Gastrointestinal entamoebiasis in captive anurans in North America

Infections with Entamoeba spp. are recognized as a cause of clinical disease in many species including humans and reptiles; however, cases in amphibians are under-reported. Investigation of a mortality event among a captive population of Cranwell's horned frogs Ceratophrys cranwelli at a production facility in Florida, USA, revealed that deaths were due to the newly described Entamoeba species CT1. Infection caused severe necroulcerative gastroenterocolitis with a predilection for the colon. To date, this Entamoeba species has only been described in invasive cane toads Rhinella marina in Australia. Retrospective screening of archived anuran cases from a zoological pathology service identified 8 cases from captive populations that had histological evidence of gastrointestinal entamoebiasis. Molecular characterization was positive in 3 cases. Two cases, 1 in a Puerto Rican crested toad Peltophryne lemur and 1 in an Amazon milk frog Trachycephalus resinifictrix, showed 100% homology to E. ranarum and 1 case in a White's tree frog Litoria caerulea showed 100% homology to Entamoeba sp. CT1. This is the first report of novel Entamoeba sp. CT1 being associated with clinical disease in anurans within North America and also the first report of this Entamoeba species causing disease within managed collections as far back as 2003.

Occurrence and genetic identifications of porcine Entamoeba, E. suis and E. polecki, at Tangerang in West Java, Indonesia

Entamoeba suis and E. polecki subtype (ST) 1 and ST3 recently have been inferred to be virulent in pigs. However, because relevant molecular epidemiological surveys have been limited, the prevalences of these species remain unknown and their pathogenicities are still controversial. We surveyed 196 fecal samples of pigs (118 of adults, 78 of piglets) at Tangerang in West Java, Indonesia, in 2017, employing PCR using porcine Entamoeba-specific primers. E. suis was the more frequently detected species, observed in 81.1% of samples, while E. polecki ST1 and ST3 were detected in 18.4% and 17.3% of samples, respectively; mixed infections (harboring 2-3 species or subtypes of Entamoeba) were confirmed in 29.3% of positive samples. Statistically significant differences in the positive rates were not seen between adult pigs and piglets, except for those of E. polecki ST3. The prevalences of Eimeria spp. and/or Cystoisospora suis (79.1%), strongyles (55.6%), and Strongyloides spp. (6.1%) were also observed morphologically in the samples. Further chronological or seasonal investigations of pigs and humans in these high-prevalence areas are needed to assess the virulence of the Entamoeba parasites, including the effects on pig productivity, and to evaluate the zoonotic impacts of these organisms.

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.

Invasive Colonic Entamoebiasis in Wild Cane Toads, Australia

We detected a disease syndrome in free-ranging Australian cane toads involving atypical behavior and emaciation that is associated with a previously undescribed Entamoeba sp. that infiltrates the colonic lining, causing it to slough. The organism may become seasonally pathogenic when toads are under hydric and nutritional stress.

Morphological and molecular characterization of an uninucleated cyst-producing Entamoeba spp. in captured Rangeland goats in Western Australia

Uninucleated Entamoeba cysts measuring 7.3×7.7μm were detected in faecal samples collected from wild Rangeland goats (Capra hircus) after arrival at a commercial goat depot near Geraldton, Western Australia at a prevalence of 6.4% (8/125). Sequences were obtained at the 18S rRNA (n=8) and actin (n=5) loci following PCR amplification. At the 18S locus, phylogenetic analysis grouped the isolates closest with an E. bovis isolate (FN666250) from a sheep from Sweden with 99% similarity. At the actin locus, no E. bovis sequences were available, and the isolates shared 94.0% genetic similarity with E. suis from a pig in Western Japan. This is the first report to describe the morphology and molecular characterisation of Entamoeba from Rangeland goats in Western Australia and the first study to produce actin sequences from E. bovis-like Entamoeba sp.

