ABSTRACT
Abstract Background: The state of Chiapas has held the first place of extreme poverty in Mexico. The majority of Chiapas' municipalities are inhabited by marginalized, indigenous populations, who usually present diarrhea of unknown etiology. We evaluated the nutritional status, intestinal parasites, and common bacterial pathogens, including DEC (diarrheagenic Escherichia coli) strains, in 178 children under five years of age with a high (rural) and a moderate (urban) degree of marginalization. Methods: Z-scores for anthropometric indexes from the children were obtained, whereas intestinal parasites were investigated by using a direct coproparasitoscopic analysis and a concentration method. DEC strains were detected by polymerase chain reaction (PCR). Results: The stunting prevalence in children from the rural and urban regions was 79.8 and 7.5%, respectively. Only children from rural municipalities were parasitized (72.6%), being Ascaris lumbricoides and Entamoeba histolytica/Entamoeba dispar the most prevalent parasites (57.1 and 38.1%, respectively). More than half of the children presented moderated ascariasis. Besides Giardia intestinalis, these parasites were associated with stunting. The prevalence of DEC strains was similar in both regions. Conclusions: Only children from the Chiapas Highlands (rural zone) exhibited high prevalences of stunting and intestinal parasites. A reevaluation of social development programs should be in place to address stunting and intestinal parasitoses, mainly in rural regions of Chiapas, to avoid adverse functional consequences on these children.
Resumen Introducción: El estado de Chiapas ha ostentado el primer lugar de pobreza extrema en México. La mayor parte de la población de los municipios de Chiapas es indígena, vive en condiciones de marginación y padece de diarrea de etiología desconocida. Este trabajo evaluó el estado nutricional, la presencia de parásitos intestinales y patógenos bacterianos comunes, además de cepas DEC (Escherichia coli diarreogénica) en 178 niños menores de cinco años, provenientes de una localidad con alto grado de marginación (rural) y de una con moderada marginación (urbana). Métodos: Se obtuvieron los puntajes Z de los índices antropométricos de los niños. Los parásitos intestinales se investigaron con el método coproparasitoscópico directo y un método de concentración. Las cepas DEC se detectaron mediante reacción en cadena de la polimerasa. Resultados: La prevalencia de desmedro en niños de la zona rural y urbana fue de 79.8 y 7.5%, respectivamente. Únicamente los niños de la zona rural estuvieron parasitados (72.6%), y los más prevalentes fueron Ascaris lumbricoides y Entamoeba histolytica/Entamoeba dispar (57.1 y 38.1%, respectivamente). Más de la mitad de los infantes exhibieron ascariasis moderada. Estos parásitos, además de Giardia intestinalis, se asociaron con el desmedro. En ambas regiones, la prevalencia de DEC fue similar. Conclusiones: Solo los niños de los Altos de Chiapas (zona rural) exhibieron alta prevalencia de desmedro y parásitos intestinales. Para evitar las consecuencias adversas entre los infantes, es necesario reevaluar los programas de desarrollo social para combatir el desmedro y la parasitosis intestinal, principalmente en las regiones rurales de Chiapas.
Subject(s)
Child, Preschool , Female , Humans , Infant , Male , Rural Population/statistics & numerical data , Urban Population/statistics & numerical data , Growth Disorders/epidemiology , Intestinal Diseases, Parasitic/epidemiology , Poverty , Nutritional Status , Prevalence , Cross-Sectional Studies , Diarrhea/epidemiology , Intestinal Diseases, Parasitic/parasitology , Mexico/epidemiologyABSTRACT
Intestinal parasitic infections remain a major public health problem in many parts of Thailand, particularly in rural areas. This study aimed to determine the prevalence of intestinal parasitic infections and associated risk factors among the people living in Huai Sai sub-district, Bang Khla district, Chachoengsao Province, central Thailand. A cross-sectional survey was carried out from June 2017 to August 2017 which included a total of 224 participants. Stool samples were examined using a simple direct smear and formalin ethyl acetate concentration technique. Association between risk factors and intestinal parasitic infections was assessed using multivariate logistic regression analysis. The overall prevalence of intestinal parasitic infections was 16.1%. Soil-transmitted helminth infections (14.3%) were more common than protozoan infections (1.8%). The most common intestinal parasites were hookworms (6.7%) followed by Strongyloides stercoralis, (5.0%), Ascaris lumbricoides (1.3%) and Trichuris trichiura (1.3%). Entamoeba histolytica/dispar (1.0%), Giardia intestinalis (0.4%), and Blastocystis hominis (0.4%) were the protozoans identified. A high prevalence of infections was found in male participants of ≥40 years who raised dogs in the households and did not wear boots while working fields. Multivariate analysis showed a significant association of intestinal parasitic infections with gender with the adjusted odds ratio (OR) of 2.4 and 95% confidence interval (CI) of 1.1–5.2 (P=0.020). The results showed a high prevalence of soil-transmitted helminth infections among adults in rural communities which were particularly apparent regarding the skin-penetrating species of nematodes. A greater focus on intervention is required by improving sanitation and personal hygiene to prevent the spread of intestinal parasitic infections.
