Amebiasis

Investigation of Parasites in Food Handlers in Turkey

Increasing world population parallelly also brings an increase in food production and consumption. As food consumption increases, so do foodborne infections. In cases where adequate food safety and hygiene is not provided in places such as restaurants, dormitories, prisons, hospitals where mass feeding is made outside the home, many parasitic agents can be transmitted to people through food. People working in the food processing and distribution sector and who are in the position of porters play an important role in the spread of parasites, as they can transmit parasitic agents to food through fingernails and hands. Parasites such as Enterobius vermicularis, Entamoeba histolytica, and Giardia intestinalis can be transmitted to food and then to patients through nails and hands. This study was planned to investigate the presence of parasites in hospital food production and distribution workers, such as cooks and waiters, using various methods. Stool and serum samples were taken from 100 food production and distribution workers. Stool samples were examined by native-Lugol, concentration, trichrome, acid-fast staining, and cellophane tape methods. E. histolytica antigen in stool and Toxoplasma and Taenia antibodies in serum were searched by enzyme-linked immunosorbent assay. Parasites were detected in 59% people, and 41 were evaluated as negative. This positivity was 71.9% (23/32) in the 45-61 age range. Blastocystis sp. (27%), Toxoplasma (25%), E. histolytica (10%), Taenia spp. (7%), E. vermicularis (7%), Entamoeba coli (7%), G. intestinalis (5%), Chilomastix mesnili (1%), and I. butschlii (1%) were detected in food handlers. High Toxoplasma antibody positivity (25%) suggests the possibility of transmission to kitchen workers through ways, such as infected raw meat. However, the detection of E. histolytica, Taenia spp., E. vermicularis, G. intestinalis parasites in workers at significant levels poses a significant risk for society consuming these foods. As a result, it is important to investigate the presence of parasites in the employee dealing with food production and distribution to protect patients from parasitic infections especially in hospitals where the people are immunocompromised and more susceptible, and where mass meals are eaten.

Amoebiasis: Advances in Diagnosis, Treatment, Immunology Features and the Interaction with the Intestinal Ecosystem

This review of human amoebiasis is based on the most current knowledge of pathogenesis, diagnosis, treatment, and Entamoeba/microbiota interactions. The most relevant findings during this last decade about the Entamoeba parasite and the disease are related to the possibility of culturing trophozoites of different isolates from infected individuals that allowed the characterization of the multiple pathogenic mechanisms of the parasite and the understanding of the host-parasite relationship in the human. Second, the considerable advances in molecular biology and genetics help us to analyze the genome of Entamoeba, their genetic diversity, and the association of specific genotypes with the different amoebic forms of human amoebiasis. Based on this knowledge, culture and/or molecular diagnostic strategies are now available to determine the Entamoeba species and genotype responsible for invasive intestinal or extraintestinal amoebiasis cases. Likewise, the extensive knowledge of the immune response in amoebiasis with the appearance of new technologies made it possible to design diagnostic tools now available worldwide. Finally, the understanding of the interaction between the Entamoeba species and the intestinal microbiota aids the understanding of the ecology of this parasite in the human environment. These relevant findings will be discussed in this review.

Prevalence and molecular characterization of Entamoeba moshkovskii in diarrheal patients from Eastern India

BACKGROUND

Importance of the amphizoic amoeba Entamoeba moshkovskii is increasing in the study of amoebiasis as a common human pathogen in some settings. Limited studies are found on the genetic and phylogenetic characterization of E. moshkovskii from India; hence remain largely unknown. In this study, we determined the prevalence and characterized the E. moshkovskii isolates in eastern India.

METHODS

A three-year systemic surveillance study among a total of 6051 diarrhoeal patients from ID Hospital and BC Roy Hospital, Kolkata was conducted for E. moshkovskii detection via a nested PCR system targeting 18S rRNA locus. The outer primer set detected the genus Entamoeba and the inner primer pair identified the E. moshkovskii species. The 18S rRNA locus of the positive samples was sequenced. Genetic and phylogenetic structures were determined using DnaSP.v5 and MEGA-X. GraphPad Prism (v.8.4.2), CA, USA was used to analyze the statistical data.

RESULT

4.84% (95%CI = 0.0433-0.0541) samples were positive for Entamoeba spp and 3.12% (95%CI = 0.027-0.036) were infected with E. moshkovskii. E. moshkovskii infection was significantly associated with age groups (X2 = 26.01, P<0.0001) but not with gender (Fisher's exact test = 0.2548, P<0.05). A unique seasonal pattern was found for E. moshkovskii infection. Additionally, 46.56% (95%CI = 0.396-0.537) were sole E. moshkovskii infections and significantly associated with diarrheal incidence (X2 = 335.5,df = 9; P<0.0001). Sequencing revealed that the local E. moshkovskii strains were 99.59%-100% identical to the prototype (GenBank: KP722605.1). The study found certain SNPs that showed a correlation with clinical features, but it is not necessarily indicative of direct control over pathogenicity. However, SNPs in the 18S rRNA gene could impact the biology of the amoeba and serve as a useful phylogenetic marker for identifying pathogenic E. moshkovskii isolates. Neutrality tests of different coinfected subgroups indicated deviations from neutrality and implied population expansion after a bottleneck event or a selective sweep and/or purifying selection in co-infected subgroups. The majority of FST values of different coinfected subgroups were <0.25, indicating low to moderate genetic differentiation within the subgroups of this geographical area.

CONCLUSION

The findings reveal the epidemiological significance of E. moshkovskii infection in Eastern India as the first report in this geographical area and expose this species as a possible emerging enteric pathogen in India. Our findings provide useful knowledge for further research and the development of future control strategies against E. moshkovskii.

The influence of COVID-19 barrier measures on the positivity rate of typhoidal salmonellosis and amoebiasis in the Buea Health District, South West Region of Cameroon

Typhoidal salmonellosis and amoebiasis are prevalent in the Buea Health District (BHD) and it is evident that hand hygiene can reduce the transmissibility of these diseases. The barrier measures enforced by the government, in the wake of the corona virus disease 2019 (COVID-19) pandemic has led to behavioural changes which may have had an influence on the positivity rate of these diseases. This study seeks to determine the influence of COVID-19 barrier measures and the implementation of COVID-19 vaccination on the positivity rate of typhoidal salmonellosis and amoebiasis in the BHD. A retrospective study, with purposive and random sampling methods were used to select health facilities in BHD, whose laboratory records were reviewed using a data extraction form to obtain health information of patients who tested for typhoidal salmonella and/or Entamoeba histolytica from June 1, 2018 to December 31, 2021. Chi-square test was used to compare the positivity rate in the pre-and-COVID-19 and in the pre-and-vaccination era. The positivity rate of typhoidal salmonellosis and amoebiasis dropped from 57.8% and 2.7% in the pre-COVID-19 era to 34% and 1.8% in the COVID-19 era respectively, which were significant (χ2 = 945.8; P<0.001 and χ2 = 11.8; P = 0.001 respectively). Within the COVID-19 era, the positivity rate of salmonellosis and amoebiasis decreased from 39% and 2.6% before the implementation of COVID-19 vaccination to 27.7% and 0.8% respectively in the COVID-19 vaccination era and these differences were significant (χ2 = 149.1; P<0.001 and χ2 = 33.8; P<0.001 respectively). However, the positivity rate of salmonellosis between the rainy (43.5%) and the dry (42.8%) seasons and amoebiasis between the rainy (2.2%) and the dry (2%) seasons were not significantly different (χ2 = 0.6; P = 0.429 and χ2 = 0.54; P = 0.463 respectively). A significant decline in the positivity rate of typhoidal salmonellosis and amoebiasis was observed after the implementation of COVID-19 barrier measures and vaccination.