First report of mixed Entamoeba polecki (ST 1) and E. suis infection in piglets shedding abnormalfeces by histopathological and molecular surveys

Of the three species of Entamoeba found in swine, namely E. histolytica, E. polecki and E. suis, E. histolytica can also infect humans, producing colitis or abscesses of liver and leading to death. However, the pathogenicity of other species of Entamoeba has not been fully characterized. Here, we conducted histopathology and molecular surveys on a pig farm where piglets had blackish feces or muddy diarrhea. Histopathological examination of two piglets showed necrosis of the mucous surface at the ileum, cecum, or colon, infiltration of neutrophils, and formation of ulcers. Based on morphological characteristics, E. polecki and E. suis trophozoites were mainly detected at lamina propria and surface of the lesion, respectively, and Lawsonia intracellularis, a bacterial pathogen, was also detected. Molecular analysis using the small subunit ribosomal RNA gene on other piglets and a sow revealed infection with both E. polecki and E. suis. These findings corroborate our previous reports that the two Entamoeba spp. are pathogenic in pigs as aggravations of symptoms with L. intracellularis. This is the first report about mixed infection with E. polecki and E. suis.

Genetic identification of Entamoeba polecki subtype 3 from pigs in Japan and characterisation of its pathogenic role in ulcerative colitis

To date, three Entamoeba spp. (E. suis, zoonotic E. polecki and E. histolytica) have been identified in pigs, but their pathogenicity and molecular classification have not been fully determined. Examination and pathological analysis of pigs (n=3) with diarrhoea was conducted and revealed the presence of Entamoeba organisms. We performed a genetic analysis of the isolate using the small-subunit ribosomal RNA (SSU rRNA) gene region to identify the species. A severe ulcerative colitis was observed histopathologically with inflammatory cells, including macrophages and neutrophils, infiltrating the mucous membranes of the cecum and colon. Many Entamoeba trophozoites were found at the erosion site or at ulcerative lesions. Pathogenic viruses or bacteria were not detected. The SSU rRNA sequence of the Entamoeba isolate was found to be completely homologous to that of E. polecki subtype 3.

Entamoeba infections in different populations of dogs in an endemic area of Lahore, Pakistan

Entamoeba histolytica, a protozoan parasite that affects humans and other primates all over the world. It is a common waterborne pathogen in endemic areas that have fecal oral transmission cycle. The aim of the present study was to examine the prevalence of E. histolytica and other Entamoeba species cysts in three different dog populations. Fecal samples from 600 dogs were collected and processed to detect Entamoeba cysts using the triple fecal test (light microscopy) and fecal antigens of E. histolytica were detected using a fecal antigen ELISA (TechLab E. histolytica II). Because it is impossible to differentiate E. histolytica from Entamoeba dispar and E. moshkovskii, using light microscopy we referred to all cysts morphologically consistent with E. histolytica as E. histolytica/dispar/moskovskii to reflect this uncertainty. Samples from 197 household dogs without clinical signs, 122 samples from household dogs exhibiting clinical signs of diarrhea, dysentery and vomiting and 281 stray dogs with no specific clinical signs were examined. Entamoeba histolytica-like cysts were observed in 94 (15.6%, 95% CI=±3.88) by triple fecal test microscopy and E. histolytica antigens were demonstrated in 66 (11%, 95% CI=±4.41) by fecal antigen ELISA in 600 fecal samples. Significant differences (P≤0.05) in prevalence were found between the three populations. Twenty (10.1%, 95% CI=±7.86) and 11 (5.6%, 95% CI=±7.70) of 197 fecal samples from household dogs without clinical signs were positive by microscopy and by antigen ELISA, respectively. Twenty-nine (23.8%, 95% CI=±6.58) and 23 (18.8%, 95% CI=±7.81) of 122 the fecal samples from household dogs with clinical signs were positive by microscopy and by antigen ELISA, respectively. Forty-five (16.01%, 95% CI=±5.62) and 32 (11.3%, 95% CI=±6.38) of 281 fecal samples from stray dogs were positive by microscopy and by fecal antigen ELISA, respectively. Dogs from the youngest age group (6 months to 1 year) were more likely to be E. histolytica antigen positive than were dogs from the other two older age groups, with a significant difference (P≤0.05) between all age groups. Statistically, no significant (P≥0.05) difference of prevalence was seen in male and female dogs. The local dogs had the highest prevalence rate of E. histolytica antigens (36 of 246, 14.2%, 95% CI=±6.32) followed by imported breeds (11 of 115, 9.5%, 95% CI=±10.4) and crossbred (19 of 239, 8.3%, 95% CI=±7.47), indicating a significant (P≤0.05) trend of positivity between various breeds of dogs. These findings suggest that dogs may play an important role in the epidemiology of this pathogen.

