In silico comparative analysis of cestode and human NPC1 provides insights for ezetimibe repurposing to visceral cestodiases treatment.

Visceral cestodiases, like cysticercoses and echinococcoses, are caused by cystic larvae from parasites of the Cestoda class and are endemic or hyperendemic in many areas of the world. Current therapeutic approaches for these diseases are complex and present limitations and risks. Therefore, new safer and more effective treatments are urgently needed. The Niemann-Pick C1 (NPC1) protein is a cholesterol transporter that, based on genomic data, would be the solely responsible for cholesterol uptake in cestodes. Considering that human NPC1L1 is a known target of ezetimibe, used in the treatment of hypercholesterolemia, it has the potential for repurposing for the treatment of visceral cestodiases. Here, phylogenetic, selective pressure and structural in silico analyses were carried out to assess NPC1 evolutive and structural conservation, especially between cestode and human orthologs. Two NPC1 orthologs were identified in cestode species (NPC1A and NPC1B), which likely underwent functional divergence, leading to the loss of cholesterol transport capacity in NPC1A. Comparative interaction analyses performed by molecular docking of ezetimibe with human NPC1L1 and cestode NPC1B pointed out to similarities that consolidate the idea of cestode NPC1B as a target for the repurposing of ezetimibe as a drug for the treatment of visceral cestodiases.

Taxonomic inflation or hidden diversity: unveiling the fact surrounds Lytocestus indicus (Cestoda: Caryophyllidea).

The tapeworms belonging to the order Caryophyllidea (Platyhelminthes, Eucestoda) represent a widespread group of intestinal parasites found in cypriniform and siluriform fishes. This group comprises four families (Balanotaeniidae, Capingentidae, Caryophyllaeidae, Lytocestidae), 42 genera and approximately 130 described species. Additionally, over a hundred new taxa have been reported from India. While many of these taxa are endemic and have unique evolutionary importance, a considerable number of putative new taxa were also invalidated because the quality and reliability of the published data did not meet the requirements. Various researchers have synonymised 28 species into a single representative, Lytocestus indicus (Moghe, 1925) Woodland, 1926. Consequently, L. indicus was chosen as a model organism to investigate whether there is taxonomic inflation or hidden diversity. Newly collected specimens of L. indicus were subjected to various fixatives for morphological assessment, and hologenophores of the same were obtained to determine whether true variations exist in their genotype or if they are merely fixation-induced variations. Despite morphological variations associated with fixation, molecular data indicated that they were indeed the same specimens. The taxonomic status of 43 new taxa was critically evaluated, with most of them tentatively synonymised with L. indicus. Others were also found to be conspecific with L. indicus but were classified as unavailable names based on their first description in unpublished dissertations.

First molecular characterisation of Hydatigera taeniaeformis (Cestoda: Taeniidae) from Rattus rattus in urban market centres from Tamale, Ghana.

BACKGROUND: The common cat tapeworm, Hydatigera taeniaeformis, is widely distributed across many regions of the world but its global genetic diversity, ecology, and other biological features are not fully understood. The predator-prey relationship of felids and rodents sustains the transmission in both sylvatic and synanthropic or urban settings. This study was carried out in three urban market centres in Tamale, Ghana to determine the prevalence of H. taeniaeformis infection in urban rats and characterise the local population genetics using the mitochondrial nad1 gene sequences. METHODS: From January to May 2023, rats were captured and euthanized to identity and isolate the H. taeniaeformis metacestodes. The full mitochondrial nad1 gene was amplified, sequenced and used to characterise the cestode population. RESULTS: In total 64/80 rats from the three market centres were found naturally infected with metacestodes of H. taeniaeformis. Averagely, infected rats harboured two cysts with one exceptional case of 25 cysts in one liver. Each cyst harboured one metacestode. The DNA sequences revealed four haplotypes in a star-like distribution network across the three market centres. All four haplotypes were found to be unique, clustered with H. taeniaeformis sensu stricto (s.s.) global isolates and had only marginal variation among themselves. CONCLUSION: This is the first account of the genetic variability within H. taeniaeformis in Ghana and would contribute to ongoing and future studies on African regional biogeographic distribution of the common cat tapeworm.

