Molecular identification of Entamoeba spp. in captive nonhuman primates

Genetic characterization of the Entamoeba moshkovskii population based on different potential genetic markers

Entamoeba moshkovskii, according to recent studies, appears to exert a more significant impact on diarrhoeal infections than previously believed. The efficient identification and genetic characterization of E. moshkovskii isolates from endemic areas worldwide are crucial for understanding the impact of parasite genomes on amoebic infections. In this study, we employed a multilocus sequence typing system to characterize E. moshkovskii isolates, with the aim of assessing the role of genetic variation in the pathogenic potential of E. moshkovskii. We incorporated 3 potential genetic markers: KERP1, a protein rich in lysine and glutamic acid; amoebapore C (apc) and chitinase. Sequencing was attempted for all target loci in 68 positive E. moshkovskii samples, and successfully sequenced a total of 33 samples for all 3 loci. The analysis revealed 17 distinct genotypes, labelled M1–M17, across the tested samples when combining all loci. Notably, genotype M1 demonstrated a statistically significant association with diarrhoeal incidence within E. moshkovskii infection (P = 0.0394). This suggests that M1 may represent a pathogenic strain with the highest potential for causing diarrhoeal symptoms. Additionally, we have identified a few single-nucleotide polymorphisms in the studied loci that can be utilized as genetic markers for recognizing the most potentially pathogenic E. moshkovskii isolates. In our genetic diversity study, the apc locus demonstrated the highest Hd value and π value, indicating its pivotal role in reflecting the evolutionary history and adaptation of the E. moshkovskii population. Furthermore, analyses of linkage disequilibrium and recombination within the E. moshkovskii population suggested that the apc locus could play a crucial role in determining the virulence of E. moshkovskii.

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.

Molecular characterization of Blastocystis and Entamoeba of muskoxen and sheep in Greenland

Molecular characterisation of endobionts that are shared among human and non-human hosts can help shed light on the epidemiology and inform studies that aim to unravel the role of these organisms in health and disease. Two of the most common of shared endobionts include the single-celled intestinal protists Blastocystis and Entamoeba. Here, we present the first known data on genetic diversity and host specificity of these two genera in Greenland. Faecal DNA samples from 243 muskoxen and 44 sheep were submitted to metabarcoding of nuclear small subunit ribosomal DNA. Entamoeba- and Blastocystis-specific sequences were clustered, and consensus sequences were subjected to taxonomic query. Using MinION-based sequencing, near-complete nuclear small subunit ribosomal DNA sequences were obtained from four faecal samples. Of the 243 muskox samples, 180 (74%) and 19 (8%) were positive for Blastocystis and Entamoeba, respectively. Forty (91%) and six (14%) of the 44 sheep samples were positive for Blastocystis and Entamoeba, respectively. Blastocystis subtypes (ST) 10, 14, 21, 24-26, and a novel subtype (ST40) were identified. Colonisation by more than one subtype was common. ST40 was common in muskoxen but limited to Northeast Greenland. Entamoeba bovis and the E. bovis-associated ribosomal lineages (RL) 1 and 8 were found, and three conditional lineages (CL) 3, 4, and 10 were confirmed; CL10 was promoted to RL12. Several novel lineages were identified, all of which were linked to the E. bovis complex. In conclusion, Blastocystis was far more common than Entamoeba and found in approximately three of every four animals; both can be considered common colonisers of large herbivorous mammals in Greenland. Multiple subtypes/lineages of both genera were commonly observed, some of which were novel, but most of which are seen in many other parts of the world.

Gastrointestinal parasites in non-human primates in zoological institutions in France

Gastrointestinal parasites are frequently encountered in captive non-human primates and infestation may have severe consequences on the animal's health status. Most of these parasites are also transmissible to humans. Nevertheless, little is known about the prevalence and monitoring modalities of gastrointestinal parasitoses in non-human primates housed in zoological institutions and there are currently no guidelines available for their detection and identification. The objective of this study was to identify the main gastrointestinal parasites that may be observed in non-human primates in zoological institutions in France, as well as to develop a decision-making tree to ease their identification. Twenty-four zoological institutions were surveyed, most of which performed fecal examinations routinely on their non-human primates (91.7%). Most institutions used flotation enrichment protocols to detect gastrointestinal parasites (95.2%) and nematodes were the most frequently encountered parasites (73.0%). A total of 252 fecal samples corresponding to 68 different non-human primate species from these institutions were analyzed using sedimentation and flotation protocols. Protozoa (47.3%) were found to be more frequent than helminths (15.6%). Furthermore, old-world monkeys exhibited a higher parasite load (93.6%) than any other non-human primate species category. Compiled data from fecal examinations allowed the development of a decision-making tree and diagnostic atlas to facilitate parasite diagnosis in captive non-human primates.

Prevalence and Molecular Identification of Entamoeba spp. in Non-human Primates in a Zoological Garden in Nanjing, China

Objective

Entamoeba spp. are globally distributed zoonotic parasites that infect various hosts, among which non-human primates (NHPs) have been identified as one of the most common hosts of these parasites. Consequently, the infections of Entamoeba spp. in captive NHPs from Nanjing Hongshan Forest Zoo in China were investigated in order to assess their zoonotic potential.

Methods

A total of 120 fresh fecal samples, including 19 species of NHPs, were collected from four breeding bases of the zoo from May to June 2019. The infections of six species of Entamoeba spp. were detected by PCR using the 16S or 18S rDNA-specific primers, and the positive samples were sequenced and analyzed.

Results

Entamoeba spp. were detected as positive in 59 NHPs fecal samples (49.17%), including five Entamoeba species: Entamoeba histolytica (7.50%), E. dispar (22.50%), E. coli (22.50%), E. chattoni (10.00%) and E. nuttalli (1.67%). Infection with one Entamoeba species was more common (35%) than co-infections (13.33%) or infections with three Entamoeba species (0.83%). There was a significantly higher prevalence rate of Entamoeba spp. in the species Pongo pygmaeus and Macaca mulatta than in Papio sp., Mandrillus sphinx, and Saimiri sciureus.

Conclusion

Entamoeba spp. are highly prevalent in the NHPs raised in Nanjing Hongshan Forest Zoo. Therefore, attention should be paid to the development of containment strategies of Entamoeba spp. in this zoological garden.

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.

