Entamoeba Histolytica: Updates in Clinical Manifestation, Pathogenesis, and Vaccine Development

Molecular regulation of NLRP3 inflammasome activation during parasitic infection

Parasitic diseases are a serious global health concern, causing many common and severe infections, including Chagas disease, leishmaniasis, and schistosomiasis. The NLRP3 inflammasome belongs to the NLR (nucleotide-binding domain leucine-rich-repeat-containing proteins) family, which are cytosolic proteins playing key roles in the detection of pathogens. NLRP3 inflammasomes are activated in immune responses to Plasmodium, Leishmania, Toxoplasma gondii, Entamoeba histolytica, Trypanosoma cruzi, and other parasites. The role of NLRP3 is not fully understood, but it is a crucial component of the innate immune response to parasitic infections and its functions as a sensor triggering the inflammatory response to the invasive parasites. However, while this response can limit the parasites' growth, it can also result in potentially catastrophic host pathology. This makes it essential to understand how NLRP3 interacts with parasites to initiate the inflammatory response. Plasmodium hemozoin, Leishmania glycoconjugate lipophosphoglycan (LPG) and E. histolytica Gal/GalNAc lectin can stimulate NLRP3 activation, while the dense granule protein 9 (GRA9) of T. gondii has been shown to suppress it. Several other parasitic products also have diverse effects on NLRP3 activation. Understanding the mechanism of NLRP3 interaction with these products will help to develop advanced therapeutic approaches to treat parasitic diseases. This review summarizes current knowledge of the NLRP3 inflammasome's action on the immune response to parasitic infections and aims to determine the mechanisms through which parasitic molecules either activate or inhibit its action.

Effect of Stevioside (Stevia rebaudiana) on Entamoeba histolytica Trophozoites

Human amoebiasis still represents a major health problem worldwide. Metronidazole has been used as the most common drug to treat the disease; however, it is also known that the drug causes undesirable side effects. This has led to the search for new pharmacological alternatives which include phytochemical compounds with antiamoebic effects. We analyzed the amoebicidal activity of stevioside (STV), a diterpene glycoside present in Stevia rebaudiana, on trophozoites of E. histolytica. Different concentrations of STV were tested, and an inhibitory concentration of 50% of cell viability (IC50) was determined with an exposition of 9.53 mM for 24 h. Trophozoites exposed to STV showed morphological changes evidenced by the decrease in the basic structures related to the movement and adherence to the substrate, as well as ultrastructural features characterized by a loss of regularity on the cell membrane, an increase in cytoplasmic granularity, and an increase in apparent autophagic vacuoles. Also, the decrease in cysteine protease expression and the proteolytic activity of trophozoites to degrade the cell monolayer were analyzed. A histological analysis of hamster livers inoculated with trophozoites and treated with STV showed changes related to the granulomatous reaction of the liver parenchymal tissue. Our results constitute the first report related to the possible use of STV as a therapeutic alternative in amoebiasis.

Unusual pediatric lung infections: imaging findings

Pediatric lung infections continue to be a leading cause of pediatric morbidity and mortality. Although both pediatric and general radiologists are familiar with typical lung infections and their imaging findings in children, relatively rare lung infections continue to present a diagnostic challenge. In addition, the advances in radiological imaging and emergence of several new lung infections in recent years facilitated the need for up-to-date knowledge on this topic. In this review article, we discuss the imaging findings of pediatric lung infections caused by unusual/uncommon and new pathogens. We review the epidemiological, clinical, and radiological imaging findings of viral (coronavirus disease 2019, Middle East respiratory syndrome, bird flu), bacterial (Streptococcus anginosus, Francisella tularensis, Chlamydia psittaci), and parasitic lung infections (echinococcosis, paragonimiasis, amoebiasis). Additional disorders whose clinical course and imaging findings may mimic lung infections in children (hypersensitivity pneumonitis, pulmonary hemorrhage, eosinophilic pneumonia) are also presented, to aid in differential diagnosis. As the clinical presentation of children with new and unusual lung infections is often non-specific, imaging evaluation plays an important role in initial detection, follow-up for disease progression, and assessment of potential complications.

Beyond schistosomiasis: unraveling co-infections and altered immunity

Schistosomiasis is a neglected tropical disease caused by the helminth Schistosoma spp. and has the second highest global impact of all parasites. Schistosoma are transmitted through contact with contaminated fresh water predominantly in Africa, Asia, the Middle East, and South America. Due to the widespread prevalence of Schistosoma, co-infection with other infectious agents is common but often poorly described. Herein, we review recent literature describing the impact of Schistosoma co-infection between species and Schistosoma co-infection with blood-borne protozoa, soil-transmitted helminths, various intestinal protozoa, Mycobacterium, Salmonella, various urinary tract infection-causing agents, and viral pathogens. In each case, disease severity and, of particular interest, the immune landscape, are altered as a consequence of co-infection. Understanding the impact of schistosomiasis co-infections will be important when considering treatment strategies and vaccine development moving forward.

Amoebic Liver Abscess: Potential Application of New Diagnostic Techniques for an Old Pathogen

Amoebic liver abscess is a severe and potentially life-threatening infection requiring prompt diagnosis and early targeted treatment. Diagnosis is challenging because conventional diagnostic methods such as light microscopy and serology are often unreliable. Molecular techniques have emerged as an additional diagnostic tool, suddenly becoming the new diagnostic reference standard. More recently, commercial multiplex PCR panels, including FilmArray, have been introduced, which permit the simultaneous detection of several enteric pathogens including Entamoeba histolytica in stool samples. We report a case of an amoebic liver abscess promptly diagnosed by FilmArray gastrointestinal panel performed on liver drainage fluid.

A Case of Entamoeba histolytica Liver Abscess in an Immigrant Patient

Entamoeba histolytica is a pathogenic protozoan endemic to Asia, Africa, and Central and South America. However, with increased travel and emigration, it is becoming a common parasitic infection leading to many worldwide deaths. We present a case of a young Hispanic male immigrant with an amebic liver abscess. This case report highlights the complexities of diagnosing and treating E. histolytica infection.

Combatting infectious diarrhea: innovations in treatment and vaccination strategies

INTRODUCTION

The escalating prevalence of infectious diseases is an important cause of concern in society. Particularly in several developing countries, infectious diarrhea poses a major problem, with a high fatality rate, especially among young children. The condition is divided into four classes, namely, acute diarrhea, invasive diarrhea, acute bloody diarrhea, and chronic diarrhea. Various pathogenic agents, such as bacteria, viruses, protozoans, and helminths, contribute to the onset of this condition.

AREAS COVERED

The review discusses the scenario of infectious diarrhea, the prevalent types, as well as approaches to management including preventive, therapeutic, and vaccination strategies. The vaccination techniques are extensively discussed including the available vaccines, their advantages as well as limitations.

EXPERT OPINION

There are several approaches available to develop new-improved vaccines. In addition, route of immunization is important and aerosols/nasal sprays, oral route, skin patches, powders, and liquid jets to minimize needles can be used. Plant-based vaccines, such as rice, might save packing and refrigeration costs by being long-lasting, non-refrigerable, and immunogenic. Future research should utilize predetermined PCR testing intervals and symptom monitoring to identify persistent pathogens after therapy and symptom remission.

Differential diagnosis of human Entamoeba infections: Morphological and molecular characterization of new isolates in Argentina

Entamoeba infections occur worldwide, with higher frequency in countries of low socioeconomic status and poor public health. Since Entamoeba histolytica has long been recognized as the only pathogenic species, making a differential diagnosis of other morphologically identical Entamoeba is important. This study aimed to determine the prevalence of Entamoeba species in two populations from Argentina, make a differential diagnosis by PCR and characterize Entamoeba isolates at the SSU rRNA gene. A total of 493 serial fecal samples were obtained from individuals in the provinces of Buenos Aires (n=210) and Misiones (n=283). Samples were examined by conventional methods (formalin-ethyl acetate and Willis flotation) and specific PCRs to differentiate Entamoeba species. Entamoeba isolates were characterized by sequencing a fragment of the SSU rRNA gene. The overall prevalence of Entamoeba infection was 12.4%, being more prevalent in Buenos Aires than in Misiones (14.8% vs. 10.6%). A case of E. histolytica confirmed by PCR and sequence analysis was reported for the first time in Buenos Aires. Moreover, new genetic data on Entamoeba coli and Entamoeba dispar were recorded. The phylogenetic analysis revealed a congruence between morphological characteristics and SSU rRNA gene sequences. This study increases the amount of information on the distribution of these species in Argentina and the region of the Americas.