Subject(s)
Adult , Animals , Dogs , Humans , Male , Ancylostomatoidea , Ascaris lumbricoides , Blastocystis hominis , Cross-Sectional Studies , Entamoeba , Entamoeba histolytica , Family Characteristics , Formaldehyde , Giardia lamblia , Helminths , Hygiene , Logistic Models , Multivariate Analysis , Odds Ratio , Parasites , Prevalence , Protozoan Infections , Public Health , Risk Factors , Rural Population , Sanitation , Strongyloides stercoralis , Thailand , TrichurisABSTRACT
El diagnóstico de la amibiasis ha estado basado por décadas en el análisis microscópico. Sin embargo, conociendo la existencia de amibas no patógenas morfológicamente similares a Entamoeba histolytica, este procedimiento tiene sus criterios de análisis establecidos por la OMS que permiten obtener un diagnóstico más preciso. El desconocimiento de estos criterios ha llevado a una sobreestimación de esta parasitosis. En el marco de una investigación descriptiva, no experimental y transversal, se aplicó una encuesta, previa validación y consentimiento informado al analista presente en el momento de la entrevista, representando la muestra que estuvo conformada por 20 laboratorios distribuidos en 10 municipios del Estado Carabobo. Se pudo constatar, que 65% de los laboratorios cuenta con infraestructura adecuada. El 15% posee equipamiento para el diagnóstico serológico. Ninguno de los laboratorios posee microscopios con un micrómetro. El 65% del personal debe rotar por más de dos áreas de trabajo y 85% procesa las muestras de heces después de dos horas de recibida. El 45% de los encuestados aplica criterios de rechazo de las muestras pero sólo 40% da instrucciones acerca de su recolección. El 100% de los encuestados omite el uso de métodos de concentración, coloraciones especiales y uso del objetivo de inmersión. Sólo 10% afirma reportar el Complejo Entamoeba histolytica/dispar y 20% haber reportado a E. hartmanni. El 75% del personal desconoce las pautas de la OMS. Se concluye que en los laboratorios evaluados, el cumplimiento de la normativa para una adecuado y preciso diagnóstico de E. histolytica es deficiente.
For decades the diagnosis of amoebiasis has been based on microscopic analysis. However, due to the existence of nonpathogenic amoebae morphologically similar to E. histolytica, for a more accurate diagnosis WHO provides some criteria for this procedure. Ignorance about analysis criteria has led to an overestimation of this parasitic infection. Through a descriptive, nonexperimental and cross-sectional survey and prior validation and informed consent, analysts participating in an interview represented the sample which consisted of 20 laboratories distributed in 10 municipalities of Carabobo State. Absolute and relative frequencies obtained by statistical data processing software (SPSS 11.0) showed that 65% of laboratories have appropriate infrastructure and reference material. 15% have equipment for serological diagnosis. None of the laboratories has a microscope with a micrometer. 65% of the staff has to rotate through two work areas, and 85% processes stool samples after two hours of reception. 45% of analysts apply sample rejection criteria and only 40% provide instructions about proper collection. 100% omitted the use of concentration methods, special stains and using immersion objective. Only 10% reported E. histolytica/dispar complex and 20% mentioned reporting E. hartmanni. 75% of analysts are unaware of WHO guidelines. We conclude that in the assessed laboratories, compliance with regulations for a proper and accurate diagnosis of E. histolytica is poor.