Feeding sites promoting wildlife-related tourism might highly expose the endangered Yunnan snub-nosed monkey (Rhinopithecus bieti) to parasite transmission

An increasing number of studies have found that the implementation of feeding sites for wildlife-related tourism can affect animal health, behaviour and reproduction. Feeding sites can favour high densities, home range overlap, greater sedentary behaviour and increased interspecific contacts, all of which might promote parasite transmission. In the Yunnan snub-nosed monkey (Rhinopithecus bieti), human interventions via provisioning monkeys at specific feeding sites have led to the sub-structuring of a group into genetically differentiated sub-groups. The fed subgroup is located near human hamlets and interacts with domesticated animals. Using high-throughput sequencing, we investigated Entamoeba species diversity in a local host assemblage strongly influenced by provisioning for wildlife-related tourism. We identified 13 Entamoeba species or lineages in faeces of Yunnan snub-nosed monkeys, humans and domesticated animals (including pigs, cattle, and domestic chicken). In Yunnan snub-nosed monkeys, Entamoeba prevalence and OTU richness were higher in the fed than in the wild subgroup. Entamoeba polecki was found in monkeys, pigs and humans, suggesting that this parasite might circulates between the wild and domestic components of this local social–ecological system. The highest proportion of faeces positive for Entamoeba in monkeys geographically coincided with the presence of livestock and humans. These elements suggest that feeding sites might indirectly play a role on parasite transmission in the Yunnan snub-nosed monkey. The implementation of such sites should carefully consider the risk of creating hotspots of disease transmission, which should be prevented by maintaining a buffer zone between monkeys and livestock/humans. Regular screenings for pathogens in fed subgroup are necessary to monitor transmission risk in order to balance the economic development of human communities dependent on wildlife-related tourism, and the conservation of the endangered Yunnan snub-nosed monkey.

Frequency of enteroparasites in Cebidae and Callitrichidae primates at the Zoológico de Cali, Colombia: zoonotic implications

Introducción.

Los enteroparásitos pueden generar problemas en animales bajo cuidado humano en zoológicos y centros de acogida. Los animales silvestres presentan bajas cargas parasitarias, pero estas pueden ser mayores y llevar a manifestaciones clínicas cuando se trata de animales resguardados en recintos, lo que aumenta los gastos en tratamientos y cuidados médicos. Por otro lado, algunos enteroparásitos pueden causar infecciones zoonóticas en los cuidadores, los visitantes y otros animales del zoológico, así como afectar los programas de recuperación de especies amenazadas de extinción.

Objetivos.

Determinar la presencia y prevalencia de enteroparásitos con potencial de transmisión zoonótica en primates de las familias Cebidae y Callitrichidae del Zoológico de Cali, entre septiembre y noviembre de 2017.

Materiales y métodos.

Se hizo un estudio transversal prospectivo, para lo cual se recolectaron muestras seriadas de 50 individuos pertenecientes a siete especies de dos familias de primates y se analizaron mediante examen coprológico, flotación y coloración Kinyoun, entre septiembre y noviembre de 2017.

Resultados.

Según su prevalencia, los géneros de parásitos hallados en las siete especies de primates evaluadas, fueron Blastocystis spp., Trichomonas spp., Giardia spp., Entamoeba spp., Strongyloides spp., Cyclospora sp. y Trichuris sp.

Conclusiones.

Por lo menos, seis de los géneros de parásitos identificados tienen implicaciones zoonóticas, lo cual hace necesario establecer las posibles vías de infección de los primates del Zoológico de Cali e implementar protocolos de manejo que reduzcan el riesgo de transmisión a los humanos y a otros animales de la colección. Además, se presenta la información relevante sobre el potencial zoonótico de los enteroparásitos hallados.

Taxon-Specific Proteins of the Pathogenic Entamoeba Species E. histolytica and E. nuttalli

The human protozoan parasite Entamoeba histolytica can live in the human intestine for months or years without generating any symptoms in the host. For unknown reasons, amoebae can suddenly destroy the intestinal mucosa and become invasive. This can lead to amoebic colitis or extraintestinal amoebiasis whereby the amoebae spread to other organs via the blood vessels, most commonly the liver where abscesses develop. Entamoeba nuttalli is the closest genetic relative of E. histolytica and is found in wild macaques. Another close relative is E. dispar, which asyptomatically infects the human intestine. Although all three species are closely related, only E. histolytica and E. nuttalli are able to penetrate their host’s intestinal epithelium. Lineage-specific genes and gene families may hold the key to understanding differences in virulence among species. Here we discuss those genes found in E. histolytica that have relatives in only one or neither of its sister species, with particular focus on the peptidase, AIG, Ariel, and BspA families.

First Detection and Molecular Identification of Entamoeba in Yaks from China

BACKGROUND

Yak, a predominant livestock of plateau areas, is known as a host to many parasites. And the genus Entamoeba, the third-common cause of the mortality worldwide from parasitic diseases, was discovered in yaks once.

METHODS

We investigated the distribution and species of Entamoeba spp. from yaks in Qinghai province, northwestern China, by collecting 1027 yak fecal samples. All samples were divided according to seven geographical sites, four seasons, and two age groups of yaks. After extracting DNA, polymerase chain reaction (PCR) was performed to amplify the 18S rRNA gene, and sequences were analyzed with phylogenetic method.

RESULTS

We observed an overall Entamoeba positive rate of 36.32% (373/1027) in yaks from Qinghai province. The common species included Entamoeba bovis (284/373), Entamoeba sp. MG107/BEL (79/373), Entamoeba sp. ribosomal lineage (RL) two (8/373), and Entamoeba sp. RL9 (2/373). According to the result of statistical analysis, Entamoeba infection rate was the highest in summer and significantly differed from that observed during other seasons (P < 0.05). The yaks from Golog had the highest prevalence of Entamoeba among all geographical origins in Qinghai province (P < 0.05). However, no significant difference was observed (P > 0.05) among different age groups, as evident from a positive rate of 39.58% in ≤ 6-month and 36.16% in > 6-month yaks.

CONCLUSION

These results indicate the prevalence and predominant species of Entamoeba in yaks. To our knowledge, this is the first study to report E. bovis, Entamoeba sp. RL2, and Entamoeba sp. RL9 in Chinese yaks.

Review of zoonotic amebiasis: Epidemiology, clinical signs, diagnosis, treatment, prevention and control

Amebiasis is a disease caused by the protozoan parasite Entamoeba histolytica, which mainly shows symptoms of acute diarrhea, dysentery, amebic colitis, and amebic liver abscesses. As the fourth leading parasitic cause of human mortality, E. histolytica mainly infect children in developing countries, transmitted by food and water contamination. In the majority of infected individuals, Entamoeba sp. asymptomatically colonizes the large intestine and self-limiting, while in others, the parasite breaches the mucosal epithelial barrier to cause amebic colitis and can disseminate to soft organs to cause abscesses. Metronidazole (MTZ) is the recommended and most widely used drug for treating the invasive amebiasis. No amebiasis vaccine has been approved for human clinical trials to date, but many recent vaccine development studies hold promise. For the prevention and control of amebiasis, improvement of water purification systems and hygiene practices could decrease disease incidence. In this review, we focus on the epidemiology, transmission, clinical signs, pathogenesis, diagnosis, treatment, prevention and control of the zoonotic amebiasis.

