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Fig. 4 | Parasites & Vectors

Fig. 4

From: Abdominal angiostrongyliasis in the Americas: fifty years since the discovery of a new metastrongylid species, Angiostrongylus costaricensis

Fig. 4

Proposed model of Angiostrongylus costaricensis–intermediate host interactions. These events are based on Sarasinula linguaeformis (syn. S. marginata) and Omalonyx spp. experimental infections [9, 72, 74,75,76]. a L1 larvae can infect mollusks using two main pathways: transdermal or oral infection. In the first, L1 larvae penetrate the mollusk’s tegument through the mucous gland pores and ducts. Then, larvae reach fibromuscular tissues by direct migration or embolization in hemolymph vessels to the kidney and other viscera. Molting to L2 stage occurs after 4 days of infection. During oral infection, L1 larvae reach fibromuscular tissues by penetrating the oral, intestinal, or rectal mucosa (1), through the kidneys (2), or through the hemolymph vessels (3). Only L1 larvae located in fibromuscular tissues molt until L3 stage. b After L1 larvae penetrate mollusk tissues and reach hemolymph vessels, either by oral or transdermal routes, poor perilarval granulomatous reactions with amebocytes are started after two to six hours post-infection. L1 to L2 transitioning is a strong cellular stimulus for amebocyte proliferation in the hemolymph. As the cellular response progresses, it is possible to observe different degrees of granulomas around the L2s, some of which become epithelioid cells. Some granulomas containing L2 larvae or in L2–L3 transition larvae will be located on the wall of vessels adjacent to different fibromuscular tissues, especially those anatomical regions juxtaposed with the acinus and ducts of the mucous glands of the tegument. In these cases, granulomatous reactions will degenerate hemolymph vessels and glandular tissues, giving the already mature and mobile L3 larvae access to glandular ducts in order to be shed in the mollusk’s mucous secretions. This figure was created using BioRender.com

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