Subtype Distribution of Blastocystis in Thai-Myanmar Border, Thailand

Blastocystis sp. is a common zoonotic intestinal protozoa which has been classified into 17 subtypes (STs). A cross-sectional study was conducted to determine the prevalence and subtype distribution of Blastocystis in villagers living on the Thai-Myanmar border, where the risk of parasitic infection is high. A total of 207 stool samples were collected and DNA was extracted. PCR and sequencing using primers targeting small-subunit ribosomal RNA (SSU rRNA) gene were performed. The prevalence of Blastocystis infection was 37.2% (77/207). ST3 (19.8%; 41/207) was the predominant subtype, followed by ST1 (11.6%; 24/207), ST2 (5.3%; 11/207), and ST4 (0.5%; 1/207). A phylogenetic tree was reconstructed using the maximum likelihood (ML) method based on the Hasegawa-Kishino-Yano + G + I model. The percentage of bootstrapped trees in which the associated taxa clustered together was relatively high. Some sequences of Blastocystis positive samples (TK18, 39, 46, 71, and 90) were closely related to animals (pig and cattle) indicating zoonotic risks. Therefore, proper health education in parasitic prevention for the villagers should be promoted to improve their personal hygiene. Further longitudinal studies are required to monitor the prevalence of parasitic infections after providing health education and to investigate Blastocystis ST in animals living in these villages.

Frecuencia y fuentes de Blastocystis sp . en niños de 0 a 5 años de edad atendidos en hogares infantiles públicos de la zona urbana de Calarcá, Colombia / Blastocystis sp . frequency and sources among children from 0 to 5 years of age attending public day care centers in Calarcá, Colombia

Introducción. No se han descrito las fuentes potenciales de infección por Blastocystis sp . en Colombia. Objetivos. Estimar la frecuencia de Blastocystis sp . y explorar posibles asociaciones entre la infección, las manifestaciones clínicas y algunas fuentes ambientales. Materiales y métodos. Se llevó a cabo un estudio descriptivo con una población de 1.993 menores de 5 años (lactantes y preescolares) de estratos socioeconómicos 1 y 2, atendidos en hogares infantiles de Calarcá, Colombia. Se calculó una muestra de 275 y se seleccionó aleatoriamente a los participantes en 10 % de los hogares infantiles. Se practicaron exámenes coprológicos y encuestas y se tomaron muestras para la identificación del parásito en heces, uñas, animales domésticos y algunas fuentes ambientales. Se hicieron preparaciones en fresco con lugol al 1 % y se utilizó una técnica de concentración con formol-éter. Se estimaron prevalencias y razones de momios; para las variables cualitativas se utilizó el test de ji al cuadrado y, para las cuantitativas, la prueba t de Student. Resultados. La prevalencia de infección en los niños fue de 57,5 %. Hubo asociación estadísticamente significativa entre la presencia del parásito en heces y su hallazgo en recipientes de agua de panela (OR=1,70; IC 95% 1,05-2,79), en los pisos de madera o de tierra en la vivienda (OR=3,43; IC 95% 1,12-10,48), y en alimentos diferentes a la leche en el tetero (OR=3,23; IC 95% 1,41-4,41); y se encontró una prevalencia alta sin asociación en muestras de uñas (OR=1,62; IC 95% 0,99-2,67). La diarrea fue más frecuente en niños con Blastocystis sp. (45 %) que en aquellos sin el parásito (33 %) (OR: 1,95; IC 95% 0,99-2,77) (p<0,05). Conclusiones. Blastocystis sp . se asoció significativamente con síntomas de diarrea en los niños menores de 5 años y se encontró distribuido ampliamente en el ambiente y en el agua. Se requeriría determinar si hay huéspedes específicos para genotipos patógenos por medio de técnicas moleculares.