Mediastinal extension of amoebic liver abscess: A case report on the rare thoracic complication of Entamoeba histolytica

Amoebic liver abscess is one frequently encountered intra-abdominal infection, caused by Entamoeba histolytica and has various abdominal and thoracic life-threatening complications. Herein, describe a case of a 30-year-old female, who suffered from multiple amoebic liver abscesses and presented with massive right-sided pleural effusion. She was managed with recommended antibiotics and pigtail catheter for liver abscess and an intercostal drainage tube for massive pleural effusion. However, postintercostal drainage, her chest X-ray demonstrated a right mediastinal shadow, which was confirmed as an intrathoracic extension of the hepatic liver abscess on computed tomography. An ultrasound-guided pigtail catheter was manipulated and placed at the site of thoracic communication. This led to clinical and radiological improvement, but unfortunately, she developed ventilator-acquired pneumonia and died due to her illness. The case represents an uncommon complication of amoebic liver abscess, which is rarely described and adds more knowledge on the thoracic complexities of this infectious disease.

Fulminant Amebic Enteritis in the Perinatal Period

Pregnancy is a known risk factor for amebic enteritis, which develops into potentially fatal fulminant amebic enteritis in some cases. We describe a case of a 27-year-old non-immunosuppressed pregnant woman with fulminant amebic enteritis complicated with cytomegalovirus enteritis. She improved with intensive care and intravenous metronidazole and ganciclovir but eventually required subtotal colectomy for intestinal stenosis. It is difficult to diagnose amebic enteritis, especially in a non-endemic area. Amebic enteritis must be considered as a differential diagnosis for refractory diarrhea with bloody stools in women in the perinatal period, even those without immunosuppression.

Frequency of Entamoeba Complex in Individuals Referred to the Medical Laboratories in Jahrom City, South of Iran

This study aimed to determine the prevalence of Entamoeba histolytica, Entamoeba dispar, and Entamoeba moshkovskii, using microscopic and molecular methods in Jahrom city (Fars Province), south of Iran. Stool samples were collected from 360 outpatients referred to the medical laboratories in Jahrom city. Standard parasitological methods, including direct wet mount examination, formalin-ether sedimentation technique, and trichrome staining techniques, were used for detection of Entamoeba complex. Nested polymerase chain reaction (PCR) was used to identify the genus/species of Entamoeba. Entamoeba complex cysts were detected in 2.5% (9/360) of samples by microscopic methods, while 11 isolates were considered positive for the Entamoeba complex by nested PCR. Among them, 2 (18.18%) out of 11 samples were E. histolytica, 5 (45.45%) were E. dispar, and 4 (36.36%) were E. moshkovskii. Molecular positivity was more prevalent among females (4.16%), people living in rural areas (3.44%), and people over 60 years old (13.33%). Considering the clinical manifestations, the Entamoeba complex infection in patients with fever (7.69%), severe diarrhea (5.10%), and nausea (5%) was high. This study reported the presence of E. histolytica, E. dispar, and E. moshkovskii in Jahrom city. Therefore, we suggest more public health interventions in Jahrom city.

Unusual metal ion cofactor requirement of Entamoeba histolytica choline and ethanolamine kinase isoforms

The de novo biosynthesis of phosphatidylcholine and phosphatidylethanolamine in Entamoeba histolytica is largely dependent on the CDP-choline and CDP-ethanolamine pathways. Although the first enzymes of these pathways, EhCK1 and EhCK2, have been previously characterized, their enzymatic activity was found to be low and undetectable, respectively. This study aimed to identify the unusual characteristics of these enzymes in this deadly parasite. The discovery that EhCKs prefer Mn²⁺ over the typical Mg²⁺ as a metal ion cofactor is intriguing for CK/EK family of enzymes. In the presence of Mn²⁺, the activity of EhCK1 increased by approximately 108-fold compared to that in Mg²⁺. Specifically, in Mg²⁺, EhCK1 exhibited a V_max and K_0.5 of 3.5 ± 0.1 U/mg and 13.9 ± 0.2 mM, respectively. However, in Mn²⁺, it displayed a V_max of 149.1 ± 2.5 U/mg and a K_0.5 of 9.5 ± 0.1 mM. Moreover, when Mg²⁺ was present at a constant concentration of 12 mM, the K_0.5 value for Mn²⁺ was ~ 2.4-fold lower than that in Mn²⁺ alone, without affecting its V_max. Although the enzyme efficiency of EhCK1 was significantly improved by about 25-fold in Mn²⁺, it is worth noting that its K_m for choline and ATP were higher than in equimolar of Mg²⁺ in a previous study. In contrast, EhCK2 showed specific activity towards ethanolamine in Mn²⁺, exhibiting Michaelis-Menten kinetic with ethanolamine (K_m = 312 ± 27 µM) and cooperativity with ATP (K_0.5 = 2.1 ± 0.2 mM). Additionally, we investigated the effect of metal ions on the substrate recognition of human choline and ethanolamine kinase isoforms. Human choline kinase α2 was found to absolutely require Mg²⁺, while choline kinase β differentially recognized choline and ethanolamine in Mg²⁺ and Mn²⁺, respectively. Finally, mutagenesis studies revealed that EhCK1 Tyr129 was critical for Mn²⁺ binding, while Lys233 was essential for substrate catalysis but not metal ion binding. Overall, these findings provide insight into the unique characteristics of the EhCKs and highlight the potential for new approaches to treating amoebiasis. Amoebiasis is a challenging disease for clinicians to diagnose and treat, as many patients are asymptomatic. However, by studying the enzymes involved in the CDP-choline and CDP-ethanolamine pathways, which are crucial for de novo biosynthesis of phosphatidylcholine and phosphatidylethanolamine in Entamoeba histolytica, there is great potential to discover new therapeutic approaches to combat this disease.

Diversity and Plasticity of Virulent Characteristics of Entamoeba histolytica

The complexity of clinical syndromes of amebiasis, caused by the parasite Entamoeba histolytica, stems from the intricate interplay between the host immune system, the virulence of the invading parasite, and the surrounding environment. Although there is still a relative paucity of information about the precise relationship between virulence factors and the pathogenesis of Entamoeba histolytica, by accumulating data from clinical and basic research, researchers have identified essential pathogenic factors that play a critical role in the pathogenesis of amebiasis, providing important insights into disease development through animal models. Moreover, the parasite's genetic variability has been associated with differences in virulence and disease outcomes, making it important to fully understand the epidemiology and pathogenesis of amebiasis. Deciphering the true mechanism of disease progression in humans caused by this parasite is made more difficult through its ability to demonstrate both genomic and pathological plasticity. The objective of this article is to underscore the heterogeneous nature of disease states and the malleable virulence characteristics in experimental models, while also identifying persistent scientific issues that need to be addressed.

Advances in Protozoan Epigenetic Targets and Their Inhibitors for the Development of New Potential Drugs

Protozoan parasite diseases cause significant mortality and morbidity worldwide. Factors such as climate change, extreme poverty, migration, and a lack of life opportunities lead to the propagation of diseases classified as tropical or non-endemic. Although there are several drugs to combat parasitic diseases, strains resistant to routinely used drugs have been reported. In addition, many first-line drugs have adverse effects ranging from mild to severe, including potential carcinogenic effects. Therefore, new lead compounds are needed to combat these parasites. Although little has been studied regarding the epigenetic mechanisms in lower eukaryotes, it is believed that epigenetics plays an essential role in vital aspects of the organism, from controlling the life cycle to the expression of genes involved in pathogenicity. Therefore, using epigenetic targets to combat these parasites is foreseen as an area with great potential for development. This review summarizes the main known epigenetic mechanisms and their potential as therapeutics for a group of medically important protozoal parasites. Different epigenetic mechanisms are discussed, highlighting those that can be used for drug repositioning, such as histone post-translational modifications (HPTMs). Exclusive parasite targets are also emphasized, including the base J and DNA 6 mA. These two categories have the greatest potential for developing drugs to treat or eradicate these diseases.

