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Clinical Features:
Human infections can be asymptomatic.
However, because these larvae continue to grow and wander in the human host, infections often result in severe disease manifestations.
Much like toxocariasis, infection with Baylisascaris can result in visceral larva migrans (VLM) or ocular larva migrans (OLM) syndromes.
The larvae of B. procyonis have a tendency to invade the spinal cord, brain, and eye of humans, resulting in permanent neurologic damage, blindness, or death.
Human infection with Baylisascaris appears to be rare. To
date, 13 well documented Baylisascaris encephalitis cases, and 1
suspected case in a young girl with CNS larva migrans, have been reported.
The prevalence of subclinical cases is unknown. Because there is no widely available definitive diagnostic test for humans infected with this parasite, many cases are not diagnosed initially.
Laboratory
Diagnosis:
Human
infections are difficult to diagnose, and often the diagnosis is by
exclusion of other causes. Results from complete blood count (CBC)
and cerebrospinal fluid (CSF) examination would be consistent with
parasitic infection, but tend to be nonspecific. Examination of
tissue biopsies can be extremely helpful if a section of larva is
contained, but removing an appropriate piece of tissue where the larva is
actually present can be problematic. Ocular examinations revealing a
migrating larva, larval tracks, or lesions consistent with a nematode
larva are often the most significant clue to infection with Baylisascaris.
Serologic testing can be extremely helpful in suspected cases; however,
tests are not routinely in use nor widely available.
Diagnostic
findings
Treatment:
No drugs have
been demonstrated to be totally effective for the treatment of
baylisascariasis. Drugs such as albendazole have been recommended
for specific cases. For additional information, see recommendations
in The Medical Letter
(Drugs for Parasitic Infections).
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