Multi-host model-based identification of Armillifer agkistrodontis (Pentastomida), a new zoonotic parasite from China

The postmortem diagnosis of an Armillifer infection case in a cynomolgus macaque (Macaca fascicularis)

Armillifer moniliformis belongs to the order Porocephalida and family Porocephalidae, and it can cause zoonotic pentastomiasis. A suspected parasitic infection was incidentally discovered in the abdominal cavity of a cynomolgus macaque that died of persistent diarrhea. 18S rDNA amplification and sequencing revealed a high similarity (99.83%) to the Armillifer moniliformis Guangxi isolate. The isolated parasite was named the Armillifer moniliformis Yunnan isolate (GenBank accession no. HM048870). Our report presents a case of Armillifer moniliformis infection in macaques. The results indicated that early quarantine and diagnosis should be employed for animal health.

Tongue worm (subclass: Pentastomida) infection and treatment in two domesticated reptiles - A case report

Tongue worms (Subclass: Pentastomida) are endoparasites found in carnivorous reptiles, fish, amphibians, birds, and mammals. Several pentastomids cause pentastomiasis, a zoonotic disease. We encountered tongue worm infection in two reptiles imported into Japan: a Wahlberg's velvet gecko (Homopholis wahlbergii) bred in Germany and a wild-caught green tree python (Morelia viridis) from the Republic of Indonesia. The infecting tongue worms were identified as Raillietiella sp. and Armillifer sp. in the gecko and python, respectively, based on morphological and molecular analyses. Gecko is a newly recorded definitive host harboring Raillietiella tongue worm. Live tongue worms were first detected in domestic reptiles in Japan, and this indicates a risk that these tongue worms could be spread to other animals, as well as humans. Therefore, the diagnosis and treatment of infected pets are of importance. In the case of the two infected reptiles, the availability of fecal egg examination for diagnosis was shown. In addition, the effectiveness of treatment with 200 μg/kg/day ivermectin orally once weekly was demonstrated, without no side-effects and no re-detection of eggs after the cessation of treatment.

28S rRNA sequences for Linguatula spp

Identification of specimens belonging to the genus Linguatula (Pentastomida) is relatively easy due to their unique morphology. However, differentiation between species of Linguatula can be challenging for several reasons, including considerable differences between different developmental stages of the parasite within and between species. Currently, 18S rRNA and Cox1 sequences are the only available comparable sequences in GenBank, but recent research has discussed the utility of 28S rRNA for pentastomid phylogenetics. This study presents 28S rRNA gene sequences for two members of the genus Linguatula. Sequences of 28S rRNA were successfully obtained from well-identified samples of L.serrata (collected in Australia) and L.nuttalli (collected in South Africa), with voucher specimens. Phylogenetic analysis of the 28S rRNA region showed 6% difference between L.serrata and L.nuttalli, with low levels of intraspecific variation. In comparison, 18S rRNA and Cox1 sequences from the same specimens showed 0.23% and 13% interspecific differences, respectively. The results of this study show that 28S rRNA has greater genetic diversity to allow for improved differentiation between species of Linguatula than 18S rRNA but is on par with Cox1. Records that do not provide adequate morphological or molecular data to justify independent specific diagnoses must be regarded cautiously, and the need for continued research on species of Linguatula, using a combined morphological and molecular analysis, across a number of different hosts, development stages, geographical regions and molecular markers is highlighted.

An annotated checklist of the eukaryotic parasites of humans, exclusive of fungi and algae

The classification of "parasites" in the medical field is a challenging notion, a group which historically has included all eukaryotes exclusive of fungi that invade and derive resources from the human host. Since antiquity, humans have been identifying and documenting parasitic infections, and this collective catalog of parasitic agents has expanded considerably with technology. As our understanding of species boundaries and the use of molecular tools has evolved, so has our concept of the taxonomy of human parasites. Consequently, new species have been recognized while others have been relegated to synonyms. On the other hand, the decline of expertise in classical parasitology and limited curricula have led to a loss of awareness of many rarely encountered species. Here, we provide a comprehensive checklist of all reported eukaryotic organisms (excluding fungi and allied taxa) parasitizing humans resulting in 274 genus-group taxa and 848 species-group taxa. For each species, or genus where indicated, a concise summary of geographic distribution, natural hosts, route of transmission and site within human host, and vectored pathogens are presented. Ubiquitous, human-adapted species as well as very rare, incidental zoonotic organisms are discussed in this annotated checklist. We also provide a list of 79 excluded genera and species that have been previously reported as human parasites but are not believed to be true human parasites or represent misidentifications or taxonomic changes.

