Abstract Blastocystis spp. is a very frequent parasite in human fecal matter, but the polymorphic nature and the number of Blastocystis in a sample can complicate its detection by microscopy. The objective of the present work was to describe the dynamics of Blastocystis morphotypes in the short term in a simple culture medium and to determine its applicability to use it as a complement to coproparasitological analysis and for morphological, biochemical and molecular studies of the parasite. Ten stool samples with Blastocystis were cultured in an adapted Pavlova medium and examined during 6 days by microscopy to record the forms and the count. The development was regular and abundant and the shapes were of variable sizes and clearly identifiable. The tested culture could be used for the detection of Blastocystis when microscopic diagnosis is dubious, for studies of diagnostic sensitivity and specificity or when it is necessary to increase the load to perform other studies.

Resumen Blastocystis spp. es un parásito muy frecuente en materia fecal humana, pero la naturaleza polimórfica y el número de Blastocystis en la muestra pueden complicar su detección por microscopía. El objetivo del trabajo fue describir la dinámica de los morfotipos de Blastocystis a corto plazo en un medio de cultivo simple y determinar su aplicabilidad para utilizarlo como complemento del análisis coproparasitológico y para estudios morfológicos, bioquímicos y moleculares del parásito. Se sembraron 10 muestras de materia fecal con Blastocystis en un medio Pavlova adaptado, se examinaron diariamente por examen microscópico durante 6 días y se registraron las formas y el recuento. El desarrollo fue regular y abundante y las formas fueron de tamaños variables y claramente identificables. El cultivo ensayado puede ser útil para la detección de Blastocystis cuando existan dudas diagnósticas por microscopía, para estudios de sensibilidad y especificidad diagnóstica o cuando se requiera aumentar la carga para realizar otros estudios.

Resumo Blastocystis spp. é um parasita muito frequente nas fezes humanas, mas a natureza polimórfica e o número de Blastocystis na amostra podem complicar a sua detecção através do microscópio. O objetivo do trabalho foi descrever a dinâmica dos morfotipos de Blastocystis no curto prazo em um meio de cultura simples e determinar sua aplicabilidade para ser utilizado como complemento da análise coproparasitológica e para estudos morfológicos, bioquímicos e moleculares do parasita. Foram semeadas dez amostras de fezes com Blastocystis em um meio Pavlova adaptado e examinadas diariamente através de exame microscópico durante 6 dias, registrando as formas e fazendo recontagem. O desenvolvimento foi regular e abundante e as formas foram de tamanhos variáveis e claramente identificáveis. A cultura testada pode ser útil para a detecção de Blastocystis quando houver dúvidas diagnósticas por microscopia; para estudos de sensibilidade e especificidade diagnóstica ou quando for necessário aumentar a carga para a realização de outros estudos.

Resumo Blastocystis é o parasita unicelular do intestino do homem e outros animais, mais prevalente em seres humanos. Apresenta grande variedade genética com múltiplos subtipos (ST). Embora tenha sido associada a distúrbios intestinais e extraintestinais, sua patogenicidade é debatida. Foram analisadas 461 amostras de fezes de pacientes sintomáticos (n=380) e assintomáticos (n= 81) de hospitais de Bahía Blanca, Argentina; foi solicitado consentimento informado e preenchida uma ficha epidemiológica. Foram realizadas análises coproparasitológicas, morfometria, contagem e tipificação de Blastocystis ST3 por PCR. A população era: 57,3% sexo feminino e 42,7% masculino. A prevalência de Blastocystis foi de 31,0% e de Blastocystis ST3 62%. Foram encontradas formas vacuolares, granulares e císticas, sendo as vacuolares as mais frequentes. Em 64,8% das amostras, os Blastocystis foram pequenos e escassos; 88,4% dos pacientes sintomáticos apresentaram distúrbios gastrointestinais, 4% urticária e 7,6% febre, anemia e baixo peso; 66,7% dos pacientes com urticária apresentaram Blastocystis. A presença de sintomas foi associada significativamente com Blastocystis (p˂0,002). Não foram encontradas associações estatísticas entre Blastocystis, a idade, sexo, a disponibilidade de água potável, de esgoto e o contato com animais. Dentro dos sintomas, só foi encontrada associação estatística de Blastocystis com urticária (p˂0,007). Não houve associação entre Blastocystis ST3 e sintomatologia. Os resultados destacam a alta prevalência de Blastocystis e Blastocystis ST3, a necessidade de fazer um coproparasitologico minucioso, sua associação estatística com urticária e a importância de não ignorá-lo no processo saúde-doença.