ABSTRACT
There is a clear need to perform epidemiological studies to find the true prevalence of Entamoeba histolytica around the world. The evaluation of this prevalence has been hindered by the existence of two different species which are morphologically identical, but genetically different, namely E. histolytica, which causes amebiasis, and E. dispar, which is non-pathogenic. In Brazil, the E. dispar has been detected in communities in the Southeastern (SE) and Northeastern (NE) regions with poor sanitation. However, individuals infected with E. histolytica have been identified in other regions. There is an absence of reports on the prevalence of these parasites in the state of Paraíba, which also has areas with poor sanitary conditions where a high prevalence of the E. histolytica/E. dispar complex has been detected in children from urban slums. The present study evaluated the prevalence of E. histolytica and E. dispar in 1,195 asymptomatic children between two and 10 years of age, living in a sprawling urban slum in Campina Grande, in the state of Paraíba, in Northeastern Brazil. These children were examined and their feces samples were analyzed microscopically. A total of 553 children tested positive for the E. histolytica/E. dispar complex, and 456 of the positive samples were tested with the E. histolytica II® ELISA kit. All 456 samples were negative for the presence of the adhesin E. histolytica specific antigen. The evidence suggests that in this community E. histolytica is absent and E. dispar is the dominant species.
A prevalência mundial de Entamoeba histolytica não está bem estabelecida. Este fato deve-se à complicação derivada da existência de duas espécies morfologicamente idênticas, mas geneticamente diferentes: a E. histolytica que causa amebíases e a E. dispar descrita como não patogênica. No Brasil, em comunidades com precárias condições sanitárias e endêmicas para várias parasitoses, localizadas nas regiões Sudeste (SE) e Nordeste (NE), somente E. dispar tem sido encontrada, porém outras regiões, apresentam indivíduos infectados por E. histolytica. Na região agreste do Estado da Paraíba (NE) que apresenta as mesmas precárias condições sanitárias, não tem sido reportada prevalência específica destes parasitos, embora fosse encontrada alta prevalência do complexo E. dispar/E. histolytica em crianças em favela urbana. O presente estudo foi realizado em favela da cidade de Campina Grande, Estado da Paraíba, onde 1.195 crianças de dois a 10 anos sem sintomatologia foram examinadas. Amostras de fezes destas crianças foram analisadas microscopicamente, encontrando-se 553 positivas para o complexo E. dispar/E. histolytica. Do total de amostras positivas, 456 foram submetidas à pesquisa do antígeno especifico para E. histolytica pelo teste ELISA E. histolytica II®,obtendose resultado negativo para a presença do antígeno adesina específico de E. histolytica, em todas as amostras testadas. Os resultados sugerem que nesta comunidade não há infecção por E. histolytica, e que E. dispar é a espécie dominante na região.
Subject(s)
Child , Child, Preschool , Humans , Infant , Antigens, Protozoan/blood , Entamoeba histolytica/immunology , Entamoebiasis/epidemiology , Brazil/epidemiology , Enzyme-Linked Immunosorbent Assay , Entamoeba/immunology , Entamoebiasis/diagnosis , Feces/parasitology , Poverty Areas , Prevalence , Species Specificity , Urban PopulationABSTRACT
Introduction: Epidemiological studies on amebiasis have been reassessed since Entamoeba histolytica and E. dispar were first recognized as distinct species. Because the morphological similarity of these species renders microscopic diagnosis unreliable, additional tools are required to discriminate between Entamoeba species. The objectives of our study were to compare microscopy with ELISA kit (IVD®) results, to diagnose E. histolytica infection, and to determine the prevalence of amebiasis in a sample of students from southeastern Brazil. Methods: In this study, diagnosis was based on microscopy due to its capacity for revealing potential cysts/trophozoites and on two commercial kits for antigen detection in stool samples. Results: For 1,403 samples collected from students aged 6 to 14 years who were living in Divinópolis, Minas Gerais, Brazil, microscopy underestimated the number of individuals infected with E. histolytica/E. dispar (5.7% prevalence) compared with the ELISA kit (IVD®)-based diagnoses (15.7% for E. histolytica/E. dispar). A comparison of the ELISA (IVD®) and light microscopy results returned a 20% sensitivity, 97% specificity, low positive predictive value, and high negative predictive value for microscopy. An ELISA kit (TechLab®) that was specific for E. histolytica detected a 3.1% (43/1403) prevalence for E. histolytica infection. Conclusions: The ELISA kit (IVD®) can be used as an alternative screening tool. The high prevalence of E. histolytica infection detected in this study warrants the implementation of actions directed toward health promotion and preventive measures. .