Extracts and Terpenoids from Stevia Species as Potential Anthelmintics for Neglected Tropical Diseases Caused by Cestode Parasites.

Cestodes are etiological agents of neglected diseases such as echinococcosis and cysticercosis, which are major public health problems. Antiparasitic treatment relies on a small number of approved drugs, which are often only partially effective, poorly tolerated and require prolonged administration. Thus, the discovery of novel potential treatments is critical. The Stevia genus (Asteraceae) includes species that are recognized as a source of bioactive compounds, with many species associated with medicinal uses. In this study, the cestocidal activity of four South American Stevia species that previously showed antiprotozoal activity was analyzed using a motility assay on the laboratory cestode model, Mesocestoides vogae. The four Stevia extracts showed cestocidal activity, with S. alpina var. alpina as the most active. The sesquiterpene lactones estafietin and eupatoriopicrin were purified from S. alpina var. alpina and S. maimarensis, respectively, and tested on M. vogae. Estafietin showed cestocidal activity, inhibiting parasite viability in a dose-dependent manner, even from the first day of incubation. Consistent with the motility effects, the extract of S. alpina var. alpina and estafietin induced marked alterations in the morphology of the parasite. The results of this report show that Stevia species represent a source of new molecules with potential for the treatment of neglected tropical diseases caused by cestodes.

Co-Infection of Bertiella studeri and Mycobacterium tuberculosis in a Captive Rhesus Macaque (Macaca mulatta).

Bertiella studeri, a typical intestinal cestode of nonhuman primates, accidentally infects human beings. However, B. studeri infection in monkeys has been rarely reported in recent years. A case of B. studeri infection was identified in one captive rhesus macaque with natural infection of Mycobacterium tuberculosis. This study contributes to alerting the public of this helmintic zoonosis, though its infection rate is quite lower in recent years.

First record of Hydatigera taeniaeformis in Geoffroy's cat (Leopardus geoffroyi) in Brazil.

Leopardus geoffroyi (Geoffroy's cat) is a neotropical feline considered globally threatened. In Brazil, it occurs exclusively in the Pampa biome. Its predatory habits contribute to the infection, dispersion, and continuation of the life cycle of various pathogens, including helminths, within ecosystems. However, few studies involving cestodes in wild felines are found in the literature, especially in Brazil. Therefore, we aimed to report the first case of parasitism by Hydatigera taeniaeformis in L. geoffroyi. The helminths were found in the small intestine of the necropsied feline. Specimens were analyzed morphometrically and subjected to molecular analyses for taxonomic identification. The molecular phylogeny based on the analysis of the mitochondrial gene (COX1) allowed the identification of these parasites. Thus, this is the first description of H. taeniaeformis parasitizing L. geoffroyi in Brazil. Consequently, the number of known host species parasitized by this helminth in the country and the world is increased. Additionally, a new molecular sequence is being provided, contributing to the knowledge of Hydatigera in South America.

Morphological and molecular identification of metacestodes infecting teleost fishes of Moreton Bay, Australia.

In a parasitological survey of fishes from Moreton Bay (southeastern Queensland, Australia), 169 teleost fishes, representing 54 species from 28 families, were examined for larval cestodes. Of these 54 species, 36 were found to be infected by metacestodes. Metacestodes were characterised by morphological and molecular data (the D1-D3 region of the 28S rDNA gene); these data were analysed in parallel to inform larval type allocation. Metacestodes collected represented eight morphological types, seven previously reported (Types I, II, IV, V, VI, VII, and X) and one novel type (Type XVI). Phylogenetic analyses were conducted to genetically match larval types to adult cestodes. Six of the eight larval types found were matched to adult forms: Type I metacestodes matched species of Phoreiobothrium Linton, 1889 (Onchobothriidae); Type II metacestodes matched species of Acanthobothrium van Beneden, 1849 (Onchobothriidae); Type IV metacestodes matched species of Scyphophyllidium Woodland, 1927 and Alexandercestus Ruhnke & Workman, 2013 (Phyllobothriidae); Type VI metacestodes matched species of Anthobothrium van Beneden, 1850 (Tetraphyllidea incertae sedis); Type X metacestodes matched species of Ambitalveolus Caira & Jensen, 2022 (Tetraphyllidea incertae sedis); and Type XVI metacestodes matched species of Platybothrium Linton, 1890 (Onchobothriidae). Based on phylogenetic topology, Type V metacestodes are inferred to match Pedibothrium Linton, 1909 (Balanobothriidae) and Type VII metacestodes are inferred to match Spongiobothrium Linton, 1889 (Rhinebothriidae). These findings support and extend the unified morphological type system proposed previously, but suggest that morphological types will ultimately be informative to identify metacestodes to a group of related genera rather than any distinct genus.