Molecular detection of Entamoeba histolytica and Entamoeba dispar infection among wild rats in Kuala Lumpur, Malaysia

Entamoeba histolytica infection is the third-greatest parasitic disease responsible for death in the world. Wild rats harbouring E. histolytica can be the possible reservoir hosts for human amoebiasis. There were numerous studies on prevalence of intestinal parasites among wild rats in Malaysia but none has reported E. histolytica. Rats were captured from Sentul and Chow Kit areas, Kuala Lumpur, Malaysia. The preserved stool samples were used for microscopy examination and molecular analysis. Out of 137 samples collected, 12 were positive for E. histolytica / E. dispar / E. moshkovskii microscopically. Two E. histolytica (1.4%), 1 E. dispar (0.7%) and 6 mixed infections of E. histolytica and E. dispar (4.3%) were detected using PCR. This is the first report of molecular detection of E. histolytica/dispar infection among wild rats in Malaysia. This study provides useful information about the potential risks of zoonotic agents and the importance of developing control measures to prevent zoonotic transmission.

Molecular epidemiology and genetic diversity of Entamoeba species in a chelonian collection

Veterinary medicine has focused recently on reptiles, due to the existence of captive collections in zoos and an increase in the acquisition of reptiles as pets. The protozoan parasite, Entamoeba can cause amoebiasis in various animal species and humans. Although amoebiasis disease is remarkably rare in most species of chelonians and crocodiles, these species may serve as Entamoeba species carriers that transmit parasites to susceptible reptile species, such as snakes and lizards, which can become sick and die. In this study, we identified the Entamoeba species in a population of healthy (disease-free) chelonians, and evaluated their diversity through the amplification and sequencing of a small subunit rDNA region. Using this procedure, three Entamoeba species were identified: Entamoeba invadens in 4.76 % of chelonians, Entamoeba moshkovskii in 3.96 % and Entamoeba terrapinae in 50 %. We did not detect mixed Entamoeba infections. Comparative analysis of the amplified region allowed us to determine the intra-species variations. The E. invadens and E. moshkovskii strains isolated in this study did not exhibit marked differences with respect to the sequences reported in GenBank. The analysis of the E. terrapinae isolates revealed three different subgroups (A, B and C). Although subgroups A and C were very similar, subgroup B showed a relatively marked difference with respect to subgroups A and C (Fst = 0.984 and Fst = 1.000, respectively; 10-14 % nucleotide variation, as determined by blast) and with respect to the sequences reported in GenBank. These results suggested that E. terrapinae subgroup B may be either in a process of speciation or belong to a different lineage. However, additional research is necessary to support this statement conclusively.

Intestinal microbial community diversity between healthy and orally infected rabbit with Entamoeba histolytica by ERIC-PCR

Enterobacterial repetitive intergenic consensus (ERIC)-PCR was applied to analyze the difference of intestinal microbial community diversity between healthy and orally infected rabbits with Entamoeba histolytica. The dynamic changes in different parts of digestive system including the duodenum, jejunum, ileum, caecum, and rectum in healthy and infected rabbits at different time points were also tested. The intestinal microbial community of the control healthy rabbits was steady, and the total number of ERIC-PCR bands in the control healthy rabbit was the least in the rectum and the most in the caecum. ERIC-PCR bands of orally inoculated rabbits did not obviously change until 24 h after postinoculation (p.i.). The numbers of the ERIC-PCR bands gradually decreased from 24 to 72 h p.i., and then, with the development of disease, the band numbers gradually increased until 6 days p.i. Sequence analysis showed that the nucleotide sequence homologies of the fragment about 1,200 bp of infected ileum sampled at 32 h p.i. were above 95 % with Sinorhizobium meliloti enterobacterial, Erwinia amylovora and Salmonella typhimurium, and the nucleotide sequence homologies of the fragment about 300 bp of infected ileum sampled at 48 h p.i. were more than 90 % with Xanthomonas campestris enterobacterial, Yersinia enterocolitica subsp., Shigella flexneri, S. meliloti enterobacterial, Yersinia pestis, Klebsiella pneumoniae subsp., and Escherichia coli. The prominent bacteria had changed after E. histolytica infection. The DNAstar of staple of ERIC-PCR showed that aerobe and facultative aerobe (E. coli, Shigella, and Salmonella) became preponderant bacilli in the intestine of orally infected rabbits with E. histolytica.