Abstract Blastocystis is the unicellular parasite of the intestine of man and other animals,most prevalent in humans. It has a great genetic variety with multiple subtypes (ST). Although it has been associated with intestinal and extraintestinal disorders, its pathogenicity remains unclear. Four hundred and sixty one stool samples from symptomatic (n=380) and asymptomatic(n=81) patients from hospitals in Bahía Blanca, Argentina were analysed; informed consent was requested and an epidemiological file was completed. Coproparasitological analysis, morphometry, counting and typing of Blastocystis ST3 were performed by PCR. The population was: 57.3% female and 42.7% male.The prevalence of Blastocystis was 31.0% and that of Blastocystis ST3 62%. Vacuolar, granular and cystic forms were found, with vacuolar forms being the most frequent. Blastocystis were small and scarce in 64.8% of the samples. Most of the symptomatic patients (88.4%) presented gastrointestinal disorders, urticaria 4% and fever, anemia and low weight 7.6%; 66.7% of the urticaria patients presented Blastocystis. The presence of symptoms was significantly associated with Blastocystis (p<0.002). No statistical associations were found between Blastocystis, age, sex, availability of drinking water, sewage, and contact with animals. Within the symptoms, only statistical association of Blastocystis with urticaria was found (p<0.007). There was no association between Blastocystis ST3 and symptomatology. The results highlight the high prevalenceof Blastocystis and Blastocystis ST3, the need for a thorough coproparasitology, their statistical association with urticaria and the importance of not ignoring it in the health-disease process.

Resumen Blastocystis es el parásito unicelular del intestino del hombre y de otros animales más prevalente en seres humanos. Presenta gran variedad genética con múltiples subtipos (ST). Aunque se ha asociado a desórdenes intestinales y extraintestinales, su patogenicidad es discutida. Se analizaron 461 muestras de materia fecal de pacientes sintomáticos (n=380) y asintomáticos (n=81) de hospitales de Bahía Blanca, Argentina; se solicitó consentimiento informado y se completó una ficha epidemiológica. Se realizaron análisis coproparasitológicos, morfometría, recuento y tipificación de Blastocystis ST3 por PCR. La población fue: 57,3% de sexo femenino y 42,7% masculino. La prevalencia de Blastocystis fue de 31% y de Blastocystis ST3 62%. Se hallaron formas vacuolares, granulares y quísticas; las vacuolares fueron las más frecuentes. En el 64,8% de las muestras los Blastocystis fueron pequeños y escasos. El 88,4% de los pacientes sintomáticos presentó trastornos gastrointestinales, el 4% urticaria y el 7,6% fiebre, anemia y bajo peso. El 66,7% de los pacientes con urticaria presentó Blastocystis. La presencia de síntomas se asoció significativamente con Blastocystis (p<0,002). No se hallaron asociaciones estadísticas entre Blastocystis, la edad, el sexo, la disponibilidad de agua potable, de cloacas y el contacto con animales. Dentro de los síntomas sólo se encontró asociación estadística de Blastocystis con urticaria (p<0,007). No hubo asociación entre Blastocystis ST3 y sintomatología. Los resultados destacan la alta prevalencia de Blastocystis y de Blastocystis ST3, la necesidad de hacer un coproparasitológico minucioso, su asociación estadística con urticaria y la importancia de no ignorarlo en el proceso salud-enfermedad.

