ABSTRACT
To observe the dynamic change of parasites in the brains of BALB/c mice infected with Angiostrongylus cantonensis in order to explore its possible mechanism of pathogenesis', BALB/c mice infected with the III stage larvae of A.cantonensis were observed and killed in different times after infection. The number and distribution of parasites in the brains of the infected mice were observed microscopically and macroscopically. It was found that the larvae of A.cantonensis were distributed in the cerebrum and cerebellum of mice in accordance with the rule of parasitization of worms in the host, i.e.multiplication at first and then dropping in number. And the places where the parasites located were damaged due to mechanical action or inflammatory reactions. The time of onset of symptoms, such as ataxia and twitch was coincided with the dynamic changes in the brains of the infected mice.