Subject(s)
Adolescent , Child , Female , Humans , Male , Antigens, Protozoan/analysis , Entamoebiasis/diagnosis , Feces/parasitology , Brazil/epidemiology , Cross-Sectional Studies , Enzyme-Linked Immunosorbent Assay , Entamoeba histolytica/isolation & purification , Entamoeba/isolation & purification , Entamoebiasis/epidemiology , Entamoebiasis/parasitology , Predictive Value of Tests , Reagent Kits, Diagnostic , Sensitivity and Specificity , Species SpecificityABSTRACT
Para determinar la prevalencia de Entamoeba histolytica como productora de diarrea, se realizó un estudio en niños menores de cinco años con diarrea que asistieron a diversas consultas del Servicio Autónomo Hospital Universitario de Maracaibo, Venezuela. A las muestras de heces obtenidas, se les realizó examen macroscópico, microscópico con solución salina fisiológica 0,85% y lugol, así como coloración de Kinyoun. El resto de la muestra se congeló hasta la extracción del ADN y luego se amplificaron mediante PCR separadas para E. histolytica y E. dispar. De las 50 muestras analizadas mediante examen microscópico, ninguna presentó trofozoítos y/o quistes de Entamoeba histolytica/dispar/moshkovskii, ni coccidios intestinales. Los parásitos detectados fueron Giardia lamblia (6%), Blastocystis sp. (6%), Pentatrichomonas hominis (2%), Ascaris lumbricoides (2%) y Trichuris trichiura (2%). Mediante PCR, 6 muestras (12%) presentaron ADN de E. dispar y 2 (4%) ADN de E. histolytica. Ningún niño presentó asociación de ambas amibas. Los dos niños que presentaron E. histolytica tenían 1 año de edad. E. dispar si fue detectada en niños de menor edad. Se sugiere que la prevalencia de E. histolytica en niños menores de cinco años con diarrea es realmente baja.
To determine the prevalence of Entamoeba histolytica as a producer of diarrhea, a study was conducted in children, less than five years of age, with diarrhea who attended several out patient clinics of the Servicio Autónomo Hospital Universitario, Maracaibo, Venezuela. A macroscopic and microscopic examination with physiological saline, lugol and Kinyoun staining were performed to the stool samples obtained. The remainder of the sample was frozen until DNA extraction, and PCR amplification was performed separately for E. histolytica and E. dispar. Microscopic examination showed no trophozoites and/or cysts of Entamoeba histolytica/dispar/moshkovskii, or intestinal coccidians in any of the 50 samples analyzed. Parasites detected were Giardia lamblia (6%), Blastocystis sp. (4%), Pentatrichomonas hominis (2%), Ascaris lumbricoides (2%) and Trichuris trichiura (2%). By PCR, six samples (12%) had DNA of E. dispar and two (4%) had DNA from E. histolytica; no child showed association of both amoebae. The two children who had E. histolytica were one-year-old. E. dispar was detected in younger children. We suggest that the prevalence of E. histolytica in children under five years is really low.