An Entamoeba sp. strain isolated from rhesus monkey is virulent but genetically different from Entamoeba histolytica☆

An Entamoeba sp. strain, P19-061405, was isolated from a rhesus monkey in Nepal and characterized genetically. The strain was initially identified as Entamoeba histolytica using PCR amplification of peroxiredoxin genes. However, sequence analysis of the 18S rRNA gene showed a 0.8% difference when compared to the reference E. histolytica HM-1:IMSS human strain. Differences were also observed in the 5.8S rRNA gene and the internal transcribed spacer (ITS) regions 1 and 2, and analysis of the serine-rich protein gene from the monkey strain showed unique codon usages compared to E. histolytica isolated from humans. The amino acid sequences of two hexokinases and two glucose phosphate isomerases also differed from those of E. histolytica. Isoenzyme analyses of these enzymes in the monkey strain showed different electrophoretic mobility patterns compared with E. histolytica isolates. Analysis of peroxiredoxin genes indicated the presence of at least seven different types of protein, none of which were identical to proteins in E. histolytica. When the trophozoites from the monkey strain were inoculated into the livers of hamsters, formation of amebic abscesses was observed 7 days after the injection. These results demonstrate that the strain is genetically different from E. histolytica and is virulent. Revival of the name Entamoeba nuttalli is proposed for the organism.

Introducing reptiles into a captive collection: the role of the veterinarian

The successful introduction of reptiles into a captive collection depends on providing optimal husbandry and veterinary attention. An important role of the veterinarian in this process is the prevention of disease introduction, which may affect both the introduced and the resident animals. This review focuses on preventive veterinary medicine in reptiles, emphasising quarantine measures, disinfection and entry control for infectious agents. Agents discussed include those that are likely give rise to severe clinical problems on introduction into a collection of reptiles, or, in the case of Salmonella, those that pose a significant public health risk. Aetiology, clinical signs and diagnosis are discussed for the most relevant endo- and ectoparasites, bacteria and viruses including Cryptosporidium and Entamoeba, Salmonella, Dermabacter, Chlamydiales, Mycoplasma, Herpesvirus, Adenovirus, Paramyxovirus and inclusion body disease.

Entamoeba struthionis n.sp. (Sarcomastigophora: Endamoebidae) from ostriches (Struthio camelus)

In the present work we identify the species of Entamoeba from ostriches (Struthio camelus). The complete sequence of the small subunit ribosomal RNA gene from this organism has been compared with those published for other species of the genus and clear differences have been found. These results confirm previous data which showed differences on parasite morphology and class of host with the other Entamoeba species. Taking all these data together, it can be concluded that the organism from ostriches is a new species whose proposed name is Entamoeba struthionis n.sp. This species probably infects rheas (Rhea americana), but genetic analysis of isolates from this host should be performed to confirm morphological data. Also, comparison of gene sequences with data from other authors on cysts recovered from human stool samples showed the possibility that this amoeba may affect humans. Further studies are needed to determine the risk of transmission of this new species to humans.

Entamoeba histolytica infections in captive primates

A group based survey on the presence of Entamoeba histolytica and Entamoeba dispar using real-time PCR among 20 species of captive non-human primates was performed after diagnosis of E. histolytica dysentery in a spider monkey ( Ateles belzebuth hybridus). E. histolytica DNA was detected in three species of New World primates and in three species of Old World primates. In five of six E. histolytica isolates, it was possible to amplify the SREHP gene. They all revealed the same pattern after AluI digestion, indicating a common source of infection. E. dispar DNA was detected in two species of New World monkeys and three species of Old World monkeys. The results demonstrate that E. histolytica is capable of causing symptomatic and non-symptomatic infections in Old World and New World non-human primates. To our knowledge, this is the first report of E. histolytica sensu stricto in non-human primates after the redescription separating it from E. dispar in 1993.

