Evaluation of a rapid immunochromatographic test for the diagnosis of intestinal protozoan infections among patients attending a rural outreach outpatient department in Northern India

Despite great efforts, intestinal protozoan infections remain a significant healthcare concern worldwide. Although many point-of-care (POC) tests are increasingly being used, microscopic examination of stool specimens remains the mainstay for their diagnosis, especially in resource-limited settings. We assessed the utility of rapid POC tests based on immunochromatography among patients from rural Northern India. A total of 78 patients were enrolled in the study. Out of nine specimens that tested positive for Giardia duodenalis on microscopy, an immunochromatographic test (ICT) could detect only five (55.55%). Entamoeba histolytica/dispar was demonstrated in two specimens on microscopy, both of which were missed by ICT. Its overall sensitivity, specificity, and positive and negative predictive value were 50%, 98.5%, 83.3%, and 93%, respectively. Its performance was considered unsatisfactory. Although ICT-based tests provide a relatively rapid and less labor-intensive alternative, they should be used to supplement and not replace stool microscopy.

Revisiting the isolation and characterisation of Entamoeba histolytica lipopeptidophosphoglycan

The parasite Entamoeba histolytica is the cause of amoebic dysentery and liver abscess in humans. On the protozoan cell surface, a variety of glycosylated molecules are involved in the interaction with the environment, such as attachment to the colonic mucus. One of these molecules is the lipopeptidophosphoglycan (LPPG), a complex surface component with antigenic properties. Its structure is only partly known, it is a glycosylphosphatidylinositol (GPI)-linked glycoprotein with a large amount of O-glycosylation. To date, the sequence of a core protein has not been identified. In this study, we further investigated this complex surface molecule aided by the availability of the monoclonal antibody EH5, which had been raised in our laboratory. We studied the extraction of LPPG in various solvent mixtures and discovered that 2-butanol saturated water was simple and superior to other solvents used in the past. The isolated LPPG was subjected to treatment with several proteases and the Ser/Thr specific cleavage agent scandium (III) trifluoromethanesulfonate (scandium triflate). The products were probed with antibody EH5 and the blots showed that the LPPG preparation was largely resistant to standard proteases, but could be cleaved by the scandium compound. These observations could point to the existence of a Ser- or Thr-rich core protein structure.

Profiling pathogenic protozoan and their functional pathways in wastewater using 18S rRNA and shotgun metagenomics

Despite extensive research, little is known about the composition of eukaryotic protists in environmental samples. This is due to low parasite concentrations, the complexity of parasite diversity, and a lack of suitable reference databases and standardized protocols. To bridge this knowledge gap, this study used 18S rRNA short amplicon and shotgun metagenomic sequencing approaches to profile protozoan microbial communities as well as their functional pathways in treated and untreated wastewater samples collected from different regions of South Africa. Results demonstrated that protozoan diversity (Shannon index P-value = 0.03) and taxonomic composition (PERMANOVA, P-value = 0.02) was mainly driven by the type of wastewater samples (treated & untreated) and geographic location. However, these WWTPs were also found to contain a core community of protozoan parasites. The untreated wastewater samples revealed a predominant presence of free-living, parasitic, and potentially pathogenic protists typically found in humans and animals, ranging from Alveolata (27 %) phylum (Apicomplexa and Ciliophora) to Excavata (3.88 %) (Discoba and Parasalia) and Amoebozoa (2.84 %) (Entamoeba and Acanthamoeba). Shotgun metagenomics analyses in a subset of the untreated wastewater samples confirmed the presence of public health-importance protozoa, including Cryptosporidium species (3.48 %), Entamoeba hystolitica (6.58 %), Blastocystis hominis (2.91 %), Naegleria gruberi (2.37 %), Toxoplasma gondii (1.98 %), Cyclospora cayetanensis (1.30 %), and Giardia intestinalis (0.31 %). Virulent gene families linked to pathogenic protozoa, such as serine/threonine protein phosphatase and mucin-desulfating sulfatase were identified. Additionally, enriched pathways included thiamine diphosphate biosynthesis III, heme biosynthesis, Methylerythritol 4-Phosphate Pathway, methyl erythritol phosphate (MEP), and pentose phosphate pathways. These findings suggest that protozoan pathogens may possess metabolic and growth potential within WWTPs, posing a severe risk of transmission to humans and animals if inadequately disinfected before release. This study provides a baseline for the future investigation of diverse protozoal communities in wastewater, which are of public health importance.

In tap water

Polluted resources of potable water are daily used for different purposes in Lebanon. The optical microscopy is the traditional method used for the detection of Entamoeba spp. in water despite its weak sensitivity. We aimed to characterize domestic water at Nabatieh district, South Lebanon, and to develop a simple method for Entamoeba spp. detection. A total of 70 water samples were collected from houses and schools and analyzed for physical (pH, total dissolved solids and temperature), chemical (nitrate, phosphate and sulfate) and bacterial (total and fecal coliforms) parameters. The contamination by Entamoeba spp. was examined using microscopy, then a spectrophotometric wavelength scan was recorded for 50 samples in order to determine the common peak between positive samples. High phosphate levels were detected in all the samples, with important bacterial and parasitological contaminations. The spectrophotometric analyses showed a peak repetition at the wavelength of 696 nm in the spectrum of the majority of positive samples. The number of cysts was significantly correlated to optical densities at 696 nm (R = 0.9087; p-value<0.0001). The regression analysis showed that the OD696 could statistically predict the concentration (F (1,48) = 267.02, p-value <0.001). In conclusion, potable water parameters at Nabatieh district did not meet the national and international guidelines of safe drinking water, and the detection of Entamoeba spp. cysts in potable water can be performed using a rapid spectrophotometric analysis, by the determination of the optical density at 696 nm and the application of a specific equation.

