procyonis, and also to evaluate attitudes towards wildlife diseases and B. procyonis as an occupational hazard. Knowledge was assessed using multiple choice and true-false questions; attitudes were measured using Likert-type items. A total of 659 complete or near-complete responses (missing fewer than three knowledge or attitudes items and/or non-response to some demographic fields) were collected. The median knowledge score was 7/14 questions correct (range: 0-14 correct). Generally, individuals with higher levels of education and rehabilitation experience, veterinary professionals and those who are members of professional wildlife rehabilitation groups scored above the median significantly more often (p < .01). Significantly more rehabilitators who were located in the south-east and those with part-time or infrequent commitments scored below the median overall knowledge score. There was general agreement that B. procyonis is a health risk of rehabilitators and that measures should be taken to control transmission to people and animals. Some factors explaining differences in attitudes include setting of rehabilitation (home versus animal care facility), veterinary profession, region, membership in a wildlife rehabilitation group and rehabilitation of raccoons. Findings emphasize the importance of awareness and mentorship to inform rehabilitators on the potential risks of B. procyonis and other potential zoonoses within captive wildlife settings, and the important role of professional wildlife rehabilitator groups in disseminating educational materials.