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.

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.

Prevalence of Amoebiasis and Associated Complications in India: A Systematic Review

PURPOSE

Intestinal protozoan parasites are responsible for diarrheal diseases causing significant morbidity and mortality. Entamoeba histolytica is the principle protozoan parasite associated with diarrheal infections. The infection is often associated with inaccessibility to clean drinking water and poor sanitary conditions in low- and middle-income countries including India. A comprehensive systematic review was performed to evaluate a reliable nationwide estimate for prevalence and geographic distribution of amoebiasis in India and the complications associated with it.

METHODS

We used the PRISMA guidelines to perform a systematic review and meta-analysis of articles published between the year 2001-2020. Two English language databases PubMed and Web of Science were searched to achieve relevant studies.

RESULTS

Initial searches resulted in 467 studies out of which 64 eligible articles involving data from 289,659 human subjects from 12 states and 4 union territories were included in the final analysis. Prevalence of amoebiasis ranged from 3-23% in asymptomatic population, 0.64-11% in symptomatic patients and 1-17.5% in HIV-infected patients. Highest prevalence was seen in Tamil Nadu, Andaman Nicobar Island and North East India. Extra intestinal invasion of Entamoeba histolytica leading to complications such as amoebic liver abscess, amoebic colitis, colonic perforation and ameboma were also reported. Such complications have the potential to increase healthcare burden and may prove to be fatal.

CONCLUSION

Amoebiasis remains a significant public health issue in India responsible for diarrheal diseases causing significant morbidity and mortality. Entamoeba histolytica is the principle protozoan parasite associated with amoebiasis. Public health efforts should be directed towards its control and better diagnostic methods should be employed for distinguishing between pathogenic and non-pathogenic species of Entamoeba.

Entamoeba species infection in patients seeking treatment for diarrhea and abdominal discomfort in Mukuru informal settlement in Nairobi, Kenya

Entamoeba histolytica is the only pathogenic species of the Entamoeba genus and is morphologically identical to E. dispar/E. moshkovskii (Entamoeba complex) hence cannot be microscopically differentiated. The other Entamoeba spp. found in humans (E. hartmanni, E. polecki, and E. coli) can be differentiated morphologically from this Entamoeba complex. However, some of their morphologic features overlap making differential diagnosis difficult. This study aimed at determining the occurrence of Entamoeba spp. in patients seeking treatment for diarrhea and/or abdominal discomfort at two clinics in Mukuru informal settlement in Nairobi, Kenya. Faecal samples were collected from 895 patients, examined microscopically following direct wet smear and formal-ether concentration methods. Entamoeba spp. positive faecal samples were subjected to DNA extraction and species-specific nested polymerase chain reaction of the 18S ribosomal RNA (rRNA). By microscopy, Entamoeba spp. cysts or trophozoites were detected in 114/895 (12.7%, 95% Confidence Interval (CI) 10.6-15.1) faecal samples. By nested PCR, the prevalence was: E. histolytica (7.5%, 95% CI 5.9-9.4, 67/895) and E. dispar (8.2%, 95% CI 6.5-10.2, 73/895). Among the Entamoeba spp. complex positive samples, nested PCR detected E. coli and E. hartmanni DNA in 63/114 (55.3%) and 37/114 (32.5%), samples respectively. Among the E. histolytica/E. dispar PCR negative samples (32.5%), 21 (18.4%) contained cysts of either E. coli (19) or E. hartmanni (2) by nested PCR. Entamoeba spp. infections were most common among participants aged 21-30 years; however it was not significant (P = 0.7). Entamoeba spp. infections showed an inverse relationship with diarrhea being most common among participants without diarrhea (P = 0.0). The difference was significant for E. histolytica (P = 0.0) but not significant for E. dispar (P = 0.1). Only E. dispar infections were significantly associated with sex (P = 0.0). This study highlights the need for differentiation of E. histolytica from other Entamoeba spp. by molecular tools for better management of amoebiasis.

Antineoplastic kinase inhibitors: A new class of potent anti-amoebic compounds

Entamoeba histolytica is a protozoan parasite which infects approximately 50 million people worldwide, resulting in an estimated 70,000 deaths every year. Since the 1960s E. histolytica infection has been successfully treated with metronidazole. However, drawbacks to metronidazole therapy exist, including adverse effects, a long treatment course, and the need for an additional drug to prevent cyst-mediated transmission. E. histolytica possesses a kinome with approximately 300–400 members, some of which have been previously studied as potential targets for the development of amoebicidal drug candidates. However, while these efforts have uncovered novel potent inhibitors of E. histolytica kinases, none have resulted in approved drugs. In this study we took the alternative approach of testing a set of twelve previously FDA-approved antineoplastic kinase inhibitors against E. histolytica trophozoites in vitro. This resulted in the identification of dasatinib, bosutinib, and ibrutinib as amoebicidal agents at low-micromolar concentrations. Next, we utilized a recently developed computational tool to identify twelve additional drugs with human protein target profiles similar to the three initial hits. Testing of these additional twelve drugs led to the identification of ponatinib, neratinib, and olmutinib were identified as highly potent, with EC₅₀ values in the sub-micromolar range. All of these six drugs were found to kill E. histolytica trophozoites as rapidly as metronidazole. Furthermore, ibrutinib was found to kill the transmissible cyst stage of the model organism E. invadens. Ibrutinib thus possesses both amoebicidal and cysticidal properties, in contrast to all drugs used in the current therapeutic strategy. These findings together reveal antineoplastic kinase inhibitors as a highly promising class of potent drugs against this widespread and devastating disease.

Every year, nearly a hundred thousand people worldwide die from infection by the intestinal parasite Entamoeba histolytica, despite the widespread availability of metronidazole as a treatment. Here we report that six anticancer drugs of the kinase inhibitor class possess potent anti-amoebic properties, with one of them killing both actively dividing parasite and its transmissible cysts. These anticancer kinase inhibitors, including the dual-purpose drug with both amoebicidal and cysticidal activities may be used to treat amoebiasis, especially in cancer patients or in life-threatening brain- and liver-infecting forms of the disease.