Comparison of diagnostic methods for laboratory diagnosis of the zoonotic tapeworm Dipylidium caninum in cats.

The tapeworm Dipylidium caninum is the most widely distributed cestode infecting dogs, cats, and sometimes humans, worldwide. The diagnosis of the infection caused by D. caninum is achieved via the visualization of proglottids in feces or with traditional microscopic tests, but both lack sensitivity. The present study has evaluated and compared the diagnostic performance of a PCR protocol on different feline biological samples to detect D. caninum. A sample of feces, a Scotch tape test from the perianal area, and a rectal swab were collected from a total of 100 privately owned cats from Italy and Greece. All fecal samples were subjected to macroscopic examination and to floatation. Based on the results of the above tests the cats were divided in three groups, i.e. (i) cats positive for D. caninum (regardless of positivity for other endoparasites (Group A; n = 50 cats), (ii) cats negative for D. caninum but infected by other helminths (Group B; n = 25 cats), and (iii) cats negative for intestinal endoparasites (Group C; n = 25 cats). For each sample, the DNA was extracted from feces, floatation supernatant, Scotch tape test and rectal swabs and subjected to PCR. For 33 cats from Group A, at least one sample type scored positive at PCR. Of these, all were PCR-positive in the floatation aliquot, while nine and one cats were positive by PCR on feces and Scotch tape test, respectively. Swabs were negative by PCR for all the cats. None of the samples from cats of Groups B and C was positive by any PCR. Sequences obtained from amplicons generated from samples of cats enrolled in Italy had 99-100 % identity with the recently described D. caninum feline genotype. The data presented here suggest that PCR could be a useful tool for diagnosing D. caninum infections, under certain circumstances, e.g. when proglottids are unidentified, unseen or overlooked, even though it has limitations, e.g. false negative results due to fecal PCR inhibitors, uneven distribution of parasitic elements, or to intermittent proglottid and/or egg shedding. Thus, it may not be, currently, the best diagnostic choice for dipylidiosis.

Unlocking the Biological Enigma: Influence of Host Length and Infection Site on Parasite Abundance in Ompok bimaculatus.

PURPOSE: The influence of two key factors, host length and infection site, on the host-parasite interaction in Ompok bimaculatus (Butter catfish) from Mukutmanipur Dam Lake, were investigated. METHODS: Present study involved 192 specimens of Ompok bimaculatus with varying body lengths, subjected to diverse statistical analyses. One-way analysis of variance (ANOVA) was performed for the parasite numbers for three groups (cestode, nematode and trematode). Subsequently, we conducted one-way permutational multivariate analysis of variance (PERMANOVA) followed by pairwise test to assess parasite numbers across three body sites (intestine, mesentery, and bodycavity), employing the Bray-Curtis index. Additionally, Principal Coordinate Analysis (PCoA) for the same dataset was performed using the same index. Linear regression analysis was performed for the fish length-cestode number, fish length-nematode number, fish length-trematode number and fish length-total parasite number. RESULTS: One-way ANOVA revealed no significant differences in parasite numbers among the three endo-helminth groups (cestode, nematode, and trematode). The results of PERMANOVA revealed significant differences in parasite numbers across the three body sites of the host fishes (groups) (F = 9.41, p = 0.0001). Pairwise tests further demonstrated significant differences between the intestine-mesentery, intestine-body-cavity, and mesentery-body-cavity. Additionally, Principal Coordinate Analysis (PCoA) unveiled a significant relationship between infection site and parasite number. However, linear regression analysis examining the relationship between fish length and parasite abundance indicated no significant associations. CONCLUSIONS: Through a detailed exploration of the statistical analyses, we provide insights into the host-parasite interaction, elucidating both established knowledge and novel findings in fish parasitology.

