Wild Animals in Captivity: An Analysis of Parasite Biodiversity and Transmission among Animals at Two Zoological Institutions with Different Typologies

We have conducted a 10-year-long coprological study of the animals housed in two zoological institutions (ZooAquarium and Faunia, Madrid, Spain) to assess the parasite biodiversity, prevalence, and their relation with host class, diet, and enclosure type (soil type and level of isolation from wild fauna). A total of 4476 faecal samples from 132 mammal species and 951 samples from 86 avian species were examined. The results indicated that only 12.8% of avian species had parasites at least once during the study period, whereas 62.1% of mammal species tested positive. Predominantly, protists (Entamoeba, flagellates, and ciliates) and nematodes (mainly Trichuris) were identified in the findings. Carnivorous species were primarily infected by nematodes, while herbivorous and omnivorous species were mainly infected by protists. The number of infected herbivorous and omnivorous species was significantly greater than carnivorous species. Differences were observed based on soil type (artificial, natural, mixed) and isolation level (isolated/accessible), but these differences were not statistically significant. Several parasites (Entamoeba spp., Giardia spp., Balantidoides coli, Trichuris spp.) could potentially be transmitted between humans and some mammals and birds. Regular animal analyses and a personnel health program in the institutions would minimise transmission risks between zoo animals, wildlife, and humans.

Question of agent of camel balantidiosis solved: Molecular identity, taxonomic solution and epidemiological considerations

Domestic camels (Camelus bactrianus, the Bactrian camel; and Camelus dromedarius, the dromedary) are pseudo-ruminant herbivores kept as livestock in rural, inhospitable regions (cold deserts and dry steppes of Asia, arid to semi-arid regions of Africa, western and central Asia). Their close contact with humans makes them a potential reservoir for zoonotic parasite infections, as has been suggested for human balantidiasis. However, there is confusion about the ciliate species that infects camels: Infundibulorium cameli was originally described in dromedaries, but this name has almost never been used and most authors identified their findings as Balantioides coli and, to a lesser extent, Buxtonella sulcata, a cattle ciliate. To clarify the taxonomic status of the parasite and the corresponding zoonotic significance for camels, we performed morphological characterization of cysts and genetic analysis (SSU-rDNA and ITS markers) of B. coli-like isolates from Bactrian camels from Bulgaria and from dromedaries from Spain and the United Arab Emirates. Our results indicate that the camel ciliate is not B. coli, nor is it B. sulcata, but is a different species that should be placed in the same genus as the latter. Thus, camels are not a reservoir for human balantidiasis. Although the correct genus name would be Infundibulorium according to the principle of priority, this would lead to confusion since this name has almost fallen into disuse since its initial description, but Buxtonella is almost universally used by researchers and veterinarians for the cattle ciliate. We therefore propose to apply the reversal of precedence and use Buxtonella as the valid genus name. Consequently, we propose Buxtonella cameli n.comb. as the name for the camel ciliate.

Presence and genetic diversity of enteric protists in captive and semi-captive non-human primates in côte d’Ivoire, Sierra Leone, and Peru

Little information is currently available on the occurrence and genetic diversity of pathogenic and commensal protist species in captive and semi-captive non-human primates (NHP) resident in zoological gardens or sanctuaries in low- and medium-income countries. In this molecular-based study, we prospectively collected individual faecal samples from apparently healthy NHP at the Abidjan Zoological Garden (AZG) in Côte d’Ivoire, the Tacugama Sanctuary (TS) in Sierra Leone, and the Quistococha Zoological Garden (QZG) in Peru between November 2018 and February 2020. We evaluated for the presence of pathogenic (Cryptosporidium spp., Entamoeba histolytica, Giardia duodenalis, Blastocystis sp., Enterocytozoon bieneusi, Balantioides coli) and commensal (Entamoeba dispar, Troglodytella abrassarti) protist species using PCR methods and Sanger sequencing. Giardia duodenalis was the most prevalent species found (25.9%, 30/116), followed by Blastocystis sp. (22.4%, 26/116), and E. dispar (18.1%, 21/116). We detected E. bieneusi (4.2%, 1/24) and T. abrassarti (12.5%, 3/24) only on NHP from AZG. Cryptosporidium spp., E. histolytica, and B. coli were undetected at the three sampling sites investigated here. Sequence analyses revealed the presence of zoonotic sub-assemblages BIII (n = 1) in AZG and BIV (n = 1) in TS within G. duodenalis. We identified Blastocystis subtype ST3 (100%, 6/6) in AZG, ST1 (80.0%, 12/15), ST2 (6.7%, 1/15), and ST3 (13.3%, 2/15) in TS, and ST2 (80.0%, 4/5) and ST3 (20.0%, 1/5) in QZG. The only E. bieneusi isolate detected here was identified as zoonotic genotype CAF4. Our PCR-based data indicate that potentially pathogenic protist species including G. duodenalis, Blastocystis sp., E. bieneusi, and B. coli are present at variable rates in the three NHP populations investigated here. The identification of zoonotic genotypes within these species indicates that human-NHP transmission is possible, although the extent and directionality of these events need to be elucidated in future molecular surveys.

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Giardia and Blastocystis are highly prevalent in confined non-human primates.

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Diarrhoea-causing Cryptosporidium and Entamoeba histolytica were undetected.

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First description of Enterocytozoon bieneusi genotype CAF4 in non-human primates.