Pathologie infectieuse du tube digestif : diagnostics à ne pas manquer

Le contexte récent du COVID-19 a renouvelé l’intérêt des pathologistes pour les maladies d’origine infectieuse. Cet intérêt est d’autant plus fort dans le tube digestif où les symptômes sont aspécifiques, souvent frustres avec un aspect endoscopique normal entraînant parfois une errance diagnostique. Dans ce contexte, les biopsies systématiques réalisées par le clinicien sont parfois le seul moyen de parvenir au diagnostic. Néanmoins, le diagnostic précis de ses pathologies nécessite une bonne connaissance à la fois du contexte de survenue de ces pathologies, de l’aspect histopathologique et d’une analyse rigoureuse utilisant des colorations spéciales et/ou des analyses immunohistochimiques. Certaines pathologies infectieuses du tube digestif sont bien connues par les pathologistes qui sont largement sollicités dans leurs diagnostics (gastrite à Helicobacter pylori, œsophagite à Candida albicans ou la colite à CMV), mais d’autres sont plus délicates à diagnostiquer. Dans cet article, nous présenterons, après avoir rappelé les différentes colorations spéciales utiles, des pathologies bactériennes ou parasitaires rares ou de diagnostic difficile « à ne pas manquer » dans le tube digestif.

Lysine Methyltransferase EhPKMT2 Is Involved in the In Vitro Virulence of Entamoeba histolytica

Lysine methylation, a posttranslational modification catalyzed by protein lysine methyltransferases (PKMTs), is involved in epigenetics and several signaling pathways, including cell growth, cell migration and stress response, which in turn may participate in virulence of protozoa parasites. Entamoeba histolytica, the etiologic agent of human amebiasis, has four PKMTs (EhPKMT1 to EhPKMT4), but their role in parasite biology is unknown. Here, to obtain insight into the role of EhPKMT2, we analyzed its expression level and localization in trophozoites subjected to heat shock and during phagocytosis, two events that are related to amoeba virulence. Moreover, the effect of EhPKMT2 knockdown on those activities and on cell growth, migration and cytopathic effect was investigated. The results indicate that this enzyme participates in all these cellular events, suggesting that it could be a potential target for development of novel therapeutic strategies against amebiasis.

The prevalence of intestinal parasites, undernutrition and their associated risk factors among school-age children in Sekota Town, Northeast Ethiopia: A community-based cross-sectional study

Background and Aims

In developing countries, intestinal parasitic infections and malnutrition are among the most serious health issues affecting school-aged children. They have synergetic consequences. This study aimed to determine the prevalence of intestinal parasites, undernutrition, and their associated risk factors among school-age children.

Methods

A community-based cross-sectional study was conducted from April to June 2021 among school-age children in Sekota Town, Northeast Ethiopia. Households were selected using a systematic random sampling technique. Risk factor variables were collected using pretested questionnaires. Stool samples were collected from study participants and examined using a wet mount, formol-ether concentration, and modified acid-fast techniques. The height and weight of children were also measured using a meter and a standard calibrated balance, respectively. Data were analyzed using SPSS version 26.0 statistical software.

Results

The overall prevalence of intestinal parasites among school-age children was 44.3% (178/402). About seven species of intestinal parasites were identified. The predominant parasite identified was E. histolytica/dispar (11.2%), followed by H. nana (9.2%) and G. lamblia (6.7%). The well as a source of drinking water (adjusted odds ratio [AOR] = 7.93; 95% confidence interval [CI]: 4.38-14.36), habit of open-field defecation (AOR = 7.02; 95% CI: 13.05-12.06), and being undernourished (AOR = 5.67; 95% CI: 2.98-10.79) were independent predictors of intestinal parasitic infections. On the other hand, the overall prevalence of undernutrition was 46.3%. Undernutrition was significantly more likely in children with a dietary diversity score (DDS) of 3 (AOR = 3.73, 95% CI: 2.37-5.88), meal frequency of no more than three times per day (AOR = 2.00, 95% CI: 1.71-2.98), intestinal parasite infection (AOR = 5.25, 95% CI: 3.24-8.52), and no access to school-based feeding (AOR = 3.52, 95% CI: 2.17-7.96).

Conclusion

The prevalence of intestinal parasitic infections and undernutrition was high among school-age children in Sekota Town. The results imply the need for strengthening integrated strategies for the reduction of intestinal parasitic infections and undernutrition.

Using Entamoeba muris To Model Fecal-Oral Transmission of Entamoeba in Mice

There are several Entamoeba species that colonize humans, but only Entamoeba histolytica causes severe disease. E. histolytica is transmitted through the fecal-oral route to colonize the intestinal tract of 50 million people worldwide. The current mouse model to study E. histolytica intestinal infection directly delivers the parasite into the surgically exposed cecum, which circumvents the natural route of infection. To develop a fecal-oral mouse model, we screened our vivarium for a natural murine Entamoeba colonizer via a pan-Entamoeba PCR targeting the 18S ribosomal gene. We determined that C57BL/6 mice were chronically colonized by Entamoeba muris. This amoeba is closely related to E. histolytica, as determined by 18S sequencing and cross-reactivity with an E. histolytica-specific antibody. In contrast, outbred Swiss Webster (SW) mice were not chronically colonized by E. muris. We orally challenged SW mice with 1 × 105 E. muris cysts and discovered they were susceptible to infection, with peak cyst shedding occurring between 5 and 7 days postinfection. Most infected SW mice did not lose weight significantly but trended toward decreased weight gain throughout the experiment compared to mock-infected controls. Infected mice treated with paromomycin, an antibiotic used against noninvasive intestinal disease, do not become colonized by E. muris. Within the intestinal tract, E. muris localizes exclusively to the cecum and colon. Purified E. muris cysts treated with bovine bile in vitro excyst into mobile, pretrophozoite stages. Overall, this work describes a novel fecal-oral mouse model for the important global pathogen E. histolytica. IMPORTANCE Infection with parasites from the Entamoeba genus are significantly underreported causes of diarrheal disease that disproportionally impact tropical regions. There are several species of Entamoeba that infect humans to cause a range of symptoms from asymptomatic colonization of the intestinal tract to invasive disease with dissemination. All Entamoeba species are spread via the fecal-oral route in contaminated food and water. Studying the life cycle of Entamoeba, from host colonization to infectious fecal cyst production, can provide targets for vaccine and drug development. Because there is not an oral challenge rodent model, we screened for a mouse Entamoeba species and identified Entamoeba muris as a natural colonizer. We determine the peak of infection after an oral challenge, the efficacy of paromomycin treatment, the intestinal tract localization, and the cues that trigger excystation. This oral infection mouse model will be valuable for the development of novel therapeutic options for Entamoeba infections.

Gastrointestinal parasites in Africa: A review

Data on human gastrointestinal parasites (GIP) infections in the african sub-regions and countries are mainly lacking in terms of prevalence and population stratification by afflicted age group, symptomatology, multi-parasitism, and diagnostic methods. This study aims to describe the GIP reported in african countries and discuss the extent of the burden in the african context. Only 68.42% (39/57) of african countries reported human cases of GIP with helminths (45%, CI: 40-50%, I²: 99.79%) as the predominant parasitic group infecting the african population. On a regional scale, Central Africa had the highest pooled prevalence for GIP (43%, CI: 32-54%, I²: 99.74%), while the Central African Republic led all countries with a pooled prevalence of 90% (CI: 89-92%, I²: 99.96%). The vulnerable population (patients who are minorities, children, old, poor, underfunded, or have particular medical conditions) was the most affected (50%, CI: 37-62%, I²: 99.33%), with the predominance of GIP in the 6 to <20 years age group (48%, CI: 43-54%, I²: 99.68%). Reports on multi-parasitism (44%, CI: 40-48%, I²: 99.73%) were almost double the reports of single infections (43%, CI: 27-59%, I²: 99.77%) with combined molecular and non-molecular techniques demonstrating the best performance for GIP identification. The current review spans more than 40 years of GIP reports from the african continent. Geographical characteristics, environmental factors, habits of its inhabitants, and their health status play a crucial role in GIP modulation and behaviour in its captive hosts. Strategies for regular and enhanced surveillance, policy formation, and high-level community awareness are necessary to identify the true incidence in Africa and the transmission of the pathogens via water and food.

Essential Oils and Terpenic Compounds as Potential Hits for Drugs against Amitochondriate Protists

The human anaerobic or microaerophilic protists Giardia duodenalis, Entamoeba histolytica, and Trichomonas vaginalis are classified as amitochondriate parasites, a group of unicellular organisms that lack canonical mitochondria organelles. These microorganisms suffered adaptations to survive in hostile microenvironments and together represent an increasing threat to public health in developing countries. Nevertheless, the current therapeutic drugs to manage the infections are scarce and often cause several side effects. Furthermore, refractory cases associated with the emergence of parasitic resistance are concerns that guide the search for new pharmacological targets and treatment alternatives. Herein, essential oils and terpenic compounds with activity against amitochondriate parasites with clinical relevance are summarized and insights into possible mechanisms of action are made. This review aims to contribute with future perspectives for research with these natural products as potential alternatives for the acquisition of new molecules for the treatment of amitochondriate protists.

