Check list of parasites and bacteria recorded from pangolins (Manis sp.)

Detection of tick-borne pathogens in the pangolin tick, Amblyomma javanense, from Vietnam and Laos, including a novel species of Trypanosoma

Two species of Southeast Asian pangolins (the Chinese pangolin, Manis pentadactyla and the Malayan or Sunda pangolin, Manis javanica) are critically endangered species. Therefore, knowledge on their parasitic infections is very important, especially considering ticks that can transmit which pathogens. In this study, 32 pangolin ticks (Amblyomma javanense), that were collected in Vietnam and Laos, were analyzed with molecular methods for the presence of tick-borne pathogens. Two members of the family Anaplasmataceae were shown to be present in 14 pangolin ticks, i.e., Candidatus Anaplasma pangolinii and an Ehrlichia sp. In three ticks, a single Rickettsia genotype was also detected, and in seven ticks four 18S rRNA sequence variants of a Babesia sp. Most importantly, a novel protozoan agent, tentatively called here Trypanosoma sp. "PAT14" was detected in one A. javanense nymph. These results imply the first molecular finding of any species of Anaplasma, Ehrlichia and Babesia in pangolin ticks from Vietnam and Laos. On the other hand, detection of a new tick-associated Trypanosoma sp. in A. javanense from Southeast Asia is not only important from a taxonomic point of view, but it is also the first finding of any trypanosomes in the genus Amblyomma in Eurasia and adds pangolins to the potential placental mammalian hosts of any trypanosomes.

Pangolin scales as adaptations for innate immunity against pathogens

BACKGROUND

Pangolins are the only mammals that have overlapping scales covering most of their bodies, and they play a crucial role in the ecosystem, biological research, and human health and disease. Previous studies indicated pangolin scale might provide an important mechanical defense to themselves. The origin and exact functions of this unique trait remain a mystery. Using a multi-omics analysis approach, we report a novel functional explanation for how mammalian scales can provide host-pathogen defense.

RESULTS

Our data suggest that pangolin scales have a sophisticated structure that could potentially trap pathogens. We identified numerous proteins and metabolites exhibiting antimicrobial activity, which could suggest a role for scales in pathogen defense. Notably, we found evidence suggesting the presence of exosomes derived from diverse cellular origins, including mesenchymal stem cells, immune cells, and keratinocytes. This observation suggests a complex interplay where various cell types may contribute to the release of exosomes and antimicrobial compounds at the interface between scales and viable tissue. These findings indicate that pangolin scales may serve as a multifaceted defense system, potentially contributing to innate immunity. Comparisons with human nail and hair revealed pangolin-specific proteins that were enriched in functions relating to sensing, immune responses, neutrophil degranulation, and stress responses. We demonstrated the antimicrobial activity of key pangolin scale components on pathogenic bacteria by antimicrobial assays.

CONCLUSIONS

This study identifies a potential role of pangolin scales and implicates scales, as possible determinants of pathogen defense due to their structure and contents. We indicate for the first time the presence of exosomes in pangolin scales and propose the new functions of scales and their mechanisms. This new mechanism could have implications for multiple fields, including providing interesting new research directions and important insights that can be useful for synthesizing and implementing new biomimetic antimicrobial approaches.

Molecular characterization of a novel Spiruromorpha species in wild Chinese pangolin by mitogenome sequence analysis

Pangolins are susceptible to a variety of gastrointestinal nematodes due to their burrowing lifestyle and feeding habits, and few parasitic nematodes have been reported. Here, a Chinese pangolin with old wounds on its leg and tail was rescued from the Heyuan City, Guangdong Province. The cox1 and SSU rRNA of the worms from the intestine of the Chinese pangolin had the highest sequence identity of 89.58% and 97.95% to the species in the infraorder Spiruromorpha. The complete mitogenome of the worm was further assembled by next-generation sequencing, with a size of 13,708 bp and a GC content of 25.6%. The worm mitogenome had the highest sequence identity of 78.56% to that of Spirocerca lupi, sharing the same gene arrangement with S. lupi and some species in other families under Spiruromorpha. However, the mitogenome between the worm and S. lupi showed differences in codon usage of PCGs, sequences of NCR, and tRNA secondary structures. Phylogenetic analysis showed that the worm mitogenome was clustered with S. lupi in the family Thelaziidae to form a separate branch. However, it is still difficult to identify the worm in the family Thelaziidae because the species in the family Thelaziidae are confused, specifically S. lupi and Thelazia callipaeda in the family Thelaziidae were separated and grouped with species from other families. Thus, the parasitic nematode from the Chinese pangolin may be a novel species in Spiruromorpha and closely related to S. lupi. This study enriches the data on gastrointestinal nematodes in the Chinese pangolin.