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Confined non-human primates harbour protist species with zoonotic potential.

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Cross-species (including human) transmission is possible in zoos and sanctuaries.

Enteric protists in wild western chimpanzees (Pan troglodytes verus) and humans in Comoé National Park, Côte d'Ivoire

The western chimpanzee (Pan troglodytes verus), a subspecies of the common chimpanzee, is currently listed as Critically Endangered. Human-driven habitat loss and infectious diseases are causing dramatic chimpanzee population declines and range contractions that are bringing these primates to the brink of extinction. Little information is currently available on the occurrence of diarrhoea-causing enteric protist species in chimpanzees in general, and in western chimpanzees in particular, or on the role of humans as a potential source of these infections. In this prospective molecular epidemiological study, we investigated the presence, genetic variability, and zoonotic potential of enteric protists in faecal samples from western chimpanzees (n = 124) and humans (n = 9) in Comoé National Park, Côte d'Ivoire. Parasite detection and genotyping were conducted by using polymerase chain reaction (PCR) and Sanger sequencing. The protist species found in the chimpanzee samples were Entamoeba dispar (14.5%), Blastocystis sp. (11.3%), Giardia duodenalis (5.8%), Troglodytella abrassarti (2.5%) and Cryptosporidium hominis (0.8%). The protist species found in the human samples were G. duodenalis (22.2%) and Blastocystis sp. (11.1%). Entamoeba histolytica, Enterocytozoon bieneusi, and Balantioides coli were undetected in both chimpanzee and human samples. Sequence analyses revealed the presence of Blastocystis subtype (ST) 1 (alleles 4 and 8) and ST3 (allele 24) in chimpanzees, and ST3 (allele 52) in humans. ST1 allele 8 represents a chimpanzee-adapted Blastocystis genetic variant. Cross-species transmission of pathogenic enteric protists between chimpanzees and humans might be possible in Comoé National Park, although the frequency and extent of zoonotic events remain to be fully elucidated.

Intestinal Protists in Captive Non-human Primates and Their Handlers in Six European Zoological Gardens. Molecular Evidence of Zoonotic Transmission

We assessed the occurrence, genetic diversity, and zoonotic potential of four protozoan (Cryptosporidium spp., Entamoeba histolytica, Entamoeba dispar, Giardia duodenalis), one stramenopile (Blastocystis sp.), one microsporidia (Enterocytozoon bieneusi), and two ciliate (Balantioides coli, Troglodytella abrassarti) intestinal parasite or commensal protist species in captive non-human primates (NHP) and their zookeepers from six European zoological gardens in France (n = 1), Germany (n = 1), and Spain (n = 4). Faecal samples from NHP (n = 454) belonging to 63 species within 35 genera and humans (n = 70) were collected at two sampling periods in each participating institution between October 2018-August 2021. Detection and species identification was accomplished by PCR and Sanger sequencing of the ssu rRNA and/or ITS genes. Sub-genotyping analyses using specific markers were conducted on isolates positive for G. duodenalis (gdh, bg, tpi) and Cryptosporidium spp. (gp60). Overall, 41.0% (186/454) and 30.0% (21/70) of the faecal samples of NHP and human origin tested positive for at least one intestinal protist species, respectively. In NHP, Blastocystis sp. was the most prevalent protist species found (20.3%), followed by G. duodenalis (18.1%), E. dispar (7.9%), B. coli and T. abrassarti (1.5% each), and Cryptosporidium spp. and E. bieneusi (0.9% each). Occurrence rates varied largely among NHP host species, sampling periods, and zoological institutions. The predominant protist species found in humans was Blastocystis sp. (25.7%), followed by Cryptosporidium spp. (2.9%), E. dispar (1.4%), and G. duodenalis (1.4%). Sequencing of PCR-positive amplicons in human and/or NHP confirmed the presence of Cryptosporidium in six isolates (C. hominis: 66.7%, C. parvum: 33.3%), G. duodenalis in 18 isolates (assemblage A: 16.7%, assemblage B: 83.3%), Blastocystis in 110 isolates (ST1:38.2%, ST2:11.8%, ST3: 18.2%, ST4: 9.1%, ST5: 17.3%, ST8: 2.7%, ST13: 0.9%), and E. bieneusi in four isolates (CM18: 75.0%, Type IV: 25.0%). Zoonotic transmission events involving Blastocystis ST1-ST4 were identified in four zoological institutions. Zoonotic transmission of C. hominis was highly suspected, but not fully demonstrated, in one of them. Monitoring of intestinal protist species might be useful for assessing health status of captive NHP and their zookeepers, and to identify transmission pathways of faecal-orally transmitted pathogens.

Cyst detection and viability assessment of Balantioides coli in environmental samples: Current status and future needs

The ciliate Balantioides coli is a human enteric parasite that can cause life-threatening infections. It is a food- and waterborne parasite, with cysts being the infective stage. Despite its importance as a potential pathogen, few reports have investigated its presence in environmental samples, and some issues need attention including i) The accuracy of B. coli identification. In most cases, the protozoa is identified only by its morphological traits, which can be identical to those from other parasitic ciliates of animals. Genetic analysis of cysts recovered from environmental samples is necessary for species confirmation. In addition, genetic methods used with faecal samples need to be adequately validated with environmental matrices. ii) The methodology for searching this parasite in environmental samples. The protocols include an initial phase to isolate the cysts from the matrix followed by a second phase in which concentration procedures are usually applied. The methods may be valid but are not standardised and differences between studies could affect the results obtained. iii) The areas that needs further research. The development of genetic identification methods and standardised analytical protocols in environmental samples are required, as well as the assessment of viability and infectivity of B. coli cysts. The development of axenic culture systems will boost research on this parasite.

