Baylisascaris roundworms are intestinal parasites found in many different animals. Baylisascaris infection in humans is uncommon but can be severe. While Baylisascaris can infect different types of animals, Baylisascaris procyonis, carried by raccoons, is thought to pose the greatest risk to humans because raccoons often live in close proximity to humans. Humans can acquire the parasite by ingesting the eggs of infected raccoons. Young children are at greatest risk for Baylisascaris infection because they are more likely to put contaminated soil in their mouths. Though rare, human infections can be severe if the parasite invades the eye (ocular larva migrans), organs (visceral larva migrans), or the brain (neural larva migrans). Symptoms of a Baylisascaris infection may include nausea, fatigue, an enlarged liver, loss of coordination, lack of muscle control, blindness, and coma. Baylisascaris infections cannot be spread from one person to another. No drug has been found to be completely effective against Baylisascaris infections in humans though albendazole has been used in some cases.
Source: GARD Last updated on 05-01-20
Few cases of Baylisascaris infection in humans have been reported. Most reported cases have involved the central nervous system and/or the eye. Neural larva migrans occurs when the Baylisascaris parasite invades the central nervous system. Neural larva migrans is seen mostly in infants and young children with a history of exposure to raccoons and their feces. Initial signs may be mild but may rapidly become more severe. A variety of neurological symptoms may occur including meningitis, encephalitis, loss of coordination, seizures, coma, and blindness. Several cases of neural larva migrans have been fatal, and many patients have been left with neurological impairment despite treatment. However, a few cases with better outcomes, including one apparent full recovery in a child with mild symptoms, have been reported. Ocular larva migrans (when the Baylisascaris parasite invades the eye) has been reported more frequently than neural larva migrans. Ocular larva migrans without neurological symptoms is usually reported in otherwise healthy adults with no history of exposure to raccoons. The clinical signs may include photophobia, inflammation of the retina, and loss of vision. Some visual defects can be permanent. Visceral larva migrans, when the Baylisascaris parasite invades the internal organs, has not been well described. Symptoms may include hepatomegaly and inflammation of the lungs (pneumonitis).
Last updated on 05-01-20
No drug has been found to be completely effective in treating Baylisascaris infections in humans. Albendazole is currently considered to be the drug of choice. Corticosteroids may also be given to reduce inflammation. In many cases, significant damage has already occurred by the time treatment has started. Early diagnosis and treatment provide the best chance of recovery.
Last updated on 05-01-20
Iowa State University has a factsheet that provides information on the diagnosis, treatment, and prevention of Baylisascaris infection in humans.
Last updated on 04-27-20
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