RESUMO

Scaphanocephalus is a small trematode genus belonging to the family Opistorchiidae. The genus currently contains only three species associated with marine fish as intermediate hosts and fish-eating birds as definitive hosts. Here, specimens of Scaphanocephalus were collected from the Osprey, Pandion haliaetus, and the White mullet, Mugil curema in the Yucatán Peninsula, Mexico. We report for the first-time DNA sequences of adult specimens of Scaphanocephalus, particularly S. expansus, as well as a sequence of a different species sampled as metacercaria. Morphological comparisons of Scaphanocephalus expansus confirmed the identity of the adult specimens, with minor morphological variations; Scanning electron photomicrographs were included, and the species was re-described. Phylogenetic analysis based on 28S rDNA sequences showed that Scaphanocephalus is monophyletic within Opisthorchiidae and consists of three independent lineages. Sequences of adults are identical to those of S. expansus. Instead, the sequence of the metacercaria sampled from the mesentery of Mugil curema nested with specimens reported as Scaphanocephalus sp. from a labrid fish in the Mediterranean Sea, herein named it as Scaphanocephalus sp. 2.

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Ascocotyle (Phagicola) longa is an etiological agent of human phagicolosis. Mugilids are the second intermediate host, the first being Heleobia australis, and mugilids predatory birds and mammals are its definitive hosts. The occurrence of cysts holding A. longa metacercariae is described in mugilids with a prevalence of up to 100%. The wide geographical distribution of A. longa and its intermediate hosts coupled with the rise in the consumption of raw or poorly cooked fish may elevate the risk of human infection. Therefore, in this study, we aimed to verify the distribution pattern of cysts holding A. longa in mugilids. The tissue and organ samples of these fish were processed in a domestic blender and examined under a stereoscopic microscope to identify the cysts holding the digenetic metacercariae. Of the 24 (100%) fish samples that were analyzed, 12 of Mugil curema and 12 of Mugil liza possessed cysts holding A. longa metacercariae. Digenetic cysts were identified to be present in the gills, heart, stomach, liver, intestines, mesentery, and muscular tissues collected from M. curema and M. liza. Conclusively, in M. curema, the cysts holding A. longa metacercariae were found to be distributed randomly throughout the fish body in almost every tissue and organ that was examined.

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RESUMO

Centrocestus formosanus is a digenean parasite first described from Asia, which parasitizes Melanoides tuberculata (Gastropoda: Thiaridae) at the first intermediate stage, and different fish species as second intermediate host. C. formosanus was previously recorded in Brazilian states, but never before in the southern region of this country. Recording and identification of digenean species through morphological identification is a taxonomic challenge. In light of this, we use an integrative taxonomic approach to report the occurrence of cercariae and metacercariae of C. formosanus in molluscs and fish, respectively, in an urban park located in southern Brazil. Specimens of M. tuberculata and the fishes Poecilia reticulata and Xiphophorus sp. (Poeciliidae) were collected for screening for parasites and molecular analyses using partial fragments of the 28S rDNA gene. The identification of C. formosanus obtained from molluscs and fish specimens permitted us to partially solve the life cycle of this parasite for the first time in the studied environment, demonstrating the necessity of monitoring and controlling molluscs populations. Nevertheless, our results will support future studies aiming to elucidate the life-cycle of C. formosanus in this region, since all sampled hosts' species are invasive in this environment.