Oral parasitic protozoan Entamoeba gingivalis in periodontal disease patients, northeastern Thailand

Entamoeba gingivalis is present in the oral cavity of humans and is associated with periodontal disease. Consequently, this study aimed to comprehensively investigate the E. gingivalis infection and the associated risk factors among individuals suffering from periodontal conditions. A cross-sectional descriptive study was carried out within a cohort of periodontal patients. Dental plaque specimens were meticulously collected and subsequently subjected to thorough examination using the polymerase chain reaction (PCR)-based technique targeting the small subunit ribosomal RNA (SrRNA) gene of the organism. The occurrence of risk factors for E. gingivalis infection was analyzed by the chi-square test and binary logistic regression. Out of the 230 participants, 60 were clinically diagnosed with periodontitis, while 170 were afflicted with gingivitis. Out of the 230 patients, 25 (10.9%) tested positive for E. gingivalis infections. An in-depth analysis unveiled that a significant majority of infections were recorded within subgroups characterized by a marital status (15.45%), manifestation of periodontitis (25.00%), and concomitant presence of underlying disease (20.83%). Furthermore, the high risk factor associated with E. gingivalis infection was the female (ORadj = 13.65, 95% CI = 1.08-173.21), followed by periodontitis (ORadj = 3.30, 95% CI = 1.21-9.00), respectively. The study employs a molecular diagnostic approach to screen for E. gingivalis enrichment within a subset of periodontal patients with advancing disease. The findings emphasize the necessity for further research to elucidate the pathogenesis of E. gingivalis and advocate for vigilant surveillance within a substantial population of periodontal patients.

COMPARISON BETWEEN PCR STUDY AND ELISA STUDY AMONG PATIENTS WITH DIARRHEA

Amoebic dysentery is a common infectious disease that is acquired through contaminated food and water harboring the infective stage of the parasite. Entamoeba histolytica is a parasite that is spread globally causing increasing morbidity and mortality in developing countries. To Identify the infection of Entamoeba histolytica by PCR and other lab methods among patients attending Kirkuk hospitals. Methods: The current study involved the examination of 220 fecal specimens from children under 15 years during the period of 1st January 2023 until 5th of June 2023. It involved microscopic examination of fecal samples confirmation of diagnosis with two different ELISA tests that capture E. histolytic. Also, microscopic positive samples were submitted to nucleic acid detection of E. histolytic via Real-Time PCR. The percentage of positive specimens that were tested with E. histolytica / dispar ELISA (DRG ELISA), out of 93 stool specimens, 59 (63.44%) were positive, while the remaining specimens 34 (36.56%) were negative despite being tested positive by microscopy. The DRG stool ELISA revealed sensitivity and specificity (69.28% and 97.91%) respectively and a predictive value of (97%). The sample that was the positive result with DRG ELISA was discriminated via Tech Lab E. histolytica ELISA which detects the presence of only E. histolytica alone in fecal samples. Out of 93 examined specimens, only 24 (25.81%) were positive while the remaining 69 (74.19%) were negative. DRG ELISA for E. histolytica/dispar positive results were 63.44%, while TechLab ELISA has produced 25.81% positive E. histolytica. Whereases, RT PCR results were only 20.44%. Qi square analysis was applied and yielded a significant difference v=between the method of diagnosis with P=<0.0001. Microscopy-positive Entamoeba complex is a primitive means of detection of Entamoeba complex and diagnosis should always be confirmed with superior method like ELISA or PCR.

Oral Protozoa Entamoeba Gingivalis And Trichomonas Tenax Among Periodontitis And Gingivitis Patients In Periodontology Department Dental Section Quetta

Background

A group of eukaryotic organisms that are either free-living or parasitic and feed on organic matter, such as microorganisms or organic detritus. This group is referred to as a polyphyletic classification. They can be found in a wide variety of patterns and sizes, ranging from an amoeba, which can vary its shape, to a paramecium, which has a fixed shape and a complicated structure. The objective was to find out the occurrence of Entamoeba gingivalis and Trichomonas among Dental Patients visiting the Periodontology Department Dental Section, Sandeman, Provincial Hospital Quetta.

Methods

The study design was randomized cross-sectional and conducted in the Department of Periodontology Dental Section, Sandeman Provincial Hospital Quetta, from March 2022 to February 2023. A total of 110 known cases of periodontitis and gingivitis were recruited in this study, and further to laboratory work the bacterial biofilm samples were collected from both gingivitis and periodontitis patients. The dental plaque was placed on individual glass microscope slides and a drop of saline and mixed and covered with a coverslip. The wet smear was examined immediately under 40X, and the objective for the presence and absence of motile amoebae or flagellated protozoa was recorded. .

