Self-fertilization, long-distance flash invasion and biogeography shape the population structure of Pseudosuccinea columella at the worldwide scale.

Population genetic studies are efficient for inferring the invasion history based on a comparison of native and invasive populations, especially when conducted at species scale. An expected outcome in invasive populations is variability loss, and this is especially true in self-fertilizing species. We here focus on the self-fertilizing Pseudosuccinea columella, an invasive hermaphroditic freshwater snail that has greatly expanded its geographic distribution and that acts as intermediate host of Fasciola hepatica, the causative agent of human and veterinary fasciolosis. We evaluated the distribution of genetic diversity at the largest geographic scale analysed to date in this species by surveying 80 populations collected during 16 years from 14 countries, using eight nuclear microsatellites and two mitochondrial genes. As expected, populations from North America, the putative origin area, were strongly structured by selfing and history and harboured much more genetic variability than invasive populations. We found high selfing rates (when it was possible to infer it), none-to-low genetic variability and strong population structure in most invasive populations. Strikingly, we found a unique genotype/haplotype in populations from eight invaded regions sampled all over the world. Moreover, snail populations resistant to infection by the parasite are genetically distinct from susceptible populations. Our results are compatible with repeated introductions in South America and flash worldwide invasion by this unique genotype/haplotype. Our study illustrates the population genetic consequences of biological invasion in a highly selfing species at very large geographic scale. We discuss how such a large-scale flash invasion may affect the spread of fasciolosis.

A novel HLA allele, HLA-DRB1*13:204, detected in a Brazilian unrelated hematopoietic stem cell donor.

The HLA-DRB1*13:204 allele differs from HLA*13:64 by two nucleotide substitutions at positions 181 and 189 in the exon 2.

Risk factors associated with toxoplasmosis and toxocariasis in populations of children from nine cities in southern Brazil.

This study investigated the epidemiological factors that contribute to the seroprevalence of Toxoplasma gondii and Toxocara spp. in children from Paraná state, Brazil. Immunoglobulin G (IgG) antibodies to T. gondii were detected using indirect immunofluorescence, and IgG antibodies to Toxocara were detected using an enzyme-linked immunosorbent assay. For each individual, a questionnaire was completed that contained epidemiological and clinical data. The data analysis was performed using multiple logistic regression. Of the 544 children investigated, 3.2% presented co-infection with T. gondii and Toxocara spp. Of this total, 7.4% were positive for antibodies to T. gondii, and 25% were positive for antibodies to Toxocara spp. The presence of antibodies to Toxocara spp. increased the risk of T. gondii infection (P = 0.029). Children who were 1-8 years of age were less infected by T. gondii than those who were 9-12 years of age. The variables that influenced positivity for anti-Toxocara spp. were the origin of the children and contact with sand. Children with positive serology for Toxocara spp. presented more eosinophilia compared with those with non-reactive serology. Infection with both parasites reveals the need for preventive measures, such as guidance about modes of infection, parasite control and monitoring recreational areas.

Seroprevalence of Toxocara infection in children and environmental contamination of urban areas in Paraná State, Brazil.

The objectives of this study were to evaluate the contamination by eggs of Toxocara in sandy areas or grass lawns of outdoor recreation areas that are used by children, and the frequency of seroprevalence in children, from three cities of fewer than 45,000 inhabitants in Paraná, Brazil. From May 2005 to December 2007, five samples were taken from each of 13 sandy sites and 18 grass lawns, all from plazas and public schools. Blood samples from children aged 0-12 years were analysed by immunoassay for anti-Toxocara IgG. The soil samples were processed by floatation and sedimentation. Eggs of Toxocara spp. were present in 44.7% (38/85) of the samples from grassed areas and in 21.4% (15/70) of the sand samples. The lawns were 2.16 times more contaminated than the sand (P = 0.0009). However, the epidemiological variables showed no statistically significant difference between seropositive (36.8%; 130/353), and seronegative children. The rate of seropositivity was higher in children aged 0-5 years (P = 0.03), who were 1.94 times more likely to develop persistent wheezing (P = 0.02).

Anal canal and rectal condylomatosis: exhaustive proctological examination and STD patients.

Infection of the anorectal area with some subtypes of HPV virus results in local involvement that appears as warty, papillary, condylomatous lesions. Patients exposed to high-risk HPV types, such as HPV-16, -18, and -31, are at risk for developing high-grade dysplasias or carcinomas. We reviewed 15 years (1991 - 2006) of patient records from our proctological unit and STD center and found 1,122 patients affected by anorectal condylomatosis. This study supports the importance of an exhaustive proctological examination in patients suffering from condylomatosis of the genital area, especially of the perianal zone, and in patients examined in the STD clinic, even for other reasons. An unknown anorectal condylomatosis is a frequent cause of relapse of anogenital warts. Anal warts should be examined by proctoscopy to assess the full extent of the lesions and prevent possible complications.