Detection of a Larva of Armillifer armillatus in a Potto (Perodicticus potto) from the Republic of the Congo

We determined the complete sequence of the mitochondrial DNA (mtDNA) of a parasite discovered between the subcutaneous tissue and the peritoneum of an African nocturnal non-human primate (NHP). The parasite and host sequences were obtained by a combination of Sanger sequencing and nanopore MinION techniques. Analyses of mtDNA gene arrangements and sequences unambiguously showed that the parasite investigated was the pentastomid Armillifer armillatus, also commonly named the tongue worm. The full-length mitochondrial genome of A. armillatus, measuring 16,706 bp in length, contains 13 protein-coding genes, 2 ribosomal RNA genes, and 22 transfer RNA genes, an arrangement identical to that of previously described pentastomid mitochondrial genomes. We describe here the second full mitochondrial genome of A. armillatus to date. To identify the NHP host, maximum likelihood phylogenetic analyses of a 441-bp fragment on the 12S rDNA gene and of a 1,140-bp fragment of the mitochondrial cytochrome b strongly support clustering with the African lorisid Perodicticus potto, a species that has rarely been reported as an intermediate host of this parasite.

Establishment and application of the National Parasitic Resource Center (NPRC) in China

The National Parasitic Resource Center (NPRC) was created in 2004. It is a first-level platform under the Basic Condition Platform Center of the Ministry of Science and Technology of China. The resource centre involves 21 depository institutions in 15 regions of the country, including human parasite and vector depository, animal parasite depository, plant nematode characteristic specimen library, medical insect characteristic specimen library, trematode model specimen library, parasite-vector/snail model specimen library, etc. After nearly 15 years of operation, the resource centre has been built into a physical library with a database of 11 phyla, 23 classes, 1115 species and 117,814 pieces of parasitic germplasm resources, and three live collection bases of parasitic germplasm resources. A variety of new parasite-related immunological and molecular biological detection and identification technologies produced by the resource centre are widely used in the fields of public health responses, risk assessments on food safety, and animal or plant quarantine. The NPRC is the largest and top level resource centre on parasitology in China, and it is a leading technology platform for collecting and identifying parasitic resources.

Zoonotic Parasites of Reptiles: A Crawling Threat

Reptiles are reservoirs of a wide range of pathogens, including many protozoa, helminths, pentastomids, and arthropod parasitic species, some of which may be of public health concern. In this review we discuss the zoonotic risks associated with human–reptile interactions. Increased urbanization and introduction of exotic species of reptile may act as drivers for the transmission of zoonotic parasites through the environment. In addition, being a part of human diet, reptiles can be a source of life-threatening parasitoses, such as pentastomiasis or sparganosis. Finally, reptiles kept as pets may represent a risk to owners given the possibility of parasites transmitted by direct contact or fecal contamination. Awareness of reptile-borne zoonotic parasitoses is important to advocate control, prevention, and surveillance of these neglected diseases.

Species of protozoa, helminths, pentastomids, and arthropod vectors exploit reptiles as definitive or paratenic hosts, which may represent a public health concern.

The zoonotic risk is associated with human–reptile interactions and includes environmental contamination, reptile consumption, or keeping reptiles as pets.

Exotic reptile species may introduce new zoonotic parasites in a previously nonendemic region.

Pentastomiasis and sparganosis are life-threatening food-borne parasitoses.

In our households, if precautions are not taken, reptiles may transmit zoonotic parasites by direct contact or fecal contamination.

Trained veterinarians, physicians, and public health officials are important to advocate for proper diagnostics, parasite identification and treatment, as well as for surveillance strategies and food inspection in areas where reptiles are consumed.

