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Abstract
Although rare in the developed world, amebiasis continues to be a leading cause of diarrhea and illness in developing nations with crowding, poor sanitation, and lack of clean water supply. Recent immigrants or travelers returning from endemic regions after a prolonged stay are at high risk of developing amebiasis. A high index of suspicion for amebiasis should be maintained for other high-risk groups like men having sex with men, people with AIDS/HIV, immunocompromised hosts, residents of mental health facility or group homes. Clinical presentation of intestinal amebiasis varies from diarrhea to colitis and dysentery. Amebic liver abscess (ALA) is the most common form of extraintestinal amebiasis. Various diagnostic tools are available and when amebiasis is suspected, a combination of stool tests and serology should be sent to maximize the yield of testing. Treatment with an amebicidal drug such as metronidazole/tinidazole and a luminal cysticidal agent such as paromomycin for clinical disease is indicated. However, for asymptomatic disease treatment with a luminal cysticidal agent to decrease chances of invasive disease and transmission is recommended.
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Affiliation(s)
- Shipra Gupta
- West Virginia University School of Medicine, One Medical Center Drive, HSC 9214, Morgantown, WV 26506, USA.
| | - Layne Smith
- West Virginia University School of Pharmacy, One Medical Center Drive, Morgantown, WV-26506, USA
| | - Adriana Diakiw
- West Virginia University School of Medicine, One Medical Center Drive, HSC 9214, Morgantown, WV 26506, USA
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Dos Santos Zanetti A, Malheiros AF, de Matos TA, Dos Santos C, Battaglini PF, Moreira LM, Lemos LMS, Castrillon SKI, da Costa Boamorte Cortela D, Ignotti E, Espinosa OA. Diversity, geographical distribution, and prevalence of Entamoeba spp. in Brazil: a systematic review and meta-analysis. ACTA ACUST UNITED AC 2021; 28:17. [PMID: 33812449 PMCID: PMC8019558 DOI: 10.1051/parasite/2021028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 03/11/2021] [Indexed: 11/29/2022]
Abstract
The genus Entamoeba includes a variety of widely distributed species adapted to live in the digestive tracts of humans and a large variety of animals of different classes. The objective of this study was to investigate the prevalence, distribution, and molecular epidemiology of Entamoeba spp. in different classes of hosts in Brazil. Studies that analyzed hosts from several classes, including humans and domestic, wild, or captive animals, were considered. The pooled prevalence of Entamoeba spp. was calculated using the random-effects model. A total of 166 studies on humans and 16 on animals were included. The prevalence of Entamoeba spp. in the Brazilian population was 22% (95% CI: 21–24). The state with the highest prevalence was Paraiba with 72%, followed by Federal District with 53%, and Rondonia with 50%. In immunocompromized patients, the prevalence was 18%, and cancer (36%) was the most prevalent cause of immunosuppression. The prevalence of Entamoeba spp. in animal hosts was 12% (95% CI: 7–17). Captive wild animals and domestic farm animals showed the highest prevalence, with 16% and 15%, respectively. The species found more often were E. coli (86.5%), E. dispar (7.9%), and E. histolytica (3.1%). In conclusion, a high prevalence (22%) of Entamoeba spp. was found in the Brazilian population, with a prevalence of up to 50% mainly in the northern, northeastern, and central-western regions. The pathogenic species E. histolytica is distributed in most Brazilian regions, with significant prevalence percentages. Among animals, unidentified Entamoeba species were most prevalent in mammals.