Linear enamel hypoplasia at Xcambó, Yucatán, during the Maya Classic period: An evaluation of coastal marshland impact on ancient human populations.

Non-specific stress markers such as linear enamel hypoplasia (LEH) have been associated in the literature with a large number of possible conditions disrupting the individual's homeostasis, though metabolic strain originating synergistically by disease and malnutrition has been held to be the main cause behind enamel disruption. The analysis of LEH in the Maya Classic period site of Xcambó, located along the northern coast of the Yucatán peninsula, reveals high exposure to stressful conditions during infancy regardless of age and sex. Yet, the inhabitants of the site were of a medium to high social and economic status, with access to balanced and protein-rich nutritional resources, which should have functioned as a cultural buffer to the impact of stress. In the light of this apparent contradiction, this paper discusses the impact of environmental conditions on the record of metabolic stress. Our conclusions pose a cautionary caveat for inferring nutrition and status in ancient pre-antibiotic populations solely from the occurrence of linear enamel hypoplasia.

Real-time PCR strategy for rapid discrimination among main lymnaeid species from Argentina.

Snails of the Family Lymnaeidae act as an intermediate hosts of Fasciola hepatica worldwide. The taxonomy of lymnaeid species is relevant for epidemiological studies and molecular strategies are increasingly used for that purpose. This work presents the first report of a real-time PCR approach used to identify the most important lymnaeid species in the Southern Cone of South America. Species discrimination is based on the sequence polymorphism located within the helix E10-1 of the variable region V2 of the 18S rRNA genes, which yields amplicons with clearly different melting temperatures. This procedure minimises the risk of carry-over contamination because it does not require post-PCR manipulations, and the whole protocol can be completed in less than 4h with a single snail foot as starting material. This method was successfully carried out in a blind study that included a panel of 20 Galba truncatula, 5 Lymnaea viatrix, 5 Lymnaea diaphana and 5 Pseudosuccinea columella specimens from different endemic areas for fasciolosis. This molecular approach constitutes a key laboratory tool complementing ecological studies that ultimately will promote more efficient control strategies.

Initial stage of development and migratory behavior of Toxocara canis larvae in BALB/c mouse experimental model.

In the present study, the initial developmental stage of Toxocara canis eggs and larvae, and number of recovered larvae from BALB/c mouse-infected organs are described. In vitro culture of T. canis detects the frequencies of interphasic, mitotic and embryonated eggs only within a 7-day period. Analysis by egg counting was carried out for 32 days. The results showed that at 7 days after cultivation, the frequency of larvae was 50.4% and that this frequency reached 52.8% in 32 days. In the experimental infection of BALB/c mice with T. canis, the number of recovered larvae statistically increased in the brain and liver, with doses of approximately 200 and 1000 eggs. After 7 days of infection, a larger number of larvae were obtained in the lung and liver, although a maximum amount was found in the brain after a 15- or 30-day post-infection period.

Initial stage of development and migratory behavior of Toxocara canis larvae in BALB/c mouse experimental model

In the present study, the initial developmental stage of Toxocara canis eggs and larvae, and number of recovered larvae from BALB/c mouse-infected organs are described. In vitro culture of T. canis detects the frequencies of interphasic, mitotic and embryonated eggs only within a 7-day period. Analysis by egg counting was carried out for 32 days. The results showed that at 7 days after cultivation, the frequency of larvae was 50.4% and that this frequency reached 52.8% in 32 days. In the experimental infection of BALB/c mice with T. canis, the number of recovered larvae statistically increased in the brain and liver, with doses of approximately 200 and 1000 eggs. After 7 days of infection, a larger number of larvae were obtained in the lung and liver, although a maximum amount was found in the brain after a 15- or 30-day post-infection period.

Comparison of two coprological methods for the veterinary diagnosis of fasciolosis

Compararam-se a sensibilidade dos métodos padrão de sedimentação fecal (MPSF) e modificado da tamisação e coloração das fezes (MTCF)-quatro tamises, ambos empregados no diagnóstico de infecção por Fasciola hepatica. Amostras de fezes foram obtidas de 51 bovinos oriundos de uma área endêmica por fasciolose no Sudoeste da Argentina. Cada amostra foi colocada em um recipiente contendo formalina 5%. Oito mililitros da suspensão, equivalente a 2g de fezes, foram usados em cada método testado, registrando-se o número de ovos por amostra. A porcentagem de amostras positivas pelo MTCF (27/51) foi maior que a apresentada pelo MPSF (11/51), o que representou 60% de amostras falso-negativas. A porcentagem de concordância pelos dois métodos foi 41%. A complexidade do MPSF pode diminuir sua sensibilidade pela perda de ovos durante o processamento. Estes resultados confirmaram que o MPSF subestima a contagem de ovos e que o método MTCF é mais confiável.