Results

out of 110 known cases of periodontitis and gingivitis 91 (83%) patients were males and 19 (17%) were females among 110 patients, 40 (36%) patients were periodontitis and 70 (64%) patients were gingivitis. Among 40 (36%) periodontitis patients 3(7.5%) were Entamoeba gingivalis and 4(10%) were Trichomonas Tenax while 70 (64%) cases of Gingivitis 20 (28%) of Entamoeba gingivalis and 1(1%) Trichomonas tenax was recorded. No patient had both species of protozoa were seen in this study.

Conclusion

The results of this study revealed the frequency of occurrence of E. gingivalis and T. tenax and the state of periodontitis and gingivitis. The prevalence of E. gingivalis was higher than T. tenax. We recommended further research with a higher number of patients and may use more advanced and reliable laboratory techniques such as PCR and electron microscopy.

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.

Entamoeba gingivalis and Trichomonas tenax: Protozoa parasites living in the mouth

OBJECTIVE

This review article aims to summarize the existing data on the history, biology and potential pathogenicity of Entamoeba gingivalis and Trichomonas tenax in periodontal disease, as well as the available techniques for laboratory diagnosis.

DESIGN

A detailed review of scientific literature available up to October 1, 2022 in three databases (PubMed, Scopus and Web of Science) was performed relevant to biology, biochemistry, epidemiology, and experimental studies on infection by E. gingivalis and T. tenax, as well as laboratory techniques for the diagnosis of both protozoa in periodontal diseases.

RESULTS

Accumulated evidence over the decades indicates that the protozoa E. gingivalis and T. tenax are able to interact with host cells and induce inflammation in the periodontal tissue by promoting the expression of pro-inflammatory molecules and the recruitment of neutrophils, contributing to the periodontal disease process. Among the available techniques for the laboratory diagnosis, culture and molecular assays seems to be the best tools for detection of both protozoan parasites.

CONCLUSIONS

E. gingivalis and T. tenax are potentially pathogens that colonize the oral cavity of humans and may cause periodontal disease.

Entamoeba gingivalis is associated with periodontal conditions in Chinese young patients: A cross-sectional study

Background

This study investigated the prevalence and relative abundance of Entamoeba gingivalis (E. gingivalis) in Chinese young patients with different periodontal conditions, and its association with subgingival microbial composition, periodontal parameters, and cytokines in gingival crevicular fluid.

Methods

Participants (age: 18–45 years) diagnosed with stage II–IV periodontitis, gingivitis, or periodontal health underwent periodontal examination and sampling. Subgingival plaque was analyzed by 16S+18S sequencing for E. gingivalis detection and microbial analysis. The distribution of E. gingivalis in subgingival plaque was illustrated by fluorescence in situ hybridization. Interleukin-1β, interleukin-8, and tumor necrosis factor-α in gingival crevicular fluid were measured by multiplexed flow cytometric assay.

Results

This cross-sectional study included 120 sites from 60 participants. The prevalence and relative abundance of E. gingivalis were significantly increased in periodontitis (p<0.05). The sites were classified into three subgroups according to the relative abundance of E. gingivalis: negative group (Eg0, n=56); low-abundance group (Eg1, n=32); and high-abundance group (Eg2, n=32). The subgingival microflora in the subgroups showed stepwise changes at both the phylum and genus levels. The microflora compositions were significantly altered from Eg0 to Eg2 (p<0.001). Co-occurrence network analysis showed that Porphyromonas, Treponema, Tannerella, Filifactor, TG5, and Desulfobulbus were highly correlated with E. gingivalis (r>0.6, p<0.001). Correlation analysis showed that E. gingivalis was closely associated with important periodontal parameters and cytokines (p<0.01).

Conclusion

E. gingivalis was enriched in periodontitis and closely associated with subgingival microbial dysbiosis, periodontal parameters and cytokines in gingival crevicular fluid. Thus, it may be an important pathogen in periodontal disease.

Identification and Semi-quantification of Protozoa from the Digestive System Microbiota of the Lobster Cockroach Nauphoeta cinerea Oliver, 1789 (Insecta:Blattaria)

INTRODUCTION

The lobster cockroach Nauphoeta cinerea (N. cinerea) is indicated as a promising non-mammalian model, because it presents behavioral and biochemical alterations also observed in conventional models. In this research, we identified and characterized the distribution of protozoa that inhabit the digestive system (DS) of N. cinerea cockroaches.

METHODS

The adult specimens of N. cinerea used in this study (n = 32) were obtained at the Federal University of Santa Maria, dissected and had their visceral contents observed in bright-field microscopy without staining and after application of lugol, Ziehl-Neelsen staining, EA36 trichrome and simulated dark-field microscopy with application of nankin ink. The presence of protozoa in different portions of the DS was semi-quantified by a system of crosses (+).

RESULTS

The main taxa observed were: amoebas (Archaemebae:Entamoebida), gregarins (Apicomplexa:Eugregarinide), coccidia (Apicomplexa:Eucoccidiorida), kinetoplastids (Kinetoplastea:Kinetoplastida) and oxymonads (Preaxostyla:Oxymonadida). The highest prevalence of amoebas and gregarines was observed in the medial portion of the DS, while for the other groups, this was seen in the final portion, and in the case of coccidia, such prevalence was specially evidenced by the alcohol-acid coloration. In the present work, the great biological diversity that exists in the microbiota of the digestive system of Nauphoeta cinerea was demonstrated, being possible to find several pathogenic species for humans such as Entamoeba histolytica/dispar/moshkovskii, Cryptosporidium sp. and Cyclospora cayetanensis. There is still a lot to know about the interactions between endocommensal protozoa and their respective invertebrate hosts, so the best way to clarify such relationships is through molecular and genetic test.