High-throughput phenotypic screen identifies a new family of potent anti-amoebic compounds

Entamoeba histolytica is a disease-causing parasitic amoeba which affects an estimated 50 million people worldwide, particularly in socioeconomically vulnerable populations experiencing water sanitation issues. Infection with E. histolytica is referred to as amoebiasis, and can cause symptoms such as colitis, dysentery, and even death in extreme cases. Drugs exist that are capable of killing this parasite, but they are hampered by downsides such as significant adverse effects at therapeutic concentrations, issues with patient compliance, the need for additional drugs to kill the transmissible cyst stage, and potential development of resistance. Past screens of small and medium sized chemical libraries have yielded anti-amoebic candidates, thus rendering high-throughput screening a promising direction for new drug discovery in this area. In this study, we screened a curated 81,664 compound library from Janssen pharmaceuticals against E. histolytica trophozoites in vitro, and from it identified a highly potent new inhibitor compound. The best compound in this series, JNJ001, showed excellent inhibition activity against E. histolytica trophozoites with EC50 values at 0.29 μM, which is better than the current approved treatment, metronidazole. Further experimentation confirmed the activity of this compound, as well as that of several structurally related compounds, originating from both the Janssen Jump-stARter library, and from chemical vendors, thus highlighting a new structure-activity relationship (SAR). In addition, we confirmed that the compound inhibited E. histolytica survival as rapidly as the current standard of care and inhibited transmissible cysts of the related model organism Entamoeba invadens. Together these results constitute the discovery of a novel class of chemicals with favorable in vitro pharmacological properties. The discovery may lead to an improved therapy against this parasite and in all of its life stages.

In silico analysis of a Skp1 protein homolog from the human pathogen E. histolytica

SCF complex consisting of Skp1, Cullins, F-box proteins, is the largest family of E3 ubiquitin ligases that promotes ubiquitination of many substrate proteins and controls numerous cellular processes. Skp1 is an adapter protein that binds directly to the F-box proteins. In this study, we have presented the first comprehensive analysis of the presence of peptides or proteins in the human pathogen Entamoeba histolytica having homology to Skp1protein. The occurrence of other protein components of the SCF complex has been identified from protein-protein interaction network of EhSkp1A. Studying the role of Skp1protein in this pathogen would help to understand its unique chromosome segregation and cell division which are different from higher eukaryotes. Further, owing to the development of resistance over several drugs that are currently available, there is a growing need for a novel drug against E. histolytica. Proteins from ubiquitin-proteasome pathway have received attention as potential drug targets in other parasites. We have identified four homologs of Skp1 protein in E. histolytica strain HM-1: IMSS. Molecular docking study between EhSkp1A and an F-box/WD domain-containing protein (EhFBXW) shows that the F-box domain in the N-terminal region of EhFBXW interacts with EhSkp1A. Therefore, the results of the present study shall provide a stable foundation for further research on the cell cycle regulation of E. histolytica and this will help researchers to develop new drugs against this parasite.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12639-022-01523-0.

Intestinal Parasitic Infections, Treatment and Associated Factors among Pregnant Women in Sao Tome and Principe: A Cross-Sectional Study

Background. Intestinal parasitic infections (IPIs) are a public health problem in developing countries such as Sao Tome and Principe (STP) although the pregnancy burden of IPIs is unknown in this endemic country. Thus, the aim of this study was to determine the prevalence of IPIs, prescribed anthelmintics, and associated factors among pregnant women admitted to Hospital Dr. Ayres de Menezes (HAM). Methods. A hospital-based cross-sectional study was conducted among pregnant women admitted to the HAM who had undergone antenatal copro-parasitological screening. Data were abstracted from antenatal care (ANC) cards regarding parasitological results and anthelmintic prescriptions. A structured questionnaire face-to-face interview was also applied. Pregnant women with an IPI (210) were compared to noninfected women (151). Data analysis was performed using SPSS version 25.0. Odds ratios (ORs) with 95% confidence intervals (CIs) for factors associated with IPIs were estimated using multiple logistic regression models. A $p$ value <0.05 was considered statistically significant. Results. A total of 361 participants (210 IPI and 151 no-IPI) with a mean age of 26.96 (SD: 7.00) were included. The overall prevalence of IPI was 58.2% (95% CI 52.9 to 63.3), mainly due to helminthiasis, with a 55.9% (95% CI 50.7–61.2%) rate. Ascaris lumbricoides (90.9%) was the most predominant parasite species identified followed by Trichuris trichiura (13.8%). Polyparasitism was observed in 25 cases (11.9%). Anthelmintics were prescribed to 23% of pregnant women. S intercalatum (11) and E histolytica (7) infections were not adequately treated. IPI was significantly associated with primary education (AOR 1.73 (95% CI: 1.10–2.71)), unemployment (AOR 1.94 (95% CI: 1.20–3.13)), and parity of five or above (AOR 3.82 (95% CI: 1.32–11.08)). Conclusion. This study highlights the IPI burden, associated factors, and missing treatment opportunities among pregnant women with STP. This study is a useful tool for policymakers in STP to enhance the health of women and their unborn babies.

Intestinal Parasitic Infection and Nutritional Status in Children under Five Years Old: A Systematic Review

Intestinal parasitic infections are common infectious diseases causing many health problems and impaired growth and physical development.. Children under five years old are the most vulnerable to infections, due to their immature immunity and feeding and exploratory behaviours. This systematic review aimed to assess the relationship between intestinal parasitic infections and undernutrition among children under 5 years old. Fifteen studies met the inclusion and exclusion criteria and were classified as high-quality studies. Twelve parasites were reported, including Ascaris lumbricoides, Cryptosporodium spp., Entamoeba histolytica, Enterobius vermicularis, Giardia lamblia, hookworm, Hymenolepis nana, Strongyloides sterocalis, Taenia spp. and Trichuris trichuria. Ascariasis is the most reported infection, with a prevalence ranging from 10.77% in Ethiopia to 57.14% in Malaysia, and is correlated with stunting (OR 2.17 (95% CI 1.14, 4.13), p = 0.02). Giardiasis is the second most reported infection, with a prevalence ranging from 4.43% in Ethiopia to 66.33% in the Central African Republic, and is related to an increased risk of stunting (OR 2.34 (95% CI 1.07, 5.10), p = 0.03)), wasting (OR 2.90 (95% CI 1.12, 7.49, p = 0.03)), and being underweight (OR 1.53 (95% CI 1.02, 2.29, p = 0.04)). The third and fourth most prevalent infections are T. trichiura and hookworm infections. Intestinal parasitic infections can occur very early in life and cause significant growth retardation. It is important to understand the prevalence and effects of infection based on the parasite species in order to implement therapeutic interventions and prevention controls.

Entamoeba histolytica: Membrane and Non-Membrane Protein Structure, Function, Immune Response Interaction, and Vaccine Development

Entamoeba histolytica is a protozoan parasite that is the causative agent of amoebiasis. This parasite has caused widespread infection in India, Africa, Mexico, and Central and South America, and results in 100,000 deaths yearly. An immune response is a body's mechanism for eradicating and fighting against substances it sees as harmful or foreign. E. histolytica biological membranes are considered foreign and immunogenic to the human body, thereby initiating the body's immune responses. Understanding immune response and antigen interaction are essential for vaccine development. Thus, this review aims to identify and understand the protein structure, function, and interaction of the biological membrane with the immune response, which could contribute to vaccine development. Furthermore, the current trend of vaccine development studies to combat amoebiasis is also reviewed.