Estudio del foco en un caso de fasciolosis humana en Neuquén / A focus study from a case of human fascioliasis in Neuquén

El objetivo del trabajo fue realizar un estudio de foco relacionado con un caso de fasciolosis humana ocurrido en abril de 2002 en Loncopué, Neuquén, Argentina. La confirmación diagnóstica se efectuó en mayo de 2002 por el test de ELISA. En noviembre de 2002 se realizó un muestreo en el área rural donde se ubicaba la vivienda de la paciente, ya restablecida, y se le tomó una nueva muestra de sangre. El suero de la paciente continuó reactivo para antígenos de Fasciola hepatica. Se muestrearon plantas de berro para detectar metacercarias. Se recolectaron caracoles en cuatro canales de riego conectados a un canal principal. Los caracoles fueron trasladados vivos para su identificación, medición y examen de infección. Se recolectaron 35 muestras fecales de ganado de cría. No se observaron metacercarias en las hojas de berro examinadas (n=222). Se recolectaron 130 caracoles identificados como Lymnaea viatrix y 2 de 101 ejemplares (2%) estaban infectados con larvas de F. hepatica. Las prevalencias en el ganado adulto fueron: 100% (10/10) para caprinos, 82% (9/11) para ovinos y 86% (6/7) para bovinos. El número de huevos eliminados por las cabras (mediana = 20.7; Q1=6.2; Q3=34.5) y ovejas (4, 18, 13) infectadas, resultó mayor que el eliminado por vacas (0.3; 0.3; 1.7) (p<0.01). La práctica de control local no tuvo efecto aparente en este caso, por lo que deberían revisarse los calendarios de tratamiento y los antiparasitarios utilizados. Los resultados muestran que el ganado criado a pequeña escala por los pobladores debe incluirse en los programas de control. Se discute la posible importancia de la fasciolosis humana en Argentina. (AU)

Epidemiología de la enfermedad de Chagas en San Roque, Corrientes: infestación por triatominos y seroprevalencia humana / Epidemiology of Chagas disease in San Roque, Corrientes: Triatomine infestation and human seroprevalence

El objetivo fue evaluar la presencia de triatominos en ecotopos domésticos y extradomésticos localizados en el área circundante a una comunidad de palmas, determinar el índice de infección de los triatominos y estimar la prevalencia humana de individuos serorreactivos al Trypanosoma cruzi. Los muestreos se efectuaron en primavera de 1998 y en verano de 1999 en Colonia Laurel, Departamento San Roque, Corrientes, Argentina. La colección de triatominos se realizó por el método de captura/ hora/ hombre. La identificación del T. cruzi se efectuó según criterios morfológicos y por PCR. El diagnóstico de la infección chagásica se llevó a cabo en pobladores voluntarios mediante las pruebas de hemaglutinación indirecta e inmunofluorescencia indirecta. Se analizaron 16 viviendas, 11 resultaron infestadas por Triatoma infestans y dos por Triatoma sordida. Se colectaron 122 ejemplares de T. infestans de todas las edades. La infección por T. cruzi fue 16.7%. Triatoma infestans fue la especie predominante en el domicilio y T. sordida en el peridomicilio. El 77.9% (88/113) de los pobladores se analizaron serológicamente y la prevalencia fue 26.1%. La tasa de infección fue relativamente alta en el grupo etario de 0-10 años. El porcentaje de seropositividad se incrementó con la edad y ascendió al 66.6% en los pobladores de más de 40 años. La presencia de T. infestans, de pobladores serorreactivos y de niños seropositivos ≤4 años, así como las condiciones precarias de vida, indican que la endemia chagásica continúa siendo un problema en el área de estudio. (AU)

Estudio del foco en un caso de fasciolosis humana en Neuquén / A focus study from a case of human fascioliasis in Neuquén