Introduction: There are no reports of the potential sources of Blastocystis sp . in Colombia. Objectives: To estimate the frequency of Blastocystis sp . and explore possible associations among infection, clinical manifestations and environmental sources. Materials and methods: A descriptive study was conducted; a representative sample was calculated from a population of 1,993 children less than 5 years old of the lowest socioeconomic levels (1 and 2) attending day care centers in Calarcá, Colombia. The calculated sample size was 275 children, who were selected randomly in 10 % of the centers. Stool testing, questionnaires and sampling to identify the parasite in feces, nails, pets and environmental sources, were performed. Fresh preparations were made with 1% iodine solution, and a concentration technique with formalin-ether was used. Prevalence and odd ratios were estimated; the chi-square test was utilized for qualitative variables, and Student´s t for the quantitative ones. Results: The prevalence of infection in children was of 57.5%. A statistically significant association was found between the Blastocystis sp . positive stool tests and the presence of the parasite in containers of sugar cane beverage (OR=1.70; 95% CI: 1.05-2.79), wood or ground floors (OR=3.43; 95% CI: 1.12-10.48) and in foods other than bottled milk (OR=3.23; 95% CI: 1.41-4.41) . A non-significant high prevalence was found in nails (OR=1.62; 95% CI: 0.99-2.67), as well as a significantly higher prevalence of diarrhea (OR=1.95; 95% CI: 0.99-2.77) in children with Blastocystis sp . (45%) as compared with those without the parasite (33%; p<0.05). Conclusions: Blastocystis sp . showed a significant association with diarrhea symptoms in children 0 to 5 years old and was widely distributed in the environment and in water. It is necessary to determine if there are specific hosts with pathogenic potential through molecular techniques.

Parasitosis intestinales en Argentina: principales agentes causales encontrados en la población y en el ambiente / Intestinal parasitoses in Argentina: Major causal agents found in the population and in the environment

Las parasitosis intestinales se encuentran ampliamente distribuidas en el mundo, con mayor prevalencia en los países en desarrollo. Principalmente afectan a los niños, en los que además provocan disminución del desarrollo físico y mental, situación que puede potenciarse enormemente cuando se suma a un estado nutricional deficiente. La Organización Mundial de la Salud las considera una de las principales causas de morbilidad, estrechamente ligada a la pobreza y relacionada con inadecuada higiene personal, incorrecta manipulación de los alimentos crudos, falta de servicios sanitarios, falta de provisión de agua potable y contaminación fecal del ambiente. Algunas enfermedades parasitarias se vinculan con condiciones de transmisión que existen universalmente, por lo que son cosmopolitas, mientras que otras tienen distribución geográfica variable. En los últimos años, debido a la globalización, el movimiento de personas de zonas endémicas a regiones no endémicas ha permitido la diseminación de ciertas parasitosis. Y aunque también influyen en la frecuencia de algunas de estas enfermedades las costumbres de los pueblos, las condiciones ambientales son un factor determinante para la supervivencia de los parásitos. En nuestro país, debido a la diversidad de suelos y condiciones climáticas que existen, es posible hallar variedad de agentes causales de estas parasitosis. El objetivo de este trabajo fue realizar una revisión bibliográfica de los agentes parasitarios causantes de enfermedades entéricas encontrados en la República Argentina, tanto en materia fecal de personas como en el ambiente, ya que la contaminación parasitaria de este último constituye un indicador directo del riesgo de infección por parásitos intestinales.

Intestinal parasitic diseases are widely spread in the world, with the highest prevalence in developing countries. Children are mainly affected, showing a decrease in physical and mental development, as well as the expected manifestations of the disease. This situation can be greatly enhanced in children with poor nutritional status. The World Health Organization considers intestinal parasitic diseases a major cause of morbidity, closely linked to poverty and poor personal hygiene, inappropriate handling of raw food, lack of sanitation, lack of potable water supply, and environmental fecal contamination. Some parasitic diseases are cosmopolitan while others have variable geographic distribution, due to different factors such as the presence of exclusive intermediate hosts. In the past few years, globalization allowed the spread of certain parasites from endemic to non-endemic regions. Even though people's customs influence on the frequency of certain parasites, environmental conditions are a determinant factor for parasite survival. In our country, due to the variety of soils and climatic conditions, several causative agents of these parasitoses can be found. The aim of this work was to review the literature on the intestinal parasitic agents found in Argentina in human fecal samples and its environment, as parasitic contamination constitutes a direct indicator of the infection risk by intestinal parasites.

