In patients with elevated eosiniphils, serology can be used to confirm a diagnosis of Angiostrongylias rather than infection with another parasite. There are a number of immunoassays that can aid in diagnosis, however serologic testing is available in few labs in the endemic area, and is frequently too non-specific. Some cross reactivity has been reported between "A. cantonensis" and trichinosis, making diagnosis less specific.

The most definitive diagnosis always arises from the identification of larvae found in the CSF or eye, however due to this rarity a clinical diagnosis based on the above tests is most likely.

Lumbar puncture should always be done is cases of suspected meningitis. In cases of eosiniphilc meningitis it will rarely produce worms even when they are present in the CSF, because they tend to cling to the end of nerves. Larvae are present in the CSF in only 1.9-10% of cases. However, as a case of eosiniphilic meningitis progresses, intracranial pressure and eosiniphil counts should rise. Increased levels of eosinophils in the CSF is a trademark of the eosiniphilic meningitis.