Oral Colonization by Entamoeba gingivalis and Trichomonas tenax: A PCR-Based Study in Health, Gingivitis, and Periodontitis

Background

The etiology of periodontitis remains unclear, as is the place of gingivitis in its pathophysiology. A few studies linked the colonization by oral parasites (Entamoeba gingivalis and Trichomonas tenax) to periodontal disease and its severity. The aim of the current study was to estimate the prevalence of these oral parasites among healthy individuals, and in patients with gingivitis and periodontitis in Jordan.

Methods

The study was conducted during July 2019–December 2019. Samples were composed of saliva and periodontal material including dental plaque sampled with probes. The detection of oral parasites was done using conventional polymerase chain reaction (PCR).

Results

The total number of study participants was 237: healthy (n=94), gingivitis (n=53) and periodontitis (n=90). The prevalence of E. gingivalis was 88.9% among the periodontitis patients, 84.9% among the gingivitis patients and 47.9% in the healthy group. For T. tenax, the prevalence was 25.6% among the periodontitis patients, 5.7% among the gingivitis patients and 3.2% in the heathy group. Positivity for E. gingivalis was significantly correlated with the presence of periodontal disease compared to the healthy group with odds ratio (OR) of 6.6. Periodontal disease was also correlated with lower monthly income (OR=8.2), lack of dental care (OR=4.8), and history of diabetes mellitus (OR=4.5). Colonization by E. gingivalis was correlated with gingivitis (OR=6.1) compared to the healthy group. Colonization by E. gingivalis and T. tenax were significantly correlated with periodontitis (OR=6.4 for E. gingivalis, and OR=4.7, for T. tenax) compared to the healthy group. T. tenax was only detected among individuals with generalized periodontal disease compared to its total absence among those with localized disease (19.6% vs. 0.0%; p=0.039). The co-infection rate by the two oral parasites was 11.0%.

Conclusions

The higher prevalence of human oral parasites in periodontal disease compared to healthy individuals appears to be more than a mere marker for the disease and might also be associated with disease severity and potential for progression. Thus, the dogmatic view of E. gingivalis and T. tenax as commensals needs to be re-evaluated and their contribution to pathophysiology of periodontal diseases cannot be neglected.

Detection of enteropathogens and research of pesticide residues in Lactuca sativa from traditional and agroecological fairs

Agroecological production represents a new reality in vegetable farming. Thus, the study aimed to search for the presence of pesticides in agroecological samples and microbiological and parasitological contamination in Lactuca sativa L. of agroecological and conventional fairs in Alagoas. Thirty-two samples were collected, a hygienic-sanitary checklist was performed, along with coliform, Salmonella spp., Staphylococcus aureus research and Gas Chromatography with Mass Spectrometer (GC-MS) for pesticide research; using two methodologies for parasitological studies. Thirty-two samples were analyzed, with a sanitary adequacy level at 45% and 38% for fairs (agroecological and conventional) respectively, with three samples (9.4%) in total, being adequate to the microbiological pattern according to RDC no. 12/2001. Among the 23 samples which were tested positive for parasites, 69.5% originated from samples extracted at conventional fairs, and 53% of every positive samples presented Entamoeba coli as the main contaminant. All together, no traces of deltamethrin were detected, but in two of the samples a peak retention for diphenoconazole was detected. In conclusion, the fairs represent an adequate environment for human pathogens and indicators. Therefore greater hygiene training of vegetable traders and consumers in the state of Alagoas is required, especially in conventional fairs, which presented more critical microbiological and parasitological indexes comparing to fairs with agroecological products; however, the presence of difenoconazole in two samples of agricultural fairs suggests accidental contamination or indiscriminate use of this chemical in the production of Lactuca sativa, however, products with agroecological origin represents a better choice for the consumers.

Protozoa and oral health: a systematic review

Gingivitis and periodontitis (GP) are the main diseases of the oral cavity. The ethiology of GP have never been completely understood, however, loss of balance between the host immune system and the microbial virulence of GP pathogens may be considered the trigger of GP. In fact, the immune system, activated by microbiological agents, attacks the host and not the biofilm bacteria, causing the destruction of periodontal tissue, alveolar bone, and loss of teeth. Parasites may play an important role in the pathology of GP. The first studied and the most common parasite in the oral cavity is Entamoeba gingivalis. A possible link between E. gingivalis and GP has never been demonstrated completely, however E. gingivalis is infrequently found in people without GP. In addition, there is evidence that E. gingivalis could favour the onset and progression of GP. In conclusion, we can assert that E. gingivalis and GP may be correlated. This relationship can open new therapeutical approaches for treating GP, particularly in cases refractory to therapy.

Contamination of coins and banknotes as sources of transmission of parasitic pathogens: a pilot study from Iran

OBJECTIVE

This study was conducted to determine the presence, type, and rate of parasitic contamination in Iranian currencies.

STUDY DESIGN

This was a cross-sectional study.