Subject(s)
Child, Preschool , Female , Humans , Infant , Male , Diarrhea/parasitology , Entamoeba histolytica/isolation & purification , Polymerase Chain Reaction , Cross-Sectional Studies , Prospective Studies , VenezuelaABSTRACT
El género Entamoeba comprende varias especies, de las cuales, seis pueden habitar en el intestino grueso del hombre: Entamoeba histolytica, Entamoeba dispar, Entamoeba moshkovskii, Entamoeba polecki, Entamoeba coli y Entamoeba hartmanni. Las tres primeras son morfológicamente idénticas, pero solo E. histolytica es considerada patógena, produciendo la amibasis; mientras que E. dispar y E. moshkovskii son consideradas no patógenas. La diferenciación entre estas amibas no puede efectuarse mediante examen microscópico, que es la técnica más utilizada para el diagnóstico de la amibiasis; se recomiendan para ello, métodos de biología molecular (PCR) o detección de coproantigenos de E. histolytica mediante ELISA. Más recientemente, el aumento en el descubrimiento de casos en humanos de parasitismo por E. moshkovskii, provoca una complicación mayor, pues entonces debe discriminarse entre las tres amibas para realizar un diagnóstico de laboratorio definitivo. Por otro lado, persisten los problemas técnicos en cuanto a un método rápido, sencillo y poco costoso que permita a los laboratorios de rutina distinguir entre E. histolytica, E. dispar y E. moshkovskii. Por los momentos, se recomienda reportar los trofozoítos y/o quistes morfológicamente compatibles con E. histolytica, como complejo Entamoeba o como E. histolytica/dispar/moshkovskii.
The genus Entamoeba contains many species, of which six can live in the large intestine of man: Entamoeba histolytica, Entamoeba dispar, Entamoeba moshkovskii, Entamoeba polecki, Entamoeba coli and Entamoeba hartmanni. The first three are morphologically identical, but only E. histolytica is considered pathogenic, producing amibiasis, whereas E. dispar and E. moshkovskii are considered non-pathogenic. Differentiation between these amoebas cannot be made by microscopic examination, which is the most widely used technique for diagnosing amibiasis. To differentiate, molecular biological methods (PCR) or detection of E. histolytica coproantigens by ELISA are the recommended methods. More recently, an increase in the discovery of human cases of parasitism by E. moshkovskii has provoked a major complication, because laboratory tests should discriminate among the three amoebas for a definitive diagnosis. In addition, technical problems remain regarding a rapid, simple and inexpensive method that allows routine laboratories to distinguish between E. histolytica, E. dispar and E. moshkovskii. At present, the recommendation is to report trophozoites and/or cysts morphologically compatible with E. histolytica, as complex Entamoeba or as E. histolytica/dispar/moshkovskii.
Subject(s)
Humans , Male , Female , Entamoeba histolytica/parasitology , Entamoeba/parasitology , Bacterial Infections/diagnosis , Bacterial Infections/prevention & control , ParasitologyABSTRACT
This study investigated the effect of breast-feeding in protection against protozoan infection in infants with persistent diarrhea. Infants were classified into 2 groups; 161 breast-fed infants and the same number of non-breast-fed infants. Microscopic examinations of stool were done for detection of parasites and measuring the intensity of infection. Moreover, serum levels of IgE and TNF-alpha were measured by ELISA. Cryptosporidium spp., Entamoeba histolytica/Entamoeba dispar, Giardia lamblia, and Blastocystis sp. were demonstrated in infants with persistent diarrhea. The percentage of protozoan infections was significantly lower in breast-fed infants than that in the non-breast-fed infants. The levels of IgE and TNF-alpha were significantly lower in the breast-fed group than in the non-breast-fed group. There were significant positive associations between the serum levels of IgE and TNF-alpha and the intensity of parasite infection in the breast-fed group. It is suggested that breast-feeding has an attenuating effect on the rate and intensity of parasite infection.
Subject(s)
Female , Humans , Infant , Antigens, Protozoan/analysis , Diarrhea, Infantile/diagnosis , Entamoeba , Entamoeba histolytica/isolation & purification , Entamoebiasis/diagnosis , Enzyme-Linked Immunosorbent Assay , Feces/parasitology , Giardia lamblia , Giardiasis/diagnosis , Intestines/parasitology , Protozoan Infections/diagnosis , Tumor Necrosis Factor-alpha/metabolismABSTRACT
Background: Entamoeba histolytica and Entamoeba dispar are morphologically identical. However, the former is highly pathogenic and the latter is not. Aim: To differentiate Entamoeba histolytica from Entamoeba dispar through ELISA and PCR techniques in Colombian isolates from feces. Material and Methods: Descriptive study of Colombian fecal samples from 53 males and 47 women, that were positive for the complex E. histolytica/E. dispar on light microscopy. Positive samples were cultured on Robinson medium to isolate trophozoites. The presence of specific Gal/ GalNAc-lectin was determined by ELISA and polymerase chain reaction in genomic DNA, using the combination of three nucleotides that recognize a variable region of 16S small subunit ribosomal RNA, generating a 166 base pair (bp) product for E. histolytica and 752 pb product for E. dispar. Results: After verification, only eight of the 100 samples were positive for the complex E. histolytica/E. dispar and were cultivated. Isolates were obtained in six cultures, one corresponded to E. histolytica and six to E. dispar. Conclusions: The presence of E. histolytica/E. dispar complex was largely overestimated with light microscopy. In the few samples where isolates were obtained, the technique described differentiated between both strains.