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Affiliation(s)
- Andernice Dos Santos Zanetti
- Post-Graduation Program in Environmental Science, Faculty of Agricultural and Biological Sciences, State University of Mato Grosso (UNEMAT), Tancredo Neves Ave., 1095 - Cavalhada II, Caceres, 78217-042 Mato Grosso, Brazil
| | - Antonio Francisco Malheiros
- Post-Graduation Program in Environmental Science, Faculty of Agricultural and Biological Sciences, State University of Mato Grosso (UNEMAT), Tancredo Neves Ave., 1095 - Cavalhada II, Caceres, 78217-042 Mato Grosso, Brazil
| | - Tatiane Amorim de Matos
- Post-Graduation Program in Environmental Science, Faculty of Agricultural and Biological Sciences, State University of Mato Grosso (UNEMAT), Tancredo Neves Ave., 1095 - Cavalhada II, Caceres, 78217-042 Mato Grosso, Brazil
| | - Carolina Dos Santos
- Post-Graduation Program in Environmental Science, Faculty of Agricultural and Biological Sciences, State University of Mato Grosso (UNEMAT), Tancredo Neves Ave., 1095 - Cavalhada II, Caceres, 78217-042 Mato Grosso, Brazil
| | - Paula Franciene Battaglini
- Residency in Infectious Diseases, Júlio Miller University Hospital, Federal University of Mato Grosso, Luis Philippe Pereira Leite St., Alvorada, Cuiabá, 78048-902 Mato Grosso, Brazil
| | - Luciana Melhorança Moreira
- Faculty of Agricultural and Biological Sciences, State University of Mato Grosso (UNEMAT), Tancredo Neves Ave., 1095 - Cavalhada II, 78217-042 Caceres, Mato Grosso, Brazil
| | - Larissa Maria Scalon Lemos
- Department of Nursing, Faculty of Health Sciences, State University of Mato Grosso (UNEMAT), Tancredo Neves Ave., 1095 - Cavalhada II, Caceres, 78217-042 Mato Grosso, Brazil
| | - Solange Kimie Ikeda Castrillon
- Post-Graduation Program in Environmental Science, Faculty of Agricultural and Biological Sciences, State University of Mato Grosso (UNEMAT), Tancredo Neves Ave., 1095 - Cavalhada II, Caceres, 78217-042 Mato Grosso, Brazil
| | - Denise da Costa Boamorte Cortela
- Department of Medicine, Faculty of Health Sciences, State University of Mato Grosso (UNEMAT), Tancredo Neves Ave., 1095 - Cavalhada II, 78217-042 Caceres, Mato Grosso, Brazil
| | - Eliane Ignotti
- Post-Graduation Program in Environmental Science, Faculty of Agricultural and Biological Sciences, State University of Mato Grosso (UNEMAT), Tancredo Neves Ave., 1095 - Cavalhada II, Caceres, 78217-042 Mato Grosso, Brazil
| | - Omar Ariel Espinosa
- Faculty Estacio of Pantanal (Estacio FAPAN), São Luís, 2522 St - Cidade Nova, Caceres, 78201-000 Mato Grosso, Brazil
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Al-Areeqi MA, Sady H, Al-Mekhlafi HM, Anuar TS, Al-Adhroey AH, Atroosh WM, Dawaki S, Elyana FN, Nasr NA, Ithoi I, Lau YL, Surin J. First molecular epidemiology of Entamoeba histolytica, E. dispar and E. moshkovskii infections in Yemen: different species-specific associated risk factors. Trop Med Int Health 2017; 22:493-504. [PMID: 28151567 DOI: 10.1111/tmi.12848] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVES To investigate the molecular epidemiology of Entamoeba histolytica, E. dispar and E. moshkovskii infections among rural communities in Yemen. METHODS In a community-based study, faecal samples were collected from 605 participants and examined by wet mount, formalin-ether sedimentation, trichrome staining and nested multiplex PCR techniques. Demographic, socio-economic and environmental information was collected using a pre-tested questionnaire. RESULTS Overall, 324 (53.6%) of the samples were positive for Entamoeba cysts and/or trophozoites by microscopic examination. Molecular analysis revealed that 20.2%, 15.7% and 18.2% of the samples were positive for E. histolytica, E. dispar and E. moshkovskii, respectively. Multivariate analysis showed different sets of species-specific risk factors among these communities. Educational level was identified as the significant risk factor for E. histolytica; age and gender were the significant risk factors for E. moshkovskii; and sources of drinking water and consumption of unwashed vegetables were the significant risk factors for E. dispar. Moreover, living in coastal/foothill areas and presence of other infected family members were risk factors for both E. histolytica and E. moshkovskii infections. CONCLUSION The study reveals that Entamoeba spp. infection is highly prevalent among rural communities in Yemen, with E. histolytica, E. dispar and E. moshkovskii differentiated for the first time. Identifying and treating infected family members, providing health education pertinent to good personal and food hygiene practices and providing clean drinking water should be considered in developing a strategy to control intestinal parasitic infections in these communities, particularly in the coastal/foothill areas of the country.