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Balantioides coli is mainly considered a foodborne parasite for humans.

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Detection methods in environmental samples are not standardised.

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Correct identification should be made by genetic analysis.

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Methods for B. coli cyst viability and infectivity assessment are to be developed.

Molecular Detection and Characterization of Intestinal and Blood Parasites in Wild Chimpanzees (Pan troglodytes verus) in Senegal

Simple Summary

Western chimpanzees are currently listed as a Critically Endangered subspecies. Human encroachment has taken a toll on this great ape due to fragmented habitat and the exchange of pathogens. This epidemiological study investigated the occurrence and genetic diversity of intestinal and blood parasites in faecal samples from wild chimpanzees living in the Dindefelo Community Nature Reserve, Senegal. We paid special attention to potential human-driven sources of infection and transmission pathways. Potential diarrhoea-causing protist parasites (e.g., Cryptosporidium spp., Giardia duodenalis, Entamoeba histolytica) were detected at low infection rates (and densities) or absent, whereas commensals (Entamoeba dispar) or protist of uncertain pathogenicity (Blastocystis sp.) were far more abundant. We detected Sarcocystis spp. in chimpanzee faeces. Blood protist parasites such as Plasmodium spp. and Trypanosoma brucei spp. (the etiological agents of malaria and sleeping sickness, respectively, in humans) were also found at low prevalences, but microfilariae of the nematode Mansonella perstans were frequently found. Molecular analyses primarily revealed host-adapted species/genotypes and an apparent absence of gastrointestinal clinical manifestations in infected chimpanzees. Zoonotic events of still unknown frequency and directionality may have taken part between wild chimpanzees and humans sharing natural habitats and resources.

Abstract

Wild chimpanzee populations in West Africa (Pan troglodytes verus) have dramatically decreased as a direct consequence of anthropogenic activities and infectious diseases. Little information is currently available on the epidemiology, pathogenic significance, and zoonotic potential of protist species in wild chimpanzees. This study investigates the occurrence and genetic diversity of intestinal and blood protists as well as filariae in faecal samples (n = 234) from wild chimpanzees in the Dindefelo Community Nature Reserve, Senegal. PCR-based results revealed the presence of intestinal potential pathogens (Sarcocystis spp.: 11.5%; Giardia duodenalis: 2.1%; Cryptosporidium hominis: 0.9%), protist of uncertain pathogenicity (Blastocystis sp.: 5.6%), and commensal species (Entamoeba dispar: 18.4%; Troglodytella abrassarti: 5.6%). Entamoeba histolytica, Enterocytozoon bieneusi, and Balantioides coli were undetected. Blood protists including Plasmodium malariae (0.4%), Trypanosoma brucei (1.3%), and Mansonella perstans (9.8%) were also identified. Sanger sequencing analyses revealed host-adapted genetic variants within Blastocystis, but other parasitic pathogens (C. hominis, P. malariae, T. brucei, M. perstans) have zoonotic potential, suggesting that cross-species transmission between wild chimpanzees and humans is possible in areas where both species overlap. Additionally, we explored potential interactions between intestinal/blood protist species and seasonality and climate variables. Chimpanzees seem to play a more complex role on the epidemiology of pathogenic and commensal protist and nematode species than initially anticipated.

Occurrence and Genetic Diversity of Protist Parasites in Captive Non-Human Primates, Zookeepers, and Free-Living Sympatric Rats in the Córdoba Zoo Conservation Centre, Southern Spain

Little information is currently available on the epidemiology of parasitic and commensal protist species in captive non-human primates (NHP) and their zoonotic potential. This study investigates the occurrence, molecular diversity, and potential transmission dynamics of parasitic and commensal protist species in a zoological garden in southern Spain. The prevalence and genotypes of the main enteric protist species were investigated in faecal samples from NHP (n = 51), zookeepers (n = 19) and free-living rats (n = 64) by molecular (PCR and sequencing) methods between 2018 and 2019. The presence of Leishmania spp. was also investigated in tissues from sympatric rats using PCR. Blastocystis sp. (45.1%), Entamoeba dispar (27.5%), Giardia duodenalis (21.6%), Balantioides coli (3.9%), and Enterocytozoon bieneusi (2.0%) (but not Troglodytella spp.) were detected in NHP. Giardia duodenalis (10.5%) and Blastocystis sp. (10.5%) were identified in zookeepers, while Cryptosporidium spp. (45.3%), G. duodenalis (14.1%), and Blastocystis sp. (6.25%) (but not Leishmania spp.) were detected in rats. Blastocystis ST1, ST3, and ST8 and G. duodenalis sub-assemblage AII were identified in NHP, and Blastocystis ST1 in zookeepers. Giardia duodenalis isolates failed to be genotyped in human samples. In rats, four Cryptosporidium (C. muris, C. ratti, and rat genotypes IV and V), one G. duodenalis (assemblage G), and three Blastocystis (ST4) genetic variants were detected. Our results indicate high exposure of NHP to zoonotic protist species. Zoonotic transmission of Blastocysts ST1 was highly suspected between captive NHP and zookeepers.

