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

Case Summaries

Oklahoma and Arkansas. In May 2013, a female, aged 31 years with a history of Chiari malformation, and who owned a pet raccoon, was evaluated in Oklahoma for headaches and generalized pain. Analysis of CSF was consistent with eosinophilic meningitis (60% eosinophils), and Baylisascaris procyonis antibody was detected in both blood and CSF. The pet raccoon was removed from the home, and the patient was treated with albendazole and corticosteroids for 3 weeks and clinically improved; however, 16 months later, she was reevaluated in Arkansas for worsening headaches, nausea, photophobia, and sensory deficits. Baylisascaris procyonis antibody was again detected in CSF and serum, and the patient was retreated with albendazole and corticosteroids. It was unclear if this episode was caused by a recurrent or persistent infection. A ventriculoperitoneal shunt was placed to correct increased intracranial pressure. She survived with persistent neurologic deficits including intermittent headaches, sensory changes on her right side, diplopia, and gait disturbances.

Ohio. In May 2014, a male, aged 15 months from rural Ohio was brought to the hospital with lethargy and seizures and was found to have eosinophilic meningitis based on CSF testing. Despite the family’s report that the child had no exposure to raccoons, clinical suspicion for baylisascariasis was high, based on the elevated CSF eosinophil count, and the fact that the family lived in an area where raccoons were prevalent. CSF samples were negative for Baylisascaris procyonis antibody; however, a serum sample was positive. The child was treated with albendazole and corticosteroids and survived without neurologic complications. It was later discovered that the patient’s father hunted raccoons and stored raccoon pelts in a garage, where the child often played.

Massachusetts. In December 2014, a female, aged 32 years from rural Massachusetts was admitted to the hospital with a history of rapidly progressive right-sided sensory and motor deficits and decreased ability to concentrate. CSF contained 15% eosinophils but was negative for Baylisascaris procyonis antibody; however, serum was positive. All other microbiologic testing on CSF and serum was negative. The patient was hospitalized for several weeks. Large enhancing brain lesions found on MRI completely resolved with corticosteroid treatment alone (4). The patient showed a marked clinical improvement thereafter. Although no direct exposure to raccoons or raccoon feces was ever reported, the patient was known to hike in rural areas where raccoons are commonly found.

California. In June 2015, a male, aged 63 years from northern California was evaluated at a local hospital for a 2-week history of progressive memory impairment, loss of motor function, fatigue and confusion. He was found to have both peripheral blood and CSF eosinophilia (8% and 34%, respectively). He worked as a contractor, and his family reported that he rarely washed his hands before meals. Raccoons had been observed under his home and at his rural jobsite. Baylisascaris procyonis antibody was detected in both blood and CSF. The patient was treated with albendazole and corticosteroids for 6 weeks; 4 months after his diagnosis, he demonstrated partial recovery of cognitive and motor function (7).

In August 2015, a male, aged 3 years from California with a history of spastic paraplegia was admitted to the hospital with altered mental status and hypotonia and developed seizures while hospitalized. CSF analysis revealed 88% eosinophils and MRI findings were consistent with meningitis. Although no direct contact or evidence of feces ingestion was observed or reported, the child lived in a neighborhood where raccoons were common. Results of testing on both serum and CSF detected Baylisascaris procyonis antibody. The patient was treated with albendazole and corticosteroids and was discharged to rehabilitation after a prolonged hospitalization. The patient suffered persistent neurologic deficits, including right-sided paralysis, incontinence, dysphagia, and apraxia.

Virginia. In August 2015, a female, aged 10 months from rural Virginia was found to have eosinophilic meningitis after being evaluated for altered mental status and seizures. The patient lived on a farm with her family and several dogs. There had been a witnessed episode of geophagia. Baylisascaris procyonis antibody was detected in both serum and CSF. She was treated with albendazole and corticosteroids and survived with substantial neurologic impairment. Although no specific raccoon exposure was reported, raccoons infected with Baylisascaris procyonis have been reported in Virginia (1).