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Affiliation(s)
- Mona A Al-Areeqi
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.,Department of Parasitology, Faculty of Medicine and Health Sciences, Sana'a University, Sana'a, Yemen
| | - Hany Sady
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.,Department of Medical Laboratories, Faculty of Medical Sciences, Hodeidah University, Hodeidah, Yemen
| | - Hesham M Al-Mekhlafi
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.,Department of Parasitology, Faculty of Medicine and Health Sciences, Sana'a University, Sana'a, Yemen.,Endemic and Tropical Diseases Unit, Medical Research Center, Jazan University, Jazan, Saudi Arabia
| | - Tengku Shahrul Anuar
- Integrative Pharmacogenomics Institute, Universiti Teknologi MARA, Puncak Alam Campus, Selangor, Malaysia.,Department of Medical Laboratory Technology, Faculty of Health Sciences, Universiti Teknologi MARA, Puncak Alam Campus, Selangor, Malaysia
| | - Abdulelah H Al-Adhroey
- Department of Community Medicine, Faculty of Medicine and Health Sciences, Thamar University, Dhamar, Yemen
| | - Wahib M Atroosh
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Salwa Dawaki
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Fatin Nur Elyana
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Nabil A Nasr
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Init Ithoi
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Yee-Ling Lau
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Johari Surin
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.,Centre for Research and Innovation, Taylor's University, Selangor, Malaysia
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Abstract
Amebiasis is a disease caused by the protozoan parasite Entamoeba histolytica. This ameba can colonize the human intestine and persist as a commensal parasite, similar to Entamoeba dispar, an ameba considered to be non-pathogenic. The similarities between E. histolytica and E. dispar make the latter an attractive model for studies aimed at clarifying the pathogenesis of amebiasis. However, in addition to being an interesting experimental model, this relative of E. histolytica remains poorly understood. In the 1990, it was believed that E. dispar was unable to produce significant experimental lesions. This scenario began to change in 1996, when E. dispar strains were isolated from symptomatic patients in Brazil. These strains were able to produce liver and intestinal lesions that were occasionally indistinguishable from those produced by E. histolytica. These and other findings, such as the detection of E. dispar DNA sequences in samples from patients with amebic liver abscess, have revived the possibility that this species can produce lesions in humans. The present paper presents a series of studies on E. dispar that begin to reveal a new facet of this protozoan.
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Affiliation(s)
- Fabrício Marcus Silva Oliveira
- Department of General Pathology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Elisabeth Neumann
- Department of Microbiology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Maria Aparecida Gomes
- Department of Parasitology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Marcelo Vidigal Caliari
- Department of General Pathology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
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Ali IKM, Haque R, Siddique A, Kabir M, Sherman NE, Gray SA, Cangelosi GA, Petri WA. Proteomic analysis of the cyst stage of Entamoeba histolytica. PLoS Negl Trop Dis 2012; 6:e1643. [PMID: 22590659 PMCID: PMC3348168 DOI: 10.1371/journal.pntd.0001643] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Accepted: 03/30/2012] [Indexed: 11/23/2022] Open
Abstract
Background The category B agent of bioterrorism, Entamoeba histolytica has a two-stage life cycle: an infective cyst stage, and an invasive trophozoite stage. Due to our inability to effectively induce encystation in vitro, our knowledge about the cyst form remains limited. This also hampers our ability to develop cyst-specific diagnostic tools. Aims Three main aims were (i) to identify E. histolytica proteins in cyst samples, (ii) to enrich our knowledge about the cyst stage, and (iii) to identify candidate proteins to develop cyst-specific diagnostic tools. Methods Cysts were purified from the stool of infected individuals using Percoll (gradient) purification. A highly sensitive LC-MS/MS mass spectrometer (Orbitrap) was used to identify cyst proteins. Results A total of 417 non-redundant E. histolytica proteins were identified including 195 proteins