Characterisation of the tongue worm, Linguatula serrata (Pentastomida: Linguatulidae), in Australia

We describe adult males and females and a nymph belonging to Linguatula serrata in Australia, based on light and scanning electron microscopies. In addition, 18S and Cox1 sequence data have also been provided and were compared with similar sequences in GenBank. Our specimens had identical 18S sequences and limited genetic distance in Cox1 region which fell within the intra-specific range observed for Linguatula spp. suggesting that they all belong to one species. Phylogenetic analyses showed that Australian specimens were grouped with L. serrata in Europe where the species was first found and described. A number of L. serrata from Iran and Bangladesh formed a distinct group. The genetic distance between these Linguatula and Australian/European L. serrata ranged from 0.46% to 2.21% which is larger than the genetic distance observed between L. arctica and Australian/European L. serrata (0.12%) suggesting that they belong to a different species. As pointed out previously by several other authors, L. serrata comprises more than one species and those from the Palearctic region (including Iran and Bangladesh) should not be automatically named L. serrata unless there is enough evidence for the identification. To accurately address the complex taxonomy of Linguatula spp. a detailed morphological and genetic characterisation of numerous developmental stages of the parasite is necessary, to ensure morphological differences are not due to development. This however may not be achievable in the near future due to significant reduction in expertise as well as research funding awarded in this area of research to understand the basics of our planet.

Occurrence of Kalicephalus, Strongyloides, and Rhabdias nematodes as most common gastrointestinal parasites in captive snakes of German households and zoological gardens

Nowadays, snakes established as domestic exotic pets, harboring numerous (zoonotic) gastrointestinal parasites. In this parasitological survey, we used direct saline fecal smears (DSFS) to examine 586 stool samples from 71 different snake species either kept as pets in households or in zoological gardens in Germany. In addition to DSFS, carbol-fuchsin-fecal smears (n = 296), coproantigen ELISA tests (n = 98), and immunofluorescence assays (IFA; n = 77) for the detection reptile Cryptosporidium infections were conducted. Complete dissections of deceased snakes (n = 63) were also performed in order to gain data on endoparasite species burdens affecting domestic snakes. Overall, examined fecal samples contained 20 different parasite taxa: Ancylostomatid Kalicephalus spp. were the most prevalent nematode species (3.3%), followed by Strongyloides/Rhabdias (2.6%), flagellated protozoan trophozoites (e. g., Proteromonadida, Reteromonadida) (2.3%), Monocercomonas spp. (1.9%), Entamoeba spp. (1.4%), unsporulated coccidian oocysts (1.4%), Kapsulotaenia spp. (0.9%), Capillaria spp. (0.7%), indet. trematodes (0.5%), pentastomids (0.5%), spirurids (0.4%), Eimeria spp. (0.4%), ascarids (0.4%), Blastocystis sp. (0.2%), heterakids (0.2%), cestodes (Proteocephalidae) (0.2%), Plagiorchis spp. (0.2%), Cryptosporidium spp. (0.2%), Caryospora epicratesi (0.2%), and Sarcocystis spp. (0.2%). For Cryptosporidium, four carbol-fuchsin-stained smears (1.4%), 12 (12.2%) coproantigen ELISA-examined samples and 5.2% of examined samples were diagnosed with IFA. Fourteen (22.2%) of dissected snakes showed infections with various pathogenic nematode genera and 8 of them (12.7%) died due to protozoan parasitic infections. High prevalences of intestinal protozoan parasites resulting in severe pathological findings observed in dissected snakes call for more detailed investigations on gastrointestinal parasites.