METHODS

Coins and banknotes of different denominations were randomly collected from sellers and markets in Tabriz, Northwest of Iran, for examining parasitic contamination.

RESULTS

Entamoeba coli and Giardia intestinalis were the most identified species of parasites in this study. Other parasites detected were Cryptosporidium parvum, Ascaris lumbricoides, Entamoeba histolytica, Fasciola hepatica, and Toxocara cati. A high rate of parasitic contamination was found in banknotes compared with coins, and a statistically significant association was found between parasitic contamination and the apparent condition of the currencies. The notes of lower denominations showed the highest contamination rates. The highest parasitic contamination was found in coins and banknotes obtained from public toilet services, butchers, and beggars.

CONCLUSIONS

The findings emphasize the role of circulating coins and banknotes in the risk of pathogenic parasite transmission.

Presence of Trichomonas tenax and Entamoeba gingivalis in peri-implantitis lesions

OBJECTIVE

The aim was to investigate the presence of Entamoeba gingivalis and Trichomonas tenax in peri-implantitis lesions.

METHOD AND MATERIALS

A total of 141 individuals were included in this study, of which 40 had clinically healthy implants (group H); the remaining were associated with peri-implantitis (group P). Gingival crevicular fluid was collected using absorbent paper, followed by a dental plaque sample from the peri-implant sulcus/pocket using a titanium curette. The samples were transferred into an Eppendorf tube. Each specimen was divided into two parts. One part was examined under a light microscope at a 10 × and 40 × magnification to detect parasites. The other part was spread on a microscope slide, stained with Giemsa stain, and examined under a microscope at 100 × magnification. Pearson chi-square test was used in the statistical analysis of data, with a significance level of P < .05.

RESULTS

Although there was no presence of parasite around the healthy implants, two parasites were detected in peri-implantitis lesions. Out of 101 lesions, 31 (30.7%) showed E gingivalis, and 34 (33.6%) presented with T tenax. There was a statistically significant difference between the presence of E gingivalis and demographic data including gender, education status, frequency of dental visits, and brushing frequency. Presence of T tenax in lesions was correlated with frequency of dental visits (P < .05). It was observed that E gingivalis and T tenax were mostly detected in the mandible (P = .004 and .014, respectively) in comparison with the maxilla.

CONCLUSION

This study showed that peri-implantitis lesions were involved with E gingivalis and T tenax, in contrast to the healthy areas.

Assessment of the parasitological quality of water stored in private cisterns in rural areas of Tunisia

Limited access to safe water enhances poverty, hunger and diseases. This study evaluated the drinking water quality stored in home-based systems, located in rural areas of Tunisia. Water management was also documented as an improvement of good practice as most of the water contamination could be related to behavioral patterns. Thirty-nine water samples from five different sources (rainwater, truck cistern, mix, etc.) were screened for enteric parasitic contamination with the modified Bailenger technique. This technique allowed the detection of three protozoa: Giardia spp.; Entamoeba histolytica/dispar/moshkovskii; Entamoeba coli and one helminth specie: Ascaris spp. The overall prevalence of these intestinal parasites was approximately 97% with a relatively high frequency of protozoa over helminths and more specifically E. histolytica/dispar/moshkovskii. This incidence could be correlated to the lack of hygiene practices, sanitation and education. This situation requires the need for frequent monitoring of the water quality and management in these areas.

Entamoeba Encystation: New Targets to Prevent the Transmission of Amebiasis

Amebiasis is caused by Entamoeba histolytica infection and can produce a broad range of clinical signs, from asymptomatic cases to patients with obvious symptoms. The current epidemiological and clinical statuses of amebiasis make it a serious public health problem worldwide. The Entamoeba life cycle consists of the trophozoite, the causative agent for amebiasis, and the cyst, the form responsible for transmission. These two stages are connected by "encystation" and "excystation." Hence, developing novel strategies to control encystation and excystation will potentially lead to new measures to block the transmission of amebiasis by interrupting the life cycle of the causative agent. Here, we highlight studies investigating encystation using inhibitory chemicals and categorize them based on the molecules inhibited. We also present a perspective on new strategies to prevent the transmission of amebiasis.

Imaging and identification of waterborne parasites using a chip-scale microscope

We demonstrate a compact portable imaging system for the detection of waterborne parasites in resource-limited settings. The previously demonstrated sub-pixel sweeping microscopy (SPSM) technique is a lens-less imaging scheme that can achieve high-resolution (<1 µm) bright-field imaging over a large field-of-view (5.7 mm×4.3 mm). A chip-scale microscope system, based on the SPSM technique, can be used for automated and high-throughput imaging of protozoan parasite cysts for the effective diagnosis of waterborne enteric parasite infection. We successfully imaged and identified three major types of enteric parasite cysts, Giardia, Cryptosporidium, and Entamoeba, which can be found in fecal samples from infected patients. We believe that this compact imaging system can serve well as a diagnostic device in challenging environments, such as rural settings or emergency outbreaks.

Epidemiology of Blastocystis hominis and other intestinal parasites among the immigrant population in northeastern Taiwan by routine physical examination for residence approval

BACKGROUND AND PURPOSE

Blastocystis hominis has not been reported as an endemic disease in Taiwan, but high prevalence rates have been found among immigrants. Due to the increasing number of immigrants in Taiwan, B. hominis may become a public health problem in Taiwan. This study was performed to determine the prevalence of B. hominis among immigrant populations.