that were never detected in trophozoite-derived proteomes or expressed sequence tag (EST) datasets, consistent with cyst specificity. Cyst-wall specific glycoproteins Jacob, Jessie and chitinase were positively identified. Antibodies produced against Jacob identified cysts in fecal specimens and have potential utility as a diagnostic reagent. Several protein kinases, small GTPase signaling molecules, DNA repair proteins, epigenetic regulators, and surface associated proteins were also identified. Proteins we identified are likely to be among the most abundant in excreted cysts, and therefore show promise as diagnostic targets. Major Conclusions The proteome data generated here are a first for naturally-occurring E. histolytica cysts, and they provide important insights into the infectious cyst form. Additionally, numerous unique candidate proteins were identified which will aid the development of new diagnostic tools for identification of E. histolytica cysts. We used tandem mass spectrometry to identify E. histolytica cyst proteins in 5 cyst positive stool samples. We report the identification of 417 non-redundant E. histolytica proteins including 195 proteins that were not identified in existing trophozoite derived proteome or EST datasets, consistent with cyst specificity. Because the cysts were derived directly from patient samples with incomplete purification, a limited number of proteins were identified (N = 417) that probably represent only a partial proteome. Nevertheless, the study succeeded in identifying proteins that are likely to be abundant in the cyst stage of the parasite. Several of these proteins may play roles in E. histolytica stage conversion or cyst function. Proteins identified in this study may be useful markers for diagnostic detection of E. histolytica cysts. Overall, the data generated in this study promises to aid the understanding of the cyst stage of the parasite which is vital for disease transmission and pathogenesis in E. histolytica.
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Affiliation(s)
- Ibne Karim M. Ali
- Division of Infectious Disease and International Health, University of Virginia Health System, Charlottesville, Virginia, United States of America
- * E-mail: (IKMA); (WAP)
| | - Rashidul Haque
- International Center for Diarrhoeal Disease Research Bangladesh, Mohakhali, Dhaka, Bangladesh
| | - Abdullah Siddique
- International Center for Diarrhoeal Disease Research Bangladesh, Mohakhali, Dhaka, Bangladesh
| | - Mamun Kabir
- International Center for Diarrhoeal Disease Research Bangladesh, Mohakhali, Dhaka, Bangladesh
| | - Nicholas E. Sherman
- W. M. Keck Biomedical Mass Spectrometry Core, University of Virginia Health Sciences Center, Charlottesville, Virginia, United States of America
| | - Sean A. Gray
- Seattle Biomedical Research Institute, Seattle, Washington, United States of America
| | - Gerard A. Cangelosi
- Seattle Biomedical Research Institute, Seattle, Washington, United States of America
| | - William A. Petri
- Division of Infectious Disease and International Health, University of Virginia Health System, Charlottesville, Virginia, United States of America
- * E-mail: (IKMA); (WAP)
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Ventura-Juárez J, Barba-Gallardo LF, Muñoz-Fernández L, Martínez-Medina L, Márquez-Díaz F, Sosa-Díaz SJ, Gerardo-Rodríguez M, González-Romo R, Campos-Rodríguez R. Immunohistochemical characterization of human fulminant amoebic colitis. Parasite Immunol 2007; 29:201-9. [PMID: 17371457 DOI: 10.1111/j.1365-3024.2007.00934.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In cases of fulminant amoebic colitis we have determined the interactions between Entamoeba histolytica trophozoites and immune cells in order to better understand the pathophysiology of amoebic colitis. Eleven specimens of amoebic colitis and five specimens of colon without amoebic lesions were studied. Trophozoites and immune cells were located by topographic stains, histochemistry and immunohistochemistry. Trophozoites were seen in both damaged and undamaged areas of the colonic mucosa. Specimens of fulminant amoebic colitis showed: (a) an increase in IgA+, IgG+ B cells and neutrophils; (b) a reduction in IgM+ B cells, CD8+ T cells, macrophages, eosinophils and mast cells; and (c) no change in the number of NK and CD4+ T cells. The cellular infiltrate in amoebic colitis may represent the combined effects of amoebic monocyte locomotion inhibitory factor and switching of IgM+ B cells to IgG+ and IgA+ plasma cells, induced by amoebic antigens. Tissue damage in the absence of trophozoites may result from ischaemia or host immune responses.
