Search, find, and penetrate: ultrastructural data of furcocercariae of Cardiocephaloides longicollis (Digenea, Strigeidae) explain their transmission and infection strategy into fish hosts

Yoneva, Aneta; Beest, Gabrielle S. van; Born-Torrijos, Ana

doi:10.1007/s00436-022-07448-0

Cited by 3 publications

(1 citation statement)

References 60 publications

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“…The sensory receptors with moderately long and short unciliated sensilla located on the anterior body, including the ventral sucker, are likely intended to locate and recognize the most suitable sites for host penetration. Furthermore, the sensory papillae with shorter cilia may be more sensitive to different pressures, suggesting a tango-/mechanoreceptive function to perceive the host once the cercariae touch the host [41,42]. Some receptor types were site-specific, such as the long, unciliated receptors located in the anterior dorsal region of the cercarial body, which could serve to orient the cercariae in the water column by alternating between swimming and resting periods [43] or could also serve as drag anchors during resting periods [44].…”

Section: Discussionmentioning

confidence: 99%

New Data on the Larval Stages of Leptophallus nigrovenosus (Digenea, Plagiorchiata)

Poonlaphdecha,

Ribas,

Martínez-Silvestre

et al. 2024

Animals

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(1) Background: Leptophallus nigrovenosus, an esophageal parasite that primarily affects water snakes of the genus Natrix, has a known life cycle that involves snail and amphibian hosts. However, the biological aspects, chaetotaxic patterns, and pathogeny of this parasite in its hosts have not been fully elucidated. (2) Methods: Snails (Planorbarius metidjensis) were collected in Spain and examined for cercaria emergence. The larvae were used to experimentally infect Salamandra salamandra, and metacercariae were isolated. Their chaetotaxy was studied using microscopy and scanning electron microscopy. The eye histology was also examined. (3) Results: The cercariae displayed distinctive morphological characteristics. The results of this study revealed three types of ciliated sensory papillae on the cercarial teguments, suggesting an adaptation for host detection and orientation. The metacercariae isolated from subcutaneous tissues showed oval bodies covered in spines. The chaetotaxy patterns matched those of Leptophallinae species. This is the first report of the presence of L. nigrovenosus in the snail P. metidjensis. Additionally, this study detected metacercariae in the eyes of S. salamandra, emphasizing the need for further research on trematode infections in amphibian eyes. (4) Conclusions: Members of the genus Salamandra can serve as secondary intermediate hosts for L. nigrovenosus, and the presence of metacercariae in amphibian eyes may have implications for the survival and habitat management of these amphibians. Understanding this parasite’s prevalence, transmission dynamics, and impacts on host populations is crucial for conservation strategies.

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Section: Discussionmentioning

confidence: 99%

New Data on the Larval Stages of Leptophallus nigrovenosus (Digenea, Plagiorchiata)

Poonlaphdecha,

Ribas,

Martínez-Silvestre

et al. 2024

Animals

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Form and Function in the Digenea, with an Emphasis on Host–Parasite and Parasite–Bacteria Interactions

Rinaldi,

Paz Meseguer,

Cantacessi

et al. 2024

Advances in Experimental Medicine and Biology

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The Versatility of Simplicity: Structures of Cardiocephaloides longicollis Used for Different Purposes during Cercarial Transmission

Beest

Montero

Padrós

et al. 2022

Integrative and Comparative Biology

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Transmission and infection strategies are critical for completing the life cycles of trematode parasites, which are characterized by complex life cycles involving multiple hosts and stages. Transmission between the first and second intermediate hosts typically relies on cercariae, a free-swimming larval stage that displays a series of behaviors to efficiently disperse, locate, attach to, and infect the next host. The aim of this study is to provide detailed information on behaviors used by furcocercariae (bifurcated tail) during its transmission from the snail to the fish host, using the laboratory-established model of Cardiocephaloides longicollis (Strigeidae). These cercariae are released from snails into seawater, where they swim, locate, penetrate the skin of fish, and encyst as metacercariae in their brain. In a series of in vivo assays, freshly-emerged cercariae were used to visually study their behavior and locomotion. Histopathology of experimentally infected gilthead seabreams with C. longicollis, taken at sequential post-infections times, were analysed to localize the migrating cercariae to the fish brain. Our results show that simplicity and versatility are the key features for the success of cercariae transmission by using their organs for different purposes. While 80% of the behavior was spent in a resting position, the most common swimming behavior was with tail-first, which is commonly described in furcocercariae to reach the host microhabitat. However, C. longicollis relies more on the furcae of the tail by using them as a propeller providing thrust and guidance when they swim, instead of using the tail stem. After attaching to the fish skin, cercariae rapidly creep on it using the oral- and ventral-suckers simulating a leech-like movement until they find a suitable penetration site. To penetrate, cercariae press the cephalic structures against the skin, while the ventral sucker anchors the cercariae to it. After this, they switch their locomotion to a slow peristaltic movement, opening the path through tissues with the help of their cephalic structures and anchoring their body with their surface spines. This is consistent with the post-penetration histological analyses, which suggested that C. longicollis cercariae move between the cells of the connective tissue and muscle fibers when migrating towards the fish's brain, without provoking relevant tissue damage or host responses. Understanding the versatility of cercarial structures to adapt to external conditions enriches our knowledge on parasites and their transmission ecology, opening the door to the design of avoidance methods in fish farms struggling with harmful parasites.

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Search, find, and penetrate: ultrastructural data of furcocercariae of Cardiocephaloides longicollis (Digenea, Strigeidae) explain their transmission and infection strategy into fish hosts

Cited by 3 publications

References 60 publications

New Data on the Larval Stages of Leptophallus nigrovenosus (Digenea, Plagiorchiata)

New Data on the Larval Stages of Leptophallus nigrovenosus (Digenea, Plagiorchiata)

Form and Function in the Digenea, with an Emphasis on Host–Parasite and Parasite–Bacteria Interactions

The Versatility of Simplicity: Structures of Cardiocephaloides longicollis Used for Different Purposes during Cercarial Transmission

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