The correct answer is D, identification of the worm in tissue sections from the eye, brain, or CSF.  Extraction of the whole worm from eye, brain, or CSF can also provide definitive diagnosis for infections caused by A. cantonensis.  EIA for detection of anti-A. cantonensis antibodies have shown promising results, but cross-reactivity with serum from patients infected with Toxocara canis, Ascaris suum, and Metastrongylus apri has been observed.  No PCR test is available for specific detection of A. cantonensis DNA.