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Affiliation(s)
- J Ventura-Juárez
- Departamento de Morfología, Centro de Ciencias Básicas, Universidad Autónoma de Aguascalientes, México.
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Abstract
The high case-fatality of severe malnutrition is due to infections, dehydration, electrolyte disturbances and heart failure. We focus on the evidence about managing these complications of severe malnutrition. Signs of circulatory collapse in severely malnourished children should be treated with intravenous or bone marrow infusion of Ringer's lactate with additional dextrose and potassium at a rate 20-40 mL/kg fast with close monitoring of vital signs. Recommendations for slow or restricted fluids in the face of shock are unsafe, and hypotonic or maintenance solutions must be avoided to prevent hyponatraemia. However, the evidence that severely malnourished children do not tolerate excessive fluid administration is good, so caution must be exercised with regards to fluids in the initial phase of treatment. There is also good evidence that wide spectrum antibiotics need to be given empirically for severe malnutrition to prevent the otherwise unavoidable early mortality. There is a need for improved protocols for tuberculosis diagnosis, HIV management and treatment of infants under 6 months with severe malnutrition. The contribution of environmental enteropathy to poor growth and nutrition during the weaning period means that there should be more priority on improving environmental health, particularly better hygiene and less overcrowding. A T-cell mediated enteropathy contributes to growth failure and malnutrition, and it is related to environmental contamination of enteric organisms in the weaning period rather than allergic responses.
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Ramos F, Morán P, González E, García G, Ramiro M, Gómez A, de León MDCG, Melendro EI, Valadez A, Ximénez C. Entamoeba histolytica and Entamoeba dispar: prevalence infection in a rural Mexican community. Exp Parasitol 2005; 110:327-30. [PMID: 15955333 DOI: 10.1016/j.exppara.2005.03.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2005] [Revised: 03/11/2005] [Accepted: 03/13/2005] [Indexed: 12/01/2022]
Abstract
The frequency of Entamoeba histolytica and Entamoeba dispar infection was analyzed in a rural community in the state of Morelos, Mexico, through PCR technique by using specie specific primer. The E. histolytica specie was detected in 33 of 290 analyzed stool samples (11.4%), E. dispar specie was observed in 21 samples (7.2%) and both species of Entamoeba were detected in seven samples (2.4%). So a higher E. histolytica than E. dispar frequency infection was detected (13.8 versus 9.6%). Even though in our design we did not considered the follow-up of included individuals, the absence of invasive amebiasis cases in the studied population during our stay in town was unexpected.
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Affiliation(s)
- Fernando Ramos
- Departamento de Medicina Experimental, Facultad de Medicina, UNAM, Mexico Distrito Federal, Mexico
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Srivastava S, Bhattacharya S, Paul J. Species- and strain-specific probes derived from repetitive DNA for distinguishing Entamoeba histolytica and Entamoeba dispar. Exp Parasitol 2005; 110:303-8. [PMID: 15955328 PMCID: PMC4247991 DOI: 10.1016/j.exppara.2005.02.020] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2005] [Revised: 02/25/2005] [Accepted: 02/26/2005] [Indexed: 12/15/2022]
Abstract
Entamoeba histolytica and Entamoeba dispar are two morphologically indistinguishable species that are found in the human gut. Of the two, E. histolytica is considered to be pathogenic while E. dispar is nonpathogenic. To generate molecular probes to detect and distinguish between the two species, we utilized repeat sequences present in Entamoeba genome. We have developed probes and primers from rDNA episomes, and unidentified Entamoeba EST1 repeat for this purpose, and used them for dot blot hybridization and PCR amplification. To investigate the possible existence of invasive and noninvasive strains of E. histolytica, the ability to differentiate individual isolates is necessary. For this purpose, we have utilized a modification of the AFLP procedure called 'Transposon display,' which generates and displays large number of genomic bands associated with a transposon. We have used the abundant retrotransposon, EhSINE1, for this purpose,and demonstrated its potential as a marker to study strain variation in E. histolytica. This technique could suitably be employed in carrying out significant molecular epidemiological studies and large-scale typing of this parasite.