Balantioides coli

Balantioides coli (=Balantidium coli) is the only ciliate that parasitizes humans. Pigs are the main reservoir. Other species, as camels, cattle, donkey, sheep and goat have been also proposed as reservoirs for human infections. The parasite has a direct life cycle, being transmitted by the faecal-oral route. This type of cycle and the large number of host species imply an important potential for zoonotic transmission of the parasite. Infections are most commonly found in tropical and temperate regions, with prevalence up to 100% in pigs; high prevalence values have been also recorded in some non-human primates and camels. In humans, prevalence is usually under 10% in the population at risk. The main epidemiological factors involved in the transmission of this parasite include close contact with pigs, lack of basic sanitation infrastructures (water supply, wastewater disposal) and hygiene. Individual health status, intestinal microbiota and diet are also important for the onset of the infection. Outbreaks caused by this parasite are rare; those reported to date were related to poor hygienic conditions or to catastrophic natural disasters. Balantioides coli infections can be asymptomatic and symptomatic, which can be chronic (with intermittent diarrhoea), or acute (a dysenteric form which can be life-threatening). Efective treatments include tetracycline, iodoquinol and 5-nitroimidazole compounds (metronidazole, secnidazole). The main effective individual preventive measure is the use of disinfected water for drinking and other uses. Adequate water supply infrastructures, proper disposal of wastewater and animal faeces, and regular monitoring programs on farms will help limit transmission.

Morphological and molecular characterization of a new ciliate Nyctotheroides grimi n. sp. (Armophorea, Clevelandellida) from Chinese frogs

A new species of clevelandellid ciliate, Nyctotheroides grimi n. sp., is described from the frog Fejervarya limnocharis. Light and scanning electron microscopy were used for the morphological studies, and the DNA encoding the SSU rRNA gene (SSU rDNA) and the ITS1-5.8S subunit rRNA-ITS2 region (ITS) were sequenced for genetic comparisons and phylogenetic analysis. The main distinctive morphological feature is a knob-like projection in the left-posterior end; other differential characters are the cell size, the length of the oral groove and the shape of the infundibulum. Nyctotheroides grimi possess an apical suture line in the left and right side of the anterior end and in the left side of the caudal end. In the phylogenetic analyses, the new species engroups with other Nyctotheroides species forming a monophyletic group. The high similarity in the SSU rDNA and ITS sequences between Nyctotheroides species suggests a relative recent divergence. The genetic data and the different host range support the separation of Nyctotheroides and Nyctotherus; however the morphological criterion based on the presence (in Nyctotheroides)/absence (in Nyctothterus) of an apical kinetal suture line should be modified to consider the presence of kinetal suture lines in the apical and/or the caudal left side in Nyctotheroides.

Morphological description of Opalina obtrigonoidea Metcalf, 1923 (Heterokonta, Opalinea) from Duttaphrynus melanostictus and evaluation of the ITS region as a suitable genetic marker for inter-species identification in Opalina

The redescription of Opalina obtrigonoidea Metcalf, 1923, collected from the rectum of the toads Duttaphrynus melanostictus, is presented in this paper based on detailed morphological information and molecular data. Our results revealed that O. obtrigonoidea varies greatly in body dimensions. Its morphological characteristics allow its differentiation from Opalina undulata. Surprisingly, we sequenced its SSU rDNA-ITS1-5.8S rDNA-ITS2-LSU rDNA (5' end) and found the SSU rDNA of O. obtrigonoidea is nearly identical to that of O. undulata. However, there are differences in both the ITS1 and ITS2 regions that allow their distinction and confirm the morphological differences. Our results indicate that O. obtrigonoidea and O. undulata are closely related species in which morphological and genetic markers have evolved at different speeds. Due to this, the SSU rDNA gene may not be a valid marker for inter-species identification in Opalina, but the ITS is a valid marker for differentiating species in this genus.

Genetic identification of the ciliates from greater rheas (Rhea americana) and lesser rheas (Rhea pennata) as Balantioides coli

The ciliate species Balantioides coli can be cross-transmitted between humans and several animal species. Usually harmless, sometimes it can be pathogenic and cause the death of the host. In birds, B. coli has been confirmed in ostriches by genetic analysis, but the identification from South American greater rheas (Rhea americana) and lesser rheas (Rhea pennata pennata) is tentative. Since these species are reared for commercial purposes and for reintroduction into the wild, it is necessary to elucidate whether the ciliate from rheas is B. coli to minimize health risks for humans and for other domestic and wild animals. Individual parasite cells are collected from Argentinean isolates of reared greater rheas and of wild and reared lesser rheas, and their ITS region was PCR amplified; the cloning products were sequenced and compared with sequences available in public databases. The results have shown that several sequence types are expressed at the same time in the parasite cells, and all correspond to B. coli, confirming the possibility of cross-transmission of the parasite between wild and reared South American rheas and several mammal species and humans.