Subject(s)
Female , Humans , Male , Entamoeba/metabolism , Entamoebiasis/parasitology , Colombia , DNA, Protozoan/genetics , Entamoeba histolytica/genetics , Entamoeba histolytica/isolation & purification , Entamoeba/genetics , Entamoeba/isolation & purification , Entamoebiasis/diagnosis , Enzyme-Linked Immunosorbent Assay , Feces/parasitology , Lectins , Polymerase Chain Reaction/methods , Protozoan Proteins , /genetics , Sensitivity and SpecificityABSTRACT
El objetivo de esta investigación fue determinar la frecuencia de parasitosis intestinales en el área de influencia del Ambulatorio Urbano Tipo II de Cerro Gordo, Barquisimeto, Estado Lara, realizando un estudio descriptivo transversal. Se evaluaron 106 niños entre 1 y 12 años de edad, realizando a cada uno examen de heces directo y concentrado con la técnica de Ritchie, demostrándo se parasitosis intestinal en 42,5%, predominando en escolares (48,9%), sin diferencias según el género. El agente más frecuente fue B. hominis (42,2%), seguido de G. lamblia (37,8%), Complejo Entamoeba histolytica/Entamoeba dispar (13,3%), H. nana (11,1%) y A. lumbricoides (4,4%). Se encontró parasitado 41,7% de niños con estado nutricional normal y 35,7% de malnutridos. La presencia de parasitos intestinales mostró relación con la disposición inadecuada de basura (p=0.048). El lavado inadecuado de las manos se relacionó con prurito anal (p=0.008). La calidad inadecuada del agua se relacionó con Blastocistosis (p= 0,025) y comensales (p= 0,035). No hubo relación entre parasitosis intestinales y síntomas gastrointestinales, estrato social, disposición de excretas, presencia de vectores en el hogar, lavado y conservación de alimentos, frecuencia de recolección de basura, lavado de manos, antecedente de tratamiento antiparasitario y familiar parasitado
A cross-sectional study was conducted to determine intestinal parasitism in children treated at the Cerro Gordo Type II Urban Outpatient Clinic in Barquisimeto, Lara. Feces samples were collected from 106 children (1-12 years old) and analyzed using both direct and Ritchie´s technique analyses, demonstrating intestinal parasitism in 42.5% of the children, predominantly of school age (48.9%), but independent of gender. The most frequent agent was Blastocystis hominis (42.2%), followed by Giardia lamblia (37.8%), Entamoeba histolytica/Entamoeba dispar Complex (13.3%), Hymenolepis nana (11.1%) and Ascaris lumbricoides (4.4%). For children with a normal nutritional condition, 41.7% had parasites, while this value was 35.7% for nutritionally undernourished children. The presence of intestinal parasites showed relations to the communitys trash collection management program status (p=0.048). Poor hand washing habits were significantly associated with anal pruritus (p=0.008). Inadequate water quality was related to blastocystosis (p= 0.025) and comensals (p= 0.035). The presence of parasites was not associated with specific gastrointestinal symptoms, socioeconomic status, disposition of excreta, presence of vectors in the home, food washing and storage, frequency of garbage collection, washing of hands, family parasitism history and anti-parasite treatment antecedents
Subject(s)
Humans , Male , Adolescent , Female , Infant , Child, Preschool , Child , Feces/parasitology , Intestinal Diseases, Parasitic/epidemiology , Intestinal Diseases, Parasitic/parasitology , Ascaris lumbricoides/parasitology , Blastocystis hominis/parasitology , Entamoeba histolytica/parasitology , Giardia lamblia/parasitology , Hymenolepis nana/parasitologyABSTRACT
