Larvae Of Eustrongylides Research Articles

Mercury concentration in larvae of Eustrongylides sp. (Nematoda: Dioctophymatoidea) from fish of the Brazilian Amazon

Introduction: Chemical pollution represents a great concern to aquatic organisms, especially fish. Metals enter the aquatic environment from a variety of sources, including natural biogeochemical cycles and anthropogenic sources such as industrial and residential effluents, mining and atmospheric sources. Objective: To describe the Eustrongylides sp. larvae and the interaction with their fish hosts as indicators of mercury (Hg) contamination in the Brazilian Amazon, and the distribution of Hg in the internal organs of fish species Hoplias malabaricus and Pygocentrus nattereri collected in oxbow lakes on the Tapajós River, in the municipality of Santarém, in the state of Pará. Methods: Total Hg was analyzed using the Direct Hg Analyzer - DMA-80. Concentrations of Hg in Eustrongylides sp. were compared with those found in the tissues/organs of the hosts H. malabaricus and P. nattereri. Hg concentrations in the host/parasite system were statistically compared using Principal Component Analysis. The bioconcentration factor (BCF) was calculated to assess the bioaccumulation capacity of metals in Eustrongylides sp. larvae, comparing the concentration of Hg in the parasite with that accumulated in the musculature of infected hosts. Results: Hg concentrations in all tissues/organs analyzed were higher in the parasitic species Eustrongylides sp. larvae when compared with those found in tissues/organs of H. malabaricus and P. nattereri. There was an inversely proportional relationship, showing that when Eustrongylides sp. larvae are present, the concentration in the parasite is higher than in the musculature of host fish H. malabaricus and P. nattereri. The BCF of Hg was found by comparing Eustrongylides sp. larvae/H. malabaricus muscle and was observed during a flood (BCF Hg = 15 364). Conclusions: The results confirm the greater bioaccumulative capacity of Eustrongylides sp. compared to its host. The data indicated the viability of using Eustrongylides sp. larvae in biomonitoring programs. It is worth mentioning that fish samples for Hg analysis must be free of parasites since their presence can alter the results.

<i>Contracaecum<i> spp. (NEMATODA: ANISAKIDAE) AND <i>Eustrongylides<i> spp. (NEMATODA: DIOCTOPHYMATIDAE) NEMATODE LARVAE WITH ZOONOTIC POTENCIAL FOUND IN TWO FISH SPECIES FROM TRAMANDAÍ RIVER BASIN, SOUTHERN BRAZIL

Parasitic nematodes can infect both wild and cultivated fish species and may be the source of many diseases. The consumption of raw fish meat in many countries has been the responsible of nematode related zoonosis. Knowing the risk of consumption of contaminated fish by the local communities, the main goal of this paper is to quantify and report the presence of larvae with zoonotic potential of Contracaecum spp. and Eustrongylides spp. found in two exotic fish species from the Tramandaí­­ River Basin in southern Brazil. The sample sites were two lagoons of the basin, the Itapeva lagoon and Palmital lagoon, sampled in the period of April 2018. Forty specimens of Acestrorhynchus pantaneiro and twenty specimens of Trachelyopterus lucenai were examined. A. pantaneiro presented a 58% and 4% prevalence and a mean intensity of 3.17 and 1 for Contracaecum spp. and Eustrongylides spp., respectively. Meanwhile T. lucenai presented a prevalence of 70% and 5% and a mean intensity of 1.92 and 1 of Contracaecum spp. larvae and Eustrongylides spp. larvae, respectively. Although larvae of Contracaeucum spp. are reported only in the literature in experimental infections, they were able to complete their biological cycle in some mammals with certain pathogeneses. However, larvae of Eustrongylides spp. infect humans, as reported in the literature, causing severe damage to the intestinal tract. Knowing that local populations may be at risk, we recommend that all prophylactic measures be taken in relation to fish consumption. This study also contributes to the knowledge concerning the parasitic fauna of the host species studied.

Pathology associated with larval eustrongylides sp. (nematoda: Dioctophymatoidea) infection in galaxias maculatus (actinopterygii: Galaxiidae) from patagonia, Argentina.