Endoparasitism of Greek ostriches: First report of Entamoeba struthionis and Balantioides coli

Ostrich farming is a worldwide practice and an internationally developing industry. Among challenges in livestock production are the parasitic infections. The present study aimed to the investigation of the gastrointestinal parasites biota and prevalence in ostriches raised in different areas of Greece. A total of 141 clinically healthy ostriches originating from four different localities of Greece were coprologically examined for parasites of the gastrointestinal tract. Coprological examination revealed a considerably high rate of infection (65.9%) with protozoa; however, no helminths (trematodes, cestodes and nematodes) were detected. In detail, cysts of Entamoeba struthionis have been found in 57.4% of the examined birds. Moreover, 39.0% of sampled ostriches harboured cysts of Balantioides coli (syn. Balantidium coli), while oocysts of Cryptosporidium sp. were detected at a low percentage (2.1%). Partial sequences of the small subunit rRNA (16S rRNA) gene and the ITS region were amplified from pooled Entamoeba and Balantioides positive samples, respectively, confirming for the first time the presence of Entamoeba struthionis and Balantioides coli in ostriches in Greece. Some of these parasitoses require attention as they may affect productivity performance of the animals in commercial ostrich farming and possibly pose disease risk for livestock and humans.

Are molecular tools clarifying or confusing our understanding of the public health threat from zoonotic enteric protozoa in wildlife?

Emerging infectious diseases are frequently zoonotic, often originating in wildlife, but enteric protozoa are considered relatively minor contributors. Opinions regarding whether pathogenic enteric protozoa may be transmitted between wildlife and humans have been shaped by our investigation tools, and have led to oscillations regarding whether particular species are zoonotic or have host-adapted life cycles. When the only approach for identifying enteric protozoa was morphology, it was assumed that many enteric protozoa colonized multiple hosts and were probably zoonotic. When molecular tools revealed genetic differences in morphologically identical species colonizing humans and other animals, host specificity seemed more likely. Parasites from animals found to be genetically identical - at the few genes investigated - to morphologically indistinguishable parasites from human hosts, were described as having zoonotic potential. More discriminatory molecular tools have now sub-divided some protozoa again. Meanwhile, some infection events indicate that, circumstances permitting, some "host-specific" protozoa, can actually infect various hosts. These repeated changes in our understanding are linked intrinsically to the investigative tools available. Here we review how molecular tools have assisted, or sometimes confused, our understanding of the public health threat from nine enteric protozoa and example wildlife hosts (Balantoides coli - wild boar; Blastocystis sp. - wild rodents; Cryptosporidium spp. - wild fish; Encephalitozoon spp. - wild birds; Entamoeba spp. - non-human primates; Enterocytozoon bieneusi - wild cervids; Giardia duodenalis - red foxes; Sarcocystis nesbitti - snakes; Toxoplasma gondii - bobcats). Molecular tools have provided evidence that some enteric protozoa in wildlife may infect humans, but due to limited discriminatory power, often only the zoonotic potential of the parasite is indicated. Molecular analyses, which should be as discriminatory as possible, are one, but not the only, component of the toolbox for investigating potential public health impacts from pathogenic enteric protozoa in wildlife.

Analysis of nad2 and nad5 enables reliable identification of genotypes G6 and G7 within the species complex Echinococcus granulosus sensu lato

The larval stages of tapeworms in the species complex Echinococcus granulosus sensu lato cause a zoonotic disease known as cystic echinococcosis (CE). Within this species complex, genotypes G6 and G7 are among the most common genotypes associated with human CE cases worldwide. However, our understanding of ecology, biology and epidemiology of G6 and G7 is still limited. An essential first step towards this goal is correct genotype identification, but distinguishing genotypes G6 and G7 has been challenging. A recent analysis based on complete mitogenome data revealed that the conventional sequencing of the cox1 (366 bp) gene fragment mistakenly classified a subset of G7 samples as G6. On the other hand, sequencing complete mitogenomes is not practical if only genotype or haplogroup identification is needed. Therefore, a simpler and less costly method is required to distinguish genotypes G6 and G7. We compared 93 complete mitogenomes of G6 and G7 from a wide geographical range and demonstrate that a combination of nad2 (714 bp) and nad5 (680 bp) gene fragments would be the best option to distinguish G6 and G7. Moreover, this method allows assignment of G7 samples into haplogroups G7a and G7b. However, due to very high genetic variability of G6 and G7, we suggest to construct a phylogenetic network based on the nad2 and nad5 sequences in order to be absolutely sure in genotype assignment. For this we provide a reference dataset of 93 concatenated nad2 and nad5 sequences (1394 bp in total) containing representatives of G6 and G7 (and haplogroups G7a and G7b), which can be used for the reconstruction of phylogenetic networks.

Epidemiology and identification of two species of Chilodonella affecting farmed fishes in China

The genus Chilodonella includes free-living ciliated protozoa as well as pathogenic species for freshwater fish, with Chilodonella hexasticha and Chilodonella piscicola being the most important ones. These parasites cause outbreaks with high mortalities among farmed freshwater fishes with great economic losses. There are few reports of these species in China, and their identification has been based mostly on their morphological characteristics. In the present work, the parasites causing five outbreaks occurring in China between 2014 and 2017 have been identified by morphological and genetic analysis. We provide the first records of Ctenopharingodon idella and Siniperca chuatsi as hosts of C. hexasticha, and of Procypris rabaudi and Schizothorax wangchiachii as hosts of C. piscicola. There are no differences in the gross pathological findings produced by C. hexasticha and C. piscicola, consisting in desquamation and necrosis of epithelial cells in the skin and gills and in severe fusion of gill lamellae. However, both species differ in their geographic distribution: C. piscicola was found in farms located at altitudes over 1500 m above sea level and with a water temperature ≤18 °C, while C. hexasticha was found in farms located at altitudes under 50 m above sea level and with a water temperature ≥21 °C. Present results confirm that C. hexasticha and C. piscicola are two different species that can be differenced by their morphology; however, their biological variability may lead to erroneous identifications and the diagnosis should be preferably based in genetic analysis including nuclear LSU rDNA and mitochondrial SSU rDNA sequences.