Semibalanus balanoides (L.) and Balanus crenatus Bruguière (Balanidae) Are Intermediate Hosts of Fimbriarioides intermedia (Fuhrmann, 1913) and Two Species of the Genus Microsomacanthus (Cestoda: Hymenolepidae), Parasites of Sea Ducks from the Atlantic Sector of the Arctic and Northern Pacific.

Metacestode infestation of Semibalanus balanoides (L., 1767) and Balanus crenatus Bruguiеre, 1789, collected in the Barents and White Seas and in the northern part of the Sea of Okhotsk in 2020 and 2021, respectively, was studied. A total of 313 S. balanoides from Mogilnaya Bay of Kildin Island (Barents Sea) and isolated mature wrinkled barnacles B. crenatus, two and four specimens from the Pechora Sea and Kandalaksha Bay of the White Sea, respectively, were examined in 2020. Metacestodes Fimbriarioides intermedia (Fuhrmann, 1913) (Cyclophyllidea, Hymenolepididae) were found in 1.0 ± 0.6% of S. balanoides in the Barents Sea with an invasion intensity (I. I.) of 2-5 specimens, and in one of two B. crenatus from the Pechora Sea (I. I. 15 specimens). For the first time, in both B. crenatus from the Pechora Sea, taken from the valves of the mussel Mytilus edulis, metacestodes Microsomacanthus sp. I (I. I. 13 and 20 specimens) with proboscis hooks 38-41 (39.4 ± 0.1) µm long and blades of 9.5-11 (10.7 ± 0.1) µm were obtained. One of four B. crenatus from the Kandalaksha Bay was infected with another Microsomacanthus sp. II (I. I. 19 specimens) with proboscis hooks 44.0-49.5 (45.7 ± 0.5) µm long and blades 14.0-16.0 (14.8 ± 0.07) µm long. A total of 362 S. balanoides were collected and dissected in Gizhiginskaya Bay of the northern part of the Sea of Okhotsk in 2021, of which 8.0 ± 1.4% were infected with F. intermedia metacestodes (I. I. 1-19 specimens). Study results of the infestation of S. balanoides on the Koni-Pyagin coast of the Sea of Okhotsk (according to the collections of 2006-2007) were supplemented and clarified. Description of metacestodes and the taxonomic affiliation of cysticercoids Microsomacanthus spp. are given.

Dasyrhynchus giganteus plerocercoids encysting in the musculature of Indian halibut (Psettodes erumei): seasonal prevalence, morpho-molecular characterization, and histopathological alterations.

This study investigated the prevalence, morphology, molecular identification, and histopathological effects of larval tapeworms (plerocercoids) infecting the skeletal muscles of the Indian halibut (Psettodes erumei) collected from the coastal waters of the Arabian Gulf. Numerous oval or round blastocysts, measuring 13-26 mm, were found embedded within the muscular tissues of the Indian halibut, rendering the fish unsuitable for human consumption. Morphological and molecular analyses identified the plerocercoids as Dasyrhynchus giganteus (family Dasyrhynchidae), with an overall prevalence of 15.4%. The seasonal prevalence was the highest in summer (14.6%), followed by spring (10.6%), winter (4.4%), and autumn (3.5%). Infection rates increased with fish size. Histopathological examination revealed fibrous connective tissue capsules surrounding the larvae, causing muscular atrophy and degenerative changes, with few inflammatory eosinophilic cells. Molecular and phylogenetic analysis of the 28S rDNA gene sequences confirmed the specimens as D. giganteus, clustered closely with other sequences of D. giganteus with 100% bootstrap values. This study provided valuable insights into the parasitic infection dynamics, seasonal variation, molecular identification, and histopathological effects, highlighting the importance of monitoring fish for food safety and public health implications.