Immunomodulatory effect of extracellular vesicles from Entamoeba histolytica trophozoites: Regulation of NETs and respiratory burst during confrontation with human neutrophils

Parasites release extracellular vesicles (EVs) which, in some cases, modulate the host's immune response contributing to the establishment of the infection. In this work we have isolated and characterized the EVs released by trophozoites of the human protozoan parasite Entamoeba histolytica, the causal agent of amoebiasis, when alone or in coculture with human neutrophils, and determined their effect on neutrophil NETs and ROS production. Nanoparticle tracking analysis showed that amoebic EVs are variable in size, ranging from less than 50 nm to nearly 600 nm in diameter (average of 167 nm), whereas neutrophil EVs are more uniform in size, with an average of 136 nm. In cocultures amoeba:neutrophil (1:100) most EVs are 98 nm in size, which is the typical size of exosomes. EVs from amoebae and neutrophils showed almost equal levels of ROS, which were considerably increased in EVs from cocultures. Uptake of amoebic EVs by neutrophils was demonstrated by fluorescence and resulted in a significant reduction in the oxidative burst and NET release triggered by PMA, ionophore A23187, or the amoebae itself used as stimuli. Interestingly, uptake of EVs from cocultures did not affect ROS production, but instead caused a greater delay in the onset of NETs release and in their quantity. A comparative proteomic analysis between the EVs of amoebae and neutrophils separately vs the cocultures showed a similar distribution of protein categories in the GO analysis, but differences in the expression and abundance of proteins such as the N-acetyl-D-galactosamine (GalNAc) inhibitable surface lectin and calreticulin in amoeba EVs, and various antimicrobial molecules in neutrophil EVs, such as lactoferrin and myeloperoxidase. These results highlight the importance of EVs in the immunomodulatory effects exerted by amoeba on human neutrophils.

Updates on the worldwide burden of amoebiasis: A case series and literature review

BACKGROUND

Amoebiasis is an intestinal and tissue parasitic infection caused by the protozoan Entamoeba histolytica. Despite significant medical importance and worldwide dispersion, little is known about the epidemiology and distinct geographical distribution of various clinical forms of amoebiasis in the world. In this study, we present an amoebiasis case series referred to Avicenne Hospital (Bobigny, France) from 2010 to 2022 followed by an overview of the released literature to explore diverse clinico-pathology of amoebiasis and to update the actual epidemiological situation of this parasitosis worldwide.

METHODS

The referred patients underwent a combination of clinical and parasitological examinations and imaging. The study was followed by an overview of released literature performed based on PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guideline.

RESULTS

A total of 15 patients with amoebiasis were diagnosed with an average age of 48.5 years old at the occurrence time of infection. Men (78%) were the most affected patients. Most of the cases were reported following a trip to endemic regions, such as Mali, India, Nepal, Algeria, Cameroon or Congo. All of the processed patients exhibited a hepatic amoebiasis. Amoebic abscess was observed in all cases with an average size of 6.3 cm. Of these patients, seven cases (46.7%) benefited from drainage following a risk of rupture or superinfection of the abscess. A compilation of findings extracted from 390 scientific publications via seven major medical databases, allowed us to update the main epidemiological and clinical events that has led to the current worldwide expansion of amoebiasis. We presented a clinical and epidemiological overview of the amoebiasis accompanied with a worldwide illustrative map displaying the current distribution of known amoebiasis foci in each geographical ecozone of Asia, Europe, Africa, Americas, and Australia.

CONCLUSIONS

Although Metropolitan France is not known as an endemic region of amoebiasis, amoebic liver abscess was the most frequent clinical form observed among our 15 patients processed. Most of infected patients had a history of travel to or lived-in endemic areas before arriving in France.

Assessing the prevalence and risk factors associated with Entamoeba complex infection among the Orang Asli school children in Perak, Malaysia through molecular approach

This study performed a cross-sectional investigation on the prevalence of Entamoeba complex infection comprising Entamoeba histolytica, Entamoeba dispar, and Entamoeba moshkovskii and their associated risk factors among the Orang Asli school children in three districts in Perak, Malaysia. Stool samples collected from 544 school children aged between 7 and 12 years old were examined through the nested multiplex PCR assay. The univariate and multivariate regression analyses were then carried out to determine the risk factor associated with Entamoeba complex infection. The overall prevalence of Entamoeba complex infections (E. histolytica, E. dispar and E. moshkovskii) was 21.3% (116/544). Most positive school children were infected with E. moshkovskii (10.7%; 58/544), followed by E. dispar (9.0%; 49/544) and E. histolytica (5.0%; 27/544). Not washing their hands after using the toilet was identified as the only significant risk factor for E. histolytica. The significant risk factors associated with E. moshkovskii infection included children within the age of 10-12 years old, with high BMI, living with working and non-educated mothers, no toilet in the house, not washing their hands after using the toilet, and fever. On the other hand, drinking water from the river, well, and rain was associated with a decreased risk of E. dispar infection. In conclusion, this study showed a high prevalence of Entamoeba spp. infections among the Orang Asli school children in Perak, Malaysia. Addressing the identified risk factors coupled with a holistic approach in breaking the transmission of Entamoeba complex can help improve their quality of life.

Plants of the Phytolaccaceae family with antimicrobial activity: A systematic review

Phytolaccaceae is a plant family of the order Caryophyllales, which includes species used in traditional medicine to treat diseases. The purpose of this study was to investigate Phytolaccaceae family plants with potential antimicrobial action, through a systematic review. The study was conducted following the criteria of PRISMA protocol. The search was performed in the electronic databases PubMed, Web of Science, Scopus, and LILACS, in March 2021. The search strategy used free descriptors and terms, limiting articles to the English language, regardless of publication year. The risk of bias and the quality of publications were based on the CONSORT checklist, modified for in vitro studies and SYRCLE's RoB tool for in vivo study. Five independent judges performed quality assessments of publications and risk of bias analysis. Ninety-five publications were retrieved from the databases and, after screening and eligibility criteria, 22 articles remained, from 1998 to 2019. In the selected studies, the plants were obtained from eight countries. In vivo and in vitro studies of extracts from the Phytolaccaceae family plants, evaluating antibacterial (8 publications), antifungal (8), anti-Trypanosoma (2), anti-Leishmania (2), antiviral (1), and antiamoebic (1) activities, are included. The plant species identified belong to genera Petiveria, Phytolacca, Gallesia, Trichostigma, and Seguieria. The risk of bias in the 22 publications both in vitro and in vitro was suboptimal. The evidence obtained showed that the Phytolaccaceae family, a source of plants with antimicrobial action, can serve as a basis for the creation of new herbal medicines, expanding the possibility of treatment for infectious diseases and stimulating their preservation and biodiversity. However, more high-quality studies are needed to establish the clinical efficacy of the plant.

Seasonal Prevalence of Gastrointestinal Parasites in Macaques (Macaca thibetana) at Mount Emei Scenic Area in China

The aim of the study was to elucidate the prevalence of intestinal parasites in macaques at the Mt. Emei Scenic Area of Sichuan, China. A total of 168 fecal samples were collected from yellow (n = 31), black (n = 19), new (n = 57), Leidongping (n = 57) and Wuxiangang (n = 4) macaques from 2019 to 2020. The fecal samples were tested for various gastrointestinal parasites following the microscopic detection method. The results showed that the total prevalence rate of the intestinal parasite was 51.19% (86/168), whereas the intestinal parasite with the highest prevalence was Gongylonema spp. (26.79%) for helminth and Entamoeba spp. (18.45%) for protozoa. Interestingly, the highest prevalence of intestinal parasites was observed during the summer season (86.21%), and the lowest was observed during the winter season (7.14%). There was a positive correlation observed between the human contact frequency and total prevalence rate of the intestinal parasites (p < 0.05); however, there was no correlation between the human contact frequency and total prevalence of the intestinal parasites at different seasons (p > 0.05). In conclusion, the dominant parasites Gongylonema spp. and Entamoeba spp. cause various diseases that may be transmitted to humans and other animals; therefore, there is a need for a proper management system, such as parasite control measures and population protection in the Mt. Emei Scenic Area of Sichuan, China.

Mimics of Crohn's Disease

Crohn's disease is a chronic inflammatory disease that can affect any portion of the gastrointestinal tract. Associated symptoms can vary based on the severity of disease, extent of involvement, presence of extraintestinal manifestations, and development of complications. Diagnosis is based on a constellation of findings. Many diseases can mimic Crohn's disease and lead to diagnostic conundrums. These include entities associated with the gastrointestinal luminal tract, vascular disease, autoimmune processes, various infections, malignancies and complications, drug- or treatment-induced conditions, and genetic diseases. Careful consideration of possible causes is necessary to establish the correct diagnosis.

A rare case of extraintestinal amebiasis

Background

Amoebiasis is caused by the protozoan Entamoeba histolytica, which is a rare infectious disease in developed countries. If the trophozoites enter the blood, it can spread through the body, such as brain, and lungs. Cases of simultaneous infection of multiple organs are extremely rare.