Prevalence, molecular epidemiology and zoonotic risk of Entamoeba spp. from experimental macaques in Yunnan Province, southwestern China

Amebiasis is a worldwide parasitic zoonosis, with symptoms of abdominal discomfort, indigestion, diarrhea, and even death. However, limited information about the prevalence of Entamoeba spp. in experimental nonhuman primates (NHPs) in southwestern China is available. The objective of the current study was to investigate the frequency and species identity of Entamoeba to evaluate potential zoonotic risk factors for Entamoeba spp. infection in experimental NHPs. A total of 505 fecal samples were collected from NHPs (macaques) and analyzed by PCR analysis the small subunit rRNA (SSU rRNA) gene of Entamoeba spp. Forty-seven specimens were positive for Entamoeba spp., and the prevalence of Entamoeba spp. was 9.31% (47/505). Significant differences in the prevalence rates among the three breeds (P = 0.002 < 0.01, df = 2, χ² = 12.33) and feed types (P = 0.001 < 0.01, df = 1, χ² = 10.12) were observed. Altogether, four Entamoeba species, including E. dispar (57.44%), E. chattoni (29.78%), E. histolytica (6.38%), and E. coli (6.38%), were identified by DNA sequence analysis. The results suggested a low prevalence but high diversity of Entamoeba species in experimental NHPs in Yunnan Province, southwestern China. Results of this study contribute to the knowledge of the genetic characteristics of Entamoeba spp. in NHPs.

Entamoeba histolytica infections in wild and semi-wild orangutans in Sumatra and Kalimantan

Key to the success of orangutan conservation management practices is the prevention of the introduction of infectious diseases to the remaining populations. Previous reports of Entamoeba spp. positive orangutans are of concern as Entamoeba spp. infection has been linked to morbidity and mortality in primates. It remains to be determined if the Entamoeba species infecting orangutans is the pathogenic Entamoeba histolytica. Orangutan fecal samples have been collected from orangutans from sites in Sumatra (Bukit Lawang, Ketambe, and Suaq, 241 samples from 64 individuals), and two sites in Kalimantan (Sebangau and Tuanan, 129 samples from 39 individuals). All samples were from wild orangutans except for a proportion from Sumatra which were from semi-wild (108 samples, 10 individuals). E. histolytica-specific nested PCR assays were carried out on the fecal samples. A total of 36 samples from 17 individuals tested positive for E. histolytica. When compared with published sequences using NCBI BLAST the E. histolytica positive samples showed a 98-99% concordance. The majority (76%, n = 36) of the positive isolates came from semi-wild orangutans in Bukit Lawang. This study supports the growing body of evidence that contact with humans is an important risk factor for infection of wild primates with E. histolytica.

Whole genome sequencing of Entamoeba nuttalli reveals mammalian host-related molecular signatures and a novel octapeptide-repeat surface protein

The enteric protozoa Entamoeba histolytica is the causative agent of amebiasis, which is one of the most common parasitic diseases in developed and developing countries. Entamoeba nuttalli is the genetically closest species to E. histolytica in current phylogenetic analyses of Entamoeba species, and is prevalent in wild macaques. Therefore, E. nuttalli may be a key organism in which to investigate molecules required for infection of human or non-human primates. To explore the molecular signatures of host-parasite interactions, we conducted de novo assembly of the E. nuttalli genome, utilizing self-correction of PacBio long reads and polishing corrected reads using Illumina short reads, followed by comparative genomic analysis with two other mammalian and a reptilian Entamoeba species. The final draft assembly of E. nuttalli included 395 contigs with a total length of approximately 23 Mb, and 9,647 predicted genes, of which 6,940 were conserved with E. histolytica. In addition, we found an E. histolytica-specific repeat known as ERE2 in the E. nuttalli genome. GO-term enrichment analysis of mammalian host-related molecules indicated diversification of transmembrane proteins, including AIG1 family and BspA-like proteins that may be involved in the host-parasite interaction. Furthermore, we identified an E. nuttalli-specific protein that contained 42 repeats of an octapeptide ([G,E]KPTDTPS). This protein was shown to be localized on the cell surface using immunofluorescence. Since many repeat-containing proteins in parasites play important roles in interactions with host cells, this unique octapeptide repeat-containing protein may be involved in colonization of E. nuttalli in the intestine of macaques. Overall, our draft assembly provides a valuable resource for studying Entamoeba evolution and host-parasite selection.

Intestinal Parasites of Pets and Other House-kept Animals in Moscow

A study screening pet animals (dogs, cats, chinchillas, ferrets, guinea pigs, rabbits, primates, reptiles, and hedgehogs) within Moscow city limits for intestinal parasitic diseases has been conducted over a period of 6 years. According to the study, parasitic infections caused by intestinal protozoa are found in pet animals more frequently than by intestinal helminths. Although dogs and cats exhibit the highest level of diversity of intestinal parasite species, in the group of exotic animals, helminth infection are found much less frequently and parasitic fauna is represented mostly by intestinal protozoa with a high percentage of mixed infection. The most widespread helminth infeсtion of dogs and cats is toxocarosis (respectively 2.5 and 5.7 %) and the most widespread protozoan infection is Giardia sp. (9.8 and 4.6 %). Giardia sp. was found in 47.4 % of chinchillas, Cryptosporidium sp. was more frequently found in ferrets (6.55 %), protozoa from the family Trichomonadida was found in guinea pigs (9 %), Eimeria sp. in rabbits (13.9 %), Acanthocephala in primates (15.7 %), and eggs from the generaOxyurida (59 %), along with protozoa from the family Trichomonadida, in reptiles. Capillaria sp. was most prevalent in hedgehogs (33.4 %). Acanthocephala eggs, as well as protozoa from the Giardia and Entamoeba genera, were more frequently found in primates. Parasites common to animals and humans, which may become a source of infection for the latter under certain conditions, have been identified in pet animals.

Molecular Characterization of Entamoeba spp. in Wild Taihangshan Macaques (Macaca mulatta tcheliensis) in China

BACKGROUND

Entamoeba spp. is one of the most common enteric parasites of humans and animals.

PURPOSE

However, little information is available regarding prevalence and genotypes of Entamoeba spp. in wild Taihangshan macaques (Macaca mulatta tcheliensis).

METHODS

In the present study, a total of 458 fecal samples from wild rhesus macaque in Taihangshan mountains area between September 2015 and November 2016, were collected and examined for the presence of six Entamoeba species by PCR amplification of the SSU rRNA gene.

RESULTS

The overall prevalence of Entamoeba spp. infection was 89.96% (412/458). Four species of Entamoeba detected in our survey were E. chattoni (88.43%), E. hartmanni (79.91%), E. coil (69.87%) and E. dispar (58.30%), and among these, 398 (84.93%) were mixed infections. Phylogenetic analysis revealed that isolates were clustered into four known genotypes.

CONCLUSION

The present study firstly provides important information about the prevalence and diversity of Entamoeba species infecting wild Taihangshan macaques in China. Enough attention should be paid to monitor the potential interspecies transmission in the region.