Pharyngeal Communities and Antimicrobial Resistance in Pangolins in Gabon

Wildlife can be a reservoir and source of zoonotic pathogens for humans. For instance, pangolins were considered one of the potential animal reservoirs of SARS-CoV-2. The aim of this study was to assess the prevalence of antimicrobial-resistant species (e.g., extended-spectrum β-lactamase [ESBL]-producing Enterobacterales) and Staphylococcus aureus-related complex and to describe the bacterial community in wild Gabonese pangolins. The pharyngeal colonization of pangolins sold in Gabon (n = 89, 2021 to 2022) was analyzed using culture media selective for ESBL-producing Enterobacterales, S. aureus-related complex, Gram-positive bacteria and nonfermenters. Phylogenetic analyses of ESBL-producing Enterobacterales was done using core-genome multilocus sequence typing (cgMLST) and compared with publicly available genomes. Patterns of cooccurring species were detected by network analysis. Of the 439 bacterial isolates, the majority of species belonged to the genus Pseudomonas (n = 170), followed by Stenotrophomonas (n = 113) and Achromobacter (n = 37). Three Klebsiella pneumoniae isolates and one Escherichia coli isolate were ESBL-producers, which clustered with human isolates from Nigeria (MLST sequence type 1788 [ST1788]) and Gabon (ST38), respectively. Network analysis revealed a frequent cooccurrence of Stenotrophomonas maltophilia with Pseudomonas putida and Pseudomonas aeruginosa. In conclusion, pangolins can be colonized with human-related ESBL-producing K. pneumoniae and E. coli. Unlike in other African wildlife, S. aureus-related complex was not detected in pangolins. IMPORTANCE There is an ongoing debate if pangolins are a relevant reservoir for viruses such as SARS-CoV-2. Here, we wanted to know if African pangolins are colonized with bacteria that are relevant for human health. A wildlife reservoir of antimicrobial resistance would be of medical relevance in regions were consumption of so-called bushmeat is common. In 89 pangolins, we found three ESBL-producing Klebsiella pneumoniae strains and one ESBL-producing Escherichia coli strains, which were closely related to isolates from humans in Africa. This points toward either a transmission between pangolins and humans or a common source from which both humans and pangolins became colonized.

Differences in gut microbes in captive pangolins and the effects of captive breeding

Intestinal microorganisms are crucial for health and have a significant impact on biological processes, such as metabolism, immunity, and neural regulation. Although pangolin are protected animals in China and listed as critically endangered (CR) level by The International Union for Conservation of Nature (IUCN), the population of wild pangolins has decreased sharply in recent decades. Captive breeding has been adopted to protect pangolins, but the survival is low due to gastrointestinal infections, diarrhea, and parasitic infections. Studies on intestinal microbes in pangolins may reveal the relationship between intestinal microorganisms and health and assist protection. To explore the relationship between intestinal microorganisms and pangolin health, blood parameters and intestinal microorganisms of 10 pangolins (two Manis pentadactyla and eight Manis javanica) were studied at the Shenzhen Wildlife Rescue Center. There is difference among adult Sunda pangolins (M. javanica), adult Chinese pangolins (M. pentadactyla) and sub-adult Sunda pangolins (M. javanica) in intestinal microbial composition, diversity and phenotypic diversity, which suggested that adult Sunda pangolins occupied more diversity and proportion of microbial species to resist environmental pressure than the others. Due to the captive breeding serum cortisol of pangolins was increased, and the intestinal microbial structure changed, which may affect immunity. This study provides a scientific basis for the rescue of pangolins through artificial breeding.

Heteroplasmic mitochondrial genomes of a Raillietina tapeworm in wild Pangolin

Background

Raillietina species belong to the family Davaineidae, which parasitizes in a wide variety of mammals and birds, causing stunted growth, lethargy, emaciation, and digestive tract obstruction. However, only a limited number of Raillietina species have been identified in wild animals.