El objetivo del trabajo fue realizar un estudio de foco relacionado con un caso de fasciolosis humana ocurrido en abril de 2002 en Loncopué, Neuquén, Argentina. La confirmación diagnóstica se efectuó en mayo de 2002 por el test de ELISA. En noviembre de 2002 se realizó un muestreo en el área rural donde se ubicaba la vivienda de la paciente, ya restablecida, y se le tomó una nueva muestra de sangre. El suero de la paciente continuó reactivo para antígenos de Fasciola hepatica. Se muestrearon plantas de berro para detectar metacercarias. Se recolectaron caracoles en cuatro canales de riego conectados a un canal principal. Los caracoles fueron trasladados vivos para su identificación, medición y examen de infección. Se recolectaron 35 muestras fecales de ganado de cría. No se observaron metacercarias en las hojas de berro examinadas (n=222). Se recolectaron 130 caracoles identificados como Lymnaea viatrix y 2 de 101 ejemplares (2%) estaban infectados con larvas de F. hepatica. Las prevalencias en el ganado adulto fueron: 100% (10/10) para caprinos, 82% (9/11) para ovinos y 86% (6/7) para bovinos. El número de huevos eliminados por las cabras (mediana = 20.7; Q1=6.2; Q3=34.5) y ovejas (4, 18, 13) infectadas, resultó mayor que el eliminado por vacas (0.3; 0.3; 1.7) (p<0.01). La práctica de control local no tuvo efecto aparente en este caso, por lo que deberían revisarse los calendarios de tratamiento y los antiparasitarios utilizados. Los resultados muestran que el ganado criado a pequeña escala por los pobladores debe incluirse en los programas de control. Se discute la posible importancia de la fasciolosis humana en Argentina.

Epidemiología de la enfermedad de Chagas en San Roque, Corrientes: infestación por triatominos y seroprevalencia humana / Epidemiology of Chagas disease in San Roque, Corrientes: Triatomine infestation and human seroprevalence

El objetivo fue evaluar la presencia de triatominos en ecotopos domésticos y extradomésticos localizados en el área circundante a una comunidad de palmas, determinar el índice de infección de los triatominos y estimar la prevalencia humana de individuos serorreactivos al Trypanosoma cruzi. Los muestreos se efectuaron en primavera de 1998 y en verano de 1999 en Colonia Laurel, Departamento San Roque, Corrientes, Argentina. La colección de triatominos se realizó por el método de captura/ hora/ hombre. La identificación del T. cruzi se efectuó según criterios morfológicos y por PCR. El diagnóstico de la infección chagásica se llevó a cabo en pobladores voluntarios mediante las pruebas de hemaglutinación indirecta e inmunofluorescencia indirecta. Se analizaron 16 viviendas, 11 resultaron infestadas por Triatoma infestans y dos por Triatoma sordida. Se colectaron 122 ejemplares de T. infestans de todas las edades. La infección por T. cruzi fue 16.7%. Triatoma infestans fue la especie predominante en el domicilio y T. sordida en el peridomicilio. El 77.9% (88/113) de los pobladores se analizaron serológicamente y la prevalencia fue 26.1%. La tasa de infección fue relativamente alta en el grupo etario de 0-10 años. El porcentaje de seropositividad se incrementó con la edad y ascendió al 66.6% en los pobladores de más de 40 años. La presencia de T. infestans, de pobladores serorreactivos y de niños seropositivos ≤4 años, así como las condiciones precarias de vida, indican que la endemia chagásica continúa siendo un problema en el área de estudio.

Triatoma sordida Stål 1859 (Hemiptera, Reduviidae: Triatominae) in palms of northeastern Argentina.

Several palms species provide an important habitat for triatomines and associate vertebrates in tropical America. The objective of this work is to identify the triatomine species living in the palms of rural areas in the Province of Corrientes, and to estimate the potential epidemiological risk they represent for the residents of nearby houses. The survey was carried out in a palm community in Colonia Laurel, Department San Roque, Province of Corrientes, Argentina. Samplings were performed in October, November and December 1998; January, February and March 1999; May and June 1999. Thirty palms: 27 (90%) Butia yatay (Mart.) Becc. and 3 Acrocomia aculeata (Jacq.) Lodd ex Mart. were dissected. Triatoma sordida Stål 1859 was found in 96.2% of B. yatay and in all the A. aculeata palms. A total of 272 live T. sordida was collected; 36 of them (13.2%) were found in bird nests in the frond and the remainder in other locations of the tree. The mean number of triatomines per palm was 9.6 (range 1-60, mode 2). T. sordida was collected during all the sampling months and all stages were present at all seasons. The highest population density was reached in spring and the lowest in autumn. Trypanosoma cruzi was detected in 38.5% in feces of 174 examined insects and identified as such, both by microscopical examination and PCR. This is the first finding of T. sordida populations in B. yatay, an endemic palm of South America distributed in southern Brazil, Uruguay and northeastern Argentina. The high infection prevalence found in this work suggests that T. sordida plays an essential role in the maintenance of the wild T. cruzi transmission cycle in northeastern Argentina.