Dilated cardiomyopathy and amebic gastritis in a giant anteater (Myrmecophaga tridactyla)

An approximately 11-mo-old female giant anteater (Myrmecophaga tridactyla) exhibited anorexia, lethargy, hypothermia, depression, and minimal response to external stimuli. Radiography and ultrasonography revealed an enlarged heart, with free gas and fluid in the abdomen. Abdominocentesis produced a clear brown fluid with an acute to subacute septic suppurative exudate. Cardiac ultrasonography revealed a dilated, thin-walled left ventricle with a comparatively low fractional shortening. Despite intensive supportive care, the anteater died. Postmortem findings included gastric ulceration with perforation near the pylorus. Entameba spp. and Acanthamoeba spp. were both identified in large numbers at the site of the gastric ulceration and perforation.

Clinical significance of the redefinition of the agent of amoebiasis

Entamoeba histolytica is the pathogenic species of Entamoeba that causes amoebic dysentery and other invasive disease. The morphologically similar species, E. dispar, is non-pathogenic and accounts for about 90% of the previously estimated 500 million E. histolytica infections world-wide. Because of the recent redefinition of E. histolytica and E. dispar, and the limited number of drugs available to treat amoebiasis, a new approach to treatment of individuals carrying these parasites is necessary. A meeting of eminent scientists has recently agreed that on no account should prophylaxis against amoebiasis be given, and no treatment without symptoms should be administered. The expense of treating asymptomatic individuals, both monetary and at the risk of over-use of precious drugs, does not appear to be justified. It would seem wise that we preserve currently effective anti-amoebic drugs and avoid the development of drug-resistant E. histolytica.

High prevalence of infection with Entamoeba dispar, but not E. histolytica, in captive macaques

A total of 268 nonhuman primates (20 species) kept in the Primate Research Institute, Kyoto University, Japan, were surveyed for intestinal amebas. Total positive rates as based on the presence of cysts in the stool following formalin-ether sedimentation were as follows: Entamoeba histolytica/E. dispar, 53%; E. coli, 34%; E. hartmanni, 34%; Iodamoeba buetschlii, 25%; Endolimax nana, 8%; and E. chattoni, 3%. Positive rates were higher in Old World monkeys and lower in New World monkeys. All the 141 E. histolytica/E. dispar-positive animals were Macaca monkeys. The E. histolytica/E. dispar-positive samples were analyzed by polymerase chain reaction (PCR) for identification of E. histolytica and E. dispar. E. dispar DNA was detected in 137 samples, whereas no E. histolytica DNA was seen. Zymodeme analysis and reactivity to monoclonal antibodies of cultured trophozoites also supported the presence of E. dispar and the absence of E. histolytica. When the sera of 93 macaques were examined by an indirect fluorescent antibody test, only 3 animals proved to be positive for E. histolytica, showing the lowest titer. These results demonstrate that infection with E. dispar, but not E. histolytica, is predominant in macaques.

Entamoeba dispar, but not E. histolytica, detected in a colony of chimpanzees in Japan

Chimpanzees (Pan troglodytes) residing in the Kumamoto Primate Research Park, Sanwa Kagaku Kenkyusho, were surveyed for the presence of intestinal parasites. Stool samples from 107 chimpanzees were examined by microscopy after formalin-ether sedimentation. Of these animals, 100 were infected with at least 1 species of ameba. The positivity rates recorded were as follows: Entamoeba coli, 88%; E. histolytica/E. dispar, 48%; E. hartmanni, 15%; Iodamoeba buetschlii, 8%; Endolimax nana, 4%; and Entamoeba chattoni, 2%. Polymerase chain reaction (PCR) analysis to distinguish between E. histolytica and E. dispar was performed on these samples. E. dispar DNA was detected in 60 of 107 samples (56%), including 9 that had been microscopically determined to be negative for E. histolytica/ E. dispar. In contrast, no E. histolytica DNA was detected in the 107 samples. Zymodeme analysis indicated that 10 isolates were E. dispar. When 104 chimpanzees were examined serologically for E. histolytica infection, 1 sample was scored as positive by indirect hemagglutination and another was found to be positive by an indirect fluorescent antibody test. However, both specimens were borderline-positive and were clearly negative in other tests, suggesting that they might be false-positives. These results demonstrate that the pathogenic E. histolytica was absent in this colony, regardless of the high degree of prevalence of other amebas. For an accurate diagnosis, PCR analysis is recommended in addition to microscopic examination.