Investigación de blastocystis sp. en agua de consumo humano en una población escolar de la zona rural del estado Mérida, Venezuela / Blastocystis sp. in drinking water at a rural school in Mérida, Venezuela

Para detectar la presencia de Blastocystis sp. en el agua de consumo de una escuela rural del estado Mérida, se recolectaron 36 muestras provenientes de la fuente natural que surte el tanque de distribución, del tanque y de los grifos, durante los meses de Septiembre 2008, Febrero y Diciembre del 2009 y Mayo 2010. El procesamiento de las muestras se realizó siguiendo la técnica propuesta por Suresh y col. (2005). Los resultados sugieren que el agua de consumo estaba exenta de Blastocystis o que la cantidad de quistes viables presentes en las muestras fue muy baja, lo que no permitió lograr la recuperación del parásito en el cultivo. Por ello se requiere el uso de técnicas más sensibles que permitan detectar cantidades bajas del microorganismo en aguas de consumo humano. El estudio de los hábitos de consumo de agua de la población estudiantil de la escuela rural, mostró que más de la mitad de la población consume agua hervida, esto probablemente se deba a que están conscientes que el agua a la cual tienen acceso proviene de una fuente natural no tratada

In order to determine the presence of Blastocystis sp. in drinking water at a rural school in Merida, 36 water samples were collected from natural sources that feed the distribution tank and faucets during the months of September, 2008, February and December, 2009, and May, 2010. Samples were processed using the technique proposed by Suresh et al. (2005). All samples were negative. These results suggest that the water was exempt from Blastocystis or that the quantity of viable cysts present in the samples was very low, not permitting reproduction in the culture. This report suggests the importance of using more sensitive techniques to detect low amounts of the organismin drinking water. The study of student water consumption habits at the rural school showed that more than half the population consume boiled water; probably, they are aware that the water source has not been treated for drinking

Algunas consideraciones acerca de Blastocystissp, un parásito controversial / Some considerations about Blastocystis sp, a controversial parasite / Algumas considerações sobre Blastocystis sp, Um parasita controverso

Blastocystis es un organismo unicelular, anaerobio y uno de los parásitos intestinales de mayor prevalencia a nivel mundial. Durante mucho tiempo su ubicación taxonómica fue difícil de definir. Actualmente es considerado el único parásito humano del Reino Chromista. Se le reconocen numerosas formas evolutivas (vacuolares, granulares, ameboidales, avacuolares, multivacuolares y quísticas) que conforman un ciclo vital aún en estudio. Los quistes son las formas de resistencia y transmisión. Se lo considera un parásito zoonótico con 9 subtipos que pueden tener diferentes especificidades entre hospedadores humanos y animales. Su carácter patógeno ha sido motivo también de controversia dado que puede presentar infecciones asintomáticas o sintomáticas con manifestaciones digestivas, y dérmicas, entre otras. El diagnóstico de laboratorio puede ser microscópico o mediante cultivos, serología y técnicas moleculares.

Blastocystis is an anaerobic, unicellular organism and it is one of the most prevalent among intestinal parasites. It has a worldwide distribution. Nowadays, it is considered the only human parasite that belongs to the kingdom Chromista. Many morphological forms of the parasite are known: vacuolar, granular, amoeboid, avacuolar, multivacuolar and cyst. Its life cycle is not completely understood. Cysts are the forms of resistance and transmission. It is considered a zoonotic parasite with 9 subtypes, with different specificities for human and animal hosts. Its pathogenesis is controversial because it can cause asymptomatic and symptomatic infections, with gastrointestinal and cutaneous manifestations. Laboratory diagnosis may be performed by microscopic, cultural, serological and molecular techniques.