Use of Mini-FLOTAC and Fill-FLOTAC for rapidly diagnosing parasitic infections in zoo mammals

Animals reared in restricted environments are highly susceptible to gastrointestinal infection by helminths and protozoa and therefore zoos are characterized as being parasite-rich environments. Successful implementation of control programs of these parasites in zoo environment depends upon precise and rapid diagnosing of gastrointestinal infections. The aim of this study was to demonstrate the role of the Mini-FLOTAC technique in combination with Fill-FLOTAC for rapidly diagnosing parasitic infections in zoo mammals. Fecal samples were collected from 70 animals in four different zoos located in central and southern Italy. All the samples were analyzed using Mini-FLOTAC in combination with Fill-FLOTAC. Out of the 70 pooled samples examined, 80% (24/30) were positive for at least one parasite. Among the gastrointestinal nematodes, Strongyles were the most frequent (40%), followed by Trichuris spp. (23.3%), Parascaris spp. (13.3%) and Capillaria spp. (3.3%). Among the protozoa, Blastocystis spp., Giardia spp. and Eimeria spp. were detected in 6.6%, 3.3% and 3.3%, respectively. These results show that Mini-FLOTAC in combination with Fill-FLOTAC can be used, not only for rapidly diagnosing parasitic infections in zoo mammals, but also for monitoring control programs in which large numbers of fecal samples need to be examined rapidly and reliably.

Parasitic Diseases

Captive marmosets, whether in zoos or biomedical research facilities, may become infected or infested with a variety of internal or external parasites. Modern animal housing and husbandry practices have greatly reduced the prevalence of parasitism, particularly for those parasites requiring an intermediate host. In this chapter, the author discusses selected parasitic diseases of captive marmosets. This chapter is organized phylogenetically. No attempt is made to cover all of the internal and external parasites historically reported, no matter how infrequently. Similarly, no attempt is made to cover parasites infecting or infesting other New World primates and thus potentially found in or on marmosets. The author has included those parasitisms most likely to be observed in modern animal facilities.

Identification of the gene encoding the TATA box-binding protein-associated factor 1 (TAF1) and its putative role in the heat shock response in the protozoan parasite Entamoeba histolytica

Transcription factor IID (TFIID) is a cornerstone in the transcription initiation in eukaryotes. It is composed of TBP and approximately 14 different subunits named TBP-associated factors (TAFs). TFIID has a key role in transcription of many genes involved in cell proliferation, cell growth, cell cycle, cell cycle checkpoint, and various other processes as well. Entamoeba histolytica, the protozoan parasite responsible for human amoebiasis, represents a major global health concern. Our research group has previously reported the genes coding the TATA box-binding protein (EhTBP) and TBP-related factor 1 (EhTRF1), which displayed different mRNA levels in trophozoites under different stress conditions. In this work, we identified the TBP-associated factor 1 (Ehtaf1) gene in the E. histolytica genome, which possess a well-conserved DUF domain and a Bromo domain located in the middle and C-terminus of the protein, respectively. The EhTAF1-DUF domain tertiary structure is similar to the corresponding HsTAF1 DUF domain. RT-qPCR experiments with RNA isolated from trophozoites harvested at different time points of the growth curve and under different stress conditions revealed that the Ehtaf1 gene was found slightly upregulated in the death phase of growth curve, but under heat shock stress, it was found upregulated 10 times, suggesting that Ehtaf1 might have an important role in the heat shock stress response. We also found that EhTAF1 is expressed in the nucleus and cytoplasm at 37 °C, but under heat shock stress, it is overexpressed in both the nucleus and cytoplasm, and partially colocalized with EhHSP70 in cytoplasm.

Entamoeba histolytica infection in humans, chimpanzees and baboons in the Greater Gombe Ecosystem, Tanzania

Entamoeba histolytica is an enteric parasite that infects approximately 50 million people worldwide. Although E. histolytica is a zoonotic parasite that has the potential to infect nonhuman primates, such transmission is poorly understood. Consequently, this study examined whether E. histolytica is present among humans, chimpanzees and baboons living in the Greater Gombe Ecosystem (GGE), Tanzania. The primary aims were to determine patterns of E. histolytica infection in a system with human-nonhuman primate overlap and to test associations between infection status and potential risk factors of disease. Entamoeba spp. occurred in 60.3% of human, 65.6% of chimpanzee and 88.6% of baboon samples. Entamoeba histolytica occurred in 12.1% of human, 34.1% of chimpanzee and 10.9% of baboon samples. Human E. histolytica infection was associated with gastrointestinal symptoms. This was the first study to confirm the presence of E. histolytica in the GGE. The high sample prevalence of E. histolytica in three sympatric primates suggests that zoonotic transmission is possible and stresses the need for further phylogenetic studies. Interventions targeting better sanitation and hygiene practices for humans living in the GGE can help prevent E. histolytica infection in humans, while also protecting the endangered chimpanzees and other primates in this region.

Evaluation of a PCR Method for Detection of Entamoeba polecki, with an Overview of Its Molecular Epidemiology

Entamoebapolecki is a parasite of human and nonhuman primates, other mammals, and birds. Due to overlapping morphological features, cysts of E. polecki may be confused with those of other Entamoeba species commonly found in human fecal samples, including immature cysts of Entamoeba histolytica Although the presence of E. polecki in human Entamoeba-positive stool samples may be rare, its prevalence is likely underestimated due to such confusion. Here, we give examples of diagnostic approaches applied so far and summarize data on the molecular epidemiology of E. polecki, including host specificity and phylogeography. Moreover, we evaluate a novel diagnostic conventional PCR developed for the screening of fecal samples for E. polecki The assay was highly sensitive and specific when used on genomic DNA extracted directly from stool and Swedish wastewater samples. The PCR enabled the identification of all four subtypes (ST1 to ST4) of E. polecki by PCR product sequencing. Most (23/28) subtyped E. polecki-positive samples detected in patients in Sweden between 2002 and 2015 reflected colonization by ST4 and were seen in travelers/foreigners. Two and three human cases of ST2 and ST3, respectively, were also detected. Subtypes 1, 2, and 3 were detected in 3/21 wastewater samples, suggesting local endemicity of these E. polecki subtypes; interestingly, ST4 was not detected in wastewater. In conclusion, the current PCR assay enables simple and cost-effective screening of fecal and wastewater samples for E. polecki Human cases of E. polecki appear to involve primarily ST4, while E. polecki detected in wastewater may be primarily of animal origin.

Diversity of Entamoeba spp. in African great apes and humans: an insight from Illumina MiSeq high-throughput sequencing

Understanding the complex Entamoeba communities in the mammalian intestine has been, to date, complicated by the lack of a suitable approach for molecular detection of multiple variants co-occurring in mixed infections. Here, we report on the application of a high throughput sequencing approach based on partial 18S rDNA using the Illumina MiSeq platform. We describe, to our knowledge, for the first time, the Entamoeba communities in humans, free-ranging western lowland gorillas and central chimpanzees living in the Dja Faunal Reserve in Cameroon. We detected 36 Entamoeba haplotypes belonging to six haplotype clusters, containing haplotypes possessing high and low host specificity. Most of the detected haplotypes belonged to commensal Entamoeba, however, the pathogenic species (Entamoeba histolytica and Entamoeba nuttalli) were also detected. We observed that some Entamoeba haplotypes are shared between humans and other hosts, indicating their zoonotic potential. The findings are important not only for understanding the epidemiology of amoebiasis in humans in rural African localities, but also in the context of wild great ape conservation.