Carcasses represent a trophic and reproductive resource or shelter for arthropods, which are a representative component of the decomposition process. Four experiments, one per season, were conducted in a semi-rural area of Bahía Blanca, Argentina, to study the trophic roles of cadaveric beetles, evaluating the abundance, composition and dominance during all decomposition stages and seasons. Species of necrophagous, necrophilous and omnivorous habits were found. Abundance, composition and dominance of beetles in relation to their trophic roles changed according to seasons and decomposition stages. Guilds and patterns of succession were established in relation to those periods. Trophic roles could be an indicator of beetle associations with decomposition stages and seasons.

The species Nitidula carnaria (Schaller) (Coleoptera: Nitidulidae) has economic and forensics importance. The mature larva, reared under controlled conditions of laboratory, was described for the first time. Moreover, preliminary information about the life cycle is provided. The time recorded from the instance mates placed together to the emergence of imago was 59 ± 2.4 days. This publication represents the first record of N. carnaria in South America.

La especie Nitidula carnaria (Schaller) (Coleoptera: Nitidulidae) tiene importancia económica y forense. Por primera vez, se describe la larva madura criada bajo condiciones controladas de laboratorio. Además, se suministra información preliminar del ciclo de vida. Desde la formación de parejas reproductivas hasta obtener el imago, el tiempo registrado fue de 59 ± 2,4 días. Esta publicación es el primer reporte de N. carnaria en Sudámerica.

Acanthamoeba spp. has been isolated from many habitats, including swimming pools. Investigations on its distribution are relevant because many of its species cause human diseases. The aim of the present work was to investigate, isolate and characterize protozoan of the genus Acanthamoeba from indoor swimming pools in Bahía Blanca, Argentina, in the four seasons, during the 2007-2008 period. Seven pools were studied and samples were collected from the bottom, surface and wall by scraping them. Besides, samples for bacteriological analysis were taken from each pool. The samples were analyzed by direct observation and by culturing on non nutritive agar at 37 °C and at 42 °C. The generic identification was performed according to the morphologic characteristics of cysts and trofozoites, while the amoebo-flagellate transformation test was carried out to identify Naegleria. Free-living amoebas were isolated from five of the seven swimming pools examinated, in at least one season. Naegleria genus was not found as the amoebo-flagellate transformation tests were negative in all samples. All the isolations corresponded to the genus Acanthamoeba belonging to Pussard & Pons morphological Groups II and III. Although elimination of Acanthamoeba from the water is difficult because it is a ubiquitous protozoan. which is highly resistant to the commonly used disinfectants, a thorough cleaning of the pools to minimize the risks of infection is recommended.

Acanthamoeba ha sido aislada de numerosos hábitats incluyendo piletas de natación. Estudiar su distribución es importante ya que algunas especies causan enfermedad en el hombre. El objetivo del presente trabajo fue la búsqueda, aislamiento y caracterización de protozoos del género Acanthamoeba en piscinas cubiertas de la ciudad de Bahía Blanca, Argentina, en las cuatro estaciones del año durante 2007-2008. Se estudiaron 7 piscinas y en cada una se tomaron cuatro muestras: fondo, superficie, raspado de pared y para análisis bacteriológico. Las muestras se analizaron por observación directa y por cultivo en agar no nutritivo a 37 °C y a 42 °C. La identificación genérica se realizó de acuerdo con las características morfológicas de quistes y trofozoítos y para identificar Naegleria se realizó la prueba de transformación ameboflagelar. En 5 de las 7 piscinas se aislaron amebas de vida libre al menos en una época del año. La prueba de transformación ameboflagelar resultó negativa, descartando al género Naegleria. Todos los aislamientos correspondieron al género Acanthamoeba Grupos II y III de Pussard y Pons. Si bien la eliminación de Acanthamoeba en las aguas de natatorios resulta muy difícil por tratarse de un protozoario ubicuo y sumamente resistente a los desinfectantes comúnmente utilizados, se recomienda una limpieza profunda de las piscinas que minimice los riesgos de infección.

