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Author for correspondence: S.R. Gomes, E-mail: [email protected]
Introduction
Abdominal angiostrongyliasis (AA) is an infection caused by Angiostrongylus costaricensis Morera & Cespedes, 1971, a metastrongylid nematode that lives inside mesenteric arteries (Morera, 1973). Infection with A. costaricensis occurs via ingestion of raw molluscs that harbour third-stage larvae (L3) or their mucus containing larvae released on fruit and vegetables (Bonetti and Graeff-Teixeira, 1998). L3 are able to penetrate the intestinal wall and migrate through blood or lymphatic vessels to become adult worms inside mesenteric arteries. First-stage larvae (L1) are released with rodent faeces, and may infect molluscs by penetrating their tegument or after ingestion (Morera, 1973; Mota and Lenzi, 2005). The L1 of molluscs molt twice to evolve to L3, with L3 representing the infective stage for vertebrate hosts (Morera, 1973; Mota and Lenzi, 2005).
Here we report the identification of a new mollusc host, the Chinese slug Meghimatium pictum (Stoliczka, 1873), which is a pest of vineyards in southern Brazil and is associated with human abdominal angiostrongyliasis, and we raise the hypothesis that A. costaricensis may infect humans through grape consumption.
Materials and methods
A 69-year-old female grape farmer living in a rural area of Marau (28°26′42″S, 52°12′35″W), Rio Grande do Sul, Brazil, presented with liver nodules and intestinal lesions. Following a histopathological examination, the farmer was diagnosed with abdominal angiostrongyliasis. When the area surrounding the farmer's house was searched at night, a large number of slugs with the same external characteristics were found climbing on grape plants in her backyard. Seven of these slugs were collected and digested with pepsin solution according to the method of Wallace and Rosen (1969) to recover larvae.
Larvae with a subterminal notch (suggestive of metastrongylid larvae) were subsequently inoculated per os in Swiss mice, which are susceptible to A. costaricensis infection (Mentz and Graeff-Teixeira, 2010). The experimental infection of mice was conducted under ethical clearance, CEUA 15/00443. After 30 days, adult worms were obtained and identified based on their morphology and their localization in the mesenteric arteries (Morera, 1973; Mota and Lenzi, 2005; Spratt, 2015). After the initial identification of M. pictum infection, we surveyed the area around the farm to estimate the prevalence of infection in the slug population.