Possible role played by the SINE2 element in gene regulation, as demonstrated by differential processing and polyadenylation in avirulent strains of E. histolytica

Entamoeba histolytica represents a useful model in parasitic organisms due to its complex genomic organization and survival mechanisms. To counteract pathogenic organisms, it is necessary to characterize their molecular biology to design new strategies to combat them. In this report, we investigated a less-known genetic element, short interspersed nuclear element 2 (SINE2), that is present in this ameba and is highly transcribed and polyadenylated. In this study, we show that in two different nonvirulent strains of E. histolytica, SINE2 is differentially processed into two transcript fragments, that is, a full-length 560-nt fragment and a shorter 393-nt fragment bearing an approximately 18-nt polyadenylation tail. Sequence analysis of the SINE2 transcript showed that a Musashi-like protein may bind to it. Also, two putative Musashi-like sequences were identified on the transcript. Semiquantitative expression analysis of the two Musashi-like proteins identified in the E. histolytica genome (XP_648918 and XP_649094) showed that XP_64094 is overexpressed in the nonvirulent strains tested. The information available in the literature and the results presented in this report indicate that SINE2 may affect other genes, as observed with the epigenetic silencing of the G3 strain, by an antisense mechanism or via RNA-protein interactions that may ultimately be involved in the phenotype of nonvirulent strains of E. histolytica.

Development of amoebic liver abscess in early pregnancy years after initial amoebic exposure: a case report

BACKGROUND

Infection with Entamoeba histolytica and associated complications are relatively rare in developed countries. The overall low prevalence in the Western world as well as the possibly prolonged latency period between infection with the causing pathogen and onset of clinical symptoms may delay diagnosis of and adequate treatment for amoebiasis. Amoebic liver abscess (ALA) is the most common extraintestinal manifestation of invasive amoebiasis. Pregnancy has been described as a risk factor for development of invasive amoebiasis and management of these patients is especially complex.

CASE PRESENTATION

A 30-year-old Caucasian woman in early pregnancy presented to our emergency department with abdominal pain alongside elevated inflammatory markers and liver function tests. Travel history revealed multiple journeys to tropic and subtropic regions during the past decade and a prolonged episode of intermittently bloody diarrhea during a five month stay in Indonesia seven years prior to admission. Sonographic and magnetic resonance imaging revealed a 5 × 4 cm hepatic abscess. After ultrasound-guided transcutaneous liver drainage, both abscess fluids and blood cultures showed neither bacterial growth nor microscopic signs of parasitic disease. Serological testing confirmed an infection with Entamoeba histolytica, which was treated with metronidazole, followed by eradication therapy with paromomycin. Subsequent clinical, laboratory and imaging follow-up exams showed regression of the ALA. In addition, the pregnancy completed without complications and a healthy baby boy was born 7 months after termination of treatment.

CONCLUSIONS

This case of invasive amoebiasis in early pregnancy outside of endemic regions and several years after exposure demonstrates the importance of broad differential diagnostics in the context of liver abscesses. The complex interdisciplinary decisions regarding the choice of imaging techniques as well as interventional and antibiotic therapy in the context of pregnancy are discussed. Furthermore, we present possible explanations for pregnancy as a risk factor for an invasive course of amoebiasis.

Retained gallstones: an elusive complication of laparoscopic cholecystectomy

A young, healthy woman presented to the emergency department multiple times with right upper quadrant pain and subjective fevers for over a year after her laparoscopic cholecystectomy. The patient required multiple hospital visits and extensive work-ups before finally being diagnosed with retained gallstones in her abdomen. After surgical removal of the stones, her symptoms resolved completely. The case highlights the challenges in diagnosing retained gallstones, the substantial burdens they can impose on patients, and the importance of prevention and thorough documentation.

Huge Amoebic Liver Abscess in the Left Lobe Treated by Oral Administration of Metronidazole

A man in his 60s visited a clinic with chief complaints of a fever and general malaise. Suspecting a liver abscess in the left lobe with infiltration into the subcutaneous fat tissue under the rectus abdominis muscle based on computed tomography findings, we performed fine-needle aspiration. An amoebic liver abscess was diagnosed. Remission was achieved by the oral administration of metronidazole alone without placement of a drainage tube. The results obtained in this case suggest that the first line of treatment should be a non-invasive approach with oral administration alone. Invasive intervention should then be considered depending on subsequent progress.

Evaluation of Giardia intestinalis, Entamoeba histolytica and Cryptosporidium hominis/Cryptosporidium parvum in human stool samples by the BD MAXTM Enteric Parasite Panel

Although the microscopic examination of stool samples remains the reference method of choice for the diagnosis of intestinal protistan infections, this method is time-consuming and requires experienced and well-trained operators. The purpose of this study was to evaluate the level of agreement between the BD MAX ^TM Enteric Parasite Panel (EPP) and microscopy for the detection of Giardia intestinalis (Lambl, 1859), Cryptosporidium spp. and Entamoeba histolytica Schaudinn, 1903 in stool samples. The study included faecal samples of 362 patients who were admitted to our hospital due to gastrointestinal complaints. In the microscopic examination, which was made with the native-lugol method on the stool samples that were taken from the patients, cysts, trophozoites and eggs of the parasite were examined. The diagnosis of G. intestinalis, Cryptosporidium parvum Tyzzer, 1912 and Cryptosporidium hominis Morgan-Ryan, Fall, Ward, Hijjawi, Sulaiman, Fayer, Thompson, Olson, Lal et Xiao, 2002, and E. histolytica was made in the faecal samples using the EPP assay. In the microscopic examination, Cryptosporidium spp. positive stool samples were stained with kinyoun's acid-fast. In the microscopic examination, parasites were detected in 41 (11%) of the 362 stool samples. In contrast, EPP assay identified parasites in 23 (6.3%) of the samples. In the microscopic examination, E. histolytica and Entamoeba dispar Brumpt, 1925 were detected in 22 (6.1%) of the samples, G. intestinalis was seen in 15 (4.1%), and C. parvum or C. hominis were detected in three (0.8%); these values were five (1.4%), 16 (4.4%) and two (0.5%) positive with the EPP assay. Although C. parvum or C. hominis were detected as positive in the microscopic examination of three samples, only two of the samples were positive in both EPP assay and kinyoun's acid-fast method. The EPP assay is a relatively simple test that can distinguish E. histolytica and E. dispar, but it cannot replace microscopy in the diagnosis of amoebiasis. Diagnosis for G. intestinalis and C. parvum/C. hominis with the BD MAX^TM enteric parasite panel was equivalent to that with microscopy. We believe that E. histolytica must be diagnosed with nucleic acid amplification tests that have a high sensitivity and specificity like EPP assay in certain patient groups.