Myiasis is the infestation of live human and vertebrate animals with dipterous larvae which, at least for a short period, feed on the host's dead or living tissue, liquid body-substance, or ingested food. The objective of this study was to identify the flies producing myiasis in Bahía Blanca city, Argentina, from 01/03/2000 to 31/05/2005. Seventeen clinical cases were studied. The larvae obtained from lesions were forwarded from laboratories and from public and private hospitals. Part of the larvae were fixed in alcohol 70º and processed according to the Mazza & Jörg technique (1939). The other part continued growing in flasks with meat in laboratory conditions to obtain the adults. The etiological agents of myiasis were identified by observing the diagnostic characteristics of the larvae III and of the adults, and by using taxonomic keys. Myiasis was produced by Cochlyiomia hominivorax (Coquerel) in thirteen of the cases and by Phaenicia sericata (= Lucila sericata) (Meigen) (Diptera: Calliphoridae) in the other four. The cases were traumatic and aural myiasis and happened from December to March. The ages of patients were four to eighty-six years and 76.5% of the cases occurred in male patients. Given the aggressiveness of these larvae, mainly C. hominivorax, in causing human myiasis, the importance of specific and quick diagnosis and of adequate treatment must be acknowledged.

Se entiende por miasis a la infestación de vertebrados vivos por larvas de dípteros, que por lo menos durante un corto período, se alimentan de los tejidos vivos o muertos del hospedador, de sus sustancias corporales líquidas o del alimento por él ingerido. El objetivo del presente trabajo fue determinar las especies bioagentes de miasis humanas ocurridas en la ciudad de Bahía Blanca, Argentina, durante el período comprendido entre el 01/03/2000 y el 31/05/2005. Se estudiaron 17 casos clínicos. Las larvas extraídas de las lesiones fueron remitidas de laboratorios y hospitales públicos y privados de dicha ciudad. Parte de las larvas se fijó en alcohol 70° y se procesó según la técnica de Mazza & Jörg (1939). El resto se crió en condiciones de laboratorio hasta la obtención de los adultos. Se observaron las características diagnósticas de las larvas III y de los ejemplares adultos y se clasificaron taxonómicamente. Las especies bioagentes fueron: Cochliomyia hominivorax (Coquerel) en trece de los casos y Phaenicia sericata (= Lucila sericata) (Meigen) (Diptera: Calliphoridae) en los cuatro restantes. Las miasis fueron traumáticas y aurales, se presentaron durante los meses de Diciembre a Marzo, en la franja etaria de 4 a 86 años, siendo el 76,5% de los casos de presentación en pacientes masculinos. Teniendo en cuenta la voracidad de las larvas, principalmente las de C. hominivorax, resulta claro que el diagnóstico rápido de miasis y la aplicación del tratamiento adecuado son decisivos para que esta parasitosis se resuelva sin consecuencias graves para el paciente.

The aim of the present study was to detect the presence of sanitarily important parasit es in the water from Arroyo Napostá as well as in the water used for recreational purposes (public swimming-pools) and for consumption in the city of Bahía Blanca, province of Buenos Aires, Argentina. To this end, 24,000 liters of water from different sectors of Arroyo Napostá; 2,000 liters of water from each of the three public swimming-pools of Bahía Blanca; and 8,000 liters of water for consumption were collected using polypropylene spun cartridge filters with a 1 mm porosity (Cuno Micro Wind II). Further processing was conducted following Madore´s technique (1987) modified by Pezzani (2000). Detection of Cryptosporidium sp. Giardia sp. was carried out via direct immunofluorescence. Our study confirmed the presence of the following parasites in the areas of study: Hymenolepis diminuta eggs, Giardia sp cysts, Toxocara sp eggs, Entamoeba sp cysts, Endolimax sp cysts, Nematode larvae, Trichostrongylus sp eggs, Ascaris sp eggs, and Cryptosporidium sp cysts in the water from Arroyo Napostá; Hymenolepis diminuta eggs, Giardia sp cysts, Toxocara sp eggs, Entamoeba sp cysts, Endolimax sp cysts, Nematode larvae, Trichostrongylus sp eggs, Ascaris sp in the water from swimming-pools; and Cryptosporidium sp in the water for consumption. The results from the present study urge sanitary authorities from the city of Bahía Blanca to take measures in order to prevent not only humans but also animals from getting in contact with these waters which are contaminated and dangerous to health