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Affiliation(s)
- Shweta Srivastava
- School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Sudha Bhattacharya
- School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Jaishree Paul
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
- Corresponding author. Fax: +91 11 26165886. (J. Paul)
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Abstract
PURPOSE OF REVIEW Over the past decade, since it was formally recognized that Entamoeba histolytica and Entamoeba dispar were two distinct species, studies in this field have made dramatic in-roads into the understanding of E. histolytica and the pathogenesis of invasive amoebiasis. Over the same period it has also become clear that the true incidence of E. histolytica infection, particularly in vulnerable populations such as low socioeconomic children, is exceedingly high. Understanding the epidemiology, pathophysiology, and the molecular and genetic biology of the organism will not only lead to improved diagnostic and treatment options but, ultimately, to the development of a safe and efficacious vaccine. RECENT FINDINGS The recent advances in the genetic and molecular sciences have increased our understanding of the mechanisms that make E. histolytica unique among enteric protozoa in causing invasive disease. In addition, host factors, which predispose individuals or populations to infection or disease, are beginning to be elucidated. New diagnostic tools specific to E. histolytica are being exploited by clinicians and researchers to identify and treat patients as well as to add to the knowledge of the epidemiology and natural history of this infection. The ultimate goal - eradication of disease - is theoretically feasible since humans and primates are the only reservoirs of E. histolytica. Many talented and dedicated individuals are pursuing the development of an effective and safe amoebiasis vaccine. SUMMARY E. histolytica remains an important pathogen in many populations of the world and although there has been substantial progress into understanding the disease major challenges still exist.
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Affiliation(s)
- William Stauffer
- Department of Internal Medicine, Division of Infectious Disease and International Medicine, University of Minnesota, Minneapolis 55455, USA
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Abstract
It is an exciting time in the study of Entamoeba histolytica. Over the past two years, the natural history and burden of disease in humans has been redefined, mucosal immune responses associated with protection identified, and the developmental regulation of encystation outlined. The number of genes sequenced has increased from a few hundred to a few thousand, and study of the genome structure is revealing unusual repetitive elements and plasticity. DNA microarrays promise the first ability to examine global patterns of mRNA abundance. The mechanism of transcriptional control via histone modifications and sequence-specific DNA-binding proteins are to be delineated. Advances in cell biology are providing new insights into invasion through the intestinal epithelium.
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Affiliation(s)
- William A Petri
- Division of Infectious Diseases, Room 2115, MR4 Building, Lane Road, PO Box 801340, University of Virginia Health System, Charlottesville, Virginia 22908-1340, USA.
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12
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Abstract
Amebiasis is extraordinarily common in children of the developing world. This realization has come from application of diagnostic techniques that distinguish the nonpathogenic parasite Entamoeba dispar from Entamoeba histolytica. E. histolytica infection is found in children with dysentery, diarrhea, and in many cases in children with no gastrointestinal symptoms. Genetically distinct strains of E. histolytica exist but evidence is too preliminary to judge if some strains are more virulent than others. A provocative study from Tanzania has shown that pregnant women with HIV infection who are coinfected with E. histolytica are at greater risk of delivering a low birth weight infant. Perhaps the most exciting new data is the identification of acquired immunity to recurrent E. histolytica infection. Acquired immunity is linked to a mucosal immune response against a major virulence factor of the parasite, a Gal/GalNAc lectin responsible for adherence and killing of the host. Prospects for a vaccine are thus brightening at the same time that the true burden of disease is comprehended.
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Affiliation(s)
- William A. Petri
- Division of Infectious Diseases, University of Virginia School of Medicine, PO Box 801340, Charlottesville, VA 22908-1340, USA.
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