Characteristics of inflammatory reactions during development of liver abscess in hamsters inoculated with Entamoeba nuttalli

Background

Entamoeba nuttalli is an intestinal protozoan with pathogenic potential that can cause amebic liver abscess. It is highly prevalent in wild and captive macaques. Recently, cysts were detected in a caretaker of nonhuman primates in a zoo, indicating that E. nuttalli may be a zoonotic pathogen. Therefore, it is important to evaluate the pathogenicity of E. nuttalli in detail and in comparison with that of E. histolytica.

Methodology/Principal findings

Trophozoites of E. nuttalli GY4 and E. histolytica SAW755 strains were inoculated into liver of hamsters. Expression levels of proinflammatory factors of hamsters and virulence factors from E. histolytica and E. nuttalli were compared between the two parasites. Inoculations with trophozoites of E. nuttalli resulted in an average necrotic area of 24% in liver tissue in 7 days, whereas this area produced by E. histolytica was nearly 50%. Along with the mild liver tissue damage induced by E. nuttalli, expression levels of proinflammatory factors (TNF-α, IL-6 and IL-1β) and amebic virulence protein genes (lectins, cysteine proteases and amoeba pores) in local tissues were lower with E. nuttalli in comparison with E. histolytica. In addition, M2 type macrophages were increased in E. nuttalli-induced amebic liver abscesses in the late stage of disease progression and lysate of E. nuttalli trophozoites induced higher arginase expression than E. histolytica in vitro.

Conclusions/Significance

The results show that differential secretion of amebic virulence proteins during E. nuttalli infection triggered lower levels of secretion of various cytokines and had an impact on polarization of macrophages towards a M1/M2 balance. However, regardless of the degree of macrophage polarization, there is unambiguous evidence of an intense acute inflammatory reaction in liver of hamsters after infection by both Entamoeba species.

Entamoeba nuttalli is the phylogenetically closest protozoan to Entamoeba histolytica and is highly prevalent in macaques. Previous studies have indicated that E. nuttalli is virulent in a hamster model. In this study, we compared the immunopathological basis of formation of liver abscess in hamsters between E. nuttalli and E. histolytica. Mild liver tissue damage developed after intrahepatic injection of trophozoites of E. nuttalli, and lower expression levels of genes for host proinflammatory factors and amebic virulence proteins were detected at the edges of liver abscesses induced by E. nuttalli. In addition, alternatively activated macrophages were increased in E. nuttalli-induced liver abscesses in the late stage of disease progression. The lysate of E. nuttalli trophozoites also induced higher arginase expression than E. histolytica in vitro. Polarization of macrophages is likely to affect the degree of acute inflammatory reactions in liver in an animal model during E. nuttalli infection. Our data reveal new characteristics of abscess formation by E. nuttalli.

Novel Entamoeba Findings in Nonhuman Primates

In addition to well-known human-infecting species, Entamoeba species not found in humans have been identified recently in nonhuman primates (NHPs). Importantly, it has become clear that the organism identified as Entamoeba histolytica in NHPs is usually a distinct species, Entamoeba nuttalli. Many DNA-based stool surveys use species-specific detection methods and so may miss the full range of Entamoeba species present. In addition, authors may be using the same species name to describe distinct organisms. These various shortcomings may not be obvious to readers. In this review, we clarify the relationships between Entamoeba species' names based on morphological and molecular data, and highlight gaps in recently published data on Entamoeba species in wild NHPs resulting from the use of variable methodology.

Entamoeba histolytica infection in wild lemurs associated with proximity to humans

Amoebiasis, caused by Entamoeba histolytica, affects 50 million people worldwide, and results in 100,000 deaths annually. It is particularly prevalent in developing nations where poverty and poor sanitation contribute to contamination of food and water. E. histolytica is also a zoonotic protozoan parasite with the potential to infect non-human primates. Lemurs, primates endemic to Madagascar, are the most threatened mammalian group in the world due to habitat loss. As forests disappear, humans and lemurs come into more frequent contact, and the potential for E. histolytica to infect lemurs intensifies. Consequently, we screened 176 fecal samples from seven lemur species at eight sites in the rain forests of southeastern Madagascar for E. histolytica to determine if human proximity influenced lemur infection. Of samples examined, 4.0% (from three lemur species) were positive for E. histolytica. Of lemurs infected with E. histolytica, three (43%) exhibited diarrheal feces. Distance to human settlements explained the variation in E. histolytica infection seen in lemurs. These results provide the first evidence of E. histolytica in wild lemurs and highlight the need for additional work to better understand the eco-epidemiology of this potential threat to these species.

Gastrointestinal parasites in captive and free-ranging Cebus albifrons in the Western Amazon, Ecuador

Currently, there is a lack of surveys that report the occurrence of gastrointestinal parasites in the white-headed capuchin monkey (Cebus albifrons). We therefore assessed the presence and richness (= number of different parasite genera) of parasites in C. albifrons in wildlife refuges (n = 11) and in a free-ranging group near a human village (n = 15) in the Ecuadorian Amazon. In the 78 samples collected (median of 3 samples per animal), we identified a total of 6 genera of gastrointestinal parasites, representing protozoa, nematodes, acanthocephalans and cestodes. We observed a high prevalence (84%) across the 26 individuals, with the most prevalent parasite being Strongyloides sp. (76.9%), followed by Hymenolepis sp. (38.5%) and Prosthenorchis elegans (11.5%). We found Entamoeba histolytica/dispar/moskovskii/nuttalli and Capillaria sp. in only a minority of the animals (3.8%). In addition, we observed unidentified strongyles in approximately one-third of the animals (34.6%). We found a total of 6 parasite genera for the adult age group, which showed higher parasite richness than the subadult age group (5) and the juvenile age group (3). Faecal egg/cyst counts were not significantly different between captive and free-ranging individuals or between sexes or age groups. The free-ranging group had a higher prevalence than the captive group; however, this difference was not significant. The only genus common to captive and free-ranging individuals was Strongyloides sp. The high prevalence of gastrointestinal parasites and the presence of Strongyloides in both populations support results from previous studies in Cebus species. This high prevalence could be related to the high degree of humidity in the region. For the free-ranging group, additional studies are required to gain insights into the differences in parasite prevalence and intensity between age and sex groups. Additionally, our study demonstrated that a serial sampling of each individual increases the test sensitivity.