El objetivo del presente trabajo fue detectar la presencia de parásitos de importancia sanitaria para el hombre, en el arroyo Napostá, en aguas recreacionales (piscinas públicas) y de consumo en Bahía Blanca (Provincia de Buenos Aires) Argentina. Se recolectaron 24.000 litros de agua de diferentes sectores del arroyo Napostá, 2.000 litros de cada una de las tres piscinas públicas y 8.000 litros de agua de consumo, mediante filtros de poro de una micra de diámetro (Cuno Micro Wind). El procesamiento posterior se efectuó siguiendo la técnica de Madore (1) modificada por Pezzani (2). La detección de Cryptosporidium sp. Giardia sp. se realizó mediante inmunofluo-rescencia directa. Las formas parasitarias observadas, fueron: huevos de Hymenolepis diminuta, quistes de Giardia sp, huevos de Toxocara sp, quistes de Entamoeba sp. Quistes de Endolimax sp, larvas de Nematodos, huevos de Trichostrongylus sp, huevos de Ascaris sp y quistes de Cryptosporidium sp. en las aguas del Arroyo Napostá; huevos de Hymenolepis diminuta, quistes de Giardia sp, huevos de Toxocara sp, quistes de Entamoeba sp. quistes de Endolimax sp, larvas de Nematodos, huevos de Trichostrongylus sp, huevos de Ascaris sp. en agua de piscina; y quistes de Cryptosporidium sp. en agua de consumo. En conclusión es necesario que las autoridades sanitarias adopten medidas tendientes a evitar que el hombre y los animales tomen contacto con estas aguas contaminadas y peligrosas para la salud

The geometrical patterns of egg cells of Triatoma patagonica Del Ponte, 1929, a species considered to be an active vector of Chagas' disease, were studied by scanning electron microscopy (SEM). Eggs of known age were selected according to their morphological characteristics, namely those which were 5 days old, 14 days old, and those which were hatched. Images of the exchorion were registered in the cephalic, caudal, and medial areas. The results showed that T. patagonica eggs evidence that in their cephalic and caudal areas, cells have either an hexagonal, pentagonal, or quadrilateral configuration, while in the medial area, cells have mainly an hexagonal configuration. It was also observed that the geometrical patterns of the different parts of the egg undergo no changes during embryonal development.

Se estudiaron por microscopía electrónica de barrido (SEM) los patrones geométricos de las células de huevos de Triatoma patagonica Del Ponte, 1929, especie considerada vector activo de la enfermedad de Chagas. Se seleccionaron huevos de edad conocida: 5 días, 14 días y eclosionados, según sus características morfológicas y se registraron imágenes del exocorion en las zonas cefálica (opérculo), caudal y media. Los resultados obtenidos mostraron que los huevos de T. patagonica presentan en sus zonas cefálica y caudal, células con forma de hexágonos, pentágonos y cuadriláteros y en la media principalmente hexágonos. Se observó que los patrones geométricos de las distintas partes del huevo no cambian durante el desarrollo embrionario.

The aim of the present investigation was to identify the fly producing myiasis in a patient with pediculosis. The patient was a male adult with a severe Pediculus humanus capitis' infestation and a lesion on his head containing larvae. Examination of these larvae revealed that they were Cochliomyia hominivorax. In this clinical case, the post-scratch lesions were infected with C. hominivorax' s larvae. It is the first time that the myiasis-pediculosis association has been mentioned in the literature

Un paciente, adulto, masculino, presentaba al momento de la consulta una severa infestación por Pediculus humanus capitis y una lesión en la cabeza de donde emergían larvas. El material extraído de la herida del paciente correspondió a Cochliomyia hominivorax. En este caso clínico, las lesiones producidas por el rascado del propio paciente permitieron atraer moscas C. hominivorax las que depositaron sus huevos en ellas de donde eclosionaron sus larvas que ocasionaron la miasis cutánea.