Methods

We analyzed and annotated the complete mitochondrial (mt) genome of a worm from the intestine of a wild pangolin using Illumina sequencing of whole genomic DNA.

Results

These findings showed the presence of two mtDNA sequences in Raillietina sp., designated as mt1 and mt2, with the lengths of 14,331 bp and 14,341 bp, respectively. Both the mts genomes of Raillietina sp. comprised 36 genes, containing 12 protein-coding genes (PCGs), 2 ribosomal RNAs, and 22 transfer RNAs. Gene arrangements of both mt genomes of Raillietina sp. were similar to those of most flatworms, except for taeniids, which shift positions between tRNAL1 and tRNAS2 genes. Twenty of 22 tRNA secondary structures of Raillietina sp. had a typical cloverleaf structure similar to Raillietina tetragona. Sequence differences between the mt1 and mt2 genomes were 4.4%, and this difference arises from the mtDNA heteroplasmic mutations. Moreover, heteroplasmic mtDNA mutations were detected in PCGs, tRNAs, rRNAs, NCRs, and intergenes, but the highest proportion of heteroplasmy of 79.0% was detected in PCGs, indicating the occurrence of mtDNA heteroplasmy in Raillietina sp. To our knowledge, this is the first report of mtDNA heteroplasmy in tapeworm parasites. Phylogenetic analyses of 18S rRNA, ITS2, and 12 PCG sequences demonstrated that the worm was clustered with other Raillietina species in the Davaneidae family.

Conclusions

We found a novel Raillietina species in wild pangolin with the existence of mitochondrial DNA heteroplasmy. Thus, these findings provide insights into the heterogeneity of the mt genome in parasitic cestodes, and mt genome data contributes to the understanding of pangolin-parasitic cestodes in terms of their molecular biology, epidemiology, diagnosis, and taxonomy.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05301-y.

Reference Intervals for Selected Hematology and Clinical Chemistry Measurands in Temminck's Pangolin (Smutsia temminckii)

Pangolins are the world's most trafficked non-human mammals. A significant number of Temminck's pangolins (Smutsia temminckii) are presented for veterinary care and rehabilitation in southern Africa. Little is known about the physiology and normal health of this species, making diagnosis and medical management difficult. This study aimed to establish reference intervals (RIs) for hematology and plasma clinical chemistry in the Temminck's pangolin. RIs were generated according to international guidelines using samples from 27 healthy free-living (n = 18) and rehabilitated (n = 9) pangolins. Hematology was performed using the Abaxis VetScan HM5 analyzer with manual differentials; clinical chemistry was performed using heparin plasma on the Abaxis VetScan VS2 and Cobas Integra 400 Plus analyzers. Hematology RIs were: RBC 3.88-8.31 × 10¹²/L, HGB 73-150 g/L, HCT 26-51%, MCV 59-72 fL, MCH 15.6-21.4 pg, MCHC 257-325 g/L, RDW 14.3-19.1%, WBC 1.80-10.71 × 10⁹/L. Vetscan VS2 clinical chemistry RIs were: albumin 27-41 g/L, ALP 26-100 U/L, ALT 25-307 U/L, amylase 267-826 U/L, bilirubin 4-10 μmol/L, calcium 2.1-2.2 mmol/L, globulin 21-55 g/L, glucose 3.8-10.0 mmol/L, phosphate 1.3-2.6 mmol/L, potassium 3.6-5.9 mmol/L, sodium 132-140 mmol/L total protein 52-84 g/L, and urea 5.3-11.4 mmol/L. RIs for creatinine were not calculated as analytical imprecision exceeded analytical performance goals. Cobas Integra clinical chemistry RIs were: albumin 22-33 g/L, ALP 20-104 U/L, ALT 17-291 U/L, amylase 466-1,533 U/L, bilirubin 1-14 μmol/L, calcium 2.0-2.4 mmol/L, creatinine <58 μmol/L, globulin 23-49 g/L, glucose 3.6-10.1 mmol/L, phosphate 1.0-2.2 mmol/L, potassium 3.1-5.8 mmol/L, sodium 137-150 mmol/L, total protein 47-72 g/L, and urea 6.0-12.5 mmol/L. There was significant bias between the two chemistry analyzers for several measurands. Differences were found for some analytes between free-living and rehabilitated animals, probably reflecting differences in nutrition and hydration. These are the first RIs generated for Temminck's pangolin. These results will allow veterinarians to better determine pangolin health status, formulate optimal treatment plans and increase patient survival rates in this endangered species.

