Angiostrongylus costaricensis and the intermediate hosts: observations on elimination of L3 in the mucus and inoculation of L1 through the tegument of mollucs

Bonetti, Vera Cristina Brandão Diniz de Oliveira; Graeff-Teixeira, Carlos

doi:10.1590/s0037-86821998000300006

Cited by 24 publications

(25 citation statements)

References 10 publications

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“…Since the notion that mollusks infected with A. cantonensis can shed larvae in their mucus trails was first suggested, other workers have found no or very few A. cantonensis larvae secreted from infected mollusks (3,7,8). Similar results have been obtained for excretion of other Angiostrongylus species (6,15,25,28).…”

Section: Discussionsupporting

confidence: 64%

PCR-Based Detection ofAngiostrongylus cantonensisin Tissue and Mucus Secretions from Molluscan Hosts

Qvarnström

Sullivan

Bishop

et al. 2007

Appl Environ Microbiol

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Angiostrongylus cantonensis is a common cause of human eosinophilic meningitis. Recent outbreaks of this infection have shown that there is a need to determine the distribution of this nematode in the environment in order to control transmission. A. cantonensis is generally identified morphologically in the molluscan intermediate host by microscopic examination, which can be labor-intensive. The aim of this study was to develop a PCR-based method to detect A. cantonensis directly from molluscan tissue. A total of 34 Parmarion cf. martensi (Simroth) semislugs, 25 of which were naturally infected with A. cantonensis, were used to develop this assay. Tissue pieces (approximately 25 mg) were digested with pepsin-HCl to recover third-stage larvae for morphological identification or were used for DNA extraction. PCR primers were designed to amplify 1,134 bp from the Angiostrongylus 18S rRNA gene, and the amplicons produced were sequenced for identification at the species level. Both microscopy and the PCR-DNA sequencing analysis indicated that the same 25 semislugs were positive for A. cantonensis, showing that the two methods were equally sensitive and specific for this application. However, morphological detection requires access to living mollusks, whereas molecular analysis can also be performed with frozen tissue. The PCR-DNA sequencing method was further evaluated using tissue from Veronicella cubensis (Pfeiffer) slugs and mucus secretions from infected P. martensi. To our knowledge, this is the first use of a PCR-based method to confirm the presence of A. cantonensis in mollusks collected in the environment.

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Section: Discussionsupporting

confidence: 64%

PCR-Based Detection ofAngiostrongylus cantonensisin Tissue and Mucus Secretions from Molluscan Hosts

Qvarnström

Sullivan

Bishop

et al. 2007

Appl Environ Microbiol

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“…This hypothesis is supported by data on U . pallikuukensis , whose larvae do not emerge from the intermediate gastropod hosts, until they have reached the infective stage around three weeks post infection [ 25 ].…”

Section: Discussionmentioning

confidence: 99%

Release of Lungworm Larvae from Snails in the Environment: Potential for Alternative Transmission Pathways

et al. 2015

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BackgroundGastropod-borne parasites may cause debilitating clinical conditions in animals and humans following the consumption of infected intermediate or paratenic hosts. However, the ingestion of fresh vegetables contaminated by snail mucus and/or water has also been proposed as a source of the infection for some zoonotic metastrongyloids (e.g., Angiostrongylus cantonensis). In the meantime, the feline lungworms Aelurostrongylus abstrusus and Troglostrongylus brevior are increasingly spreading among cat populations, along with their gastropod intermediate hosts. The aim of this study was to assess the potential of alternative transmission pathways for A. abstrusus and T. brevior L3 via the mucus of infected Helix aspersa snails and the water where gastropods died. In addition, the histological examination of snail specimens provided information on the larval localization and inflammatory reactions in the intermediate host.Methodology/Principal FindingsTwenty-four specimens of H. aspersa received ~500 L1 of A. abstrusus and T. brevior, and were assigned to six study groups. Snails were subjected to different mechanical and chemical stimuli throughout 20 days in order to elicit the production of mucus. At the end of the study, gastropods were submerged in tap water and the sediment was observed for lungworm larvae for three consecutive days. Finally, snails were artificially digested and recovered larvae were counted and morphologically and molecularly identified. The anatomical localization of A. abstrusus and T. brevior larvae within snail tissues was investigated by histology. L3 were detected in the snail mucus (i.e., 37 A. abstrusus and 19 T. brevior) and in the sediment of submerged specimens (172 A. abstrusus and 39 T. brevior). Following the artificial digestion of H. aspersa snails, a mean number of 127.8 A. abstrusus and 60.3 T. brevior larvae were recovered. The number of snail sections positive for A. abstrusus was higher than those for T. brevior.ConclusionsResults of this study indicate that A. abstrusus and T. brevior infective L3 are shed in the mucus of H. aspersa or in water where infected gastropods had died submerged. Both elimination pathways may represent alternative route(s) of environmental contamination and source of the infection for these nematodes under field conditions and may significantly affect the epidemiology of feline lungworms. Considering that snails may act as intermediate hosts for other metastrongyloid species, the environmental contamination by mucus-released larvae is discussed in a broader context.

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“…Together with Conejo and Morera (1988), we share the same hypothesis of L 3 elimination as an accidental process in which random location near excretory ducts enables larval elimination through mucous secretion after mechanical rupture of the granulomas or perilarval amebocyte reactions. This fact might explain the low recovery of larvae from the mollusk's body, both in natural (Rambo et al 1997) and experimental infection (Bonetti & Graeff-Teixeira 1998) since elimination is apparently independent of larval maturation and possibly depends on mechanic and accidental processes. It is relevant to remember that L 3 are inactive, or immobile inside the mollusks, unable to achieve active elimination.…”

Section: Discussionmentioning

confidence: 99%

Angiostrongylus costaricensis and experimental infection of Sarasinula marginata II: elimination routes

Mendonça

Carvalho

Mota

et al. 2003

Mem. Inst. Oswaldo Cruz

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2, 4, 6, and 8 h post-infection and at days 1, 2, 4, 5, 6, 8, 10, 11, 12, 14, 15, 16, 20, 21, 22, 25, 26, 28, and 30 post-infection; the mollusks were then fixed and stained. Diverse organs involved throughout the course of the migratory routes of larvae from oral penetration on were specified and the mechanisms of larval access to the fibromuscular layer through the kidney, rectum, and vascular system were defined. The elimination of L 3 , derived from oral and/or cutaneous infections, appears to depend on granulomas located close to the excretory ducts of mucous cells.

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Angiostrongylus costaricensis and the intermediate hosts: observations on elimination of L3 in the mucus and inoculation of L1 through the tegument of mollucs

Abstract: Human accidental infection with

Cited by 24 publications

References 10 publications

PCR-Based Detection ofAngiostrongylus cantonensisin Tissue and Mucus Secretions from Molluscan Hosts

PCR-Based Detection ofAngiostrongylus cantonensisin Tissue and Mucus Secretions from Molluscan Hosts

Release of Lungworm Larvae from Snails in the Environment: Potential for Alternative Transmission Pathways

Angiostrongylus costaricensis and experimental infection of Sarasinula marginata II: elimination routes

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