Molecular detection and genotyping of intestinal protozoa from different biogeographical regions of Colombia

Background

Intestinal parasitic protozoa represent a serious problem of public health particularly in developing countries. Protozoa such as Blastocystis, Giardia intestinalis, Entamoeba histolytica and Cryptosporidium spp. are associated with diarrheal symptoms. In Colombia, there is little region-specific data on the frequency and circulating genotypes/species of these microorganisms. Therefore, the main objective of our study was to employ molecular detection and genotyping of G. intestinalis and Blastocystis, Cryptosporidium and Entamoeba spp. in samples from different biogeographical regions of Colombia.

Methods

We collected 649 human fecal samples from five biogeographical regions of Colombia: the Amazon, Andean, Caribbean, Orinoco and Pacific regions. Blastocystis, G. intestinalis, Cryptosporidium spp. and Entamoeba complex were detected by microscopy and conventional PCR. Molecular genotyping was conducted to identify Blastocystis subtypes (STs) (18s), G. intestinalis assemblages (triose phosphate isomerase and glutamate dehydrogenase) and Cryptosporidium species (18s). Genetic diversity indices were determined using dnasp.5.

Results

We detected G. intestinalis in 45.4% (n = 280) of samples, Blastocystis in 54.5% (n = 336) of samples, Cryptosporidium spp. in 7.3% (n = 45) of samples, Entamoeba dispar in 1.5% (n = 9) of samples, and Entamoeba moshkovskii in 0.32% (n = 2) of samples. Blastocystis STs 1–4, 8 and 9 and G. intestinalis assemblages AII, BIII, BIV, D and G were identified. The following Cryptosporidium species were identified: C. hominis, C. parvum, C. bovis, C. andersoni, C. muris, C. ubiquitum and C. felis. The Caribbean region had the highest frequency for each of the microorganisms evaluated (91.9% for G. duodenalis, 97.3% for Blastocystis, 10.8% for Cryptosporidium spp., 13.5% for E. dispar and 2.7% for E. moshkovskii). The Orinoco region had a high frequency of Blastocystis (97.2%) and the Andean region had a high frequency of G. intestinalis (69.4%). High and active transmission was apparent in several regions of the country, implying that mechanisms for prevention and control of intestinal parasitosis in different parts of the country must be improved.

Entamoeba histolytica and amoebic liver abscess in northern Sri Lanka: a public health problem

Entamoeba histolytica (E. histolytica) is a facultative protozoan parasite implicated in amoebic liver abscesses (ALA), the most common extraintestinal manifestation of this infection. E. histolytica is endemic to sub-tropical and tropical countries and has been a major public health concern in northern Sri Lanka (SLK) for the last three decades. This has been attributed to a multitude of factors such as poor sanitation, hygiene, male sex, middle age, overcrowding, unsanitary practices in the production of indigenous alcoholic beverages, and alcohol consumption. Additionally, while rates of E. histolytica have declined substantially throughout the rest of the island, largely due to better infrastructure, it remains pervasive in the northern peninsula, which is generally less developed. Infection arises primarily from fecal-oral transmission through the consumption of contaminated drinking water containing cysts. Upon ingestion, cysts multiply into trophozoites and colonize the host colonic mucosa using lectin and cysteine proteases as virulence factors, leading to host invasion. Symptoms occur along a spectrum, from asymptomatology, to pyrexia, abdominal cramping, and amoebic dysentery. Colonization of the colon results in the formation of distinct flask-shaped ulcers along the epithelium, and eventual penetration of the lamina propria via the production of matrix metalloproteinases. ALA then develops through trophozoite migration via the mesenteric hepatic portal circulation, where microabscesses coalesce to form a single, large right-lobe abscess, commonly on the posterior aspect. The progression of infection to invasive disease is contingent on the unique interplay between host and pathogen factors, such as the strength of host-immunity to overcome infection and inherent pathogenicity of the Entamoeba species. As a preventable illness, E. histolytica complications such as ALA impose a significant burden on the healthcare system. This mini-review highlights epidemiological trends, risk factors, diagnostic modalities, treatment approaches, and opportunities for prevention of E. histolytica-induced ALA, to help address this endemic problem on the island of SLK.

Human Milk Oligosaccharides: Health Benefits, Potential Applications in Infant Formulas, and Pharmacology

The first months of life are a special time for the health development and protection of infants. Breastfeeding is the natural and best way of feeding an infant, and positively influences their development and health. Breast milk provides the ideal balance of nutrients for the infant and contains countless bioactive ingredients such as immunoglobulins, hormones, oligosaccharides and others. Human milk oligosaccharides (HMOs) are a very important and interesting constituent of human milk, and are the third most abundant solid component after lactose and lipids. They are a structurally and biologically diverse group of complex indigestible sugars. This article will discuss the mechanisms of action of HMOs in infants, such as their anti-adhesive properties, properties modulating the immune system, and impact on bacterial flora development. Many health benefits result from consuming HMOs. They also may decrease the risk of infection by their interactions with viruses, bacteria or protozoa. The commercial use of HMOs in infant formula, future directions, and research on the use of HMOs as a therapy will be discussed.

Parasitic Infections

Parasitic infections of the gastrointestinal tract are a cause of morbidity to millions of individuals worldwide. These parasites are endemic in underdeveloped countries with poor sanitation allowing for spread through contaminated water supplies. While much is known about these parasites, the cutaneous manifestations caused by infection are infrequently reported in the literature. The deposition of the parasites into the perianal region often leads to significant skin irritation. Cutaneous findings vary from a mild pruritus ani to a macular rash to even severe perianal ulceration. This article discusses the perianal cutaneous findings caused by the parasitic illnesses, amebiasis, schistosomiasis, Enterobius vermicularis , strongyloidiasis, and cutaneous larva migrans, as well as their respective management.

Clinical characteristics and treatment outcomes in a cohort of patients with pyogenic and amoebic liver abscess

Background

We describe the clinical features of a cohort of patients with liver abscesses and investigate relationships between clinical, radiological and microbiological findings and mortality.

Methods

Retrospective review of pyogenic (PLA) or amoebic liver abscesses (ALA) diagnosed and treated at a major infectious diseases department in London over 9 years.