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In this study, Scaphanocephalus parasite (Platyhelminthes: Heterophyidae) metacercariae were found in Siganus argenteus (forktail rabbitfish or streamlined spinefoot) in the Arabian Gulf of Jubail province, Saudi Arabia. The findings may constitute new host and locality records for this parasite. Based on the number of black spots containing parasite cysts per fish, our study indicated that Siganus argenteus had high infection intensities of encysted metacercariae belonging to the genus Scaphanocephalus. Of the 3500 S. argenteus specimens examined, 800 (22.9%) showed multiple black cysts over the entire body surface, including the membranous parts of fins, while none were seen on the internal organs. The prevalence of infection was highest in summer (June-August) (8.8%). The excysted metacercariae differed morphologically from previously identified Scaphanocephalus spp. Molecular analysis of rDNA showed 100% identity with an unnamed Scaphanocephalus sp. reported in Caribbean fish. Therefore, our findings may indicate a new species of this previously rarely recorded fish parasite. The histopathological examination revealed that the encysted parasites were restricted to the dermal layer of the skin and surrounded by melanophores and a fibrous connective tissue capsule, with focal myositis and Zenker's necrosis in the underlying muscle tissue. The characteristically 'winged' parasite was clearly observed within the cysts. The high prevalence of Scaphanocephalus infection in siganid fish we detected requires further epidemiological study.

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The intestinal trematode, Haplorchis taichui (Nishigori, 1924), is an important in public health that causes infection in humans and animals especially in Asia and in parts of Africa and the Americas. Haplorchis taitui metacercariae were found in the gills of Cyprinion macrostomus (Heckel) and Capoeta barroisi persica (Karaman) collected from the Shapour River. Morphological excysted metacercariae were identified as wet mounts under a stereomicroscope. Then, the samples were subjected to molecular analysis. The result showed that 69% of examined fish (n=30) were diagnosed infected with encysted metacercariae in gills. The mean intensity was 8.3±16.9 parasites per fish. The morphometrical values agree with the findings of other studies with the small differences and polymerase chain reaction product length and nucleotide sequence analysis of 18S ribosomal deoxyribonucleic acid gene showed a similarity of over 99% between the specimens and the Haplorchis taichui (Nishigori, 1924) recorded in GenBank.(AU)

O trematódeo intestinal, Haplorchis taichui (Nishigori, 1924), é importante na saúde pública que causa infecção em humanos e animais, especialmente na Ásia e em partes da África e das Américas. Haplorchis taitui metacercariae foram encontradas nas brânquias de Cyprinion macrostomus (Heckel) e Capoeta barroisi pérsica (Karaman) coletadas no rio Shapour. Metacercárias foram identificadas microscopicamente sob um estereomicroscópio. Em seguida, as amostras foram submetidas à análise molecular. O resultado mostrou que 69% dos peixes examinados (n=30) foram diagnosticados infectados com metacercárias encistadas em brânquias. A intensidade média foi de 8,3±16,9 parasitas por peixe. Os valores morfométricos concordam com os achados de outros estudos com as pequenas diferenças e o comprimento do produto da reação em cadeia da polimerase e a análise da sequência nucleotídica do gene do ácido desoxirribonucleico ribossômico 18S mostraram uma similaridade de mais de 99% entre as amostras e o Haplorchis taichui (Nishigori, 1924) registrado no GenBank.(AU)

El trematodo intestinal, Haplorchis taichui (Nishigori, 1924), es importante en la salud pública que causa infección en humanos y animales, especialmente em Asia y em partes de África y América. Se encontraron Haplorchis taitui metacercariae en las branquias de Cyprinion macrostomus (Heckel) y Capoeta barroisi persica (Karaman) colectadas del río Shapour. Las metacercarias se identificaron bajo un microscopio estereoscópico. Luego, las muestras fueron sometidas a análisis molecular. El resultado mostró que el 69% de los peces examinados (n=30) fueron diagnosticados infectados con metacercarias enquistadas en las branquias. La intensidad media fue de 8.3±16.9 parásitos por pece. Los valores morfométricos concuerdan con los hallazgos de otros estudios con las pequeñas diferencias y la longitud del producto de reacción en cadena de la polimerasa y el análisis de la secuencia de nucleótidos del gen del ácido desoxirribonucleico ribosómico 18S mostró una similitud de más del 99% entre las muestras y el Haplorchis taichui (Nishigori, 1924) registrado en GenBank.(AU)