Minnesota. In December 2015, a male, aged 7 years from rural Minnesota was evaluated at an ophthalmology clinic for a 1-week history of worsening vision in his right eye. Ocular examination and retinal imaging revealed a larva compatible in size with Baylisascaris procyonis. Routine blood tests showed no evidence of eosinophilia, and the patient had no neurologic abnormalities. He lived in an area where raccoons were common. Serum tests detected Baylisascaris procyonis antibody. CSF was not tested. The patient was treated with albendazole, and corticosteroids, and retinal photocoagulation laser therapy, and had near total recovery of his vision upon completion of therapy.

Discussion

The geographic distribution, clinical presentations, exposure history, and sequelae reported in this case series are similar to those previously reported (3,8); however, unlike most case reports of Baylisascaris procyonis infection, there were no deaths in this series. The patients in this series all lived in areas where raccoons are common. In all six patients with neural larva migrans, substantial eosinophilia was detected in the CSF, which is often found in Baylisascaris procyonis central nervous system disease (8). In the single case of ocular larva migrans, a larva compatible in size with Baylisascaris procyonis was visualized on retinal imaging. In all cases, antibody to Baylisascaris procyonis was detected by rBpRAG1 Baylisascaris immunoblot assay in a serum sample, a CSF sample, or both. All patients were treated with recommended regimens for baylisascariasis and all seven survived, although four were left with serious neurologic complications as a consequence of their infection.

The findings in this report are subject to at least two limitations. First, detection of Baylisascaris procyonis antibody is not a confirmation of current or active infection, but rather reflects a history of exposure to the parasite at some point. Other disease processes might have caused or contributed to the clinical presentation of the patients described here. However, in the absence of alternative, confirmed diagnoses, and given a history of raccoon exposure with compatible symptoms and response to baylisascariasis treatment, the patients presented were most likely infected with Baylisascaris procyonis. Second, all illnesses in this series were identified from specimens tested at CDC, and might represent an underestimate of the actual number of illnesses. Additional, undiagnosed illnesses, or illnesses diagnosed with testing conducted elsewhere were not collected in this series.

Because of the severity of most recognized illnesses associated with this disease, prevention and treatment of Baylisascaris procyonis infection are critical. Transmission can be prevented by avoiding contact with raccoons and their feces. Handwashing after contact with soil or outdoor play, and educating children not to put soil in their mouths are important prevention strategies. In addition to raccoons, other species of animals, such as kinkajous (9) and skunks that might be kept as pets can serve as Baylisascaris hosts and shed eggs in their feces. Wild animals should not be kept as pets, and susceptible exotic animal hosts should be tested and treated by a veterinarian if indicated. Although uncommon, infected dogs can also shed Baylisascaris procyonis eggs, therefore regular testing and deworming of dogs by a veterinarian is important. Avoiding and safely clearing raccoon latrines can minimize the risk for accidental infection as well.

Treatment after a possible exposure to Baylisascaris procyonis, such as ingestion of raccoon feces, oral exposure to objects contaminated with raccoon feces or playing or working near raccoon latrines, is crucial to prevent the devastating sequelae of Baylisascaris procyonis infection (3). Physicians caring for patients with suspected or confirmed ingestion of raccoon feces should consider preemptive treatment to inhibit larval migration before development of clinical manifestations. Treatment should begin as soon as infection is considered, even if consideration is based on clinical suspicion or epidemiologic history alone. Patients with suspected exposure to Baylisascaris procyonis should immediately be started on a course of 20–50 mg/kg oral albendazole per day for 10–20 days, while further diagnostic investigations are being conducted (6). Additional information on Baylisascaris procyonis prevention, diagnosis and treatment, and sending samples to CDC for testing is available at http://www.cdc.gov/parasites/baylisascaris/.