Detection of Entamoeba dispar DNA in macaque feces by polymerase chain reaction

We used the polymerase chain reaction (PCR) to determine the prevalence of Entamoeba histolytica and E. dispar in the wild population of macaque monkeys (Macaca fuscata) in Mt. Takasaki, Oita Prefecture, Japan. Of the 101 samples collected, 41 (42.57%) were found to be positive for E. dispar. However, no E. histolytica was detected from the collected samples. The results of this survey demonstrate the high prevalence of E. dispar in macaque monkeys in the study area. Moreover, they provide additional baseline information on naturally acquired infectious agents of macaque monkeys and offer an accurate tool for detection of E. histolytica and E. dispar, which are needed for biomedical research using nonhuman primate models.

Secnidazole vs. paromomycin: comparative antiprotozoan treatment in captive primates

The antiprotozoan activity of secnidazole was studied in Cercocebus t. torquatus, Cercopithecus campbelli, Erythrocebus patas (Cercopithecidae), and Gorilla gorilla (Pongidae) compared with that of paromomycin in Cercocebus t. lunulatus (Cercopithecidae), E. patas, and G. gorilla (Pongidae) by coprological analysis. The antiprotozoan activity of both drugs depended on the parasite species and the host species. The drugs acted in a similar way on Entamoeba coli parasitising C. t. torquatus, and E. patas. This activity was different from that observed on I. buestchlii from the same host species. Nevertheless, E. coli parasitising cercopithecids and pongids responded to drugs differently.

Rapid postmortem invasion of cecal mucosa of macaques by nonpathogenic Entamoeba chattoni

Although Entamoeba histolytica is the third leading parasitic cause of death in the world, most infections in humans are asymptomatic and restricted to the intestinal lumen. Entamoeba histolytica infections have also been reported in most species of captive nonhuman primates, with New World monkeys being particularly susceptible to fatal invasive amebiasis. In contrast, Old World monkeys appear to be resistant to the disease, although tissue invasion in asymptomatic monkeys has been reported. Our initial objectives were to determine the incidence, the predisposing factors, and the light microscopic and ultrastructural features of invasive amebiasis in Macaca mulatta (rhesus) and and M. fasicularis (cynomolgus) macaques. Our findings indicate that nonpathogenic E. chattoni in macaques can invade cecal mucosa rapidly (within 1 hr) after death. Therefore, the presence of invasive Entamoeba trophozoites in routinely collected necropsy materials should be interpreted with caution, particularly in cases where tissue fixation is delayed.

Intestinal inflammation associated with flagellates in snakes

The intestines of 51 snakes with histologically diagnosed or suspected amoebiasis were reinvestigated immunohistochemically with an Entamoeba invadens antibody. In 22 cases, trophozoites of Entamoeba invadens stained positively in the inflamed intestinal wall, but the protozoa visible in the pathologically changed intestines of a further 20 snakes were negative. On the basis of light and electron microscopical findings, these protozoa were identified as flagellates.

Entamoeba bovis Liebetanz 1905 recorded from large ruminants in Egypt

Investigations carried out on trematode parasites affecting cattle and buffaloes in Ismailia Governorate revealed a degree of infection with Fasciola sp. attaining 6.95% among the former, and 16.16% among the latter. Concerning Paramphistomum sp. infection, it was 43.83% among cattle and 9% among buffaloes. During these studies, it appeared that cattle or buffaloes having no infection with Fasciola sp. or those being infected with Paramphistomum sp. only proved to harbour Entamoeba bovis trophozoites with a percentage of about 85% in cattle, and 80% among buffaloes. This protozoan parasite was also recovered from the gall bladders and bile ducts of slaughtered beef cattle that had no infection with liver flukes. The morphological picture of the fresh E. bovis trophozoite as well as its cyst were described, and the significance of such parasite on its host was discussed.

Necrotic colitis associated with Entamoeba histolytica infection in a cat

A 3-year-old Persian cat developed bloody diarrhoea. On histological examination, a marked necrotic colitis with a large number of invading protozoan parasites was observed. The protozoan was identified as Entamoeba histolytica by light and electron microscopy. This is the first report describing spontaneous amoebiasis in cats.