Assuntos

RESUMO

The intestinal trematode, Haplorchis taichui (Nishigori, 1924), is an important in public health that causes infection in humans and animals especially in Asia and in parts of Africa and the Americas. Haplorchis taitui metacercariae were found in the gills of Cyprinion macrostomus (Heckel) and Capoeta barroisi persica (Karaman) collected from the Shapour River. Morphological excysted metacercariae were identified as wet mounts under a stereomicroscope. Then, the samples were subjected to molecular analysis. The result showed that 69% of examined fish (n=30) were diagnosed infected with encysted metacercariae in gills. The mean intensity was 8.3±16.9 parasites per fish. The morphometrical values agree with the findings of other studies with the small differences and polymerase chain reaction product length and nucleotide sequence analysis of 18S ribosomal deoxyribonucleic acid gene showed a similarity of over 99% between the specimens and the Haplorchis taichui (Nishigori, 1924) recorded in GenBank.

O trematódeo intestinal, Haplorchis taichui (Nishigori, 1924), é importante na saúde pública que causa infecção em humanos e animais, especialmente na Ásia e em partes da África e das Américas. Haplorchis taitui metacercariae foram encontradas nas brânquias de Cyprinion macrostomus (Heckel) e Capoeta barroisi pérsica (Karaman) coletadas no rio Shapour. Metacercárias foram identificadas microscopicamente sob um estereomicroscópio. Em seguida, as amostras foram submetidas à análise molecular. O resultado mostrou que 69% dos peixes examinados (n=30) foram diagnosticados infectados com metacercárias encistadas em brânquias. A intensidade média foi de 8,3±16,9 parasitas por peixe. Os valores morfométricos concordam com os achados de outros estudos com as pequenas diferenças e o comprimento do produto da reação em cadeia da polimerase e a análise da sequência nucleotídica do gene do ácido desoxirribonucleico ribossômico 18S mostraram uma similaridade de mais de 99% entre as amostras e o Haplorchis taichui (Nishigori, 1924) registrado no GenBank.

El trematodo intestinal, Haplorchis taichui (Nishigori, 1924), es importante en la salud pública que causa infección en humanos y animales, especialmente em Asia y em partes de África y América. Se encontraron Haplorchis taitui metacercariae en las branquias de Cyprinion macrostomus (Heckel) y Capoeta barroisi persica (Karaman) colectadas del río Shapour. Las metacercarias se identificaron bajo un microscopio estereoscópico. Luego, las muestras fueron sometidas a análisis molecular. El resultado mostró que el 69% de los peces examinados (n=30) fueron diagnosticados infectados con metacercarias enquistadas en las branquias. La intensidad media fue de 8.3±16.9 parásitos por pece. Los valores morfométricos concuerdan con los hallazgos de otros estudios con las pequeñas diferencias y la longitud del producto de reacción en cadena de la polimerasa y el análisis de la secuencia de nucleótidos del gen del ácido desoxirribonucleico ribosómico 18S mostró una similitud de más del 99% entre las muestras y el Haplorchis taichui (Nishigori, 1924) registrado en GenBank.

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We report for the first time the infection of dolphins with Ascocotyle longa found in the intestines of three different species, Sotalia guianensis, Steno bredanensis, and Tursiops truncatus gephyreus, which were found washed ashore along the southeastern and southern Brazilian coast. The worms were identified based on morphological and molecular data using the 28S rDNA gene and the COI gene. Specimens of A. longa from the pinniped Otaria flavescens were also analyzed. As the first isolation of A. longa from cetaceans, the present study increases the distribution area and range of definitive hosts of this trematode, and provides new molecular data to complement the phylogeny of the group in future studies, thus contributing to the scientific knowledge of this potentially zoonotic parasite.

