Infection with Toxocara canis is a common world-wide
human helminthiasis, which rarely elicits central nervous system
(CNS) impairment. A case-control study to investigate this discrepancy
was
carried out, in which the cases were 27 adult
neurological inpatients for whom a definite aetiological diagnosis was
lacking,
and for whom positive immunodiagnosis
of toxocariasis had been obtained, both in cerebrospinal fluid (CSF) and
in
serum. Two control groups were used. Controls
were adult inpatients with other neurological diseases who had no evidence
of
T. canis infection of the CNS. Multivariate
logistic regression analysis did not reveal any positive relation between
case status and clinical signs. A significant
association was observed between case status and an elevated CSF cell count.
Rural residence, ownership of dogs, and
dementia were shown to be risk factors for toxocaral infection of CNS.
These
results suggest that migration of T. canis
larvae in the human brain does not frequently induce a recognizable neurological
syndrome but is correlated with the
association of several risk factors including exposure to dogs, a status
possibly responsible for repeated low-dose infections.