Results

One hundred forty-one patient records were identified; 132 (93.6%) had PLA and 9 (6.4%) ALA. No organism was identified in 38.6% (51/132); a single bacterial species was isolated in 47.0% (62/132) of PLA, ≥ 2 in 14.4% (19/132). There was weak evidence of variation in abscess size by type of microorganism, with streptococcal PLA typically larger (p = 0.03 for Streptococcus milleri group, p = 0.05 for non-milleri streptococci). Patients with ALA were younger (median 41, IQR 37–51 years) than those with PLA (median 68, IQR 50.5–78 years) (p = 0.003) and all were male (9/9, 100%, (p = 0.03)), with a history of recent travel in the majority (6/9, 66.7% (p = 0.003)). C-reactive protein was higher in ALA than in PLA (p = 0.06). In the entire cohort, loculation (HR = 2.51 (95% CI 1.00–6.32), p = 0.04) and baseline ALP (HR = 4.78 (95% CI 1.19–19.2) per log₁₀ increase, p = 0.03) were associated with mortality. 16S ribosomal RNA (rRNA) analysis was used in a subset of culture-negative cases and increased the diagnostic yield by 13%.

Conclusions

Clinical or radiological features cannot be used to distinguish between PLA and ALA, or help identify the bacterial cause of PLA. However, ALA is more common in young, male patients with a history of travel. 16S rRNA analysis of abscess fluid has a role in improving microbiological diagnosis in culture-negative cases.

Electronic supplementary material

The online version of this article (10.1186/s12879-019-4127-8) contains supplementary material, which is available to authorized users.

Approach to amoebic colitis: Epidemiological, clinical and diagnostic considerations in a non-endemic context (Barcelona, 2007-2017)

Background

Amoebic colitis is the most frequent clinical manifestation of invasive intestinal infection due to Entamoeba histolytica and a common cause of diarrhoea worldwide. Since higher transmission rates are usually related to poor health and exposure to unhygienic conditions, cases reported in Europe usually involve immigrants and international travellers. The goal of this study was to characterise both the clinical and the epidemiological features of a European population diagnosed with amoebic colitis and then to evaluate the diagnostic tools and therapeutic options applied.

Methods and results

This was a retrospective observational study in which data from all patients diagnosed with amoebic colitis attending at the International Health Units of two tertiary referral hospitals, Germans Trias i Pujol University Hospital (Badalona, North Barcelona Metropolitan Area) and Vall d’Hebron University Hospital (Barcelona city) between 2007 and 2017 were analysed. During the study period 50 patients were diagnosed with amoebic colitis. Thirty-six (72%) were men, and immigrants accounted for 46% of all cases. Antecedents of any international travel were reported for 28 (56%), the most frequent destinations having been the Indian subcontinent, South and Central America and sub-Saharan Africa. Preexisting pathological conditions or any kind of immunosuppression were identified in 29 (58%) patients; of these, 13 (26%) had HIV infection—all of them men who have sex with men—and 5 (10%) had inflammatory bowel disease. Diarrhoea, abdominal pain and dysentery were the most frequently recorded symptoms of invasive amoebae. Diagnosis was made through microbiological study in 45 (90%) and/or histological identification of amoebae in colon biopsies in 10 (20%). After treatment with metronidazole (82%) or tinidazole (8%), all patients had good outcomes. Post-acute intraluminal treatment was indicated in 28 (56%).

Conclusions

Amoebic colitis should be suspected in patients with diarrhoea and compatible epidemiological risk factors (immigration, travelling abroad or men who have sex with men), especially if some degree of immunosuppression concurs. These risk factors must be taken into account in any diagnostic approach to inflammatory bowel disease (IBD), and active searches for stool parasites should be performed in such cases to rule out misdiagnosis or simultaneous amoebic infection. Treatment should include intraluminal anti-amoebic treatment in order to avoid relapse and prevent further spread of the disease.

Nontravel-related invasive Entamoeba histolytica infection with probable heterosexual transmission

Introduction

In industrialized countries, amebiasis usually occurs in migrants and travelers returning from areas where the disease is endemic, primarily by ingestion of contaminated food or water. Person-to-person transmission can occur, mainly by fecal-oral contact, but sexual transmission has also been described [1,[3], [4], [5]].

Presentation of case

We report a man with Entamoeba histolytica colitis and a large liver abscess (16.5 × 14 cm) in Portugal, who had no relevant travel history and whose only risk factor was his heterosexual partner. The abscess required drainage of 1950 mL of “chocolate-milk” purulent fluid, with rapid symptomatic improvement. The diagnosis was established by real-time reverse transcription PCR for Entamoeba histolytica in the liver aspirate, with positive IgG antibodies. He received a total of 16 days of ceftriaxone and metronidazole followed by 7 days of paromomycin.

Conclusion

As enteric infections may be sexually transmitted, in industrialized countries, even in the absence of travel, sexual history should not be neglected.

Seroprevalence data at a private teaching hospital in Kenya: An examination of Toxoplasma gondii, cytomegalovirus, rubella, hepatitis A, and Entamoeba histolytica

Background

Relevant seroprevalence data for endemic pathogens in a given region provide insight not only into a population’s susceptibility to acute infection or risk for reactivation disease but also into the potential need for policy initiatives aimed at reducing these risks. Data from sub-Saharan Africa are sparse and since Aga Khan University Hospital Nairobi is an internationally accredited hospital equipped with a laboratory electronic medical record system, analysis of pertinent local seroprevalence data has been made possible.

Methods

We have analyzed serology data from laboratory electronic records at a 300 bed tertiary private teaching hospital in Kenya for the dates, 2008 to 2017 for Toxoplasma gondii, cytomegalovirus, and rubella, which were used primarily for antenatal screening. We also analyzed the data from hepatitis A and amebiasis serologies, which were used primarily for diagnostic purposes.

Results

For T. gondii, cytomegalovirus, and rubella, we used IgG serology to determine seroprevalence, finding rates of 32%, 86%, and 89%, respectively. There was no significant age-related difference in the 20 to 49 year old age range for any of these three pathogens. Of the Hepatitis A IgM tests that were ordered, 33% were positive with a peak positive rate of 70% in the five to nine year old age range. The seroprevalence of amebiasis was 4% and all cases of seropositivity were accompanied by compatible clinical illness (hepatic abscess).

Conclusions

These data provide insight into seroprevalence rates of selected pathogens that can be used to guide screening and diagnostic laboratory testing as well as private and public immunization practices.

Primary cecal pathologies presenting as acute abdomen and critical appraisal of their current management strategies in emergency settings with review of literature

Background:

The importance of cecal pathologies lie in the fact that being the first part of the large intestine, any disease involving the cecum affects the overall functioning of the large bowel. Primary cecal pathologies presenting as acute abdomen have not been described in any previous study in terms of presentation, management, and outcome.

Objectives:

The objective of this study was to identify the reported causes of primary cecal pathologies presenting as acute abdomen and the various causes presenting in our setting, the to discuss morbidity and mortality associated with cecal pathologies, and to critically analyze the various management modalities employed in an emergency setting.

Materials and Methods:

This is a retrospective analysis of a prospectively collected data of all adult patients admitted to our unit in the last 10 years for acute abdomen, in whom cecal pathology was identified as the primary offending agent.