Case presentation

Here we report a case of simultaneous infection of amoeba in pulmonary pleura, urinary system and central nervous system. Although the patient received anti amoeba treatment, the prognosis of the patient was poor.

Conclusions

In this patient, multiple extraintestinal amebic infections in the absence of clinically confirmed intestinal amebiasis or amebic liver abscess are rare and pose diagnostic challenges. The disseminated amebiasis has significantly increased the mortality. Early diagnosis and appropriate treatment may reduce the mortality of disseminated amebiasis.

Intestinal parasites in stool testing among refugees at a primary care clinic in Toronto, Canada

Background

Enteric parasites are endemic in many of the countries from which refugees originate. Clinical guidelines vary in approaches to screening for and treating intestinal parasites in refugee receiving countries. This study aims to investigate the prevalence and species of intestinal parasites identified in stool ova and parasite (O&P) specimens in a sample of newly arrived refugees in Toronto, Canada.

Methods

We conducted a retrospective chart review of 1042 refugee patients rostered at a specialized primary care clinic in Toronto from December 2011 to September 2016. Patients who completed recommended stool O&P analyses were included. Basic sociodemographic and clinical variables and results of stool O&P were examined.

Results

419 patients (40.2%) had a stool O&P positive for any protozoan or helminth species. Sixty-nine patients (6.6%) had clinically significant parasite species (excluding B hominis, D fragilis, and E dispar, given their lower risk for causing symptoms/complications): 2.3% had clinically significant protozoans and 4.2% had helminths on stool analysis.

Conclusion

Given the relatively low prevalence of clinically significant parasites identified, our findings do not support universal screening for enteric parasites with stool O&P among refugee claimants/asylum seekers. However, stool analysis should be considered in certain clinical situations, as part of a more tailored approach.

Entamoeba histolytica and Probable Effect on Production Microsatellite Instability in Colorectal Cancer

The mortality rate of Entamoeba histolytica is still high and approximately 100,000 per year. Environmental factors and different pathogens can cause microsatellite instability (MSI) positive, which may be one reason for colorectal cancer. MSI status can play an essential role in treatment. Moreover, E. histolytica might be one of the pathogens which raise the incidence of colorectal cancer. Therefore, the probable relationship of E. histolytica with MSI production was evaluated. Four hundred samples of colorectal biopsies based on pathological reports were divided into four groups: colitis, polyps, hyperplasia or dysplasia, and adenocarcinoma. The prevalence of E. histolytica was examined with PCR and immunohistochemical staining (IHC) for the light chain lectin HK-9. The adenocarcinoma formalin-fixed paraffin-embedded colorectal tumours sections were tested for MSI genes. We detected E. histolytica in 6% and 4% of colitis samples by PCR and IHC technique, respectively. However, it did not identify in polyp and hyperplasia samples. The MSI test was examined in the colorectal cancer group, which became positive in 19%. Entamoeba histolytica was detected in 26.3% (5/19) of MSI-positive and 2.5% (2/81) of MSI-negative cases by IHC technique however was not identified by PCR assay in this group. It is concluded PCR and IHC assay is recommended as complementary tests in colitis biopsies. Simultaneous PCR and IHC negative results could confirm the non-existence of the parasite with more confidence. Consequently, E. histolytica might be one of the biotic  factors which raise the incidence of colorectal cancer because of the coincidence of the IHC positive results in MSI-positive adenocarcinoma.

Successful treatment with metronidazole and paromomycin for fulminant amoebic colitis during cytotoxic chemotherapy in a patient with small-cell lung cancer

We report the case of a 64-year-old man with advanced small-cell lung cancer who developed fulminant amoebic colitis during cytotoxic chemotherapy. During the first cycle of carboplatin/etoposide treatment, febrile neutropenia and grade 4 neutropenia developed. Because diarrhea, abdominal pain, and bloody stool were observed, abdominal computed tomography was performed, showing intussusception, and extensive colectomy and colostomy were performed. Histopathology of the colon revealed gastrointestinal necrosis and perforation due to Entamoeba histolytica infection. Amoebiasis improved after treatment with metronidazole and paromomycin. The second cycle of carboplatin/etoposide with dose reduction was completed, resulting in a partial response to small-cell lung cancer.

The results of this case suggest that paromomycin is an additional option for amoebiasis during cytotoxic chemotherapy, and persistent diarrhea during cytotoxic chemotherapy should alert clinicians to consider the development of amoebiasis.

Giant Amoebic Liver Abscess: A Rare Diagnosis in a Rural Setting of Sub-Saharan Africa

Background

Extraintestinal amoebiasis is an uncommon complication of Entamoeba histolytica infection, occurring in about 5-10% of patient. Prompt diagnosis and management is essential to prevent complications. However, diagnosis and management in resource-limited settings is very challenging owing to limited diagnostic tools and nonspecific clinical symptoms. Therefore, our case report underscores the role of incisive clinical evaluation, basic investigation, and nonsurgical management of giant amoebic abscess in resource-limited settings. Case Presentation. A 13-year-old female Cameroonian presented with subacute onset of upper abdominal pain, high fever, and chest pain for one week. Before presentation, she had been on treatment at a local traditional practitioner during which her symptoms worsen. After clinical evaluation and basic investigation, she was diagnosed with a giant amoebic liver abscess. She was resuscitated and placed on nonsurgical management. Follow-up after 1 month was significant for complete recovery.

Conclusion

Amoebic liver abscess is a rare complication of Entamoeba histolytica infection with devastating complications. The diagnosis of this disease requires high index of suspicion in resource-limited settings. Good clinical evaluation and timely nonsurgical therapy can provide recovery to some patients.

Probing the Peculiarity of EhRabX10, a pseudoRab GTPase, from the Enteric Parasite Entamoeba histolytica through In Silico Modeling and Docking Studies

Entamoeba histolytica (Eh) is a pathogenic eukaryote that often resides silently in humans under asymptomatic stages. Upon indeterminate stimulus, it develops into fulminant amoebiasis that causes severe hepatic abscesses with 50% mortality. This neglected tropical pathogen relies massively on membrane modulation to flourish and cause disease; these modulations range from the phagocytic mode for food acquisition to a complex trogocytosis mechanism for tissue invasion. Rab GTPases form the largest branch of the Ras-like small GTPases, with a diverse set of roles across the eukaryotic kingdom. Rab GTPases are vital for the orchestration of membrane transport and the secretory pathway responsible for transporting the pathogenic effectors, such as cysteine proteases (EhCPs) which help in tissue invasion. Rab GTPases thus play a crucial role in executing the cytolytic effect of E. histolytica. First, they interact with Gal/Nac lectins required for adhering to the host cells, and then, they assist in the secretion of EhCPs. Additionally, amoebic Rab GTPases are vital for encystation because substantial vesicular trafficking is required to create dormant amoebic cysts. These cysts are the infective agent and help to spread the disease. The absence of a "bonafide" vesicular transport machinery in Eh and the existence of a diverse repertoire of amoebic Rab GTPases (EhRab) hint at their contribution in supporting this atypical machinery. Here, we provide insights into a pseudoRab GTPase, EhRabX10, by performing physicochemical analysis, predictive 3D structure modeling, protein-protein interaction studies, and in silico molecular docking. Our group is the first one to classify EhRabX10 as a pseudoRab GTPase with four nonconserved G-motifs. It possesses the basic fold of the P-loop containing nucleotide hydrolases. Through this in silico study, we provide an introduction to the characterization of the atypical EhRabX10 and set the stage for future explorations into the mechanisms of nucleotide recognition, binding, and hydrolysis employed by the pseudoEhRab GTPase family.

Characteristics of endoscopic and pathological findings of amebic colitis

Background

The clinical features of amoebic colitis resemble those of inflammatory bowel disease (IBD), and therefore the risk of misdiagnosis is very high. The aim of this study was to analyse the characteristics of the endoscopic and pathological findings of amebic colitis and the lessons from our patients, which were useful for diagnosing the amebic colitis timely and avoiding the serious complication.

Methods

We retrospectively reviewed data of all amebic colitis admitted to Beijing Friendship Hospital from January 2015 to January 2020. Cases were diagnosed by clinical presentation, laboratory examinations, and colonoscopy with biopsy and histological examination, no ELISA stool antigen or PCR tests were used.