METHODS

Stool examination data from the Immigrant Physical Examination for Residence Approval in 2006 were examined.

RESULTS

Among the 932 immigrants from 4 countries, 188 individuals (20.2%) were infected with B. hominis. The prevalence was higher among immigrants from Southeast Asian countries (Indonesia, 26.4%; Vietnam, 20.6%; The Philippines, 19.3%) than among those from China (7.6%). Coinfection with intestinal parasites of fecal-oral transmission (Endolimax nana and Entamoeba hartmannii) was a risk factor for B. hominis infection (odds ratio, 16.9; 95% confidence interval, 6.84-43.55). No significant differences in prevalence for sex and age were observed.

CONCLUSION

To prevent local transmission and endemic spread of B. hominis, obligatory routine health screening for immigrant populations and early eradication of the infection are important policies for this high-risk group.

The occurrence in Pakistan of a human Entamoeba of the polecki type

1. The occurrence of cysts of the polecki type in an apparently healthy person in Pakistan is recorded.

2. The possible relationship of the polecki type cysts and the minuta form of E. histolytica is discussed.

An experimental study ofEntamoeba muris(Grassi, 1879); its morphology, affinities and host-parasite relationship

1. A description of the morphology and life history (excluding metacystic development) ofEntamoeba murisis given.

2. The descriptions of species of amoebae found in rats (Rattus norvegicus and R. rattus) and mice (Mus musculus) by previous authors are critically discussed, and it is concluded that one species,Entamoeba muris, is present.

3 Experiments on cross-infection of rats and mice withE. murisare described, together with observations on the course of these infections.

4. The transference of an amoeba morphologically similar toE. murisfromCricetus auratusto rats and mice is described.

5. An account is given of unsuccessful attempts to establish an infection ofEntamoeba coliin rats and mice.

6. Observations on the incidence and hostrestriction ofE. murisare discussed.

7. The affinities ofE. coliandE. murisare discussed and it is concluded that, although E. muris resemblesE. colimorphologically, it differs fromE. colion physiological grounds.

Nuclear division in Entamoeba invadens Rodhain, 1934

1. Examination of dividing trophozoites of E. invadens revealed that the peripheral granules did not contribute directly to the formation of chromosomes. Material for the chromosomes seemed to be derived from the karyosome and the perikaryosomal particles. No centrioles and spindle mechanism were noticed.

2. The nucleus showed Feulgen-positive material at all stages; in the interphase the reaction was faint because of the poor staining of the karyosome and widely dispersed perikaryosomal particles. The intensity of the staining reaction increased with the onset of division and continued so till late anaphase.

3. Nuclear division in the cyst was found to be different from that of the trophozoites and involved the formation of a typical spindle.

4. Karyosomes of the nuclei of the uni-, bi-, tetra-nucleate cysts were all positive to Feulgen staining.

5. Observations on amoebae undergoing cytokinesis showed that the process of division supports the amoeboid movement theory of cleavage put forward by Chalkley (1935, 1951).

Thanks are due to Dr P. Tate for constant guidance and encouragement during the course of this work and to Dr E. W. McConnachie for kindly giving the cultures and for critically reading through the manuscript. The work was carried out during the tenure of a Royal Society and Nuffield Foundation Commonwealth Bursary.

Factors affecting the growth and behaviour of axenic strains ofEntamoeba invadensRodhain, 1934

1. Axenic strains ofEntamoeba invadenscan be maintained indefinitely, by serial culture, in saline containing a slice of liver. Growth in this medium is poor, the amoebae are vacuolated, and few cysts are formed.

2. The optimum concentration of NaCl for amoebic growth in this medium is 0·75–1·0%, and the optimum pH is 5·7–6·1.

3. The source of the liver tissue in the medium is unimportant, but, of several tissues tested, liver was the only one which supported amoebic growth in serial culture.

4. Suspensions of minced liver also supported amoebic growth, but the growth-promoting activity of the liver was removed completely by centrifugation, autoclaving, and Seitz- or glass-filtration. Heat treatment at 50–60° C. and prolonged storage at 8° C. partially inactivated the liver.

5. Growth in axenic saline-liver medium does not affect the ability ofE. invadensto grow and undergo mass encystation when reassociated with suitable bacteria.

Experimental production of pure mixed strains of Entamoeba histolytica

1. Dobell's observations on the production of pure mixed strains of Entamoeba histolytica have been repeated and confirmed.

2. It has been demonstrated that the method devised by Rao did not sterilize the cysts of E. histolytica but merely killed all non-sporing organisms, while the spores of all spore-forming bacteria were unaffected.

The food habits of Entamoeba histolytica in its commensal phase

1. After a general consideration of the host-parasite relations between E. histolytica and man, a case is made for the recognition of a commensal phase in the life history of this amoeba.

2. This view is supported by observations on the food habits of E. histolytica in chronic cases and carriers of human amoebiasis.

3. From these observations it is evident that from 30 to 100% of trophic amoebae in such cases have ingested bacteria derived from the contents of the large bowel.

Enteric protozoal diseases

The most common protozoal agents infecting the gastrointestinal tract of cats are Giardia spp, Cryptosporidium spp, Cystoisospora spp, Sarcocystis spp, Besnoitia spp, Hammondia spp, Toxoplasma gondii, Entamoeba histolytica, and Tritrichomonas fetus.