Results:

Our analysis of 43 patients revealed cecal perforation secondary to amebic colitis along with the simultaneous presence of liver abscess to be the most common primary cecal entity met in practice as acute abdomen. Other pathologies that were encountered included volvulus, diverticulitis, and idiopathic typhlitis. Primary acute cecal pathologies are associated with high mortality rates (≈42%). Delay in diagnosis seems to be the most important factor contributing to high mortality as these conditions are commonly misdiagnosed as appendicular pathology. Most of our patients were managed by conservative colonic resection with proximal diversion. This seems to be a more plausible option in current practice in an emergency setting (mortality rate ≈ 36%) as hemicolectomy is associated with proportionately higher mortality rates (67%).

Conclusion:

A high index of suspicion, timely and adequate pre-operative workup, optimal resuscitation, and surgical conservatism with proximal diversion might help in early accurate identification of these conditions and possibly improved outcome.

Nuclear transport in Entamoeba histolytica: knowledge gap and therapeutic potential

Entamoeba histolytica is the protozoan parasite that causes human amoebiasis. It is one of the leading parasitic disease burdens in tropical regions and developing countries, with spread to developed countries through migrants from and travellers to endemic regions.Understanding E. histolytica's invasion mechanisms requires an understanding of how it interacts with external cell components and how it engulfs and kills cells (phagocytosis). Recent research suggests that optimal phagocytosis requires signalling events from the cell surface to the nucleus via the cytoplasm, and the induction of several factors that are transported to the plasma membrane. Current research in other protozoans suggests the presence of proteins with nuclear localization signals, nuclear export signals and Ran proteins; however, there is limited literature on their functionality and their functional similarity to higher eukaryotes.Based on learnings from the development of antivirals, nuclear transport elements in E. histolytica may present viable, specific, therapeutic targets.In this review, we aim to summarize our limited knowledge of the eukaryotic nuclear transport mechanisms that are conserved and may function in E. histolytica.

Novel Entamoeba Findings in Nonhuman Primates

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

Practical Guidance for Clinical Microbiology Laboratories: Laboratory Diagnosis of Parasites from the Gastrointestinal Tract

This Practical Guidance for Clinical Microbiology document on the laboratory diagnosis of parasites from the gastrointestinal tract provides practical information for the recovery and identification of relevant human parasites. The document is based on a comprehensive literature review and expert consensus on relevant diagnostic methods. However, it does not include didactic information on human parasite life cycles, organism morphology, clinical disease, pathogenesis, treatment, or epidemiology and prevention. As greater emphasis is placed on neglected tropical diseases, it becomes highly probable that patients with gastrointestinal parasitic infections will become more widely recognized in areas where parasites are endemic and not endemic. Generally, these methods are nonautomated and require extensive bench experience for accurate performance and interpretation.

A Unique Case of Empyema Secondary to Amoebic Liver Abscess

An amoebic liver abscess is an extraintestinal manifestation of amoebiasis that can present with complaints such as right upper quadrant pain and fever. It might not necessarily be associated with abdominal complaints and can have many other atypical presentations. It may present with lung diseases, cardiac diseases, or brain abscesses. We present a case of a patient with empyema secondary to amoebic liver abscess whose diagnosis was delayed due to an unusual presentation. A combination of radiology, serology, and therapeutic interventions led to the accurate management of the patient.

Entamoeba histolytica Infection in Female Sex Workers: A Matched Case-Control Study in Durango, Mexico

Background

Infection with Entamoeba histolytica (E. histolytica) can be potentially transmitted by sexual contact. The seroepidemiology of E. histolytica in female sex workers has not been studied. The aim of the study was to determine whether E. histolytica is associated with the occupation of female sex work. In addition, the correlates of E. histolytica seroprevalence in female sex workers were also investigated.

Methods

We performed an age- and gender-matched case-control study of 187 female sex workers and 374 women without sex work. Cases and controls were tested for the presence of E. histolytica IgG antibodies using a commercially available enzyme-linked immunoassay. Seroprevalence association with the characteristics of female sex workers was determined by bivariate analysis.

Results

Anti-E. histolytica IgG antibodies were found in five (2.7%) of 187 female sex workers and in 16 (4.3%) of 374 controls (odds ratios (OR) = 0.61; 95% confidence intervals (CI): 0.22 - 1.70; P = 0.34). Mean optical density of the immunoassay in seropositive cases and controls was 1.35 ± 0.93 and 0.73 ± 0.45, respectively (P = 0.05). Seroprevalence of E. histolytica infection did not vary significantly with age, education, socioeconomic level, or health status of sex workers. Seropositivity to E. histolytica did not correlate with work characteristics such as duration in the occupation, condom use, type of sex, or a history of sexually transmitted diseases, or with behavioral variables such as washing hands before eating, or consumption of untreated water.

Conclusions

Results indicate that female sex workers do not have an increased risk for E. histolytica infection in Durango City, Mexico. Further studies to determine the risk of infection with E. histolytica by sexual contact should be conducted.

Parasites

Parasites are an important cause of human disease worldwide. The clinical severity and outcome of parasitic disease is often dependent on the immune status of the host. Specific parasitic diseases discussed in this chapter are amebiasis, giardiasis, cryptosporidiosis, cyclosporiasis, cystoisosporiasis, microsporidosis, granulomatous amebic encephalitis, toxoplasmosis, leishmaniasis, Chagas disease, malaria, babesiosis, strongyloidiasis, and scabies.

Primary Pulmonary Amebiasis Complicated with Multicystic Empyema

Amebiasis is a parasitic infection caused by the protozoan Entamoeba histolytica. While most infections are asymptomatic, the disease could manifest clinically as amebic dysentery and/or extraintestinal invasion in the form of amebic liver abscess or other more rare manifestations such as pulmonary, cardiac, or brain involvement. Herein we are reporting a case of a 24-year-old male with history of Down syndrome who presented with severe right side pneumonia complicated with multicystic empyema resistant to regular medical therapy. Further investigation revealed a positive pleural fluid for E. histolytica cysts and trophozoites. The patient was diagnosed with primary pleuropulmonary amebiasis and he responded promptly to surgical drainage and metronidazole therapy. In patients from endemic areas all physicians should keep a high index of suspicion of amebiasis as a cause of pulmonary disease.

Diagnostic errors of right lower quadrant pain in children: beyond appendicitis

Right lower quadrant pain in children can result from various underlying conditions other than acute appendicitis. The common mimics of acute appendicitis are related to acute gastrointestinal and genitourinary diseases. Diagnosis of right lower quadrant pain in the pediatric population can be challenging, especially when the symptoms are often nonspecific. This article reviews the currently available imaging techniques for evaluating a child with right lower quadrant pain and the spectrum of differential diagnoses with a focus on imaging clues to a specific diagnosis.