Probability of Trypanosoma cruzi transmission by Triatoma infestans (Hemiptera: Reduviidae) to the opossum Didelphis albiventris (Marsupialia: Didelphidae).

The probability of Trypanosoma cruzi transmission to opossums by independent events of predation and fecal contamination during feeding ("biting") with positive Triatoma infestans was estimated. Negative female opossums were challenged for 23 hr with 10 infected third and fourth instars of T. infestans, and tests for positivity for T. cruzi by xenodiagnosis were performed at 30, 60, and 90 days. From these data, seven probability parameters were estimated by maximum likelihood, and likelihood ratio statistics confidence intervals were calculated. Simultaneous estimation of p1 (probability that a "bite" will infect an opossum), p3 (probability that a bug that has been eaten by an opossum will infect it), and p6 (probability that the opossum will become infected if faced with an infected triatomine), resulted in p1 = 0.06, p3 = 0.075, and p6 = 0.059. On average, each opossum should be exposed to an average of 700 encounters with bugs during its life, resulting in about eight potentially infective contacts, to produce the 35% opossum prevalence found in the field.

Characterization of Triatoma guasayana biotopes in a hardwood forest of Santiago del Estero, Argentina.

Triatoma guasayana is a silvatic triatomine species distributed in Argentina, Bolivia and Paraguay. The study was performed in a secondary forest of Santiago del Estero, Argentina. The abundance of T. guasayana was evaluated by census in the following wild biotopes: quimiles (Opuntia quimilo), chaguares (dry bromeliads), logs and underground burrows. Ten biotopes of each type were dismantled in winter (August) and another 40 in summer (January); all fauna was recorded. The biotopes most infested by T. guasayana were quimiles (65%), followed by chaguares (55%), and logs (25%). Quimiles and chaguares were infested in both seasons, whereas logs were positive only in summer and burrows were never infested. Infestation and abundance were higher in summer than in winter. The biotope structure is a key factor for T. guasayana colonization. The larger number of refuges, the constant presence of blood sources and suitable inner microclimatic conditions offered by quimiles may favour the persistence of T. guasayana colonies. The richness of invertebrate fauna per type of biotope was ranked in the same order as that of T. guasayana, suggesting similar microhabitat requirements for all studied arthropods.

Triatoma infestans in Greater Buenos Aires, Argentina.

The Health Administration Agencies of many municipalities in Greater Buenos Aires (GBA) receive frequent reports on triatomines in houses. The aim of this work was to identify and describe the dispersal foci of Triatoma infestans in an urban neighborhood of GBA, and contribute to the knowledge of the epidemiological situation in the region. In June 1998, potentially infested places were entomologically evaluated. T. infestans was only detected in a hen building for egg production, which housed approximately 6,000 birds. A total of 2,930 insects were collected. Density was about 9 triatomines/m(2). The proportions of fifth instar nymphs and adults were significantly higher than those of the other stages (p<0.001). The number of triatomines collected largely exceeded the highest domestic infestation found in one house from rural endemic areas of Argentina. Though triatomines were negative for Trypanosoma cruzi, they could acquire the parasite by coming in contact with infected people living in GBA. Besides, the numerous and widely distributed places housing hens and chickens, would favor the settlement of the vector. Together, both facts may constitute a risk of parasitic vectorial transmission. It is recommended to intensify systematic activities of vector search and case detection in GBA.

Triatoma infestans in Greater Buenos Aires, Argentina

The Health Administration Agencies of many municipalities in Greater Buenos Aires (GBA) receive frequent reports on triatomines in houses. The aim of this work was to identify and describe the dispersal foci of Triatoma infestans in an urban neighborhood of GBA, and contribute to the knowledge of the epidemiological situation in the region. In June 1998, potentially infested places were entomologically evaluated. T. infestans was only detected in a hen building for egg production, which housed approximately 6,000 birds. A total of 2,930 insects were collected. Density was about 9 triatomines/m². The proportions of fifth instar nymphs and adults were significantly higher than those of the other stages (p<0.001). The number of triatomines collected largely exceeded the highest domestic infestation found in one house from rural endemic areas of Argentina. Though triatomines were negative for Trypanosoma cruzi, they could acquire the parasite by coming in contact with infected people living in GBA. Besides, the numerous and widely distributed places housing hens and chickens, would favor the settlement of the vector. Together, both facts may constitute a risk of parasitic vectorial transmission. It is recommended to intensify systematic activities of vector search and case detection in GBA