First photographic evidence and distribution of the Indian Pangolin Manis crassicaudata (Mammalia: Pholidota: Manidae) in Sariska Tiger Reserve, Rajasthan, India

The Indian Pangolin, although considered to be widely distributed due to its elusive nature and low detection probability its status and distribution records are very limited. Rampant hunting for local consumption, and illegal wildlife trade for medicinal and ornamental purposes has pushed the species towards serious decline. Herein, we report the first photographic records of the Indian Pangolin in Sariska Tiger Reserve (STR), Rajasthan, India. During our camera trapping study from June 2018 to April 2019, out of 29,220 camera trapping nights the species was recorded on four occasions, at two different locations in STR. The species was recorded in the open forest areas near natural water bodies situated in the middle of dense Anogeissus pendula forests. 

A Review of the Parasite Fauna of the Black-Bellied Pangolin, Phataginus tetradactyla LIN. (Manidae), From Central Africa with the Description of Intraproboscis sanghae n. gen., n. sp. (Acanthocephala: Gigantorhynchidae)

A new archiacanthocephalan in the family Gigantorhynchidae, Intraproboscis sanghae n. gen., n. sp. is described from females collected from the African black-bellied pangolin Phataginus tetradactyla Linn. (Manidae) in the Central African Republic. A dichotomous key to the genera of Gigantorhynchidae is provided. The specimens presented are distinct from those of the genus Gigantorhynchus Hamann, 1892 that have only 1 or 2 circles of hooks (crowns) at the apical end of the proboscis and are found in South American mammals, except for Gigantorhynchus pesteri Tadros, 1966 from baboons in Rhodesia (Zimbabwe), Africa (Amin, 2013). They superficially resemble those of the other gigantorhynchid genus Mediorhynchus Van Cleave, 1916, especially in the organization of the truncate-cone proboscis and the position of the receptacle. Species of Mediorhynchus are bird parasites. The new genus, Intraproboscis, now the third genus in Gigantorhynchidae; however, is distinguished from Mediorhynchus by having a simple proboscis receptacle that is completely suspended within the proboscis, the passage of the retractor muscles through the receptacle into the body cavity posteriorly, absence of neck, and presence of a parareceptacle structure (first finding in the Archiacanthocephala) and a uterine vesicle; among other features, including the differential dorsoventral thickness of the body wall. The receptacle in Mediorhynchus is complex, with many accessory muscles and retractor muscles passing into the body cavity dorsally and ventrally. Our specimens reached 180 mm in length and the proboscis had 34-36 rows of 6-7 ventrally lamellated, rooted hooks each anteriorly, and 15-17 spinelike hooks each posteriorly. Micropores extended into the anterior and posterior proboscis and energy dispersive x-ray analysis (EDXA) of anterior hooks showed high levels of calcium and phosphorus but negligible traces of sulfur. Spinelike hooks in the posterior proboscis had lower levels of Ca and P and slightly higher levels of S. Molecular and phylogenetic analyses based on the 18S rDNA gene placed I. sanghae in a clade with the archiacanthocephalans Mediorhynchus, Moniliformis, Macracanthorhynchus, Oncicola, and Oligacanthorhynchus.

Canine Parvovirus Infections in Taiwanese Pangolins (Manis pentadactyla pentadactyla)