Prevalence, molecular epidemiology, and zoonotic potential of Entamoeba spp. in nonhuman primates in China

Amebiasis is a major public-health concern. It has a global distribution, and is listed as the third leading parasitic cause of human mortality. To survey the prevalence and assess the potential zoonotic transmission of Entamoeba spp. in nonhuman primates (NHPs) in China, 2688 fresh fecal specimens were collected from NHPs reared in farms or zoos/parks or free ranging in 13 districts. The overall prevalence of Entamoeba spp. infection determined with microscopy analysis was 39.4% (1059/2688). Higher infection rates were detected in the free ranging group (41.1%, 169/411) and in animals <1year old (58.7%, 556/947). Gene fragments were successfully amplified 463 (87.2%) out of the 531 selected specimens (approximately half of the total microscopy-positive specimens). Polymerase chain reaction (PCR) amplification identified 386 (83.4%) Entamoeba dispar and 287 (62.0%) E. coli infections, and among these, 210 (45.4%) were mixed infections. And that the E. dispar and E. coli had also been detected in humans. In phylogenetic analysis, the E. dispar and E. coli sequences clustered with reference E. dispar and E. coli, respectively. In conclusion, nonhuman primates infected with Entamoeba species, with high prevalence and zoonotic potential, should be considered when evaluating the maintenance of Entamoeba spp. and its transmission between animal reservoirs and humans.

Molecular testing for clinical diagnosis and epidemiological investigations of intestinal parasitic infections

Over the past few decades, nucleic acid-based methods have been developed for the diagnosis of intestinal parasitic infections. Advantages of nucleic acid-based methods are numerous; typically, these include increased sensitivity and specificity and simpler standardization of diagnostic procedures. DNA samples can also be stored and used for genetic characterization and molecular typing, providing a valuable tool for surveys and surveillance studies. A variety of technologies have been applied, and some specific and general pitfalls and limitations have been identified. This review provides an overview of the multitude of methods that have been reported for the detection of intestinal parasites and offers some guidance in applying these methods in the clinical laboratory and in epidemiological studies.

Identification of Entamoeba polecki with Unique 18S rRNA Gene Sequences from Celebes Crested Macaques and Pigs in Tangkoko Nature Reserve, North Sulawesi, Indonesia

Unique species of macaques are distributed across Sulawesi Island, Indonesia, and the details of Entamoeba infections in these macaques are unknown. A total of 77 stool samples from Celebes crested macaques (Macaca nigra) and 14 stool samples from pigs were collected in Tangkoko Nature Reserve, North Sulawesi, and the prevalence of Entamoeba infection was examined by PCR. Entamoeba polecki was detected in 97% of the macaques and all of the pigs, but no other Entamoeba species were found. The nucleotide sequence of the 18S rRNA gene in E. polecki from M. nigra was unique and showed highest similarity with E. polecki subtype (ST) 4. This is the first case of identification of E. polecki ST4 from wild nonhuman primates. The sequence of the 18S rRNA gene in E. polecki from pigs was also unique and showed highest similarity with E. polecki ST1. These results suggest that the diversity of the 18S rRNA gene in E. polecki is associated with differences in host species and geographic localization, and that there has been no transmission of E. polecki between macaques and pigs in the study area.

Molecular identification of Entamoeba species in savanna woodland chimpanzees (Pan troglodytes schweinfurthii)

To address the molecular diversity and occurrence of pathogenic species of the genus Entamoeba spp. in wild non-human primates (NHP) we conducted molecular-phylogenetic analyses on Entamoeba from wild chimpanzees living in the Issa Valley, Tanzania. We compared the sensitivity of molecular [using a genus-specific polymerase chain reaction (PCR)] and coproscopic detection (merthiolate-iodine-formaldehyde concentration) of Entamoeba spp. We identified Entamoeba spp. in 72 chimpanzee fecal samples (79%) subjected to species-specific PCRs for six Entamoeba species/groups (Entamoeba histolytica, Entamoeba nuttalli, Entamoeba dispar, Entamoeba moshkovskii, Entamoeba coli and Entamoeba polecki ST2). We recorded three Entamoeba species: E. coli (47%), E. dispar (16%), Entamoeba hartmanni (51%). Coproscopically, we could only distinguish the cysts of complex E. histolytica/dispar/moshkovskii/nuttalli and E. coli. Molecular prevalence of entamoebas was higher than the prevalence based on the coproscopic examination. Our molecular phylogenies showed that sequences of E. dispar and E. coli from Issa chimpanzees are closely related to sequences from humans and other NHP from GenBank. The results showed that wild chimpanzees harbour Entamoeba species similar to those occurring in humans; however, no pathogenic species were detected. Molecular-phylogenetic methods are critical to improve diagnostics of entamoebas in wild NHP and for determining an accurate prevalence of Entamoeba species.

Comparative analysis of genotypic diversity in Entamoeba nuttalli isolates from Tibetan macaques and rhesus macaques in China

We have recently demonstrated the potentially virulent species Entamoeba nuttalli as one of the highly prevalent parasites in rhesus macaques (Macaca mulatta) in Mount Long-hu and Gui-yang in China. Tibetan macaque (Macaca thibetana) is a unique species living in China. To evaluate the prevalence of Entamoeba species in wild Tibetan macaques, we obtained 89 stool samples in Mount E-mei of Si-chuan Province in China. PCR analysis detected E. nuttalli, Entamoeba coli, and Entamoeba polecki ST2 in 17%, 42%, and 66% of the samples, respectively, whereas Entamoeba histolytica and Entamoeba dispar were undetected. This study is the first to report on the detection of E. nuttalli from Tibetan macaques. Six E. nuttalli isolates were obtained, 18S rRNA gene and six tRNA-linked short tandem repeat (STR) loci of the isolates were sequenced. The Mantel test results gave an r value of 0.97 of relationships between geographical distance and genetic diversity of Chinese E. nuttalli populations, indicating a significant isolation-by-distance effect in Chinese E. nuttalli according to the tRNA-STR loci sequences. Structural analysis of E. nuttalli isolates based on tRNA-linked STR loci demonstrated three Chinese E. nuttalli populations with their respective features, but the Gui-yang population was located in the middle. In the distance-based NJ tree, E. nuttalli isolates were divided into five different branches, and E-mei isolates were attributed to an independent branch to distinguish them from Gui-yang and Long-hu isolates. Genetic analysis in this study provided clues of the genetic differences between E. nuttalli isolates from Tibetan macaques and rhesus macaques in China.