Distinguishing Echinococcus granulosus sensu stricto genotypes G1 and G3 with confidence: A practical guide

Cystic echinococcosis (CE), a zoonotic disease caused by tapeworms of the species complex Echinococcus granulosus sensu lato, represents a substantial global health and economic burden. Within this complex, E. granulosus sensu stricto (genotypes G1 and G3) is the most frequent causative agent of human CE. Currently, there is no fully reliable method for assigning samples to genotypes G1 and G3, as the commonly used mitochondrial cox1 and nad1 genes are not sufficiently consistent for the identification and differentiation of these genotypes. Thus, a new genetic assay is required for the accurate assignment of G1 and G3. Here we use a large dataset of near-complete mtDNA sequences (n = 303) to reveal the extent of genetic variation of G1 and G3 on a broad geographical scale and to identify reliable informative positions for G1 and G3. Based on extensive sampling and sequencing data, we developed a new method, that is simple and cost-effective, to designate samples to genotypes G1 and G3. We found that the nad5 is the best gene in mtDNA to differentiate between G1 and G3, and developed new primers for the analysis. Our results also highlight problems related to the commonly used cox1 and nad1. To guarantee consistent identification of G1 and G3, we suggest using the sequencing of the nad5 gene region (680 bp). This region contains six informative positions within a relatively short fragment of the mtDNA, allowing the differentiation of G1 and G3 with confidence. Our method offers clear advantages over the previous ones, providing a significantly more consistent means to distinguish G1 and G3 than the commonly used cox1 and nad1.

The benefits of analysing complete mitochondrial genomes: Deep insights into the phylogeny and population structure of Echinococcus granulosus sensu lato genotypes G6 and G7

Cystic echinococcosis (CE) is a zoonotic disease caused by the larval stage of the species complex Echinococcus granulosus sensu lato. Within this complex, genotypes G6 and G7 have been frequently associated with human CE worldwide. Previous studies exploring the genetic variability and phylogeography of genotypes G6 and G7 have been based on relatively short mtDNA sequences, and the resolution of these studies has often been low. Moreover, using short sequences, the distinction between G6 and G7 has in some cases remained challenging. The aim here was to sequence complete mitochondrial genomes (mitogenomes) to obtain deeper insight into the genetic diversity, phylogeny and population structure of genotypes G6 and G7. We sequenced complete mitogenomes of 94 samples collected from 15 different countries worldwide. The results demonstrated that (i) genotypes G6 and G7 can be clearly distinguished when mitogenome sequences are used; (ii) G7 is represented by two major haplogroups, G7a and G7b, the latter being specific to islands of Corsica and Sardinia; (iii) intensive animal trade, but also geographical isolation, have likely had the largest impact on shaping the genetic structure and distribution of genotypes G6 and G7. In addition, we found phylogenetically highly divergent haplotype from Mongolia (Gmon), which had a higher affinity to G6.

Global phylogeography and genetic diversity of the zoonotic tapeworm Echinococcus granulosus sensu stricto genotype G1

Echinococcus granulosus sensu stricto (s.s.) is the major cause of human cystic echinococcosis worldwide and is listed among the most severe parasitic diseases of humans. To date, numerous studies have investigated the genetic diversity and population structure of E. granulosus s.s. in various geographic regions. However, there has been no global study. Recently, using mitochondrial DNA, it was shown that E. granulosus s.s. G1 and G3 are distinct genotypes, but a larger dataset is required to confirm the distinction of these genotypes. The objectives of this study were to: (i) investigate the distinction of genotypes G1 and G3 using a large global dataset; and (ii) analyse the genetic diversity and phylogeography of genotype G1 on a global scale using near-complete mitogenome sequences. For this study, 222 globally distributed E. granulosus s.s. samples were used, of which 212 belonged to genotype G1 and 10 to G3. Using a total sequence length of 11,682 bp, we inferred phylogenetic networks for three datasets: E. granulosus s.s. (n = 222), G1 (n = 212) and human G1 samples (n = 41). In addition, the Bayesian phylogenetic and phylogeographic analyses were performed. The latter yielded several strongly supported diffusion routes of genotype G1 originating from Turkey, Tunisia and Argentina. We conclude that: (i) using a considerably larger dataset than employed previously, E. granulosus s.s. G1 and G3 are indeed distinct mitochondrial genotypes; (ii) the genetic diversity of E. granulosus s.s. G1 is high globally, with lower values in South America; and (iii) the complex phylogeographic patterns emerging from the phylogenetic and geographic analyses suggest that the current distribution of genotype G1 has been shaped by intensive animal trade.