La historia de Entamoeba histolytica es muy confusa y muestra diversos conceptos erróneos acerca del parásito y su relación con el hospedador. La poca correlación entre la prevalencia de la amibiasis asintomática y sintomática originó la propuesta de tres hipótesis explicativas, entre las cuales estaba el concepto de Brumpt de que existían dos especies morfológicamente idénticas, E. dysenteriae y E. dispar. La aplicación de las técnicas moleculares modernas demostró, en forma irrefutable, que lo que se conocía clásicamente como E. histolytica se trataba realmente de dos especies, confirmándose el concepto de Brumpt casi 7 décadas después. Estudios recientes han identificado en humanos E. moshkovskii, morfológicamente indistinguible de E. histolytica y E. dispar, así como una gran diversidad genética de cada una de estas especies y heterogenicidad en virulencia entre las razas de E. histolytica. La redescripción de E. dispar y la identificación de E. moshkovskii en humanos han impactado enormemente el conocimiento de E. histolytica y la amibiasis con importantes implicaciones clínicas y epidemiológicas que han conducido a la necesidad de reevaluar la prevalencia y morbilidad de la infección en la población mundial y estudiar la distribución geográfica, prevalencia y modelo de transmisión de las razas de E. histolytica para detectar aquéllas epidemiológicamente relevantes y predecir el riesgo de la enfermedad amibiana en una población.
The history of Entamoeba histolytica is very confuse and shows several wrong concepts about the parasite and its relationship with the host. The poor correlation between the prevalence of asymptomatic and symptomatic amebiasis originated the proposal of three explicative hypothesis, among them was the concept of Brumpt that E. histolytica comprised two morphologically identical species, E. dysenteriae and E. dispar. The application of modern molecular techniques irrefutably proved that E. histolytica was really a complex of two species, confirming the concept of Brumpt almost 7 decades later. Recent studies have identified in humans E. moshkovskii, morphologically indistinguishable from E. histolytica and E. dispar, a great genetic diversity within each of these species, and heterogeneity in virulence among E. histolytica strains. The redescription of E. dispar, and the recovery of E. moshkovskii from humans have had a major impact in our understanding of E. histolytica and amebiasis with important clinical and epidemiologic implications. This has led to the need of a reevaluation of the infection in terms of prevalence and morbidity in the global population and to study the geographic distribution, prevalence, and transmission pattern of E. histolytica strains in order to detect those with epidemiologic relevance and predict the risk of amebic disease in a population.
Subject(s)
Humans , Dysentery, Amebic , Entamoeba histolyticaABSTRACT
This article presents a history of Entamoeba histolytica spanning since the remote times when it was not even recognized as a cause of human disease to the recent molecular advances. Feder Losch (1875) in Saint Petersburg, found amoebae in fecal samples but only regarded them as responsible for maintaining the inflammatory process, not as a cause of dysentery. Fritz Schaudinn (1903) established the differentiation between Entamoeba histolytica and Endamoeba coli, Schaudinn decided to call it E. histolytica because of its ability to cause tissue lysis. Emile Brumpt (1925) based on experimental studies, pointed out the existence ofE. Histolytica as a species complex, comprising two morphologically indistinguishable species, E. dysenteríae which is the cause of symptomatic infection, and Entamoeba dispar found only in asymptomatic carriers. Louis Diamond et al (1961) during the 1960s developed an axenic culture medium for E. histolytica which allowed in vivo and in vitro studies. Sargeaunt and Williams (1978) distinguished for the first time E. histolytica strains by isoenzyme electrophoresis, thus confirming thatE. hystolytica was indeed a species complex comprising both pathogenic and non-pathogenic species. William Petri et al (1987 demonstrated that the 170 kDa protein with greater antigenicity was the Gal/GalNac-specific lectin. Diamond and Clark (1993) described again Brumpt's original 1925hypothesis, concluding that there was enough evidence to support the existence of two morphologically indistinguishable species, a pathogenic and a nonpathogenic one, corresponding to E. histolytica and Entamoeba dispar respectively. The World Health Organization accepted this hypothesis in 1997.