Phylogenetic relationships and systematics of tapeworms of the family Davaineidae (Cestoda, Cyclophyllidea), with emphasis on species in rodents.

The present study aims at clarifying the poorly known phylogenetic relationships and systematics of cestodes of the family Davaineidae Braun, 1900 (Cyclophyllidea), primarily the genus Raillietina Fuhrmann, 1920 and of the subfamily Inermicapsiferinae (Anoplocephalidae) from mammals (mostly rodents, 31 new isolates) and birds (eight new isolates). Phylogenetic analyses are based on sequences of the large subunit ribosomal RNA gene (28S) and mitochondrial NADH dehydrogenase subunit 1 gene (nad1). The main phylogenetic pattern emerging from the present analysis is the presence of three independent lineages within the main clade of the subfamily Davaineinae, one of which is almost entirely confined to species from rodents and the other two show a mixture of species from birds and mammals. It is suggested that the major diversification of the main clade took place in birds, possibly in galliforms. The subsequent diversification included repeated host shifts from birds to mammals and to other birds, and from rodents to other mammals, showing that colonisation of new host lineages has been the main driver in the diversification of davaineine cestodes. It is also shown that all isolates of Inermicapsifer Janicki, 1910, mainly from rodents, form a monophyletic group positioned among Raillietina spp. in the "rodent lineage", indicating that the genus Inermicapsifer is a member of the family Davaineidae. This means that the subfamily Inermicapsiferinae and the family Inermicapsiferidae should be treated as synonyms of the Davaineidae, specifically the subfamily Davaineinae. Three additional genera generally included in the Inermicapsiferinae, i.e. Metacapsifer Spasskii, 1951, Pericapsifer Spasskii, 1951 and Thysanotaenia Beddard, 1911, are also assigned here to the Davaineidae (subfamily Davaineinae). Raillietina spp. were present in all three main lineages and appeared as multiple independent sublineages from bird and mammalian hosts, verifying the non-monophyly of the genus Raillietina and suggesting a presence of multiple new species and genera.

Allergenic response induced by Pterobothrium crassicolle (Cestoda: Trypanorhyncha) extracts in murine model.

The aim of this study was to determine the allergenic activity of components present in crude extracts of Pterobothrium crassicolle plerocerci (CPE) and blastocysts (CBE) obtained from Micropogonias furnieri in a murine model. Two groups of seven animals each received 50 µg of CPE or CBE on days 1, 35 and 120. Serum samples were tested by ELISA and Immunoblotting. Specific IgG and IgE levels were detected by ELISA, showing specific humoral responses for the primary immunization for both immunoglobulins and continuously growing titers for IgE. Positive Passive Cutaneous Anaphylaxis tests in rats sensitized with anti-CBE sera and tested by CBE, showed biologically, the allergenic activity of the extracts. The CPE and CBE showed some different recognition regions but both experimental groups recognized all regions of the extracts when tested for cross reactions, showing that CPE and CBE could share antigenic recognition sites.

Cestode diversity in shrews from islands in the Sea of Japan and the Sea of Okhotsk.

A comparative analysis of taxonomic diversity on shrew cestodes among four islands in the Sea of Japan and the Sea of Okhotsk (Sakhalin, Kunashir, Hokkaido, and Moneron) was performed. Cestode species shared among the islands were identified and their host specificity was investigated. On Sakhalin Island, 33 species of the families Hymenolepididae, Dilepididae and Mesocestoididae were recorded in four shrew species (Sorex caecutiens, S. gracillimus, S. minutissimus and S. unguiculatus). In S. caecutiens, S. gracillimus, and S. unguiculatus on Kunashir Island, 22 species of the same families were found and, on Hokkaido Island, 23 species of the families Hymenolepididae and Dilepididae were recorded. On Moneron Island, three species of cestodes were registered in S. tundrensis. The Sakhalin-Hokkaido-Kunashir complex of shrew cestodes includes eastern-Palearctic, trans-Palearctic and endemic species. High endemism (~22%) of shrew tapeworms in the Sakhalin-Kunashir-Hokkaido Islands was noted as compared to continental territories. The different numbers of cestode species in S. unguiculatus (31), S. caecutiens (29), S. gracillimus (19) and S. minutissimus (1) were found. It was concluded that the cestodes species diversity of shrews of Sakhalin-Kunashir-Hokkaido depended primarily on the history of island formation, their modern physical and geographical features, the abundance of definitive and intermediate cestodes hosts and, to a lesser extent, on the size and remoteness of the islands from the mainland and the diversity of host species.