Bacterial factors influencing the life history of Entamoeba histolytica in cultures

1. It has previously been shown [by Dobell] that, in cultures of strain K 28c, Entamoeba histolytica could be maintained indefinitely and made to pass through all the stages of its life history.

2. It was also demonstrated that all non-encysting strains of E. histolytica could be induced to encyst in vitro by substituting their concomitant bacterial flora by that of strain K 28c.

3. In order to ascertain what part each constituent of the bacterial flora of K 28c played in the life of E. histolytica, a detailed analysis of this flora was carried out. It was found to comprise eight aerobic organisms (mostly of the B. coli group) and six anaerobes.

4. The properties of individual species and varieties of bacteria were studied by adding them to cultures of the amoebae or by hatching the cysts of E. histolytica in media previously seeded with the bacteria to be tested.

5. With the same end in view two methods were devised for producing simplified strains of E. histolytica associated with from one to four species of bacteria only. By treating the cysts with acriflavine, the mixed flora could be freed of the aerobic organisms, leaving only the spores of the anaerobes. The spore-bearing anaerobes, in their turn, could be eliminated by treatment of the mixture with gentian violet. By using these methods it was possible to produce cultures of ‘synthetic’ strains of E. histolytica accompanied by any desired combination of bacteria, whose properties it was desired to investigate.

6. The results of the earlier experiments suggested that the essential constituent of the flora of K 28c was B. coli, all varieties of which appeared to promote growth, induce encystation and excystation, and generally favoured the completion of the life-cycle of the amoebae in vitro, whereas the anaerobic bacteria present in the strain appeared to be inactive as regards encystation.

7. However, later experiments have demonstrated conclusively that, although the aerobic bacteria individually induced the cysts of E. histolytica to hatch and supported the growth of the amoebae indefinitely, only one species—the anaerobe N5—was capable of promoting encystation. As regards the aerobic bacteria, their chief role is to provide the anaerobic conditions necessary for the growth of the amoebae with N5 in culture.

in an area of high endemicity

Entamoeba histolytica has been separated in recent years into 2 morphologically identical species: the apathogenic E. dispar and the pathogenic E. histolytica, only the latter being pathogenic. Although various laboratory techniques allow discrimination between the 2 species there is a lack of field data about the suitability of available diagnostic tests for use in epidemiological studies and few epidemiological studies using species-specific diagnosis have been performed at community level in endemic areas, especially in sub-Saharan Africa. We conducted a repeated cross-sectional study of 967 schoolchildren in central Côte d'Ivoire to compare and evaluate light microscopy, 2 different antigen detection assays, and one polymerase chain reaction (PCR) assay. Microscopy and a non-specific antigen capture Entamoeba enzyme-linked immunosorbent assay (ELISA) were used for the primary screening of all children (time t0). The prevalence of the E. histolytica/E. dispar species complex at t0 was 18.8% by single microscopical examination and 31.4% using the non-specific ELISA. Approximately 2 months after the initial screening, fresh stool specimens were collected on 2 consecutive days (t1 and t2) from (i) all the children who were positive by microscopy at t0 (n = 182) and (ii) 155 randomly selected children who were negative at the primary screening. These samples were tested with a second antigen detection ELISA specific for E. histolytica (n = 238) and with a species-specific PCR assay (n = 193). The second and third examinations (t1 and t2) revealed an additional 43 infections with the species complex E. histolytica/E. dispar, so that the cumulative microscopical prevalence for t1 and t2 was 27.7%. The overall prevalence of E. histolytica by species-specific ELISA antigen detection was low (0.83%), while the prevalence of E. dispar was 15%. When analysing only microscopically positive samples by PCR (n = 129), the ratio E. histolytica: E. dispar was very low (1:46), suggesting that the vast majority of Entamoeba infections in this area were apathogenic. Both species-specific tests performed well but the ELISA was easier to use for large-scale field screening.

Entamoeba gingivalis identified in a left upper neck nodule by fine-needle aspiration: a case report

We present a unique case of a 37-yr-old patient who underwent a left partial glossectomy, modified neck dissection, and radiation therapy in December 1990. In June 1991 the patient developed a 0.6 cm erythematous nodule in the left upper portion of her neck adjacent to the surgical scar. A fine-needle aspiration (FNA) of the nodule was performed. Cytologic examination revealed the presence of numerous organisms morphologically consistent with Entamoeba gingivalis. Although E. gingivalis can be found in specimens from the oral cavity, especially following radiation, it is rare to find these organisms within lesions of the head and neck region. In this case, it is believed that the patient had an increased number of organisms within her oral cavity secondary to radiation therapy. Radiation therapy also may have contributed to the formation of a fistula tract between the oral cavity and the surgical incision site which resulted in the formation of a small inflammatory nodule in the upper portion of the neck. The organisms could then travel from the oral cavity to the nodule in the neck thus explaining their presence in the FNA material.