Subject(s)
Animals , History, 19th Century , History, 20th Century , History, 21st Century , Humans , Dysentery, Amebic/history , Entamoeba histolytica , Entamoeba histolytica/classification , Entamoeba histolytica/pathogenicityABSTRACT
Amebíase invasiva, causada por Entamoeba histolytica, é microscopicamente indistinguível da espécie não-patogênica Entamoeba dispar. Com auxílio de ferramentas debioinformática, objetivou-se diferenciar Entamoeba histolytica e Entamoeba dispar por técnicas moleculares. A análise foi realizada a partir do banco de dados da National Center for Biotechnology Information; pela pesquisa de similaridade de sequências, elegeu-se o gene da cisteína sintase. Um par de primer foi desenhado (programa Web Primer) e foi selecionada a enzima de restrição TaqI (programa Web Cutter). Após a atuação da enzima, o fragmento foi dividido em dois, um com 255 pb e outro com 554 pb, padrão característico da E. histolytica.Na ausência de corte, o fragmento apresentou o tamanho de 809 pb, referente à E. dispar.
Under microscopic conditions, the invasive Entamoeba histolytica is indistinguishable from the non-pathogenic species Entamoeba dispar. In this way, the present study was carried out to determine a molecular strategy for discriminating both species by the mechanisms of bioinformatics. The gene cysteine synthetase was consideredfor such a purpose by using the resources of the National Center for BiotechnologyInformation data bank in the search for similarities in the gene sequence. In this way, a primer pair was designed by the Web Primer program and the restriction enzyme TaqI was selected by the Web Cutter software program. The DNA fragment had a size of 809 bp before cutting, which is consistent with E. dispar. The gene fragment was partitioned in a first fragment with 255 bp and a second one with 554 bp, which is similar to the genetic characteristics of E. histolytica.
Subject(s)
Amebiasis , Computational Biology/methods , Entamoeba histolytica , Parasitic DiseasesABSTRACT
Está establecido que existen dos especies distintas de amebas que originalmente fueron conocidas como Entamoeba Histolytica. Ellas son E. dispar (forma no patogénica) y E. histolytica (forma patogénica). La diferencia entre estos dos organismos es de gran importancia clínica desde que son morfológicamente indistinguibles. El diagnóstico diferencial de estas dos especies es esencial para la decisión del tratamiento y la salud pública. Se puede usar un método rápido de extracción de DNA directamente de especímenes suspendidos en formalina éter. La extracción de ADN fue usada para la identificación de las especies existentes en las herramientas por reacción de cadena polimerasa (PCR). Un total de 75 muestras recolectadas aleatoriamente fueron analizadas. Despues de la confirmación por PCR: 7/75 muestras resultaron positivas para E. histolytica, 60/75 muestras resultaron positivas para E. dispar y 8/75 resultaron negativas porque no amplificaron, pudiendo tratarse de otras amebas como E. hartmani. E. iodoamoeba, E. coli, etc. Con estos resultados podemos darnos cuenta de la magnitud de falsos positivos que se generan con los exámenes microscópicos. Estas observaciones implican que el uso del DNA extraído directamente a partir de concentración de quistes para amplificación por PCR, es una herramienta útil para obtener un diagnóstico sensitivo y preciso que puede ser aplicado incluso en epidemiología.
It has been established that two distinct species exist within what was originally known as Entamoeba histolytica. These are E. dispar (nonpathogenic form) and E. histolytica (pathogenic form). Differentiation of these two organisms is of great clinical importance since they are morphologically indistinguishable. Differential diagnosis of this two species is essential for treatment decision and public health knowledge. A simple and rapid DNA-extraction method that can be used directly on formalin-ether stool specimens. The extracted DNA was used for the identification of the species existing in the stools by polymerase chain reaction (PCR). A total of 75 randomly collected stool sample were analyzed. The samples analyzed by microscopic were 75, after confirmation by PCR: 7/75 samples resulting positive for E. histolytica, 60/75 samples resulting positive for E. dispar and 8/75 resulting negative because didn't amplify be able to be other amoebas like E. hartmani, E. iodoamoeba, E. coli, etc. With these results we can realize the magnitude of false positive that are generated with the microscopic exams. These observations imply that the use of the DNA extracted directly of the concentrate of cysts for PCR amplification is a useful tool for obtaining a sensitive and accurate diagnosis that can be applied even in epidemiology.