Diagnosis of Elaphostrongylus cervi infection in New Zealand red deer (Cervus elaphus) quarantined in Canada, and experimental determination of a new extended prepatent period.

A modified Baermann assay was used to recover dorsal-spined, first stage larvae of Elaphostrongylus cervi from feces and lungs of red deer (Cervus elaphus elaphus) from three of four herds imported from New Zealand into Canadian quarantine facilities. Tests done on a series of fecal collections showed that larval output from infected red deer was low and sporadic, casting doubt on the efficacy of the Baermann assay to detect all infected individuals in the herds. The animals had passed repeated preembarkation Baermann tests for E. cervi in New Zealand. Seven larvae recovered from these red deer were used to establish a patent infection in a naive red deer. The prepatent period was 206 days and larval shedding was intermittent. Elaphostrongylus cervi is a foreign animal parasite in continental North America, which could become irrevocably established if it were introduced. The data reported indicates that there is currently no reliable method for the detection of E. cervi infection.