Current status of Blastocystis: A personal view

Despite Blastocystis being one of the most widespread and prevalent intestinal eukaryotes, its role in health and disease remains elusive. DNA-based detection methods have led to a recognition that the organism is much more common than previously thought, at least in some geographic regions and some groups of individuals. Molecular methods have also enabled us to start categorizing the vast genetic heterogeneity that exists among Blastocystis isolates, wherein the key to potential differences in the clinical outcome of Blastocystis carriage may lie. In this review we summarize some of the recent developments and advances in Blastocystis research, including updates on diagnostic methods, molecular epidemiology, genetic diversity, host specificity, clinical significance, taxonomy, and genomics. As we are now in the microbiome era, we also review some of the steps taken towards understanding the place of Blastocystis in the intestinal microbiota.

PREVALENCE, RISK FACTORS AND SYMPTOMS ASSOCIATED TO INTESTINAL PARASITE INFECTIONS AMONG PATIENTS WITH GASTROINTESTINAL DISORDERS IN NAHAVAND, WESTERN IRAN

We studied the prevalence of intestinal parasites (IPs), their risk factors and associated symptoms among patients with gastrointestinal disorders. A total of 1,301 participants aged 22 days-90 years were enrolled in this study. We used a structured questionnaire to obtain socio-demographic and stool examination to investigate intestinal parasite infections. Data analysis was performed using SPSS16. The overall prevalence of intestinal parasites (IPs) was 32.2% (419/1,301). Three hundred and fifty nine cases/1,301 (27.6%) were infected with a single parasite and 60/1,301 cases (4.6%) presented polyparasitism. The most common IP was Blastocystis sp. 350/1,301 (26.9%), followed by Entamoeba coli 38/1,301 (2.92%), Giardia lamblia 30/1,301 (2.3%) and Cryptosporidium spp. 17/1,301 (1.3%). Regarding the socio-demographic variables, educational status (p = 0.001), contact with domestic animals and soil (p = 0.02), age above 15 years (p = 0.001) and seasons (p = 0.001) were significantly associated to intestinal parasitic infections. Concerning clinical characteristics, the presence of IPs was significantly associated to diarrhea (OR = 1.57; CI 95% = 1.24-1.98; p < 0.001) and dysentery (OR = 1.94; CI 95% = 1.03-3.66; p < 0.04). Our findings suggest that IPs are one of the main causal agents of gastrointestinal disorders. Improving the knowledge on local risk factors such as poverty, low level of education, poor sanitation, contact with soil and contact with domestic animal is warranted.

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

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

Development of RNA Interference Trigger-Mediated Gene Silencing in Entamoeba invadens

Entamoeba histolytica, a protozoan parasite, is an important human pathogen and a leading parasitic cause of death. The organism has two life cycle stages, trophozoites, which are responsible for tissue invasion, and cysts, which are involved in pathogen transmission. Entamoeba invadens is the model system to study Entamoeba developmental biology, as high-grade regulated encystation and excystation are readily achievable. However, the lack of gene-silencing tools in E. invadens has limited the molecular studies that can be performed. Using the endogenous RNA interference (RNAi) pathway in Entamoeba, we developed an RNAi-based trigger gene-silencing approach inE. invadens We demonstrate that a gene's coding region that has abundant antisense small RNAs (sRNAs) can trigger silencing of a gene that is fused to it. The trigger fusion leads to the generation of abundant antisense sRNAs that map to the target gene, with silencing occurring independently of trigger location at the 5' or 3' end of a gene. Gene silencing is stably maintained during development, including encystation and excystation. We have used this approach to successfully silence two E. invadens genes: a putative rhomboid protease gene and a SHAQKY family Myb gene. The Myb gene is upregulated during oxidative stress and development, and its downregulation led, as predicted, to decreased viability under oxidative stress and decreased cyst formation. Thus, the RNAi trigger silencing method can be used to successfully investigate the molecular functions of genes inE. invadens Dissection of the molecular basis of Entamoeba stage conversion is now possible, representing an important technical advance for the system.

Identification of Entamoeba moshkovskii in Treated Waste Water Used for Agriculture

We conducted an observational study to determine the prevalence of Entamoeba spp., in samples collected in a waste water treatment plant that provides water for agricultural irrigation. Samples were collected weekly over a period of 10 weeks at representative contamination stages from within the treatment plant. Protozoan identification was performed via light microscopy and culture. PCR amplification of small subunit rRNA gene sequences of E. histolytica/dispar/moshkovskii was performed in culture positive samples. Light microscopy revealed the presence of Entamoeba spp., in 70% (14/20) of the raw waste water samples and in 80% (8/10) of the treated water samples. PCR amplification after culture at both 24 and 37°C revealed that 100% (29/29) of the raw waste water samples and 78.6% (11/14) of the treated waste water were positive for E. moshkovskii. We report the first isolation of E. moshkovskii in Colombia, confirmed by PCR. Recent reports of E. moshkovskii pathogenic potential suggest this finding could constitute a public health risk for people exposed to this water.

Amebic Liver Abscess in Israeli Travelers: A Retrospective Study

Amebic liver abscess (ALA) is endemic in developing countries. The epidemiology and clinical characteristics of the disease in developing countries are well described. Travelers from nonendemic countries can serve as a model for the natural history of ALA. Currently, the available literature on travelers is limited. This is a retrospective observational study on Israeli travelers diagnosed with ALA. Data regarding travel history, clinical presentation, imaging, and treatment were collected and analyzed. Among 6,867 ill returning Israeli travelers, amebiasis was diagnosed in 53 travelers (0.77%), of whom 14 were with ALA (0.2%). Twelve ALA cases (86%) had an exposure in the Indian subcontinent. The male to female ratio was 1:1, with no significant clinical differences between the sexes. The average lag period between exposure and onset of symptoms was 17.1 months. The lack of male predominance and the prolonged lag period may imply that behavioral factors are pivotal in the development of ALA. Larger case series of travelers are required.

Molecular prevalence of Entamoeba histolytica/dispar infection among patients attending four health centres in north-west Ethiopia

The prevalence of amoebiasis is often overestimated owing to its epidemiological overlap with the non-pathogenic Entamoeba dispar To provide evidence for this conjecture, a cross-sectional study was conducted from November 2013 to January 2015. A range of 180-200 µg of semi-solid and formed stools and 200 µL of diarrhoeic stool samples were used for DNA extraction from microscopically E. histolytica/dispar positive samples using the QIAamp® DNA Stool Mini Kit according to manufacturers' instructions. Nested PCR targeting 18S ribosomal RNA gene was used. In 422 microscopically positive E. histolytica/dispar stools, molecular prevalence revealed that E. histolytica infestation was present in only 1.7% (95% confidence interval [CI], 0.47-2.93) and E. dispar was found in 42.2% (95% CI, 37.49-46.91), while 56.2% (95% CI, 51.47-60.93) had neither E. histolytica nor E. dispar (P < 0.001). We conclude that infestation with E. histolytica is rarer in our study areas than was previously believed. Hence, accurate differentiation of E. histolytica and E. dispar is crucial.

