CDC reports rare roundworm infection that can migrate to the eyes

A CDC report describes 7 cases of infectious Baylisascaris procyonis, also known as raccoon roundworm, which can cause eosinophilic meningitis and ocular larva migrans.

From May 2013 to December 2015, 7 cases were identified in Arkansas, California, Ohio, Oklahoma, Massachusetts, Minnesota and Virginia through testing at CDC, including 6 cases of central nervous system disease and 1 case of ocular disease. Although the patients survived, half were left with severe neurologic deficits.

Baylisascaris procyonis eggs are passed in raccoon feces and cause infection when soil or materials contaminated with feces are ingested. Young children are at particular risk for infection if they place contaminated objects or fingers into their mouths or have syndromes such as pica or geophagia.

Once ingested, larvae migrate to the brain, eye and other organs. If the condition is not promptly diagnosed and treated it can be fatal to humans or cause severe neurologic events, according to the CDC report.

In the single case of ocular larva migrans, a larva was detected on retinal imaging. The other 6 patients had neural larva migrans with substantial eosinophilia detected in the CSF, a typical finding in B. procyonis central nervous system disease. B. procyonis antibodies were detected by rBpRAG1 Baylisascaris immunoblot assay in a serum sample, a CSF sample or both.

Laboratory and clinical diagnosis can be challenging since there is no commercially available serologic test in the United States. Although identification of larvae in tissue or specimens is confirmatory, this is not always possible or practical, according to the CDC. If it is not considered in the differential diagnosis, baylisascariasis can be missed.

The recommendations for prevention include:

• monitoring children when playing outdoors, particularly when contacting soil
• avoiding exposure to raccoons and their feces that harbor the roundworms
• clearing areas where raccoons defecate
• frequent hand washing
• educating children to keep unwashed hands out of their mouths

When B. procyonis infection is suspected, physicians should:

• treat patients as quickly as possible with oral albendazole
• consider pre-emptive treatment to protect the patient against larval ocular and neurological migration