First molecular characterization of Balantioides coli (Malmsten, 1857) isolates maintained in vitro culture and from feces of captive animals, Rio de Janeiro, Brazil

Ciliate protozoa of the genus Balantioides can parasitize a variety of animals. The morphology of the evolutionary forms of the parasite and the host species affected have long been the only characteristics used to taxonomically identify the species of these protozoa, but these variables are not very precise. To confirm species identity, molecular biology tools are currently used. In this context, this study aimed to analyze protozoan isolates maintained in culture medium and from fecal samples from captive animals in Rio de Janeiro, Brazil, by means of molecular tools. Forty isolates maintained in Pavlova modified medium (30 were isolated from feces of pigs and 10 from feces of cynomolgus macaques) were analyzed. In addition, 34 fecal samples (8 from pigs, 8 from cynomolgus macaques and 18 from rhesus macaques) containing Balantioides coli-like cysts were analyzed. All samples were subjected to DNA extraction and the polymerase chain reaction (PCR) to amplify the fragment ITS1 - 5.8s rRNA - ITS2, and the PCR products were purified and sequenced. All samples (100%) presented sequences that were grouped in the Balantioides coli cluster. The type A0 variant predominated. These sequences were 96% to 99% identical to those deposited in GenBank, including a B. coli sequence that had been obtained from human fecal material in Bolivia. It seems that the culturing system did not select variants, because this variant was also seen in the amplified sequences of fecal samples containing cysts. The isolate sequences in the cultures showed few ambiguities and substitutions, thus generating reliable chromatograms. This was the first study to identify B. coli in captive animals in Brazil, through molecular biology. In addition, it was the first to evaluate a large panel of isolates of the parasite through culturing.

New mitogenome and nuclear evidence on the phylogeny and taxonomy of the highly zoonotic tapeworm Echinococcus granulosus sensu stricto

Cystic echinococcosis, a zoonotic disease caused by Echinococcus granulosus sensu lato (s. l.), is a significant global public health concern. Echinococcus granulosus s. l. is currently divided into numerous genotypes (G1-G8 and G10) of which G1-G3 are the most frequently implicated genotypes in human infections. Although it has been suggested that G1-G3 could be regarded as a distinct species E. granulosus sensu stricto (s. s.), the evidence to support this is inconclusive. Most importantly, data from nuclear DNA that provide means to investigate the exchange of genetic material between G1-G3 is lacking as none of the published nuclear DNA studies have explicitly included G2 or G3. Moreover, the commonly used relatively short mtDNA sequences, including the complete cox1 gene, have not allowed unequivocal differentiation of genotypes G1-G3. Therefore, significantly longer mtDNA sequences are required to distinguish these genotypes with confidence. The main aim of this study was to evaluate the phylogenetic relations and taxonomy of genotypes G1-G3 using sequences of nearly complete mitogenomes (11,443bp) and three nuclear loci (2984bp). A total of 23 G1-G3 samples were analysed, originating from 5 intermediate host species in 10 countries. The mtDNA data demonstrate that genotypes G1 and G3 are distinct mitochondrial genotypes (separated by 37 mutations), whereas G2 is not a separate genotype or even a monophyletic cluster, but belongs to G3. Nuclear data revealed no genetic separation of G1 and G3, suggesting that these genotypes form a single species due to ongoing gene flow. We conclude that: (a) in the taxonomic sense, genotypes G1 and G3 can be treated as a single species E. granulosus s. s.; (b) genotypes G1 and G3 should be regarded as distinct genotypes only in the context of mitochondrial data; (c) we recommend excluding G2 from the genotype list.

Supplemental description of Nyctotheroides pyriformis n. comb. (=Macrocytopharynxa pyriformis (Nie, 1932) Li et al. 2002) from frog hosts with consideration of the validity of the genus Macrocytopharynxa (Armophorea, Clevelandellida)

The morphological revisions of Macrocytopharynxa pyriformis (Nie, 1932) Li et al., 2002; collected from the rectum of Fejervarya limnocharis (=Rana limnocharis), are presented in this paper: (1) two surfaces of the organism are not identical - left side narrower and convex, right broader and flat or slightly concave; (2) infundibulum is large and well-developed with no "fold" or "plicature" present in the middle or posterior portion; (3) micronucleus is tiny and ovoid shaped and always embedded in the middle concavity of macronucleus, which can be well revealed by ammoniacal silver staining. Our phylogenetic analysis based on SSU-rDNA showed that M. pyriformis fell into the Nyctotheroides clade, within which four definite Nyctotheroides species were involved - N. cordiformis, N. deslierresae, N. parvus and N. hubeiensis. In combination with their morphological features, we discussed the reliability of using karyophore organelles or kinetal suture patterns as the generic taxonomic criteria. Besides, we considered that the genus Macrocytopharynxa is a junior synonym of Nyctotheroides and we transfer its type species to Nyctotheroides as Nyctotheroides pyriformis n. comb. The phylogenetic pattern of the family Nyctotheridae was also indicated in our work, but it will be necessary to analyze more species from fishes and reptiles before coming to a sound conclusion.

Morphology of Nyctotheroides hubeiensis Li et al. 1998 from Frog Hosts with Molecular Phylogenetic Study of Clevelandellid Ciliates (Armophorea, Clevelandellida)

The morphology of Nyctotheroides hubeiensis (Acta Hydrobiol. Sin. 1998, 22(suppl.):187), collected from the rectum of Phelophylax nigromaculatus, is presented in this paper based on detailed morphological information and molecular data. Our phylogenetic analysis showed that N. hubeiensis fell into the Nyctotheroides clade, which was strongly supported as monophyletic and clustered as basal to the genera Nyctotherus and Clevelandella. Also, the monophyly of the Order Clevelandellida and the affinity of parasitic nyctotherids and free-living metopids were indicated in our work. The origin of clevelandellid ciliates as well as their possible evolutionary history was also discussed here; however, the analysis of more species from other vertebrate hosts (fish, reptiles) should be made before a well-supported conclusion can be drawn.