Results

16 patients were diagnosed with amebic colitis by the colonoscopy accompanied by biopsy and microscopic examination. At first time, 12 (75%) patients were misdiagnosed as IBD. Cecum was the most common site of amebic colitis (100%), and the caecum and rectum were also involved in many lesions (68.75%). Multiple lesions of erosion and/or ulcer were recognized in all patients (100%).The endoscopic findings included multiple irregular shaped ulcers and erosions with surrounding erythema, and the ulcers and erosions were covered by the white or yellow exudates. The intervening mucosae between the ulcers or erosions were normal. The features of rectums can be divided to 2 types: in 6 patients (54.5%), the irregular ulcer or erosions covered with white or yellow exudates were observed in rectum and cecum, and the bloody exudates in rectum were more severe than those in cecum; in other 5 patients (45.5%), rectal lesions were much less severe than those in cecum, the small superficial erosion or reddened mucosa were observed in the rectal ampulla. All patients were diagnosed as detection of amebic trophozoites from HE-stained biopsy specimens. The number of trophozoites ranged from 1/HPF to > 50/HPF. Among 16 cases, mild architectural alteration of colon crypt were observed in 10 cases (62.5%), and serious architectural alteration of colon crypt was found which had crypt branch in 1 case (16.7%). Cryptitis was observed in 12 cases (75%) and its severity was mild or moderate. No crypts abscess was observed in all cases.

Conclusions

The colonoscopy with histological examination are very important to diagnose the amebic colitis. Detect the amoebic trophozoites in the exudates by histological examination is the vital. Sometimes a negative biopsy does not rule out amebiasis, repeated biopsies may be needed to make the diagnosis.

"Stranger things" in the gut: uncommon items in gastrointestinal specimens

Organic (such as parasites or vegetable remnants) and inorganic substances may be encountered during routine pathology diagnostic work up of endoscopic gastrointestinal biopsy samples and major resections, causing possible diagnostic conundrums for the young and not so young pathologists. The main aim of this review is the description of the most frequent oddities one can encounter as foreign bodies, in gastrointestinal pathology, on the basis of the current literature and personal experience. The types of encountered substances are divided into four principal categories: parasites (helminths such as Enterobius vermicularis, Strongyloides, Schistosoma, and Anisakis, and protozoa such as Entamoeba, Giardia and some intestinal coccidia); drugs and pharmaceutical fillers (found as deposits and as bystanders, innocent or not); seeds (possibly confused with worms) and plant remnants; pollutants (secondary to post-resection or post-biopsy contamination of the sample). An ample library of images is provided in order to consent easy referencing for diagnostic routine.

The flip side of reactive oxygen species in the tropical disease-Amoebiasis

Entamoeba histolytica is the conductive agent of amoebiasis. Upon the parasite's infection, macrophages and neutrophils are activated by interferon γ, IL-13 and tumour necrosis factor. These immune cells then carry out the amoebicidal activity by releasing nitric oxide synthase and reactive oxygen species (ROS). This review talks about the protective and destructive role of ROS in Eh. E. histolytica has defence strategies against oxidative stress which is a result of excess ROS production. They possess antioxidants for their defence such as L-Cysteine, flavodiiron proteins, peroxiredoxin and trichostatin A, which contribute to the parasite's virulence. The ROS are harmful to the host cells as excess ROS production stimulates cell death by mechanisms like apoptosis and necroptosis. NADPH oxidase (NOX) is a key source of ROS in mammalian cells and causes apoptosis of host cells via the protein kinase transduction pathway. This review provides insights into why NOX inhibitors that could be a potent antiparasitic drug, is not effective for in vivo purposes. This paper also gives an insight into a solution that could be a potent source in generating new treatment and vaccines for amoebiasis by targeting parasite development.

Epidemiology of clinically relevant Entamoeba spp. (E. histolytica/dispar/moshkovskii/bangladeshi): A cross sectional study from North India

BACKGROUND

Entamoeba infections have major impact on millions of the people worldwide. Entamoeba histolytica has long been accepted as the only pathogenic species. However, recent reports of other Entamoeba spp. in symptomatic cases have raised questions on their pathogenicity.

METHODOLOGY/PRINCIPAL FINDINGS

Total 474 stool samples and 125 liver aspirates from patients with intestinal and extra intestinal manifestations and from community were included. Sewage samples from the hospital and the city were also included. Microscopic examination and molecular detection were performed to detect presence of E. histolytica/ dispar/ moshkovskii/ bangladeshi. The associated demographic and socioeconomic factors were statistically analyzed with the presence of Entamoeba. Microscopy detected Entamoeba spp. in 5.4% stool and 6.4% liver aspirate samples. Through nested multiplex PCR, prevalence of Entamoeba spp. in intestinal and extra-intestinal cases was 6.6% (20/301) and 86.4% (108/125) respectively and in asymptomatic population was 10.5% (13/123). Sewage samples did not show presence of any Entamoeba spp. Uneducated subjects, low economic conditions, untreated drinking water, consumption of raw vegetables and habit of not washing hands before meals were significantly associated with presence of Entamoeba spp.

CONCLUSIONS

E. histolytica still remains the only Entamoeba spp. in invasive extra intestinal infections. E. dispar was detected in both asymptomatic and symptomatic intestinal infections. Routine identification of Entamoeba spp. should incorporate PCR based detection methods.

Extended Release of Metronidazole Drug Using Chitosan/Graphene Oxide Bionanocomposite Beads as the Drug Carrier

This study depicts the facile approach for the synthesis of chitosan/graphene oxide bionanocomposite (Chi/GO) beads via the gelation process. This is the first-ever study in which these Chi/GO beads have been utilized as a drug carrier for the oral drug delivery of metronidazole (MTD) drug, and investigations were made regarding the release pattern of the MTD drug using these Chi/GO beads as a drug carrier for a prolonged period of 84 h. The MTD is loaded on the surface as well as the cavity of the Chi/GO beads to result in MTD-Chi/GO bionanocomposite beads. The MTD drug loading was found to be 683 mg/g. Furthermore, the in vitro release patterns of pure drug and the drug encapsulated with Chi/GO beads are explored in simulated gastric as well as simulated intestinal fluids with phosphate-buffered saline (PBS) of pH 1.2 and 7.4, respectively. As-synthesized bionanocomposite beads have shown excellent stability and capacity for extended release of the MTD drug as compared to the pure drug in terms of bioavailability in both media. The cumulative release data are fitted with the Korsmeyer-Peppas kinetics and first-order reaction kinetics at pH 1.2 and 7.4. The synthesized bionanocomposite beads have good potential to minimize the multiple-dose frequency with the sustained drug release property and can reduce the side effects due to the drug.

A Comparative Analysis of Microscopy, Coproantigen Serology, and Nested Multiplex PCR in the Laboratory Diagnosis of Entamoeba histolytica Infection

Objectives  Amoebiasis is caused by the most common intestinal protozoan parasite Entamoeba histolytica . This parasite causes amoebic colitis, which is manifested by diarrhea, followed by dysentery. The laboratory diagnosis of intestinal amoebiasis in most cases is by microscopic examination of stool samples. Other nonroutine methods include coproantigen enzyme-linked immunosorbent assay (ELISA) from stool samples, serum ELISA for antibodies, stool culture, isoenzyme analysis, and polymerase chain reaction (PCR). The present study aimed to comparatively analyze the different diagnostic modalities used for the detection of E. histolytica from the stool sample of patients with intestinal amoebiasis.

Materials and Methods  This study was undertaken with 631 patients, during a period of 3 years, from January 2017 to December 2019. Stool specimen obtained from each patient was subjected to direct microscopic wet mount examination, coproantigen ELISA, and nested multiplex PCR, respectively.

Results  Out of all the patients tested, 5.2% were positive for E. histolytica. Among the positive cases, stool microscopy was positive in 3.17%, coproantigen ELISA was positive in 29 (4.6%) cases, and PCR was positive in 30 (4.75%) cases.

Statistical Analysis  The prevalence of E. histolytica infection was summarized as percentages. The three diagnostic tests done were statistically analyzed, taking microscopy as the gold standard. The agreement between techniques (microscopy, coproantigen ELISA, and PCR) was analyzed with kappa statistics. Sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy were summarized as percentage with 95% confidence interval.

Conclusion  In all suspected amoebiasis cases, a combination of stool microscopy, coproantigen testing with molecular detection of the parasite offers the best approach to diagnosis of this parasitic infection.

Secondary pleuropulmonary amoebiasis due to liver abscess rupture: A complication case report in low resource setting

BACKGROUND

Pleuropulmonary amoebiasis caused by complications of amoebic liver abscess (ALA) is rare.