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RESUMO

Abstract Ascocotyle (Phagicola) longa is an etiological agent of human phagicolosis. Mugilids are the second intermediate host, the first being Heleobia australis, and mugilids predatory birds and mammals are its definitive hosts. The occurrence of cysts holding A. longa metacercariae is described in mugilids with a prevalence of up to 100%. The wide geographical distribution of A. longa and its intermediate hosts coupled with the rise in the consumption of raw or poorly cooked fish may elevate the risk of human infection. Therefore, in this study, we aimed to verify the distribution pattern of cysts holding A. longa in mugilids. The tissue and organ samples of these fish were processed in a domestic blender and examined under a stereoscopic microscope to identify the cysts holding the digenetic metacercariae. Of the 24 (100%) fish samples that were analyzed, 12 of Mugil curema and 12 of Mugil liza possessed cysts holding A. longa metacercariae. Digenetic cysts were identified to be present in the gills, heart, stomach, liver, intestines, mesentery, and muscular tissues collected from M. curema and M. liza. Conclusively, in M. curema, the cysts holding A. longa metacercariae were found to be distributed randomly throughout the fish body in almost every tissue and organ that was examined.

Resumo Ascocotyle (Phagicola) longa é o agente etiológico da fagicolose humana. Os mugilídeos são os segundos hospedeiros intermediários. O primeiro é Heleobia australis e pássaros e mamíferos predadores de mugilídeos, os hospedeiros definitivos. A ocorrência de cistos contendo metacercárias de A. longa é descrita em mugilídeos, com até 100% de prevalência. A ampla distribuição geográfica de A. longa e seus hospedeiros intermediários, acompanhado do aumento do consumo de peixe cru ou mal cozido, pode aumentar o risco de infecção humana, portanto o objetivo do presente estudo foi verificar o padrão de distribuição de cistos, contendo metacercárias de A. longa, em mugilídeos. Amostras de tecidos e órgãos desses peixes foram processadas em liquidificador doméstico e observadas em microscópio estereoscópico à procura de cistos contendo metacercárias do digenético. Todos os 24 (100%) mugilídeos, 12 Mugil curema e 12 Mugil liza examinados apresentaram cistos contendo metacercária de A. longa. Foram observados cistos do digenético nas brânquias, coração, estômago, fígado, intestino, mesentério e tecido muscular de M. curema e de M. liza. Em M. curema, os cistos contendo metacercárias de A. longa estão distribuídos de forma aleatória por praticamente todos os tecidos e órgãos dos mugilídeos examinados.

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RESUMO

Here we describe a new heterophyid species, Heterophyes yacyretana n. sp., and resolve its life cycle experimentally. We found the prosobranch snail Aylacostoma chloroticum in Candelaria, Province of Misiones, Argentina (a sector of the High Paraná River affected by the Yacyretá Dam), naturally infected with opisthorchioid cercariae. These cercariae lacked pigmented eyespots as well as body pigment and possessed 7 pairs of penetration glands arranged in 2 lateral bands, together with 18 pairs of flame cells and a V-shaped excretory vesicle. We exposed specimens of 21 fish species to emerging cercariae and obtained metacercariae from the muscles of the caudal peduncle of 3 species of siluriform fish, and adults from chicks infected with experimentally obtained metacercariae from the albino variety of the bronce corydoras, Corydoras aeneus. The new species differs from other species in the genus by the number of sclerites on the genital sac, the distribution of the vitelline follicles, and the combination of the size relationship of the suckers and the genital sac with respect to the posterior extent of intestinal ceca. Heterophyes yacyretana is the first species of the genus reported from the Americas.

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Fish-borne heterophyid trematodes are known to have a zoonotic potential, since at least 30 species are able to infect humans worldwide, with a global infection of around 7 million people. In this paper, a 'state-of-the-art' review of the South American heterophyid species is provided, including classical and molecular taxonomy, parasite ecology, host-parasite interaction studies and a list of species and their hosts. There is still a lack of information on human infections in South America with undetected or unreported infections probably due to the information shortage and little attention by physicians to these small intestinal flukes. Molecular tools for specific diagnoses of South American heterophyid species are still to be defined. Additional new sequences of Pygidiopsis macrostomum, Ascocotyle pindoramensis and Ascocotyle longa from Brazil are also provided.

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