Invasive entamoebae in pronghorn (Antilocapra americana) from Wyoming

Trophozoites and cysts of an amoeba resembling Entamoeba bovis were recovered from soft stools of captive pronghorn fawns (Antilocapra americana). Chronic or intermittent diarrhea was observed in most individuals in two groups of hand-raised 1- to 8-mo-old pronghorns. Ileocecal lymph nodes were mildly to moderately enlarged. Microscopic lesions were characterized by lymphoid hyperplasia, focal necrosis and pyogranulomatous inflammation in lymph nodes and focal necrosis and diffuse nonsuppurative enteritis in ileum and cecum. In 12 of 17 fawns, trophic stages of amoebae were observed in the submucosa of the cecum and/or the cortex of the ileocecal lymph node. This is the first report of E. bovis-like organisms invading and causing pathological changes in the tissues of their host.

Invasive amebiasis in naturally infected New World and Old World monkeys with and without clinical disease

Histopathological preparations of cecum and colon from monkeys naturally infected with invasive Entamoeba histolytica were examined to determine the distribution of amebae in the tissues and the types of lesions, if any, associated with them. Infections were studied in 3 New World species (10 Callicebus moloch, 1 C. torquatus, and 2 Aotus trivirgatus) and 3 Old World species (8 Macaca mulatta, 6 Erythrocebus patas, and 1 Cercopithecus aethiops). Amebiasis was recorded as the principal or a contributing cause of death of all of the 13 New World monkeys and in 6 of the 15 Old World monkeys; amebiasis was detected in the rest of the monkeys only after tissues were re-examined specifically for amebae. Amebae causing no apparent damage were found in the lamina propriae, mainly at the muscularis mucosae. Most frequent were colonies or aggregates of amebae in the crypts between the epithelium and basement membrane, causing either no evident necrosis or changes ranging from necrosis and disarrangement of adjacent cells to complete destruction of the epithelium and reduction of the cells to pyknotic bodies. A lesion interpreted as possibly characteristic of carrier-state invasive amebiasis was destruction of the epithelium in patches of mucosal crypts, not leading to ulceration. Uncommon but present in both New and Old World monkeys were typical areas of surface erosion and classical flask-shaped ulcers. The observations show that in some species of Old World monkeys amebiasis can be invasive without causing clinical disease.

Primates as a source of Entamoeba histolytica, their zymodeme status and zoonotic potential

A survey of 17 species of non-human captive primates in Quebec, Canada, revealed that 40% of the animals were infected with the protozoan Entamoeba histolytica. Isoenzyme analysis of lysates prepared from cultured amebic isolates showed them to belong to either a zymodeme III or VIII, and therefore, characteristic of non-pathogenic strains of E. histolytica from humans. These isolates were also of low virulence in gerbil ceca. Serum samples from infected and uninfected primates had negative titres for E. histolytica and all the animals appeared to be healthy.

Hepatic and gastric amebiasis in black and white colobus monkeys

Three cases of hepatic amebiasis and one case of gastric amebiasis were diagnosed in black and white colobus monkeys during a 9-month period. The diagnosis was difficult because of the absence of trophozoites and cysts in the feces and because of few trophozoites found in many of the hepatic lesions. Indirect hemagglutination titers were diagnostic in 2 monkeys.

Natural transmission of Entamoeba histolytica from mother cynomolgus monkeys (Macaca fascicularis) to their newborn infants under indoor rearing conditions

Natural transmission of Entamoeba histolytica from infected mother cynomolgus monkeys (Macaca fascicularis) to their newborn infants was investigated by the stool examination under indoor individually-caged conditions. Every infant became positive for E. histolytica between 5 and 10 weeks after birth. Although some infants were demonstrated to harbor the trophozoites, no overt amebic diarrhea occurred in any of the infants throughout the period of this study.