Isolation and Molecular Characterization of Entamoeba nuttalli Strains Showing Novel Isoenzyme Patterns from Wild Toque Macaques in Sri Lanka

We have proposed the revival of the name Entamoeba nuttalli for a virulent ameba strain, P19-061405, from a rhesus macaque and located it phylogenetically between E. histolytica and E. dispar. As E. nuttalli was originally described for an ameba found in a toque macaque in Sri Lanka, the prevalence and characteristics of Entamoeba species in wild toque macaques were examined. PCR analysis of 227 stool samples from six locations showed positive rates for E. nuttalli, E. dispar, and E. histolytica of 18.5%, 0.4%, and 0%, respectively. Fifteen E. nuttalli strains were cultured successfully from five locations. The 18S ribosomal RNA gene showed only three nucleotide differences in comparison with P19-061405 strain. In isoenzyme analysis, the pattern of hexokinase in Sri Lankan strains was different from that of P19-061405 strains and the difference was confirmed by analysis of the genes. Hepatic inoculation of one of the Sri Lankan E. nuttalli strains in hamsters resulted in amebic abscess formation and body weight loss. These results demonstrate that E. nuttalli is prevalent in wild toque macaques and that several characteristics of the strains are unique. We conclude that use of the name E. nuttalli is appropriate for the new Entamoeba species found in nonhuman primates.

Study of the gastrointestinal parasitic fauna of captive non-human primates (Macaca fascicularis)

The aim of this study was to examine helminths and protozoans in cynomolgus macaques (Macaca fascicularis) imported from registered breeding facilities in China and their relation to health risks for non-human primate handlers in biomedical research centers and in breeding facilities. Fresh fecal samples were collected from a total of 443 M. fascicularis and analyzed by copromicroscopical analysis, immunoenzymatic, or molecular assays. As to helminths, whose eggs were shed in 2.03% of the samples, Trichuris and Oesophagostomum were the only two taxa found, with low prevalence and low eggs per gram (EPG) values. Protozoans were more frequently detected (87.40%), with Entamoeba coli (85.19%) and Endolimax nana (79.26%) as the most prevalent species shed. Other parasites found by fecal smear examination were uninucleated-cyst-producing Entamoebas (78.52%), Iodamoeba bütschlii (42.96%), and Chilomastix mesnili (24.44%), while cysts of Balantidium coli (22.2%) were only observed by sedimentation. No coproantigens of Giardia duodenalis, Cryptosporidium spp., and Entamoeba histolytica complex were detected. Blastocystis sp. infection was noticed in 87.63% of macaques by PCR. These cynomolgus monkeys were infected with many subtypes (ST1, ST2, ST3, ST5, and ST7), where the predominant Blastocystis sp. subtypes were ST2 (77.5%), followed by ST1 (63.5%). Data collected confirmed the presence of potentially zoonotic parasites and a high parasite diversity, suggesting the need for appropriate and sensitive techniques to adequately control them and related health risks for handlers of non-human primates in biomedical research centers and in breeding facilities.

Diversity of zoonotic enterohepatic Helicobacter species and detection of a putative novel gastric Helicobacter species in wild and wild-born captive chimpanzees and western lowland gorillas

A number of Helicobacter species cause gastrointestinal or hepatic disease in humans, including H. pylori, gastric non-H. pylori helicobacters from animal origin and enterohepatic Helicobacter species. Little is known on the presence of Helicobacter species in great apes, our closest living relatives and potential reservoirs of microorganisms that might emerge in humans. The aim of the present study was to investigate the presence of gastric and enterohepatic Helicobacter species in African chimpanzees and gorillas. Fresh fecal samples were collected from wild endangered chimpanzees and critically endangered western lowland gorillas from different African National Parks, as well as wild-born captive animals from primate sanctuaries. Intact Helicobacter bacteria were demonstrated in feces by fluorescence in situ hybridization. Screening using a Helicobacter genus-specific PCR revealed the presence of Helicobacter DNA in the majority of animals in all groups. Cloning and sequencing of 16S rRNA gene fragments revealed a high homology to sequences from various zoonotic enterohepatic Helicobacter species, including H. cinaedi and H. canadensis. A number of gorillas and chimpanzees also tested positive using PCR assays designed to amplify part of the ureAB gene cluster and the hsp60 gene of gastric helicobacters. Phylogenetic analysis revealed the presence of a putative novel zoonotic gastric Helicobacter taxon/species. For this species, we propose the name 'Candidatus Helicobacter homininae', pending isolation and further genetic characterization. The presence of several Helicobacter species not only implies a possible health threat for these endangered great apes, but also a possible zoonotic transmission of gastric and enterohepatic helicobacters from these primate reservoirs to humans.

Prevalence of Entamoeba species in captive primates in zoological gardens in the UK

The aim of this study was to determine the prevalence of amoebic infection in non-human primates (NHPs) from six Zoological gardens in the United Kingdom. Initially, 126 faecal samples were collected from 37 individually identified NHPs at Twycross Zoo, UK, and were subjected to microscopic examination. A subsequent, nationwide experiment included 350 faecal samples from 89 individually identified NHPs and 73 unidentified NHPs from a number of UK captive wildlife facilities: Twycross Zoo (n = 60), Colchester Zoo (n = 3), Edinburgh Zoo (n = 6), Port Lympne Wild Animal Park (n = 58), Howletts Wild Animal Park (n = 31), and Cotswold Wildlife Park (n = 4). Samples were examined by PCR and sequencing using four specific primer sets designed to differentiate between the pathogenic E. histolytica, the non-pathogenic E. dispar, and non-pathogenic uninucleate cyst-producing Entamoeba species. In the first experiment, Entamoeba was detected in 30 primates (81.1%). Six (16.2%) primates were infected with E. histolytica species complex. The highest carriage of Entamoeba species was found in Old World Colobinae primates. In the nationwide experiment, molecular analysis of faecal samples revealed notable rates of Entamoeba infection (101 samples, 28.9%), including one sample infected with E. histolytica, 14 samples with E. dispar, and 86 samples with uninucleated-cyst producing Entamoeba species. Sequences of positive uninucleated-cyst producing Entamoeba samples from Twycross Zoo clustered with the E. polecki reference sequences ST4 reported in Homo sapiens, and are widely separated from other Entamoeba species. These findings suggest a low prevalence of the pathogenic Entamoeba infection, but notable prevalence of non-pathogenic E. polecki infection in NHPs in the UK.

Prevalence of Entamoeba nuttalli infection in wild rhesus macaques in Nepal and characterization of the parasite isolates

We have recently resurrected the name Entamoeba nuttalli Castellani, 1908 for a potentially virulent ameba isolate, P19-061405, obtained from a rhesus macaque in Kathmandu, Nepal. The ameba was morphologically indistinguishable from Entamoeba histolytica/Entamoeba dispar/Entamoeba moshkovskii, but located phylogenetically between E. histolytica and E. dispar. To evaluate the prevalence of E. nuttalli infection in wild rhesus macaques, 112 fecal samples were collected in four locations of the Kathmandu Valley. PCR analysis of DNA extracted from the feces showed positive rates of E. nuttalli, E. dispar, E. histolytica and E. moshkovskii of 51%, 12%, 0% and 0%, respectively. A total of 14 E. nuttalli isolates were obtained from four locations, of which 6 were established as axenic cultures. The sequences of the serine-rich protein gene of E. nuttalli isolates differed among four locations although no differences were found in the composition of sequence motifs. Isoenzyme pattern was analyzed in 8 isolates obtained from three locations. In hexokinase, the mobility of the slower migrating band was located between E. histolytica and E. dispar regardless of the culture conditions. These results demonstrate that E. nuttalli is highly prevalent in wild rhesus macaques in Nepal. Rhesus macaques appear to be one of the natural hosts and heterogeneity of the serine-rich protein gene might be useful for geographical typing of isolates.