Burden of major diarrheagenic protozoan parasitic co-infection among amoebic dysentery cases from North East India: a case report

Intestinal diarrheagenic polyparasitic infections are among the major public health concerns in developing countries. Here we examined stool specimens by microscopy, DNA dot blot and polymerase chain reaction (PCR) to evaluate the co-infection of four principal protozoans among amoebic dysentery cases from Northeast Indian population. The multiplex PCR confirmed Entamoeba histolytica (8.1%), Entamoeba dispar (4.8%) and mixed infection of both the parasites (3.4%) in 68 of 356 stool specimens that were positive in microscopy and/or HMe probe based DNA dot blot screening. The prevailing parasite that co-exists with E. histolytica was Giardia duodenalis (34.1%), followed by Enterocytozoon bieneusi (22.0%), Cryptosporidium parvum (14.6%) and Cyclospora cayetanensis (7.3%, P = 0.017). Symptomatic participants (odds ratio (OR) = 4.07; 95% confidence interval (CI) = 1.06, 15.68; P = 0.041), monsoon season (OR = 7.47; 95% CI = 1.40, 39.84; P = 0.046) and participants with family history of parasitic infection (OR = 4.50; 95% CI = 1.16, 17.51; P = 0.030) have significant association with overall co-infection rate. According to molecular consensus, comprehensive microscopy yielded 3.4% (12/356) false-negative and 7.6% (27/356) false-positive outcome, suggesting an improved broad-spectrum PCR-based diagnostic is required to scale down the poor sensitivity and specificity as well as implementation of integrated control strategy.

Clinical manifestations and endoscopic findings of amebic colitis in a United States-Mexico border city: a case series

Background

Invasive amebiasis is not frequently seen in the United States. It is associated with considerable morbidity in patients residing in or traveling to endemic areas. We report a case series of patients with amebic colitis in a United States-Mexico border city to alert physicians to the varied clinical manifestations.

Case presentation

Nine patients were diagnosed with amebic colitis. Mean age was 56 (38–83), 6 were males, and all were Hispanic. Common symptoms were diarrhea (56 %), hematochezia (33 %) and abdominal bloating (11 %). The diagnosis of amebic colitis was established in the following ways: 8 patients by colonoscopy with biopsy, 1 by surgery for colonic obstruction. The diagnosis of amebic colitis was confirmed in 8 patients (89 %) by amebic trophozoites present in histopathologic sections. One patient was diagnosed with amebic colitis based upon clinical symptoms, colitis on colonoscopy and visualization of amebic trophozoites on stool examination. In the 8 patients in whom colonoscopy was done, 6 (75 %) had inflammation with rectosigmoid involvement and 5 (62.5 %) had ulcerations. Infection resolved after treatment with metronidazole in most patients; however, one patient developed a liver abscess and another had a colonic perforation and later developed a liver abscess.

Conclusion

The occurrence of amebic colitis in this United States-Mexico border city hospital population was low, but in some cases potentially life-threatening. Physicians should be alert to the less common presentations of amebic colitis, such as overt gastrointestinal bleeding, exacerbation of inflammatory bowel disease, and the incidental finding of association with colon cancer, or a surgical abdomen. Rectosigmoid involvement was typically found on colonoscopy.

Evaluation of the BD Max Enteric Parasite Panel for Clinical Diagnostics

We compared the performance of the BD Max enteric parasite panel to routine microscopy and an in-house PCR for the detection of Giardia intestinalis, Entamoeba histolytica, and Cryptosporidium spp. The enteric parasite panel showed good specificity for all targets and good sensitivity for E. histolytica and Cryptosporidium spp. Sensitivity for G. intestinalis with the BD Max enteric parasite panel was equivalent to that with microscopy.

The functional biology of human milk oligosaccharides

Human milk oligosaccharides (HMOs) are a group of complex sugars that are highly abundant in human milk, but currently not present in infant formula. More than a hundred different HMOs have been identified so far. The amount and composition of HMOs are highly variable between women, and each structurally defined HMO might have a distinct functionality. HMOs are not digested by the infant and serve as metabolic substrates for select microbes, contributing to shape the infant gut microbiome. HMOs act as soluble decoy receptors that block the attachment of viral, bacterial or protozoan parasite pathogens to epithelial cell surface sugars, which may help prevent infectious diseases in the gut and also the respiratory and urinary tracts. HMOs are also antimicrobials that act as bacteriostatic or bacteriocidal agents. In addition, HMOs alter host epithelial and immune cell responses with potential benefits for the neonate. The article reviews current knowledge as well as future challenges and opportunities related to the functional biology of HMOs.

Molecular Epidemiology of Entamoeba: First Description of Entamoeba moshkovskii in a Rural Area from Central Colombia

Background

Entamoeba histolytica, E. dispar and E. moshkovskii are the most frequent species described in human infection where E. histolytica is the only true pathogen. The epidemiology of this infection is complex due to the absence of a routine exam that allows a correct discrimination of the Entamoeba species complex. Therefore, molecular methods appear as the unique epidemiological tool to accomplish the species discrimination. Herein, we conducted a cross-sectional study to determine the frequency of Entamoeba species infections in a group of asymptomatic individuals from a rural area in central Colombia.

Methodology/Principal Findings

A total of 181 fecal samples from asymptomatic children under 16 years old from the hamlet La Vírgen, Cundinamarca (Colombia) that voluntarily accepted to participate in the study were collected. The fecal samples were examined by light microscopy and DNA-extracted, subsequently submitted to molecular discrimination of E. dispar/E. histolytica/E. moshkovskii infection based on a multiplex PCR assay targeting the 18S rRNA fragment. To confirm the species description, twenty samples were randomly submitted to DNA sequencing of the aforementioned fragment. By direct microscopic examination, frequency of the complex E. histolytica/E. dispar/E. moshkovskii was 18.8% (34/181). PCR showed a frequency of 49.1% (89/181), discriminated as 23.2% (42/181) that were positive for E. dispar, 25.4% (46/181) for E. moshkovskii and 0.55% (1/ 181) for E. histolytica. Also, mixed infections were detected between E. dispar and E. moshkovskii at 4.42% (8/181) of the samples. Molecular barcoding confirmed the diagnosis depicted by the multiplex PCR assay.

Conclusions/Significance

This is the first description of E. moshkovskii in Colombia and the second report in South-America to our knowledge. Our results suggest the need to unravel the true epidemiology of Entamoeba infections around the world, including the real pathogenic role that E. moshkovskii may have.