CASE PRESENTATION

A 23 years old male, presented with shortness of breath, cough with yellowish phlegm, right chest pain, fever, bulging stomach, yellow eyes, and swelling of both legs. Abdominal ultrasound and CT scan thorax and abdomen revealed right fluidopneumothorax and liver abscess. Serological testing leads to Entamoeba histolytica infection, which was treated with metronidazole but no significant improvement on empyema and abscess liver size. Surgery was performed after percutaneous aspiration drainage failed to evacuate the abscess. HE and PAS staining from surgical tissue showed Entamoeba hystolitica infection.

DISCUSSION

Serological testing and radiological examination will be more useful in the early detection of cases of Entamoeba hystolitica infection. Surgery may be considered when purulent drainage does not show improvement in the patient's condition.

CONCLUSION

ALA complication that causes pulmonary empyema can be surgically treated if the pus cannot be drained.

A pilot metagenomic study reveals that community derived mobile phones are reservoirs of viable pathogenic microbes

There is increasing attention focussed on the risks associated with mobile phones possibly serving as ‘Trojan Horse’ fomites for microbial transmission in healthcare settings. However, little is reported on the presence of microbes on community derived mobile phones which in 2021, numbered in the billions in circulation with majority being used on a daily basis. Identify viable microbial organisms swabbed from smartphones on a university campus. Entire surfaces of 5 mobile phones were swabbed and examined for their microbial content using pre-agar-based growths followed by downstream DNA metagenomic next-generation sequencing analysis. All phones were contaminated with viable microbes. 173 bacteria, 8 fungi, 8 protists, 53 bacteriophages, 317 virulence factor genes and 41 distinct antibiotic resistant genes were identified. While this research represents a pilot study, the snapshot metagenomic analysis of samples collected from the surface of mobile phones has revealed the presence of a large population of viable microbes and an array of antimicrobial resistant factors. With billions of phones in circulation, these devices might be responsible for the rise of community acquired infections. These pilot results highlight the importance of public health authorities considering mobile phones as ‘Trojan Horse’ devices for microbial transmission and ensure appropriate decontamination campaigns are implemented.

Immune Response to the Enteric Parasite Entamoeba histolytica

Entamoeba histolytica is a protozoan parasite responsible for amoebiasis, a disease with a high prevalence in developing countries. Establishing an amoebic infection involves interplay between pathogenic factors for invasion and tissue damage, and immune responses for protecting the host. Here, we review the pathogenicity of E. histolytica and summarize the latest knowledge on immune response and immune evasion mechanisms during amoebiasis.

Foodborne Parasitic Diseases in the Neotropics - A Review

Within the Universal Declaration of Human Rights, it is stated that everyone has the right to an adequate standard of living, which ensures, as well as their family, health and well-being, and food, thereby ensuring adequate nutrition. One of the major threats to overcome this is to ensure food security, which becomes particularly challenging in developing countries due to the high incidence of parasitic diseases. The World Health Organization (WHO), considers it one of the main causes of morbidity, closely linked to poverty and related to inadequate personal hygiene, consumption of raw food, lack of sanitary services, limited access to drinking water and fecal contamination in the environment. It is estimated that more than a fifth of the world’s population is infected by one or several intestinal parasites, and that in many countries of Central and South America the average percentage of infected people is 45%, being Taenia solium, Echinococcus granulosus, Toxoplasma gondii, Cryptosporidium spp, Entamoeba histolytica, Trichinella spiralis, Ascaris spp, Trypanosoma cruzi and Fasciola hepatica some of the most important ones in the neotropics. One of the main reasons why these diseases are diffi cult to control is t he ignorance of their lifecycles, as well as symptoms and current epidemiology of the disease, which contributes to a late or erroneous diagnosis. The present work aims to discuss and make public the current knowledge as well as the general characteristics of these diseases to the general audience.

Neutrophils vs. amoebas: Immunity against the protozoan parasite Entamoeba histolytica

Entamoeba histolytica is a protozoan parasite with high prevalence in developing countries, and causes amoebiasis. This disease affects the intestine and the liver, and is the third leading cause of human deaths among parasite infections. E. histolytica infection of the intestine or liver is associated with a strong inflammation characterized by a large number of infiltrating neutrophils. Consequently, several reports suggest that neutrophils play a protective role in amoebiasis. However, other reports indicate that amoebas making direct contact with neutrophils provoke lysis of these leukocytes, resulting in the release of their lytic enzymes, which in turn provoke tissue damage. Therefore, the role of neutrophils in this parasitic infection remains controversial. Neutrophils migrate from the circulation to sites of infection, where they display several antimicrobial functions, including phagocytosis, degranulation, and formation of neutrophil extracellular traps (NET). Recently, it was found that E. histolytica trophozoites are capable of inducing NET formation. Neutrophils in touch with amoebas launched NET in an explosive manner around the amoebas and completely covered them in nebulous DNA and cell aggregates where parasites got immobilized and killed. In addition, the phenotype of neutrophils can be modified by the microbiome resulting in protection against amoebas. This review describes the mechanisms of E. histolytica infection and discusses the novel view of how neutrophils are involved in innate immunity defense against amoebiasis. Also, the mechanisms on how the microbiome modulates neutrophil function are described.

Reactivation of latent infections in solid organ transplant recipients from sub-Saharan Africa: What should be remembered?

International migration from Sub-Saharan African countries to the European Union and the United States has significantly increased over the past decades. Although the vast majority of these immigrants are young and healthy people, a minority can be affected by chronic conditions eventually leading to solid organ transplantation (SOT). Importantly, these candidates can bear geographically restricted fungal and parasitic latent infections that can reactivate after the procedure. An appropriate evaluation before transplantation followed by treatment, whenever necessary, is essential to minimize such risk, as covered in the present review. In short, infection due to helminths (Schistosoma spp. and Strongyloides stercoralis) and intestinal protozoa (Entamoeba histolytica, Giardia lamblia or Cyclospora cayetanensis) can be diagnosed by multiple direct stool examination, serological assays and stool antigen testing. Leishmaniasis can be assessed by means of serology, followed by nucleic acid amplification testing (NAAT) if the former test is positive. Submicroscopic malaria should be ruled out by NAAT. Screening for Histoplasma spp. or Cryptococcus spp. is not routinely indicated. Consultation with an Infectious Diseases specialist is recommended in order to adjust preemptive treatment among Sub-Saharan African SOT candidates and recipients.

Percutaneous catheter drainage of uncomplicated amoebic liver abscess: prospective evaluation of a clinical protocol for catheter removal and the significance of residual collections

INTRODUCTION

Patients with amoebic liver abscess (ALA) may require percutaneous catheter drainage (PCD). Once the PCD output is substantially reduced or has ceased along with clinical recovery, residual collections on radiological evaluation may concern the treating physicians. The prevalence and significance of such collections is unknown, and the subsequent approach how to tackle them is unclear.

METHODS

Consecutive patients with one or more uncomplicated ALAs requiring drainage were prospectively enrolled from 3 hospitals and managed based on a standard approach. Catheter removal was attempted after the patients fulfilled all 4 of the following criteria: disappearance of abdominal pain, absence of fever for at least 48 h, an improving trend of TLC (documented on 2 consecutive reports), and catheter drain output of < 10 ml/day for at least 2 consecutive days.

RESULTS

A total of 110 patients (mean age 46.6 ± 10.5 years, 93.6% males, 89.1% alcoholics) underwent PCD placement; 69 patients (69/110; 62.7%) met all 4 criteria within 5 days of PCD placement (optimal response) and had an uncomplicated course. Patients with suboptimal responses (41/110; 37.3%) were evaluated for local and systemic complications; the appearance of fresh collections (5/110; 4.5%), abscess rupture (2/110; 1.8%), bile leakage (3/110; 2.7%), cholangitis (2/110; 1.8%), thrombophlebitis (2/110; 1.8%) and hospital-acquired infections (2/110; 1.8%) were diagnosed and treated accordingly. Ultimately, PCD removal (based on the fulfilment of all 4 criteria) was universally successful after a median of 5 days (IQR, 4-9 days). None of the patients had symptom recurrence after PCD removal, although residual collections were still seen in 97.3% of patients at the time of PCD removal and in 92.1% and 84.9% of patients available for follow-up at 1 and 3 months, respectively.

CONCLUSION

Based on our clinical protocol, PCD removal in ALA can be successfully expedited even in the presence of residual collections. An inability to fulfill all 4 criteria within 5 days of PCD placement warrants further evaluations for local and systemic complications that require additional therapeutic measures.