Positive correlation of prevalence of Angiostongylis cantonensis in Parmarion martensi (semi-slug) with higher human neuroangiostrongyliasis (rat lungworm disease) caseloads in east Hawai'i Island.

Toward a better understanding of Angiostrongylus cantonensis infection within intermediate gastropod hosts, we evaluated prevalence of A. cantonensis in gastropods from east Hawai'i Island and Kaua'i, and used this data to begin to explore how gastropod infection may relate to human neuroangiostrongyliasis patterns in these regions. An overall infection prevalence of 43.3% was found among four of the eight species tested. Of the seven species tested from Kaua'i (n = 170) 12.9% were positive among three species, and of the two slug species tested from east Hawai'i island (n = 320) 59.4% tested positive. In east Hawai'i Island, parasite prevalence was significantly greater in Parmarion martensi (84.4%) than in Veronicella cubensis (10.2%) (P < 0.001), however, infection rates in V. cubensis on east Hawai'i Island did not significantly differ than in V. cubensis tested on Kaua'i (11.6%) (P = 0.878). Comparing parasite loads among regions within east Hawai'i Island, parasite loads were significantly greater in P. martensi from Pāhoa than in those from Hilo (P < 0.001) and in those from Kea'au than Hilo (P = 0.004), and significantly differed among these districts (P < 0.001). Based on zip code tabulation areas (ZCTA) in east Hawai'i Island, prevalence of infection of slugs collected from ZCTA's with 1-5 human cases of neuroangiostrongyliasis was 9.5%, in ZCTA's with 11-15 human cases averaged 65.7%, and in ZCTA's with 16-31 cases was 67.3%. Slug infection prevalence appears higher in ZCTA's with higher human neuroangiostrongyliasis caseloads, at least in these regions in east Hawai'i Island (P < 0.001).