Raccoon roundworm in New York

ProMed mail has a report about 2 cases of Baylisascaris procyonis infection in people in Brooklyn, New York.  Baylisascaris is the raccoon roundworm and is very commonly found in the intestinal tract of healthy raccoons. Raccoons shed this parasite in their stool, and after a short period of time, the parasite larvae become infective to other animals and people. Infective larvae can survive for a long time in the environment. People become infected by swallowing the larvae that can be found in dirt or on any object contaminated by raccoon stool. Disease in humans due to this parasite is rare but can be extremely severe.

The first case in this report involved an infant with neural larval migrans, a condition caused by migration of the roundworm larvae through the brain. Despite treatment, the child now has permanent brain damage because of this disease. Unfortunately, this is not uncommon consequence, as the infection is not usually identified until severe and irreversible damage has already occurred. The child had a history of eating soil, and swallowing soil contaminated with raccoon feces is the most likely source of infection.

The second case involved a 17-year-old with ocular larval migrans, which is caused by migration of the parasite larvae through the eye. The parasite was killed using laser therapy, however the patient lost all vision in the affected eye before the infection was identified. There was no mention of where or how the teenager may have been exposed. Infection of someone of this age is very uncommon, as most 17-year-olds are much less likely in ingest (intentionally or accidentally) raccoon stool. It would be useful to know whether this patient had a developmental disability which results in an increased likelihood of swallowing dirt or feces, or whether there may have been some other type of exposure.

Baylisascaris infections in people are extremely rare, despite the fact that a large percentage of raccoons carry this roundworm. This report of two cases occuring in the same area within a few months of each other is surprising.  Hopefully it's just a bad coincidence, and not an indication of some change in the incidence of this disease. Avoiding Baylisascaris means avoiding ingestion of raccoon stool. Sounds simple enough, but this is of particular concern with young children and people with developmental delays who are more likely to swallow contaminated dirt or stool, or put dirty/contaminated hands or objects in their mouths.

More information about Baylisascaris and preventing transmission of the infection can be found in our archives, as well as information about cleaning up raccoon latrines.

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BarfBlog - May 5, 2009 8:05 AM
CBC News reported last night that parents should be on alert for raccoon roundworm, a rare parasite transmitted through contact with the animal's feces, which has left a New York infant with brain damage and a teenager blind. Raccoon roundworm...
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samantha - May 3, 2009 11:39 PM

Thank you very much for pointing out that Baylisascaris is rare and is easily avoidable by not eating raccoon poop. Fresh poop infected with Baylisascaris is not infectious as the roundworm eggs must embryonate for 30 days before they become infectious.

Scott Weese - May 4, 2009 7:29 AM

Thanks for the comments. One clarification...it does not necessarily take 30 days for Baylisacaris eggs to become infective. The time require varies with things like temperature and humiditiy, and can be at least as low as 11 days.

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