The Prevalence of <i>Angiostrongylus cantonensis/mackerrasae</i> Complex in Molluscs from the Sydney Region

<div><p><i>Angiostrongylus cantonensis</i> and <i>Angiostrongylus mackerrasae</i> are metastrongyloid nematodes that infect various rat species. Terrestrial and aquatic molluscs are intermediate hosts of these worms while humans and dogs are accidental hosts. <i>Angiostrongylus cantonensis</i> is the major cause of angiostrongyliasis, a disease characterised by eosinophilic meningitis. Although both <i>A</i>. <i>cantonensis</i> and <i>A</i>. <i>mackerrasae</i> are found in Australia, <i>A</i>. <i>cantonensis</i> appears to account for most infections in humans and animals. Due to the occurrence of several severe clinical cases in Sydney and Brisbane, the need for epidemiological studies on angiostrongyliasis in this region has become apparent. In the present study, a conventional PCR and a TaqMan assay were compared for their ability to amplify <i>Angiostrongylus</i> DNA from DNA extracted from molluscs. The TaqMan assay was more sensitive, capable of detecting the DNA equivalent to one hundredth of a nematode larva. Therefore, the TaqMan assay was used to screen molluscs (n=500) of 14 species collected from the Sydney region. <i>Angiostrongylus</i> DNA was detected in 2 of the 14 mollusc species; <i>Cornu aspersum</i> [14/312 (4.5%)], and <i>Bradybaenia similaris</i> [1/10 (10%)], which are non-native terrestrial snails commonly found in urban habitats. The prevalence of <i>Angiostrongylus</i> spp. was 3.0% ± 0.8% (CI 95%). Additionally, experimentally infected <i>Austropeplea lessoni</i> snails shed <i>A</i>. <i>cantonensis</i> larvae in their mucus, implicating mucus as a source of infection. This is the first Australian study to survey molluscs using real-time PCR and confirms that the garden snail, <i>C</i>. <i>aspersum</i>, is a common intermediate host for <i>Angiostrongylus</i> spp. in Sydney.</p>