LOCALIZATION OF CYTOPLASMIC NUCLEIC ACID DURING GROWTH AND ENCYSTMENT OF ENTAMOEBA INVADENS

With a modified color-translating ultraviolet microscope, the distribution of material showing an absorption maximum at 265 mµ was studied in samples from whole cultures of Entamoeba invadens at intervals during growth and from cysts allowed to mature under controlled conditions. Absorption by the cytoplasm in general gradually increased as trophozoites approached the period of maximum encystment. In late trophozoites and precystic forms, the absorbing material was concentrated into small bodies which coalesced to form large crystalloids of very high specific absorption. Maximum crystallization occurred in early cysts, where cytochemical tests have shown the large crystalloids to be ribonucleoprotein. Electron micrographs show that the crystalloids are composed of particles 200 to 300 A in diameter. During cyst maturation the amount of absorbing material per cyst is not visibly reduced, but the large bodies fragment into smaller units until finally there is only a very high diffuse absorption over the entire cyst. From these and other results the hypothesis is advanced that the large crystalloids ("chromatoid bodies") are a manifestation of a special parasite-host adaptive mechanism; ribonucleoprotein is synthesized under favorable conditions, crystallized in the resistant cyst stage, and dispersed in the newly excysted amebae thereby enabling them to establish themselves in a new host by a period of quick growth.

Entamoeba gingivalis in sputum smears

Entamoeba gingivalis is a common parasite of the human buccal cavity whose rare appearance in Papanicolaou-stained sputum smears may be missed. Two such cases are described, including the morphologic features of this ameba. The trophozoites were seen to phagocytize leukocytes as well as red blood cells, in distinction to E. histiolytica, which phagocytizes only red blood cells and also can cause pulmonary abscesses. The concomitant finding of Actinomyces sp. organisms in one patient reinforces the possible symbiotic relationship between the two organisms, as has been suggested for their appearance in other extraoral sites, such as the female genital tract.

Use of a monoclonal antibody in an enzyme immunoassay for the detection of Entamoeba histolytica in fecal specimens

An indirect enzyme-linked immunosorbent assay (ELISA) was developed for the detection of Entamoeba histolytica in human feces, using both a monoclonal antibody and rabbit antisera. It detected from less than 1 to 57 trophozoites of 6 E. histolytica strains. Stool specimens were positive by ELISA in 18 of 22 (82%) patients with E. histolytica and in 3 of 186 (2%) of patients without demonstrable E. histolytica in their stools. The latter included one from a child living near an asymptomatic cyst carrier and another from a traveler with giardiasis who had recently taken antibiotics. One hundred eight of 183 microscopy-and ELISA-negative specimens contained other parasites including Giardia (49 specimens), Endolimax nana (24), Entamoeba coli (21), Iodamoeba butschlii (2), and Entamoeba hartmanni (1). This ELISA for E. histolytica is a simple, sensitive and specific diagnostic tool.

A survey of gastrointestinal parasites in a local government area of south-west Nigeria

In the course of a survey of gastro-intestinal parasites among humans in Iwo Local Government area in South-Western Nigeria, eggs of helminths found were those of Ascaris lumbricoides, Necator americanus, Trichuria trichiura and Strongyloides stercoralis while protozoan cysts encountered were those of Entamoeba histolytica and Entamoeba coli. About 51% of the 283 faecal samples were positive for parasitic ova or cysts and 24% possessed mixed infection. Incidence of Ascaris was highest followed by Trichuris and Necator. Peak of Ascaris infection was among the 1-10 years age group while that of hookworm and Trichuris was in the 11-20 years age-group. Sixteen (16) combination of mixed infections were found of which that of hookworm and Trichuris was the commonest. Incidence of polyparasitism increases with age until it reached a peak in the 21-40 years age-group.

The Mongolian gerbil (Meriones unguiculatus) as an experimental host for Entamoeba histolytica

Experimentally induced cecal and hepatic amebiasis was studied in the Mongolian gerbil (Meriones unguiculatus). Axenically cultivated Entamoeba histolytica trophozoites were inoculated into the cecum or the liver after laparotomy. Cecal infections were characterized by intense inflammation and distortion of the tissue. The intensity of the infection, measured by a standard method of scoring, was consistently high from 10 to 30 days postinoculation (p.i.). In tissue sections, disruption of the interglandular epithelium and presence of amebic ulcers and of large numbers of trophozoites were most noticeable 10 days p.i. In older infections there was cecal hypertrophy and crypt hyperplasia but only few amebae were seen. Amebic liver abscesses were well tolerated by gerbils and no mortality occurred. Growth of liver abscesses increased exponentially as the duration of the infection progressed from 5 to 30 days p.i. Liver abscesses were always confined to the inoculated liver lobe, and metastases did not occur. Early liver granulomas were discrete with well-defined walls. The abscesses had a fibrous wall and amebae were seen at their inner aspect. Older liver granulomas were coalesced, forming a single cavitary abscess with intense cellular infiltrate. Gerbils of all ages tested were equally susceptible to liver infections although larger abscesses were obtained in younger adult animals (60-80 days old). The Mongolian gerbil is proposed as a suitable animal model for experimental amebiasis because both the intestinal and hepatic aspects of the disease can be studied in it.

Successful treatment of symptomatic Entamoeba polecki infection

The second symptomatic case of Entamoeba polecki infection, the first to respond to therapy, is reported. The patient experienced intermittent episodes of abdominal cramps, diarrhea, nausea, and malaise associated with large numbers of E. polecki cysts in the stool. Following treatment with diloxanide furoate and metronidazole, all symptoms cleared and the parasite was no longer present in the stool.