Morphological and molecular identification of Tetratrichomonas flagellates from the giant anteater (Myrmecophaga tridactyla)

A tetratrichomonad flagellate found in the diarrhoeic faeces of a 5 years-old male giant anteater (Myrmecophaga tridactyla) was characterised by morphological and genetic analysis. This protozoan presents four anterior flagella of unequal length and a recurrent flagellum attached to the undulating membrane without a free end portion, and a broad axostyle projection. Numerous vacuoles of different sizes containing bacteria and digestion products were found. The complete sequence of the DNA coding for the 16S rRNA-ITS1-5.8S rRNA-ITS2 region was also obtained in order to compare this isolate with other tetratrichomonad species. The sequence obtained was identical to others previously obtained by other researchers from bovines and turtles (Geochelone sp.). It is not easily explainable how the same organism could be found in such different hosts and locations; however these results indicate that some tetratrichomonad species could have a wide host range and could survive in a wide range of environmental conditions.

Development of a specific polymerase chain reaction assay for the detection of Basidiobolus

The etiology of chronic diarrhea is complex in humans and animals. It is always necessary to evaluate a list of differential diagnosis, including bacteria, protozoa and fungi. Basidiobolomycosis is a fungal disease reported sporadically worldwide, mainly caused by B. ranarum, a frequent organism found in soil or in the intestine and skin of lizards and frogs. It is an opportunistic pathogen that causes infections characterized by granulomatous lesions in the subcutaneous tissues as well as in the intestinal wall in humans and animals. In this work we have developed a PCR technique to differentiate Basidiobolus from other causes of intestinal disease in dogs and humans. To test the specificity of the PCR assay we included closely related organisms, common intestinal microbiota and pathogenic organisms, such as Aspergillus, Candida, Cryptosporidium, Escherichia, Giardia, Mucor, Proteus, Rhizopus and Salmonella. Pythium insidiosum, which cause clinically similar disease in dogs but require a different treatment. Only Basidiobolus was positive to the PCR assay.

Genetic identification and host range of the Spanish strains of Echinococcus granulosus

Three strains of Echinococcus granulosus have been previously identified in Spain (namely 'sheep', 'horse' and 'pig'), but these Spanish strains have not been properly genotyped yet. The aim of the present research was to identify the genotype to which they correspond to. Cyst isolates were obtained from different host species, and the strain to which each belonged was established by analysis of its random amplified polymorphic DNA (RAPD) banding patterns. These results were compared to those obtained with the analysis of two mitochondrial fragment sequences (cytochrome oxidase 1 (CO1) and NADH dehydrogenase 1 (ND1)) from each isolate. The Spanish 'sheep' strain corresponded with the genotype 1 (G1) of the parasite, infecting Spanish sheep, cattle, goat, pig, wild boar and human; the Spanish 'horse' strain corresponded with the genotype 4 (G4), only infecting Spanish horses; and the Spanish 'pig' strain corresponded with the genotype 7 (G7), infecting Spanish goat, pig and wild boar. Goat, pig and wild boar can be infected by two genotypes, G1 and G7. This circumstance, and especially the possibility of sylvatic intermediate hosts serving as reservoirs of the G1 genotype of the parasite, must be taken into consideration by authorities in order to develop and evaluate effective anti-hydatidosis programmes.

Effect of two formulations of benzimidazole carbamates on the viability of cysts of Echinococcus granulosus in vivo

Two different preparations, solution and suspension, of three benzimidazole carbamate drugs, mebendazole, albendazole and ricobendazole, were compared by analyzing their in vivo activity against Echinococcus granulosus cysts in a mouse model. Polyvinylpyrrolidone was used for the elaboration of drug solutions and these formulations manifested better results in terms of reduction of number of viable hydatid cysts in mice than the reference drug suspensions. The effect was more prominent on mebendazole-treated mice, at doses of 25-50 mg/kg. There was a correlation between ED50 and pharmacokinetical parameters of AUC0-infinity and Cmax, showing that a significant improvement on solubility affects the in vivo activity of these drugs.

The effect of solubilization on the oral bioavailability of three benzimidazole carbamate drugs

The effect of solubilization by complexation with povidone on the oral bioavailability of three anthelmintic benzimidazole carbamate drugs: mebendazole (MBZ), albendazole (ABZ) and ricobendazole (RBZ), was studied in mice. The following in vitro characteristics of the initial raw materials and the drug-povidone complexes were evaluated: melting point (MP); mean dissolution time (MDT); solubility constants (Cs) in n-octanol, acid (pH 1.2) and neutral (pH 7.4) aqueous media; apparent partition coefficients (P) and capacity factors (k'W) determined by HPLC. The following in vivo parameters were also evaluated: AUC(0-infinity), C(max), T(max) and MRT. The possible relationship between in vitro characteristics and in vivo parameters was explored and it was found that an increase in solubility, especially in acidic medium, leads to an increase in AUC and C(max) and a decrease in T(max). Therefore, dissolution seems to be the absorption limiting step for these drugs. For the in vivo parameters related to the amount of absorbed drug (AUC and C(max)), the best correlation was obtained with the in vitro characteristics related to solubility which are Cs, MP and MDT. On the other hand, there were good linear correlations between T(max) which is an in vivo parameter related to the rate of drug absorption, and the lipophilia/hydrophilia (logP and log k'W) relation-parameters.