A pilot study to determine the prevalence of human rat lungworm (Angiostrongylus cantonensis) exposure on Hawaii Island

Abstract

Abstract The nematode Angiostrongylus cantonensis is a rat lungworm, a zoonotic pathogen that is the cause of human eosinophilic meningitis and ocular angiostrongyliasis. It is considered as a global, emerging infectious disease commonly known as rat lungworm disease (RLWD). Rats are the definitive hosts, mollusks are the obligatory intermediate hosts. Humans can become infected by ingesting intermediate hosts containing infective larvae in contaminated food or water. There are currently no diagnostic tests for RLWD available in Hawaii and prevalence of infection is unknown. To estimate prevalence of exposure to RLW parasites, working with Clinical Labs of Hawaii, LLP and Puna Community Medical Center in Pahoa, HI, we collected serum from 436 human volunteers from east Hawaii where most of the cases of RLWD in the USA originate. The presence of RLW antibodies were evaluated by indirect ELISA using crude antigen extracted from adult A. cantonensis nematodes. Of the 360 samples successfully analyzed, 76 (21%) were strongly positive, 166 (46%) weakly positive and 118 (33%) negative. Based on self-reported data, 92 (26%) believed they have or had RLWD, and 15 (4.2%) were definitively diagnosed. 77% of volunteers reported catchment systems as their main source of household water. More studies would need to be completed to evaluate the potential for water transmission of RLWD. Due to the potential for false positives using crude RLW antigen, results will be verified using dot-blots containing a 31 kDa protein which is expected to provide greater specificity.