Dipylidiasis cases in Japan-an update by literature survey.

Dipylidium caninum is a cosmopolitan parasite of companion animals such as dogs and cats. Accidental infection in humans occur mostly in children. Although considerable number of cases were reported from Europe and the Americas, case reports of this zoonotic disease are rather scarce from Asian countries. The aim of this study is to report the results of literature survey on dipylidiasis cases in humans in Japan. Conclusively, we have found a total of 17 cases since the first case report in from Aichi Prefecture in 1925.

Molecular identification and prevalence of plerocercoid larvae (Cestoda: Diphyllobothriidae) in some commercial fish species from Peru.

Diphyllobothriosis, a fish-borne zoonosis in South America, is mainly caused by the Pacific broad tapeworm Adenocephalus pacificus Nybelin, 1931, a parasite of considerable concern in fishery resources due to its impact on public health. A new diphyllobothrid, Diphyllobothrium sprakeri Hernández-Orts et al. Parasites Vectors 14:219, 2021, was recently described from sea lions from the Pacific Coast, but marine fish acting as intermediate hosts are unknown. The objective of this study was to confirm the presence of plerocercoid larvae of Diphyllobothriidae Lühe, 1910 (Cestoda: Diphyllobothriidea) in nine fish species of commercial importance in Peru. Of a total of 6999 fish (5861 Engraulis ringens, 853 Sciaena deliciosa, 6 Sciaena callaensis, 171 Scomber japonicus, 40 Trachurus murphyi, 40 Ariopsis seemanni, 18 Merluccius peruanus, 5 Sarda chiliensis, and 5 Coryphaena hippurus), 183 were infected with plerocercoid larvae, representing a total prevalence of 2.61% and a mean intensity of 3.2. Based on mtDNA cox1 sequences of 43 plerocercoids, a phylogenetic analysis revealed that 41 belong to A. pacificus and two to D. sprakeri. These findings are first molecular data for D. sprakeri larvae, and the infections of E. ringens and T. murphyi by plerocercoid larvae represent the first records of intermediate/paratenic hosts for this species. Hence, the findings of the current study enhance our understanding of the presence of diphyllobothriid species in commercial fish from the Southeastern Pacific Ocean and their potential impact on seafood safety for local human populations.

Tapeworms (Cestoda: Proteocephalidae) of the gars (Lepisosteidae), living fossils in America, including proposal of a new genus and a new species.

A new genus, Cordicestus, is proposed to accommodate proteocephalid tapeworms parasitising gars (Lepisosteiformes: Lepisosteidae) in North and Central America that were previously placed in the polyphyletic genus Proteocephalus Weinland, 1858. The new genus differs from other proteocephalid genera by the particular morphology of the scolex, which is small, protrudes apically but has no apical organ, and bears flat, heart-shaped (= cordis) suckers. In addition, the species of the new genus have an elongated cirrus sac with an almost straight internal vas deferens and wide, sinuous ventral osmoregulatory canals with secondary canals directed outwards. The type species of the new genus, Cordicestus singularis (La Rue, 1911) n. comb., is redescribed based on new material from the shortnose gar, Lepisosteus platostomus Rafinesque (type host), and the spotted gar, L. oculatus Winchell, in the United States. Cordicestus rafaeli n. sp. is described from the tropical gar, Atractosteus tropicus Gill, in Mexico. The new species differs from its relatives primarily by the presence of craspedote proglottids (acraspedote in other species) and some biometric features. All species of Cordicestus are revised, including unidentified specimens from A. tropicus and the Cuban gar A. tristoechus (Bloch and Schneider) in Nicaragua and Cuba, respectively, which may be new species, and a key to the identification of these taxa is provided. Molecular data available for two nominal species of the new genus indicate the possible existence of another species of Cordicestus in Lepisosteus in the USA.