Blastocystis subtypes in irritable bowel syndrome and inflammatory bowel disease in Ankara, Turkey

Blastocystis infection has been reported to be associated with irritable bowel syndrome (IBS), inflammatory bowel disease (IBD) and chronic diarrhoea. The availability of data on the subtypes of Blastocystis found in these patient groups would be of interest in understanding the significance of Blastocystis infection in chronic illness. In this study, we identify Blastocystis subtypes found in patients presenting with IBS, IBD, chronic diarrhoea and asymptomatic patients in Ankara, Turkey. Blastocystis was detected in 11 symptomatic patients by microscopy and 19 by stool culture. Stool culture was more sensitive than microscopy in identifying Blastocystis. Using standard nomenclature adopted in 2007, Blastocystis sp. subtype 3 was the most common in all groups, followed by Blastocystis sp. subtype 2. Identical subtypes of Blastocystis are found in patients with IBS, IBD and chronic diarrhoea. These particular subtypes show low host specificity and are carried by humans and some farm animals. The subtypes of Blastocystis that are commonly found in rodents and certain wild birds were not found in these patients. We suggest a model in which the severity of enteric protozoan infection may be mediated by host factors.

Protozoos intestinales en un asentamiento precario: manifestaciones clínicas y ambiente / Intestinal protozoa in a marginal settlement: clinical manifestations and environment

Los objetivos de este trabajo fueron conocer la distribución de Blastocystis hominis y Giardia lamblia en un asentamiento del Partido de La Plata (Buenos Aires), evaluar si su infección tiene manifestaciones clínicas y si su asociación con especies comensales es indicadora de la influencia de factores ambientales. Se tomaron 194 muestras fecales en 78 familias, que se analizaron mediante las técnicas de Ritchie, Carles Barthelemy y Willis. Se completaron encuestas con datos ambientales, sociales y del entorno de las viviendas. Se buscaron parásitos intestinales en muestras de agua. El 69,1% de los analizados (85,8% de las familias) estuvo parasitado con protozoos. En el 87% de los hogares positivos, hubo casos de poliparasitismo. Las especies más frecuentes fueron Blastocystis hominis y Giardia lamblia, que no se hallaron asociadas entre sí, ni con los síntomas digestivos estudiados. Blastocystis hominis se asoció con Endolimax nana (p<0,01), Entamoeba coli (p<0,01) y Enteromonas hominis (p<0,05). Ambas especies patógenas fueron más frecuentes entre las familias numerosas que viven en condiciones de hacinamiento (p≤0,05). Giardia lamblia se asoció con la promiscuidad (p<0,05) y la convivencia con caninos (p<0,01). La presencia de quistes de amebas comensales en el agua de las viviendas analizadas demuestra que ésta puede ser un factor de riesgo de infección parasitaria si no es debidamente purificada. Son necesarios mayores controles sanitarios que procuren una disposición segura de las excretas humanas y animales.

The aims of this study were to know the distribution of Blastocystis hominis and Giardia lamblia in a suburban settlement of La Plata district, Buenos Aires province, to evaluate if infections have clinical manifestations, and to determine if the association with commensal species is influenced by environmental factors. A hundred and ninety-four faecal samples of 78 families were examined using Ritchie, Carles Barthelemy and Willis techniques, and also water samples were analyzed for intestinal protozoans. Environmental and social questionnaires were fulfilled. Of the analyzed persons, 69.1% (85.8% of the families) were infected with protozoans. Eighty-seven per cent of the positive families were poli-parasitized. Blastocystis hominis and Giardia lamblia were the most frequent species and they were not associated with each other, neither with the digestive symptoms. Blastocystis hominis was associated with Endolimax nana (p<0.01), with Entamoeba coli (p<0.01) and with Enteromonas hominis (p<0.05). Giardia lamblia was associated with promiscuity (p<0.05) and the coexistence of dogs (p<0.01). The presence of cysts of commensal amoebas in the water analyzed demonstrates it could be a risk factor of parasitic infection. More strict sanitary controls are needed to avoid the faecal contamination of the environment.