Helminth infections within tissues tend to be subjected to a host response that can include encapsulation and melanization to isolate the parasite. The effectiveness of this response depends on the host species. During a survey of parasites of the native fish, Galaxias maculatus, we found conspicuous, strongly melanized exterior cysts located in the caudal peduncle of the fish. Dissection of these cysts exposed larval nematodes whose morphometrical features allowed their identification as Eustrongylides sp. Species of this genus are distributed worldwide. Galaxias maculatus was previously reported as second intermediate host to Eustrongylides sp. larvae, and the aquatic bird Podiceps major was cited as definitive host of Eustrongylides tubifex in Andean Patagonian lakes. The site of infection in the fish, and the host's response are unique among infections by larvae of Eustrongylides sp. in fishes, so the objective of this study was to describe the histological injury caused by larvae of the genus Eustrongylides parasitizing G. maculatus. Samples of fish were taken near the shore of Gutiérrez lake, in northwestern Patagonia. Some larval morphometric features were described to confirm the identity of larvae to generic level. Histopathological analysis (tissues sectioned at 5–7 μm, stained with Hematoxylin and Eosin, and Masson's Trichrome) of the caudal peduncle revealed almost complete disappearance of the epaxial musculature due to compressive atrophy and a chronic inflammatory response, associated mainly with a dense fibrotic capsule and an intense melanic deposit. This is the first description of the histopathology of an external cyst caused by Eustrongylides sp. larvae in fishes.

Diversity and similarity of the parasites in Megalechis thoracata and Callichthys callichthys (Pisces: Callichthyidae) from Brazilian Amazon

This study compared the structure and composition of the parasite communities in Callichthys callichthys and Megalechis thoracata of a tributary of the Amazon River system, northern Brazil. A total of 447 parasites was collected from 38 specimens of each host, and 44.7% and 36.8% of fish species respectively were found to be infected with 1 or more species of parasite. The similarity in parasite assemblages between hosts was high (61%) with both infected at similar levels by Genarchella genarchella , larvae of Eustrongylides sp., Rhabdochona sp. and plerocercoids of Proteocephalidae. However, the dominant parasites found in C. callichthys were metacercariae of Posthodiplostomum sp., which did not infect M. thoracata . In M. thoracata the dominant parasite was G. genarchella , and this host species was also infected by Gorytocephalus spectabilis which did not infect C. callichthys . The parasite communities were dominated by endoparasites, and species richness of parasites, Shannon diversity index and evenness were similar for both hosts. The results indicate that these fish species are intermediate hosts of the endohelminths found. Finally, the variation in the parasite community between sympatric hosts occurred probably due to the hosts’ distribution in the environment and the diet of each host species.

Morphological characterization of Eustrongylides sp. larvae (Nematoda, Dioctophymatoidea) parasite of Rhinella marina (Amphibia: Bufonidae) from Eastern Amazonia.

Absctract Eustrongylides spp. nematodes have birds as final hosts and uses other vertebrates as intermediate/paratenic host (fish, amphibians and reptiles) and have zoonotic potential. In amphibians, the larvae may be located in the subcutaneous tissues, liver and mesentery, between the muscle fibres, especially in the lower limbs. Rhinella marina, which is widely observed in Brazil, has exhibited complex diversity in its helminth fauna, reflecting the unique habitat of the Amazon biome. For the first time, this study describes the morphological aspects of third-stage larvae of Eustrongylides sp. in Rhinella marina from Santa Cruz do Ararí, Marajó Archipelago, Eastern Amazonia, using light and scanning electron microscopy.

Cutaneous Emergence of Eustrongylides in Two Persons from South Sudan

Two large, living worms were collected as they emerged from the lower limb of each of two persons in South Sudan. The worms were observed by staff of the South Sudan Guinea Worm Eradication Program during surveillance activities in communities at-risk for cases of Guinea worm disease (dracunculiasis). The worms measured 7 and 8 cm in length and were identified as fourth-stage larvae of Eustrongylides. This is the first report of such worms emerging from the skin; all five previous reports of human infection involved surgical removal of worms from the peritoneal cavity.