Platybothrium yanae sp. nov. (Cestoda: Onchobothriidae) from the whitecheek shark, Carcharhinus dussumieri (Valenciennes), off southern Iran.

Platybothrium Linton, 1890 is a genus parasitizing sharks of the families Carcharhinidae and Sphyrnidae. No new species has been assigned to the genus in the 20 years since its last treatment. In the present study, a new species is described from the Persian Gulf, which is the second report of a species of Platybothrium in the Indian Ocean. Platybothrium yanae sp. nov. differs from P. auriculatum Yamaguti, 1952, P. cervinum Linton, 1890, P. tantulum Healy, 2003, and P. kirstenae Healy, 2003 in lacking, rather than having, an accessory piece between its hooks. This new species is distinguished from its other congeners by having a particular combination of features including its measurements, morphology, and meristic features, bringing the number of valid species in the genus to 11.

Distinct evolutionary lineages of Schistocephalus parasites infecting co-occurring sculpin and stickleback fishes in Alaska.

Sculpins (coastrange and slimy) and sticklebacks (ninespine and threespine) are widely distributed fishes cohabiting 2 south-central Alaskan lakes (Aleknagik and Iliamna), and all these species are parasitized by cryptic diphyllobothriidean cestodes in the genus Schistocephalus. The goal of this investigation was to test for host-specific parasitic relationships between sculpins and sticklebacks based upon morphological traits (segment counts) and sequence variation across the NADH1 gene. A total of 446 plerocercoids was examined. Large, significant differences in mean segment counts were found between cestodes in sculpin (mean = 112; standard deviation [s.d.] = 15) and stickleback (mean = 86; s.d. = 9) hosts within and between lakes. Nucleotide sequence divergence between parasites from sculpin and stickleback hosts was 20.5%, and Bayesian phylogenetic analysis recovered 2 well-supported clades of cestodes reflecting intermediate host family (i.e. sculpin, Cottidae vs stickleback, Gasterosteidae). Our findings point to the presence of a distinct lineage of cryptic Schistocephalus in sculpins from Aleknagik and Iliamna lakes that warrants further investigation to determine appropriate evolutionary and taxonomic recognition.

Two proteocephalid cestodes in the fish Malapterurus electricus and Heterobranchus bidorsalis from Lake Nasser, Egypt: a morphological, molecular, and histopathological study.

Despite the importance of the electric catfish (Malapterurus electricus) and the African giant catfish (Heterobranchus bidorsalis) in the foodweb of Lake Nasser, Egypt, little is known about their diseases and parasitic fauna. This work describes, for the first time, cestodiasis in M. electricus and H. bidorsalis. Corallobothrium solidum and Proteocephalus sp. were identified morphologically and molecularly from M. electricus and H. bidorsalis, respectively. Using PCR, sequencing, and phylogenetic analysis, the two cestodes shared rRNA gene sequence similarities yet were unique and the two new sequences for the proteocephalid genera were submitted to the GenBank database. The prevalence of infection was 75% and 40% for the two fish species, respectively. Infections significantly increased in the summer and spring and were higher in female fish than in male fish. The intestine was the preferred site of the two adult cestodes. However, in the case of C. solidum some larval cestodes were found outside the intestine in between the skin and abdominal musculature, attached to the mesentery, and within intestinal tunica muscularis. Desquamation of the intestinal epithelium and inflammation at the site of infection in addition to congestion of the intestinal wall of the tapeworm infected fish were evident, indicating that C. solidum and Proteocephalus sp. impacted the infected fish. The larval stages of C. solidum attempted to penetrate the intestine and sometimes they were encircled within fibrous layers infiltrated with inflammatory cells. The infected fish's musculature was free of cestode infections. Preventive measures should be implemented to prevent the spread of infections.