Abstract
Rat lungworm infection is caused by a metastrongylid nematode, Angiostrongylus cantonensis. The parasite was first recorded in the pulmonary arteries and heart of domesticated rats in China in 1935: its medical importance, however, was established 10 years later when Nomura and Lin recovered A. cantonensis larvae from the cerebro-spinal fluid of a human teenager with meningitis in Taiwan in 1945.1 Since then, the parasite has become recognised as a major cause of human meningoencephalitis worldwide.2,3
In the Caribbean, A. cantonensis has been documented in wild rats in Cuba,4 Dominican Republic,5 Grenada,6 Haiti,7 and Puerto Rico.8 Human infections have been reported in Cuba4 and Martinique.9 However, the parasite appears to be absent from Barbados.10 Land snails and slugs serve as intermediate hosts for the parasite, while a range of terrestrial and freshwater invertebrates may serve as paratenic hosts.
Original investigations in Jamaica to assess the infection status of A. cantonensis followed an outbreak of eosinophilic meningitis on the island.11 They involved the collection of 437 wild rats (297 black rats, Rattus rattus, and 140 brown rats, R. norvegicus), and 777 terrestrial molluscs (representing 12 species of snails and slugs) from parishes making up the four Regional Health Authorities (RHAs) on the island.
Adults of A. cantonensis, measuring ∼10 mm, were recovered from the cardiopulmonary system of 32.0% (n = 437) of the wild rats examined. The mean intensity of infection was 15.3 worms (n = 140). Multivariate analysis (binary logistic regression model) confirmed that A. cantonensis occurred significantly more frequently in R. rattus (odds ratio [OR] = 1.76); that R. rattus also harbored significantly more worms (mean = 16.8) than R. norvegicus (mean = 11.3 worms) (Student's t = −2.241; bootstrap [two-sided] P = .02); and that the majority of rodent infections occurred in the Northeast Regional Health Authority (OR = 11.66). The Northeast RHA includes a high proportion of wet, limestone forest.
Of 777 snails and slugs examined, 12.5% harbored A. cantonensis. These included Thelidomus aspera (18.7%, n = 369), Pleurodonte sp. (29%, n = 86), Sagda sp. (11%, n = 18), Poteria sp. (20%, n = 5), and veronicellid slugs (6%, n = 34). All four genera of snails represent new host records for A. cantonensis. The widespread occurrence of the parasite, combined with increasing (> 20) reports over the last 20 years of infections in humans who never travelled abroad,12 indicates that autochthonous transmission is occurring, and that A. cantonensis represents an important emerging infection in Jamaica.
Keywords: Angiostrongyliasis, Caribbean, Eosinophilic meningitis, Jamaica, Nematodes, Rat lungworm disease, Slugs, Snails
Acknowledgements
This article is an extended abstract of a contribution to the Rat Lungworm Disease Scientific Workshop held at the Ala Moana Hotel, Honolulu, Hawai‘i in August 2011. Funding for the workshop and for this publication was provided by the National Institute of Food and Agriculture, United States Department of Agriculture, through Award No. 2011-65213-29954.
Conflict of Interest
None of the authors identifies any conflict of interest.
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