Transición parasitaria a Blastocystis hominis en niños de la zona centro del estado de Guerrero, México / Parasitic transition to Blastocystis hominis in children from center zone of Guerrero state, Mexico

Blastocystis hominis es un organismo emergente cuya prevalencia se ha incrementado en los últimos años. La frecuencia en México va de 4,0 por ciento a 62 por ciento, sin reportes previos en el estado de Guerrero. La población estudiada fueron tres localidades del estado de Guerrero: Chilpancingo, Petaquilla y Tixtla en un total de 1.138 niños preescolares y escolares, de ambos sexos. Mediante tres técnicas coproparasitóscopicas (CPS): examen directo, concentración por flotación de Faust y cultivo de Barret, se detectaron un total de 38 por ciento de niños parasitados y B. hominis ocupó el primer lugar con el 61 por ciento de los CPS positivos. El 90 por ciento de los casos fueron parasitosis única. El 58 por ciento de los niños aparentemente sanos y con B. hominis declararon tener algún síntoma gastrointestinal. La asociación de B. hominis con dolor abdominal y beber agua de la llave tuvo diferencia significativa. Proponemos una transición parasitaria a B. hominis como principal parásito del hombre, como resultado de las medidas de control para las parasitosis intestinales.

Blastocystis hominis is an enteric emergen organism found in human it's prevalence has been increasing in the lasts years. The frequency in Mexico is from 4.0 percent to 62 percent, without reports in the Guerrero state. The aim of this study was to inform the parasitic transition to B. hominis in the Central Zone of Guerrero state. The population in this study were three communities of Guerrero state: Chilpancingo, Petaquilla and Tixtla in a total of 1,138 preschools and schools children of both sexs. Three parasitological tests were used for detection of the parasite in stool specimens: micrscopy of direct smears, concentration and flotation technique and serum-solution saline culture. Global prevalence of parasites was of 38 percent and B. hominis was the principal parasite with 61 percent on the positive tests. The 90 percent were only B. hominis and 10 percent with others parasites. A total of 58 percent of the children healthy with B. hominis declarated have gastrointestinal symptoms. The association ofB. hominis with abdominal pain and drinking taste water had significant difference. We propuse a parasitic transition to B. hominis as principal human parasite, this can be the result of man-made intervention in the intestinal parasitosis control.

Restriction enzyme digestion analysis of PCR-amplified DNA of Blastocystis hominis isolates.

Genomic DNA of Blastocystis isolates released into 0.1% Triton X-100 was suitable for amplification and yielded similar results as the genomic DNA extracted with standard kit. The specific B. hominis primers (BH1: GCT TAT CTG GTT GAT CCT GCC AGT and BH2: TGA TCC TTC CGC AGG TTC ACC TAC A) successfully produced the PCR product of about 1,770 bp with all the 7 Blastocystis isolates tested. The restriction fragment length polymorphism (RFLP) patterns yielded by 13 out of 25 restriction endonucleases showed that the 7 isolates could be grouped into 4 subgroups: subgroup-1 consisted of isolate C; subgroup-2 of isolates H4 and H7; subgroup-3 of isolates KP1, Y51 and M12; and subgroup-4 of isolate 27805. The differences between subgroups manifested as clear-cut RFLP patterns. A common band of 230 bp was revealed by Eco R1 in all the Blastocystis isolates tested. The band of about 180 bp was revealed by Alu I, differentiated symptomatic from asymptomatic isolates of this parasite, and might indicate the pathogenicity of this parasite.

Blastocistose: controvérsias e indefinições / Blastocystosis: controversy and ill-defined

A blastocistose, enterite devida ao Blastocystis hominis, ainda causa controvérsias. É comum verificar que expressivo número de médicos, patologistas e profissionaisque exercem atividades no âmbito da saúde pública conhecem ainda pouco sobre aspectos nosológicos desse protozoário. Essa situação faz com que, por vezes, sejam adotadas condutas inadequadas na clínica...