Morphological and molecular description of Armillifer moniliformis larvae isolated from Sri Lankan brown palm civet (Paradoxurus montanus)

We report Armillifer moniliformis species infecting the endemic Sri Lankan brown palm civet (Paradoxurus montanus) from the Knuckles Range Forest Conservation Area, Sri Lanka. Larval stages of A. moniliformis were found during the postmortem of three civet cats found dead. Morphological studies were done by a light microscope and a scanning electron microscope (SEM). Histopathological examination was conducted using tissue samples obtained from the liver. For the molecular analysis, DNA was extracted from the isolated third-stage larvae. The NADH dehydrogenase subunit 5 (ND5) and the second internal transcribed spacer region (ITS-2), a portion of the large subunit nuclear ribosomal DNA (28S), a portion of 18S ribosomal rRNA gene (18S), and cytochrome c oxidase subunit 1 gene (COX1) were amplified using polymerase chain reaction (PCR). Excysted third-stage larvae were observed in the lungs, omentum, the pleural cavity, the abdominal cavity, and the surface of the spleen and the pericardium. Around 88 third-stage larvae were isolated from three civet cats. First-stage larvae in the liver were surrounded by outer fibrous layer over the inner germinal layer and filled with clear fluid. Slight hemorrhage, leukocyte infiltration, and mild hepatocellular degeneration in the liver were observed. The SEM examination indicated the unique oral apparatus comprises the oval-shaped mouth opening in between two pairs of curved, retractile hamuli. The sequences obtained for ND5, ITS-2, 28S, 18S, and COX1 were 301, 382, 325, 414, and 644 bp in length respectively. Morphology, sequence similarity search, sequence alignment, and phylogenetic analysis identified this parasite as A. moniliformis.

Severe infection caused by nymphs of Armillifer armillatus (Pentastomida, Porocephalidae) in a leopard, Panthera pardus, in the Kruger National Park, South Africa

The necropsy of an adult male leopard, Panthera pardus, shot in the Kruger National Park, revealed the presence of large numbers of Armillifer armillatus nymphs in the intestine, liver, spleen, mesentery, peritoneal fold, mediastinum and lungs. The animal had been observed to be blind in the right eye and severely debilitated. The infection with A. armillatus clearly contributed to its emaciation and anaemia. Armillifer armillatus is a parasite of snakes, using mammals that form part of the snakes' prey as intermediate hosts. It is also one of the pentastomids with the highest zoonotic potential in Africa. It is unclear if the leopard's partial blindness and injuries of its extremities forced it to forego larger prey items for easier prey, such as snakes, and this in turn led to exposure to this unusual parasite, or if he had simply developed a preference for snakes. The incidental finding of A. armillatus in a large carnivore emphasises the importance of necropsies in expanding our knowledge on wildlife diseases.

Severe visceral pentastomiasis in an oriental small-clawed otter with functional thyroid carcinoma

In January 2016, a 20-year-old female oriental small-clawed otter (Aonyx cinereus) from Night Safari in Singapore was euthanized and diagnosed with a thyroid gland carcinoma. Postmortem examination and histology also revealed metastasis to the regional lymph nodes and severe visceral pentastomiasis. Grossly, the lymph nodes were infested, and encapsulation was observed on the visceral serosal surface. Histopathologically, the lymph nodes were encysted by a thick fibrous connective capsule with minimal inflammatory response. Pentastomiasis has been previously reported in the smooth-coated otter (Lutrogale perspicillata) in Malaysia. This report is the first case of severe visceral pentastomiasis in an oriental small-clawed otter with functional thyroid carcinoma.

Co-infections in Visceral Pentastomiasis, Democratic Republic of the Congo

Results of PCR and histology indicate this infection is endemic to this country.

Snakeborne Armillifer pentastomiasis is an emerging human parasitic infection in rural tropical areas where snake meat is eaten. After a series of severe ocular A. grandis larval infections and anecdotal abdominal infection in Sankuru District, Democratic Republic of the Congo, during 2014–2015, we systematically investigated possible pentastomid etiology in patients who underwent surgery in the region. Histologic and molecular analyses by established pentastomid 18S rDNA- and newly developed Armillifer-specific cytochrome oxidase PCRs revealed larval pentastomid lesions in 3.7% of patients. Some persons had A. armillatus and A. grandis co-infections. Another pentastomid larva, Raillietiella sp., was molecularly detected in 1 patient who had concomitant A. grandis and A. armillatus infection. The PCRs used were suitable for detecting pentastomid species even in highly necrotic tissues. Phylogenetic analyses of Armillifer cytochrome oxidase genes detected multiple local strains.

