Lethal infection due to Armillifer armillatus (Porocephalida): A snake-related parasitic disease

Abdominal Calcifications in a Patient From the Congo Basin with History of Snake Meat Consumption: Radiographic Evidence of Prior Armillifer Infection

We report a case of a 60-year-old asymptomatic male with history of consumption of uncooked snake meat while living in the Congo basin and prior imaging showing multiple abdominal calcifications. Patient had multiple subepithelial colonic lesions identified during screening colonoscopy and microscopic examination of the lesions demonstrated a calcified nodule in the submucosa with overlying normal mucosa. However, no parasite was identified within the calcified nodule. Given the history of consumption of uncooked snake meat and the typical radiographic feature of multiple abdominal calcifications, it is very likely that the patient's radiographic abnormalities are due to prior Armillifer armillatus infection, a parasitic infection acquired from consumption of uncooked snake meat. Patient was asymptomatic at the time of evaluation and was not given anti-parasitic treatment.

Disseminated Armillifer armillatus Infestation: A Rare Cause of Acute Abdomen

We report a case of an 80-year-old symptomatic female with severe visceral Armillifer armillatus infestation who presented with complaints of progressively worsening colicky abdominal pain with associated constipation and mild abdominal distension. Imaging workup demonstrated unique radiological features of the parasite including multiple curvilinear opacities, measuring approximately 3 to 6 mm in length, scattered in the lung fields, abdomen, pelvis, and inguinal region. Histologic examination of inguinal biopsies revealed enlarged lymph nodes containing several parasitic pseudocysts. She was managed conservatively and received antihelmintics, with subsequent uneventful recovery. This case emphasizes the importance of meticulous differential diagnoses formulation. In the right clinical scenario, pentastomiasis should be considered in the differential diagnoses of patients with imaging evidence of multiple organ lesions, as a high index of suspicion is needed for the diagnosis of this entity and will help to avoid unnecessary invasive management.

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.

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.

Armillifer Infections in Humans: A Systematic Review

Armillifer is a genus of obligate parasites belonging to the Pentastomida subclass that was first described as a cause of human disease in 1847. Human infection by Armillifer is rare and not widely known. These parasites are transmitted to humans by handling or eating undercooked meat from infected snakes, which are the definitive hosts, or oral uptake of environmental ova. The aim of this systematic review was to record all available evidence regarding infections by Armillifer in humans. A systematic review of PubMed (through 21 December 2018) for studies providing epidemiological, clinical, microbiological, as well as treatment data and outcomes of Armillifer infections was conducted. A total of 26 studies, containing data of 40 patients, were eventually included in the analysis. The most common sites of infection were the peritoneal cavity, the liver, the lower respiratory and the abdominal tract. The commonest infecting species was A. armillatus and most patients were asymptomatic; however, when symptoms occurred, the commonest was abdominal pain, even though unusual presentations occurred, such as hepatic encephalopathy or neurologic symptoms. Most cases were diagnosed at surgery or by imaging, and most patients were not treated. Mortality was low, but the majority of the cases with ocular infection lead to permanent loss of vision.

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.

Human pentastomiasis in Sub-Saharan Africa

Pentastomiasis is a rare zoonotic infection but it is frequently observed in Africa and Asia. Most human infections are caused by members of the Armillifer armillatus species. They are responsible for visceral pentastomiasis in Western and Central Africa. Humans may be infected by eating infected undercooked snake meat or by direct contact with an infected reptile. An increasing number of infections are being reported in Congo, Nigeria, and Cameroon. Despite an occasionally high number of nymphs observed in human viscera, most infections are asymptomatic and often diagnosed by accident during surgery or autopsy. The clinical presentation of pentastomiasis is quite varied and depends on infected tissues. The liver, lungs, and pleura are most frequently involved. Abdominal emergencies have been reported. Diagnostic delays always occur and diagnosis focuses on the patient's lifestyle and living environment. It is mainly based on the morphological description of the parasite's calcified cuticle, the site of the lesion, and the parasite's region of origin. Most patients do not require any treatment. Personal measures such as avoidance of contact with snake droppings are recommended to prevent transmission. Imported pentastomiasis has been observed in African migrants.

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.

Ocular pentastomiasis in the Democratic Republic of the Congo

Ocular pentastomiasis is a rare infection caused by the larval stage of pentastomids, an unusual group of crustacean-related parasites. Zoonotic pentastomids have a distinct geographical distribution and utilize reptiles or canids as final hosts. Recently, an increasing number of human abdominal infections have been reported in Africa, where pentastomiasis is an emerging, though severely neglected, tropical disease. Here we describe four ocular infections caused by pentastomids from the Democratic Republic of the Congo. Two cases underwent surgery and an Armillifer grandis infection was detected by morphological and molecular approaches. Thus far, 15 other cases of ocular pentastomiasis have been reported worldwide. Twelve cases were caused by Armillifer sp., recorded almost exclusively in Africa, where such infections occur as a consequence of hunting and consuming snakes, their final hosts. Seven further cases were caused by Linguatula serrata, a cosmopolitan pentastomid whose final hosts are usually canids. Intraocular infections caused permanent visual damage in 69% and a total loss of vision in 31% of reported cases. In contrast, ocular adnexal cases had a benign clinical course. Further research is required to estimate the burden, therapeutic options and pathogenesis of this neglected disease.

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.

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.