Prevalence and genetic diversity of Entamoeba species infecting macaques in southwest China

Many colonies of macaques (Macaca fascicularis and Macaca mulatta) are maintained in China, especially in Guangxi and Guizhou. A total of 803 fresh stool samples infected with Entamoeba were obtained from three big colonies of macaques located in southwest China. The samples were examined for the presence of five Entamoeba species using PCR. Entamoeba nuttalli, Entamoeba dispar, Entamoeba coli, and Entamoeba chattoni infections were detected, but Entamoeba histolytica infection was not. This study is the first to report on the prevalence of E. nuttalli in wild macaques from China. Eighteen E. nuttalli isolates and five E. dispar isolates were obtained by culturing the samples in Tanabe-Chiba medium. The serine-rich protein (SRP), ribosomal RNA (rRNA), hexokinase (HXK), glucose-6-phosphate isomerase (GPI), and phosphoglucomutase (PGM) genes of E. nuttalli isolates were compared with other reported isolates. The results showed clear differences among the Chinese E. nuttalli isolates and other isolates based on the SRP gene sequences. However, HXK, GPI, and PGM genes of these strains were similar to those of other isolates. The rRNA genes of E. coli and E. chattoni were also amplified and analyzed from these samples. The results suggested that host species might be a more important factor than geographic location in amebic genetic diversity.

Giardia duodenalis assemblages and Entamoeba species infecting non-human primates in an Italian zoological garden: zoonotic potential and management traits

Background

Giardia duodenalis and Entamoeba spp. are among the most common intestinal human protozoan parasites worldwide and they are frequently reported in captive non-human primates (NHP). From a public health point of view, infected animals in zoos constitute a risk for animal caretakers and visitors. In this study we carried out the molecular identification of G. duodenalis and Entamoeba spp. from nine species of primates housed in the zoological garden of Rome, to better ascertain their occurrence and zoonotic potential.

Results

G. duodenalis was found only in Lemur catta (47.0%). Entamoeba spp. were detected in all species studied, with the exception of Eulemur macaco and Varecia rubra. The number of positive pools ranged from 5.9% in L. catta to 81.2% in Mandrillus sphinx; in Pan troglodytes the observed prevalence was 53.6%. A mixed Entamoeba-Giardia infection was recorded only in one sample of L. catta. All G. duodenalis isolates belonged to the zoonotic assemblage B, sub assemblage BIV. Three Entamoeba species were identified: E. hartmanni, E. coli and E. dispar.

Conclusions

Our results highlight the importance of regularly testing animals kept in zoos for the diagnosis of zoonotic parasites, in order to evaluate their pathogenic role in the housed animals and the zoonotic risk linked to their presence. A quick detection of the arrival of pathogens into the enclosures could also be a prerequisite to limit their spread into the structure via the introduction of specific control strategies. The need for molecular identification of some parasite species/genotype in order to better define the zoonotic risk is also highlighted.

Molecular differentiation of Entamoeba spp. in a rural community of Loja province, South Ecuador

Although previous epidemiological surveys in Ecuador indicate the presence of Entamoeba histolytica, prevalence data of this parasite remain scarce. Most of the studies were based on microscopic examination, which does not allow a morphological differentiation from the non-pathogenic Ent. dispar and Ent. moshkovskii. In the present study, 674 stool samples from a South Ecuadorian rural community were screened for Entamoeba spp. Subsequently, molecular identification was performed on 101 samples containing Ent. histolytica/Ent. dispar/Ent. moshkovskii cysts. The study indicated the absence of Ent. histolytica in this South Ecuadorian community and confirmed the difficulty of differentiating Entamoeba spp. based on morphological features.

High prevalence of Entamoeba infections in captive long-tailed macaques in China

Long-tailed macaques (Macaca fascicularis) are bred in China for export and for use in experiments. Entamoeba infections in captive long-tailed macaques were surveyed in one of the biggest colonies located in Guangxi Province, China. One stool sample was obtained from each of the 152 different cages representing >3,000 macaques in the colony. The samples were examined by PCR for five Entamoeba species. The number of detected Entamoeba coli infections comprised 94% of the samples, 93% for Entamoeba chattoni, and 83% for Entamoeba dispar. In contrast, Entamoeba histolytica and Entamoeba nuttalli were not detected. Six isolates of E. dispar were obtained by culture in Tanabe-Chiba medium. Analysis of serine-rich protein genes in these isolates showed two genotypes, one of which is identical to that of the E. dispar SAW760 strain in humans. This suggests transmission of E. dispar between humans and nonhuman primates. These results demonstrate that Entamoeba infections are common, but virulent Entamoeba species are absent in this colony. This work also confirms the need for monitoring with PCR-based identification of Entamoeba species for captive macaques in breeding colonies to ensure animal health and protection of humans from zoonotic hazards.

Increased sampling reveals novel lineages of Entamoeba: consequences of genetic diversity and host specificity for taxonomy and molecular detection

To expand the representation for phylogenetic analysis, ten additional complete Entamoeba small-subunit rRNA gene sequences were obtained from humans, non-human primates, cattle and a tortoise. For some novel sequences no corresponding morphological data were available, and we suggest that these organisms should be referred to as ribosomal lineages (RL) rather than being assigned species names at present. To investigate genetic diversity and host specificity of selected Entamoeba species, a total of 91 new partial small subunit rRNA gene sequences were obtained, including 49 from Entamoeba coli, 18 from Entamoeba polecki, and 17 from Entamoeba hartmanni. We propose a new nomenclature for significant variants within established Entamoeba species. Based on current data we propose that the uninucleated-cyst-producing Entamoeba infecting humans is called Entamoeba polecki and divided into four subtypes (ST1-ST4) and that Entamoeba coli is divided into two subtypes (ST1-ST2). New hosts for several species were detected and, while host specificity and genetic diversity of several species remain to be clarified, it is clear that previous reliance on cultivated material has given us a misleading and incomplete picture of variation within the genus Entamoeba.

The impact of genetic diversity in protozoa on molecular diagnostics

Detection of intestinal parasitic protists, commonly referred to as 'intestinal protozoa,' by PCR is increasingly used not only for identification or confirmation but also as a first-line diagnostic tool. Apart from the ability to sample correctly and extract parasite DNA directly from faeces, primer and probe specificity and sensitivity affect predictive values and hence the utility of diagnostic assays. Molecular characterization of intestinal protists is necessary to design primers and probes because this is the basic material for current and future improved diagnostic PCRs for either detecting all genetic variants or specifically differentiating among such variants. As an example, this paper highlights the existence of interspecific and intraspecific genetic diversity among intestinal, unicellular parasites and its implications for nucleic acid-based diagnostic assays.