Studies on the examination of imported laboratory monkey, Macaca fascicularis for E. histolytica and other intestinal parasites

Infection rate of imported monkeys, under this study, with intestinal protozoa is higher than the infection rate with intestinal nematodes. Mostly encountered protozoa were E. coli, E. nana, E. histolytica and I. butschlii. Formalin-Ether concentration method yielded higher % positive for E. histolytica than the culture method using Tanabe-Chiba medium, but the results obtained from these 2 methods correlate perfectly well with each other. Efficacy of thiabendazole against intestinal nematodes such as Strongyloides, Trichuris, Physaloptera, Oesophagostomum and Capillaria was very satisfactory.

Transmission of Spironucleus and Giardia spp. and some nonpathogenic intestinal protozoa from infested hamsters to mice

Intestinal protoza belonging to the genera Spironucleus (Hexamita), Giardia, Trichomonas and Entamoeba, carried by conventional hamsters, were successfully transmitted to and established in protozoa-free sucking or newly-weaned specified-pathogen-free inbred mice by exposure of the mice to hamster intestinal contents.

Attempted transmission of Entamoeba coli to specified-pathogen-free rodents

An attempt was made to establish whether human Entamoeba coli was transmissible from man to laboratory rodents. Cysts from 15 samples of human and 4 of primate stool were passaged into specified-pathogen free guinea-pigs, rats and mice. In only 1 instance were cysts established in mice and, eventually, in rats.

Systemic pathology of chimpanzees

Spontaneous lesions in chimpanzees have been described according to the organ system involved. These lesions have been reported in the literature or noted in chimpanzees at the 6571st Aeromedical Research Laboratory (ARL), Holloman AFB, N. Mex., over a 15-year period. some of the lesions seen at the ARL were the result of overt clinical disease, while others represent incidental findings, the significance and genesis of which were often obscure. Conditions involving the gastrointestinal tract, especially parasitic diseases, have been and continue to be of the highest frequency, with disorders involving the cardiovascular system next. Infectious diseases have been infrequent, especially in the stabilized colony, and neoplastic conditions have not been seen.

Entamoeba histolytica infection in a German shepherd dog

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Epizootic of fatal amebiasis among exhibited snakes: epidemiologic, pathologic, and chemotherapeutic considerations

An epizootic of reptilian amebiasis seems to have caused the death of 15 to 16 large and valuable captive snakes (boas, pythons, and anacondas) occupying one of 5 large display dioramas in the Steinhart Aquarium of the California Academy of Science, Golden Gate Park, San Francisco. Subsequent review of previous snake deaths in the colony indicated that of 464 snakes that had died since early 1969, 89 snakes had intestinal or hepatic lesions, and 80 of these snakes had pathologic features which involved severe intestinal ulceration, hemorrhage, and massive enteritis, with or without hepatic necrosis and destruction, condition compatible with Entamoeba invadens infection. The present epizootic began in November, 1972, with the death by acute enteritis of a red-tailed boa constrictor (Boa constrictor amarali) and was followed by the loss of 15 other large boids and pythonids. The affected snakes became immobile, refused to feed, and began to die 10 weeks after the death of the red-tailed boa. Seven boa constrictors, 4 pythons, and 4 anacondas from the same diorama died during the ensuing 10 weeks. Entamoeba invadens trophozoites were identified in the stool of the remaining living snake, a 3-m boa constrictor, and in the liver and the intestinal tissue of 1 of the dead boas examined microscopically. The parasite was also found in the stool of a giant Burmese python (Python molurus bivittatus) that died in the adjacent diorama and in the tissues of a blue-tongued skink (Tiliqua scincoides), separately housed, that died of enteritis during this period. Amebic cysts were recovered from turtle and alligator fecal samples taken from a central "swamp," or reservoir, draining the dioramas, water that is returned to the snake display areas after passage through a biological sand-gravel filter and ultraviolet radiation exposure. Cultures from these stools were positive and proved lethal to an experimentally infected boa constrictor. Treatment of the surviving snake in the affected diorama with metronidazole at the dose rate of 275 mg/kg proved rapidly effective; toxicosis was not observed. Other snakes and lizards suspected of having the infection were similarly treated and returned to normal behavior and feeding patterns. Epidemiologic considerations review the probable mode of introduction and spread of this highly lethal snake pathogen and recommendations are made for avoiding infection, prophylactic treatment, and handling of similar epizootics when they do occur among captive reptiles in aquariums, zoos, and research laboratories.