Canine parvovirus type 2 (CPV-2) is among the most important and highly contagious pathogens that cause enteric or systemic infections in domestic and nondomestic carnivores. However, the spillover of CPV-2 to noncarnivores is rarely mentioned. Taiwanese pangolins (Manis pentadactyla pentadactyla) are threatened due to habitat fragmentation and prevalent animal trafficking. Interactions between Taiwanese pangolins, humans, and domestic animals have become more frequent in recent years. However, information about the susceptibility of pangolins to common infectious agents of domestic animals has been lacking. From October 2017 to June 2019, 4 pangolins that were rescued and treated in wildlife rescue centers in central and northern Taiwan presented with gastrointestinal signs. Gross and histopathological examination revealed the main pathologic changes to be necrotic enteritis with involvement of the crypts in all intestinal segments in 2 pangolins. By immunohistochemistry for CPV-2, there was positive labeling of cryptal epithelium throughout the intestine, and immunolabeling was also present in epidermal cells adjacent to a surgical amputation site, and in mononuclear cells in lymphoid tissue. The other 2 pangolins had mild enteritis without crypt involvement, and no immunolabeling was detected. The nucleic acid sequences of polymerase chain reaction (PCR) amplicons from these 4 pangolins were identical to a Chinese CPV-2c strain from domestic dogs. Quantitative PCR revealed a higher ratio of CPV-2 nucleic acid to internal control gene in the 2 pangolins with severe intestinal lesions and positive immunoreactivity. Herein, we present evidence of CPV-2 infections in pangolins.

Identification of Amblyomma javanense and detection of tick-borne Ehrlichia spp. in confiscated Malayan Pangolins

Due to habitat destruction and illegal hunting and trade, the number of pangolins has been sharply reduced. To protect pangolins from extinction, relevant departments are combined and active action have been taken. A total of 21 confiscated Malayan pangolins were rescued in 2019, but died continuously for unknown reasons. This study aimed to investigate the reasons for the death of these pangolin and rescue them. 19 of the 21 confiscated pangolins had ticks on their body integument. A total of 303 ticks were collected and identified as Amblyomma javanense (A. javanense) according to their morphology and the sequences of 16S rRNA and internal transcribed spacer 2 (ITS2). There were multi-organ damages in the dead pangolins, especially congestion and hemorrhage in lung, heart and kidney and inflammation of which were observed using HE staining. Pathogens' nucleic acid detection showed ticks were only positive for Ehrlichia spp, with 56.7% positive rate of collected ticks (127/224), which was further confirmed in tissues from dead pangolins. Our findings confirm that ehrlichiosis caused by Ehrlichia spp. from A. javanense might accelerate the confiscated pangolin's death. More attention should be payed to tick-elimination work and the diagnoses and treatment of tick-borne diseases in the follow-up rescue operation.

Vitamin A deficiency and its treatment in captive Sunda pangolins

The high incidence of disease in captive pangolins is a major obstacle in pangolin-conservation breeding programs. Therefore, elucidating pangolins' susceptibility to disease is the key to conservation progress. At the Pangolin Research Base for Artificial Rescue and Conservation Breeding of South China Normal University (PRB-SCNU), vitamin A deficiency was diagnosed in 14 captive Sunda pangolins. Typical eye signs included lacrimal eyes, keratopathy and a blank, milky orb. The afflicted pangolins were treated with vitamins A and D for 15-30 days; all individuals recovered. We report the detection and treatment of vitamin A deficiency in captive Sunda pangolins at the PRB-SCNU. Our results could provide guidance for the future prevention and treatment of vitamin A deficiency and associated diseases in pangolin species, both to reduce the incidence of these diseases in captive pangolins and to aid conservation efforts.

Case report: Intestinal perforation and secondary peritonitis due to Acanthocephala infection in a black-bellied pangolin (Phataginus tetradactyla)

A case of Acanthocephala infection in a 5-year-old female rehabilitated and released black-bellied pangolin (Phataginus tetradactyla), which was part of a post-release monitoring program of a pangolin research operation in the Central African Republic, is described. This represents the first report of Acanthocephala infection in this species, which lead to intestinal perforation, secondary peritonitis and ultimately to the death of the animal concerned. It is of relevance to alert the pangolin conservation and research community to a so far unreported cause of death. A case history and necropsy findings, as well as preliminary parasite identification and genetic characterization which potentially revealed a new gigantorhynchid taxon are presented.

