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

Abstract

Angiostrongylus cantonensis and Angiostrongylus mackerrasae 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. Angiostrongylus cantonensis is the major cause of angiostrongyliasis, a disease characterised by eosinophilic meningitis. Although both A. cantonensis and A. mackerrasae are found in Australia, A. cantonensis 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 Angiostrongylus 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. Angiostrongylus DNA was detected in 2 of the 14 mollusc species; Cornu aspersum [14/312 (4.5%)], and Bradybaenia similaris [1/10 (10%)], which are non-native terrestrial snails commonly found in urban habitats. The prevalence of Angiostrongylus spp. was 3.0% ± 0.8% (CI 95%). Additionally, experimentally infected Austropeplea lessoni snails shed A. cantonensis 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, C. aspersum, is a common intermediate host for Angiostrongylus spp. in Sydney.

High prevalence of Angiostrongylus cantonensis (rat lungworm) on eastern Hawai‘i Island: A closer look at life cycle traits and patterns of infection in wild rats (Rattus spp.)

“…Angiostrongylus cantonensis was initially discovered in China [ 4 ], and in Hawai‘i the first human case of angiostrongyliasis was reported in 1959 [ 5 ]. This zoonotic pathogen is also found in Asia, Australia, Brazil, the Caribbean islands and other Pacific Islands and has spread to and within the US continent (Louisiana, Texas, Oklahoma, and Florida) with more than 2,800 cases of human infection reported in 30 countries [ 2 , 6 , 7 , 8 ]. Angiostrongylus cantonensis is typically described as a tropical parasite but it appears to be adapting to gastropod hosts found in more temperate climates [ 9 ].…”

Angiostrongylus mackerrasae and A. cantonensis (Nematoda: Metastrongyloidea) belong to same genetic lineage: evidence from mitochondrial protein-coding genes

“…Until recently, molecular studies were lacking for A. mackerrasae compared to the other members ( A. cantonensis and A. malaysiensis ) of the A. cantonensis species complex. A recent study indicates that A. mackerrasae and A. cantonensis are almost identical at two genetic loci (the nuclear internal transcribed spacer (ITS)-1 and 18S rRNA genes), indicating that these two taxa are conspecific (Chan et al , 2015). Another study, based on restriction enzymes for the cox3 region, failed to distinguish A. mackerrasae from A. cantonensis (Aghazadeh, 2015).…”

“…As for A. malaysiensis , A. mackerrasae , when first documented in Australia, was referred to as A. cantonensis (Mackerras & Sandars, 1954, 1955). Recent studies based on molecular markers indicate that it is highly similar to A. cantonensis (Aghazadeh, 2015; Aghazadeh et al , 2015; Chan et al , 2015). These studies did not include A. malaysiensis , another member of the A. cantonensis species complex, for comparison.…”

Annotated catalogue of species of Angiostrongylus and the related genera Gallegostrongylus, Rodentocaulus and Stefanskostrongylus (Nematoda: Metastrongyloidea, Angiostrongylidae)

“…Nonetheless, neither Chan et al . (2015) nor Song et al . (2018) synonymized the two species, indicating that more information is needed to resolve their status as distinct species, subspecies or synonyms.…”

“…However, Chan et al . (2015) detected little or no difference in 18S and ITS1 sequences between the two species, and Song et al . (2018) showed that the two species were extremely similar on the basis of mitochondrial DNA sequences.…”