The purpose of this research is to carry out an epidemiological characterization of the different types of parasitosis detected in the city of Bahía Blanca (Argentina) (1994 to 1999). To this end, the prevalence of: enteroparasitosis, trichomonosis, toxoplasmosis, Chagas disease, malaria, hydatidosis, toxocarosis, cysticercosis, and trichinellosis in human beings is reported in this study. Furthermore, the frequency and spectrum of the parasites found in the dogs´ excrements collected from the public thoroughfare as well as parasitism rates in the vegetables from the truck farms of the city are also included in the present study. The high rates of enteroparasitosis in human beings ranging from 28% to 87.9% depending on the areas of study, those in dogs´ excrements reaching a percentage of 33.1%, and the presence of vegetables from fully contaminated truck farms are indicative of a serious intestinal parasite-transmission problem in the city of Bahía Blanca urging for preventive measures in order to minimize this situation

ENTEROPARASITES IN CHILDREN LIVING IN RURAL AREAS AT THE PARTIDO DE CARMEN DE PATAGONES. PROVINCE OF BUENOS AIRES.ARGENTINA In the absence of epidemiological data on enteroparasites in a population of 0-14 year-old residents in the rural area of Partido de Carmen de Patagones, Province of Buenos Aires, Argentina, a descriptive and epidemiologic study was carried out as part of a Primary Health Care Program ( PHCP). Faecal matter and anal mucus serial parasitoscopic studies were carried out on 210 children. Results indicate that 60,5% ofthe studied population is intestinal-parasite carrier. Positive monoparasitism was of 67%, while the remaining 33% was manifested in 2-to-5 parasite forms. Parasite spectrum was registered in the following way: Entamoeba coli 31,5%, Giardia lamblia 24,7%, Enterobius vermicularis 18%, Hymenolepis nana 10,4%, Blastocystis hominis 10,3%, Chilomastix mesnili 2,5%, Uncinarias 1%, Entamoeba histolytica 0,9% and Trichuris trichiura 0,5%.Parasite distribution in the studied population was homogeneous in general except for H. nana which registered a prevalence which was higher in risk areas ( 92,4%) than in dry areas ( 7,6%).The results obtained in the present study have been communicated to the corresponding sanitary authorities.

RESUMEN Como parte del Programa de Atención Primaria de la Salud (APS) del año 1996, y en virtud de que no existían datos epidemiológicos referidos a enteroparásitos hallados en niños de 0 a 14 años, residentes en una zona rural del Partido de Carmen de Patagones, Provincia de Buenos Aires, es que se realizó el presente estudio epidemiológico descriptivo. Se estudiaron 210 niños a los que se les efectúo un estudio parasitoscópico seriado de materia fecal y mucus anal. Los resultados mostraron que el 60,5% de la población estudiada era portadora de algún parásito intestinal. El monoparasitismo hallado fue de 67%, mientras que el 33% restante presentó entre 2 y 5 formas parasitarias. El espectro parasitario fue el siguiente: Entamoeba coli 31,5%; Giardia lamblia 24,7 %; Enterobius vermicularis 18%; Hymenolepis nana 10,4%; Blastocystis hominis 10,3%; Chilomastix mesnili 2,5%; Uncinarias 1%; Entamoeba histolytica 0,9% y Trichuris trichiura 0,5%. La distribución parasitaria en los distintos sectores estudiados fue en general homogénea excepto para H. nana la cual presentó una prevalencia más alta en zonas de riego con relación a la zona seca . Los resultados obtenidos fueron comunicados a las autoridades sanitarias correspondientes