Complete Mitochondrial Genome of a Tongue Worm Armillifer agkistrodontis

Armillifer agkistrodontis (Ichthyostraca: Pantastomida) is a parasitic pathogen, only reported in China, which can cause a zoonotic disease, pentastomiasis. A complete mitochondrial (mt) genome was 16,521 bp comprising 13 protein-coding genes (PCGs), 22 tRNA genes, 2 rRNA genes, and 1 non-coding region (NCR). A phylogenetic tree drawn with the concatenated amino acid sequences of the 6 conserved PCGs (atp6, cox1-3, and nad2) showed that A. agkistrodontis and Armillifer armillatus constituted a clade Pentastomida which was a sister group of the Branchiura. The complete mt genome sequence of A. agkistrodontis provides important genetic markers for both phylogenetic and epidemiological studies of pentastomids.

Visceral pentastomiasis caused by Armillifer armillatus in a captive striped hyena (Hyaena hyaena) in Chiang Mai Night Safari, Thailand

Visceral pentastomiasis (porocephalosis) caused by Armillifer armillatus larvae was incidentally diagnosed in a female striped hyena (Hyaena hyaena) of unknown age which died unexpectedly in 2013. The hyena had been imported from Tanzania 8years earlier and have been since then in a zoo in Chiang Mai, northern Thailand. Pathological examination revealed visceral nymph migrans of pentastomes throughout the intestine, liver, diaphragm, omentum and mesentery, spleen, kidneys, and urinary bladder. Polymerase chain reaction and sequencing that targeted the pentastomid-specific 18S rRNA gene determined 100% identity with reference sequence for A. armillatus, suggesting that its ova can infect the hyena to serve as an intermediate host for the parasite. Further studies to identify the source of infection, its risk factors, and host range for A. armillatus are important to determine its zoonotic potential and to better prevent and manage the disease to protect animal and human health.

Rickettsiae, protozoa, and opisthokonta/metazoa

Rhizobiales (formerly named Rickettsiales) cause in rare instances meningitis and meningovasculitis, respectively. In case of history of exposure, infection by Rhizobiales needs to be considered since both diagnosis and therapy may be extremely difficult and pathogen-specific. The same applies to protozoa; in this chapter, Babesia species, free-living amoebae and Entamoeba histolytica infection, including severe meningitis and brain abscess, infection by Trypanosoma species (South American and African trypanosomiasis) are discussed with respect to history, epidemiology, clinical signs, and symptoms as well as differential diagnosis and therapy. Parasitic flatworms and roundworms, potentially able to invade the central nervous system, trematodes (flukes), cestodes (in particular, Cysticercus cellulosae), but also nematodes (in particular, Strongyloides spp. in the immunocompromised) are of worldwide importance. In contrast, filarial worms, Toxocara spp., Trichinella spp., Gnathostoma and Angiostrongylus spp. are seen only in certain geographically confined areas. Even more regionally confined are infestations of the central nervous system by metazoa, in particular, tongue worms (=arthropods) or larvae of flies (=maggots). The aim of this chapter is (1) to alert the neurologist to these infections, and (2) to enable the attending emergency neurologist to take a knowledgeable history, with an emphasis on epidemiology, clinical signs, and symptoms as well as therapeutic management possibilities.

Imported Armillifer pentastomiasis: report of a symptomatic infection in The Netherlands and mini-review

We report a case of symptomatic visceral Armillifer pentastomiasis in a 23-year-old female Liberian immigrant to The Netherlands. The patient was referred to the gynecologist because of lower abdominal pain. During laparotomy, multiple adhesions were seen in the lower pelvis and a hydrosalpinx with an encapsulated Armillifer nymph, most likely Armillifer armillatus, was found. Key features of the parasite's cuticle which facilitate the diagnosis of pentastomiasis, are presented. Symptomatic pentastomiasis is uncommon, and most cases are diagnosed incidentally during surgery for other reasons, or at autopsy. With regard to increasing international migration, other imported pentastomiasis cases to Europe and North America are reviewed, and more cases are likely to be seen in the future.