Parasites of an Asian Fish, the Chinese Sleeper Perccottus glenii, in the Włocławek Reservoir on the Lower Vistula River, Poland: In Search of the Key Species in the Host Expansion Process

We investigated the parasite fauna of the Chinese (Amur) sleeper Perccottus glenii Dybowski, 1877 (Perciformes: Odontobutidae) in the Włocławek Reservoir on the lower Vistula River in Poland over 4 yr (2006–2010). Chinese sleeper was unintentionally introduced from eastern Asia to the European part of Russia (near St. Petersburg) in 1916 and has since spread spontaneously throughout Asia and Europe. It is now a frequent component of the ichthyofauna in the Vistula River drainage. In total, 168 seasonally caught individuals of P. glenii were examined for parasites. The parasite community consisted of 18 taxa, including 2 core species, Trichodina domerguei and Nippotaenia mogurndae, and 3 intermediate species, Diplostomum spathaceum (metacercaria [met.]), Echinochasmus spinosus (met.), and Eustrongylides excisus (larvae), with overall prevalence 47.6%, 38.7%, 16.7%, 10.7%, and 12.5%, respectively. Poland is a new locality record for Diplostomum paracaudum (met.), Eustrongylides tubifex (larvae), and Holostephanus luehei (met.). Due to the pathological effects of infection, larvae of Eustrongylides spp. may be a factor that limits Chinese sleeper population growth in the study area.

Intestinal Helminths of River Otters (Lutra canadensis) from the Pacific Northwest

The intestinal helminth fauna of river otters, Lutra canadensis, from the Pacific Northwest was characterized by low species richness and intensity of infection. River otters from the lower Columbia River (n = 23) were infected with 9 species of helminths (83% prevalence); those from a relatively undisturbed reference area near the headwaters of the Trask and Wilson rivers on the Oregon coast (n = 6) were infected by 5 species of helminths (100% prevalence). Single species of Eucestoda (Schistocephalus solidus), Digenea (Euparyphium inerme), Acanthocephala (Corynosoma strumosum), and 8 species of Nematoda (Strongyloides lutrae; larvae of Eustrongylides sp., Anisakis sp., and Contracaecum sp.; 3 of Cystidicolidae, and Hedruris sp.) were collected. Most species are typical of piscine definitive hosts and were present as incidental parasites of river otters. Notably, specimens of Euparyphium inerme are reported for the first time in river otters from North America; occurrence of other helminths constitutes new host or geographic records for parasites in river otters in Oregon and Washington. Parasites with marine life cycles were acquired by river otters in freshwater habitats at a great distance from the ocean. The helminth fauna of river otters in the Pacific Northwest was influenced primarily by ecological factors and was indicative of eclectic food habits and the relatively extensive home ranges occupied by these mustelids.

Histological aspects of natural eustrongyloid infections of the northern water snake, Nerodia sipedon.

Encapsulated as well as unencapsulated fourth stage larvae of Eustrongylides sp. were found in four northern water snakes, Nerodia sipedon, from Virginia. Unencapsulated nematodes occurred within muscle, subcutaneous tissue and in the coelom. Encapsulated nematodes occurred in three forms: recently encapsulated, degenerating, or sclerotic; they were found on the mesentery, in muscle and subcutaneous tissue. Encapsulation was associated with muscular hypotrophy, fibroplasia and eosinophilia.

PHYSIOLOGICAL OBSERVATIONS UPON A LARVAL EUSTRONGYLIDES. XI. INFLUENCE OF OXYGEN TENSION ON THE AEROBIC AND POST-ANAEROBIC OXYGEN CONSUMPTION

1. The oxygen consumption of larval Eustrongylides ignotus shows a greater dependency on the oxygen tension at high than at low temperature.2. The post-anaerobic oxygen consumption is more dependent on the tension than the respiration of larvae that were exposed previously to well oxygenated surroundings, if experiments performed at equal temperatures are compared. This difference disappears almost completely, however, if experiments are compared in which the intensity of the oxygen consumption was equal in both sets at a tension of 760 mm. Hg.3. The implication of these data is discussed on the controversy between Harnisch and von Buddenbrock as to whether it is justified to distinguish between "primary" and "secondary aerobiosis."4. The dependency of the oxygen consumption on the tension is a true one and is not only simulated by oxygen going into physical solution in the body fluids at higher tensions.5. The larvae of Eustrongylides, in contrast to Ascaris, are not killed by a 6-hour exposure to pure oxygen.