Newly identified viral genomes in pangolins with fatal disease

Epizootic pathogens pose a major threat to many wildlife species, particularly in the context of rapidly changing environments. Pangolins (order Pholidota) are highly threatened mammals, in large part due to the trade in illegal wildlife. During July to August 2018 four sick wild pangolins (three Manis javanica and one Manis pentadactyla) exhibiting a variety of clinical symptoms were rescued by the Jinhua Wildlife Protection Station in Zhejiang province, China. Although three of these animals died, fortunately one recovered after 2 weeks of symptomatic treatment. Using meta-transcriptomics combined with reverse transcription polymerase chain reaction (RT-PCR), we identified two novel RNA viruses in two of the dead pangolins. Genomic analysis revealed that these viruses were most closely related to pestiviruses and coltiviruses, although still highly genetically distinct, with more than 48 and 25 per cent sequence divergence at the amino acid level, respectively. We named these Dongyang pangolin virus (DYPV) and Lishui pangolin virus (LSPV) based on the sampling site and hosts. Although coltiviruses (LSPV) are known to be transmitted by ticks, we found no evidence of LSPV in ticks sampled close to where the pangolins were collected. In addition, although DYPV was present in nymph ticks (Amblyomma javanense) collected from a diseased pangolin, they were not found in the local tick population. Epidemiological investigation revealed that both novel viruses might have been imported following the illegal international trade of pangolins. Hence, these data indicate that illegal wildlife trafficking not only threatens the status of pangolin populations, but may also spread epizootic pathogens.

Identifying the tick Amblyomma javanense (Acari: Ixodidae) from Chinese pangolin: generating species barcode, phylogenetic status and its implication in wildlife forensics

Zoonotic diseases transmitted through ticks and other ectoparasites often travel across the globe with illegally traded wildlife parts and products. In this study, we analyzed a confiscated case of pangolin scales and observed a few dead ticks attached. On genetic analysis, the pangolin scales were identified to be originated from Chinese pangolin (Manis pentadactyla), an IUCN listed Critically Endangered species, and ticks were identified as Amblyomma javanense. Here, we provide the first authentic physical record of A. javanense from India as a parasite of Chinese pangolin and also generated its species DNA barcode that may be useful for biologists working on ticks in species validation and constructing phylogenies across the globe.

Taxonomy, Ecology and Population Genetics of Opisthorchis viverrini and Its Intermediate Hosts

There have been considerable advances in our understanding of the systematics and ecology of Opisthorchis viverrini; however, this new knowledge has not only clarified but also complicated the situation. We now know that what was once considered to be a single species is, in fact, a species complex, with the individual species being confined to specific wetland areas. There is also a strong genetic association between the members of the O. viverrini species complex and their Bithynia snail intermediate hosts. Although this does not negate data collected before the recognition of this situation, it does lead to the caveat that regional and temporal variations in data collected may be related to the species examined. The advances in ecology have generally been spatially limited and have led, in part, to contradictory results that may well be related to nonrecognition of the species studied. It may also be related to natural temporal and spatial variation related, for example, to habitat characteristics. To understand the variation present, it will be necessary to conduct long-term (several years at least) sampling projects after defining the genetic characteristics of O. viverrini sensu lato and its Bithynia snail intermediate hosts.

The diversity and impact of hookworm infections in wildlife

Hookworms are blood-feeding nematodes that parasitize the alimentary system of mammals. Despite their high pathogenic potential, little is known about their diversity and impact in wildlife populations. We conducted a systematic review of the literature on hookworm infections of wildlife and analyzed 218 studies qualitative and quantitatively. At least 68 hookworm species have been described in 9 orders, 24 families, and 111 species of wild mammals. Black bears, red foxes, and bobcats harbored the highest diversity of hookworm species and Ancylostoma pluridentatum, A. tubaeforme, Uncinaria stenocephala and Necator americanus were the hookworm species with the highest host diversity index. Hookworm infections cause anemia, retarded growth, tissue damage, inflammation and significant mortality in several wildlife species. Anemia has been documented more commonly in canids, felids and otariids, and retarded growth only in otariids. Population- level mortality has been documented through controlled studies only in canines and eared seals although sporadic mortality has been noticed in felines, bears and elephants. The main driver of hookworm pathogenic effects was the hookworm biomass in a population, measured as prevalence, mean burden and hookworm size (length). Many studies recorded significant differences in prevalence and mean intensity among regions related to contrasts in local humidity, temperature, and host population density. These findings, plus the ability of hookworms to perpetuate in different host species, create a dynamic scenario where changes in climate and the domestic animal-human-wildlife interface will potentially affect the dynamics and consequences of hookworm infections in wildlife.