Childhood pentastomiasis: a report of three cases with the following-up data

Pentastomiasis, a zoonotic parasitic disease, has been reported commonly in Africa and Asia. It is caused by pentastomes, which are annulated but unsegmented blood-sucking endoparasites. Fewer than 20 cases have been reported during the past two decades in China, and cases in children have been especially rare. Herein, we report three cases of pediatric patients with severe systemic symptoms, focusing on the clinical features, diagnosis, and therapy of this disease. The patients were two boys and one girl aged 3 to 13years. They all had a history of snake or worm ingested from snake and initial symptoms of fever, abdominal pain, diarrhea, and weight loss. Eosinophilia, anemia and elevated serum IgE levels were noted. Moreover, the large numbers of nodules, or even calcification, in the liver and/or lungs were noted by ultrasound, CT or MRI scans. These pentastomes were identified as Armillifer moniliformis, Porocephalus taiwana and Armillifer agkistrodontis. Praziquantel and mebendazole deworming treatments were adopted for the patients. Hence, pentastomiasis should be considered in the differential diagnosis for patients with multiple organ or system lesions, especially abdominal signs, that develop after the ingestion of snakes. Ultrasound, CT and MRI scans and laparoscopic approaches might be helpful for the diagnosis.

Primary analysis of the expressed sequence tags in a pentastomid nymph cDNA library

Background

Pentastomiasis is a rare zoonotic disease caused by pentastomids. Despite their worm-like appearance, they are commonly placed into a separate sub-class of the subphylum Crustacea, phylum Arthropoda. However, until now, the systematic classification of the pentastomids and the diagnosis of pentastomiasis are immature, and genetic information about pentastomid nylum is almost nonexistent. The objective of this study was to obtain information on pentastomid nymph genes and identify the gene homologues related to host-parasite interactions or stage-specific antigens.

Methodology/Principal Findings

Total pentastomid nymph RNA was used to construct a cDNA library and 500 colonies were sequenced. Analysis shows one hundred and ninety-seven unigenes were identified. In which, 147 genes were annotated, and 75 unigenes (53.19%) were mapped to 82 KEGG pathways, including 29 metabolism pathways, 29 genetic information processing pathways, 4 environmental information processing pathways, 7 cell motility pathways and 5 organismal systems pathways. Additionally, two host-parasite interaction-related gene homologues, a putative Kunitz inhibitor and a putative cysteine protease.

Conclusion/Significance

We first successfully constructed a cDNA library and gained a number of expressed sequence tags (EST) from pentastomid nymphs, which will lay the foundation for the further study on pentastomids and pentastomiasis.

Massive visceral pentastomiasis in a long-tailed macaque - an incidental finding

BACKGROUND

An unusual case of visceral pentastomiasis in a male adult long-tailed macaque imported from China is reported.

METHODS

The monkey was part of a toxicologic study. A massive accumulation of C-shaped parasites in various visceral organs was found post-mortem.

RESULTS

Based on the morphology of the nymphs, pentastomiasis was diagnosed etiopathologically. The pentastome genus and species was identified as Armillifer agkistrodontis by PCR and respective sequencing.

CONCLUSION

Molecular diagnostic methods are necessary tools to determine the exact species involved.

Human pentastomiasis caused by Armillifer moniliformis in Malaysian Borneo

We report a case of visceral pentastomiasis caused by Armillifer moniliformis in a 70-year-old aboriginal farmer from rural Malaysian Borneo. The patient complained of upper abdominal pain, jaundice, and loss of weight. Radiological investigations and subsequent histopathological examination revealed an adenocarcinoma of the pancreas with an adjacent liver nodule containing a nymph of A. moniliformis. This report constitutes the first documented human pentastomid infection in the whole of Malaysia after nearly 40 years, and it is the third description from Malaysian Borneo. Cases of human and animal pentastomiasis in Malaysia are discussed.

Transmission of Armillifer armillatus ova at snake farm, The Gambia, West Africa

Visceral pentastomiasis caused by Armillifer armillatus larvae was diagnosed in 2 dogs in The Gambia. Parasites were subjected to PCR; phylogenetic analysis confirmed relatedness with branchiurans/crustaceans. Our investigation highlights transmission of infective A. armillatus ova to dogs and, by serologic evidence, also to 1 human, demonstrating a public health concern.