Characterization of Triatoma guasayana biotopes in a hardwood forest of Santiago del Estero, Argentina.
(73/1356)
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. (+info)
Environmental characteristics of the cemeteries of Buenos Aires City (Argentina) and infestation levels of Aedes aegypti (Diptera: Culicidae).
(74/1356)
Cemeteries with many water-filled containers, flowers, sources of human blood, and shade are favorable urban habitats for the proliferation of Aedes aegypti, a vector of yellow fever and dengue. A total of 22,956 containers was examined in the five cemeteries of the city of Buenos Aires, Argentina. The vector was found in four cemeteries that showed an average infestation level of 5.5% (617 positive out of 11,196 water-filled containers). The four cemeteries positive for Ae. aegypti showed significantly different (p<0.01) infestation levels. Vegetation cover and percentage of infestation were significantly correlated (p<0.01), but neither cemetery area nor number of available containers were significantly related to the proportion of positive vases. Our results suggest that the cemeteries of Buenos Aires represent a gradient of habitat favorableness for this vector species, some of which may act as foci for its proliferation and dispersal. (+info)
Triatoma infestans in Greater Buenos Aires, Argentina.
(75/1356)
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. (+info)
Mesorhizobium chacoense sp. nov., a novel species that nodulates Prosopis alba in the Chaco Arido region (Argentina).
(76/1356)
Low-molecular-weight RNA analysis was performed for the identification and classification of 20 Argentinian strains isolated from the root nodules of Prosopis alba. SDS-PAGE of total cellular proteins, determination of the DNA base composition, DNA-DNA reassociation experiments and physiological and biochemical tests were also carried out for these strains and the whole 16S rRNA gene was sequenced from one of the strains, strain LMG 19008T. Results of the genotypic and phenotypic characterization showed that the strains isolated in this study belong to a group that clustered in the genus Mesorhizobium. The results of DNA-DNA hybridizations showed that this group is a novel species of this genus. The name Mesorhizobium chacoense sp. nov. is proposed for this species. The type strain is LMG 19008T (= CECT 5336T). (+info)
Lessons learned in a European-Latin American collaboration for developing postgraduate education in public health.
(77/1356)
BACKGROUND: New funding from the European Union (EU) allowed the collaborative development of postgraduate education in public health between five countries in South America and Europe. METHODS: A planning meeting, two workshops, a final meeting and the use of e-mail and faxes for discussing curricula were employed. RESULTS: One new master of public health in Argentina has begun, plans for new masters in Chile have been developed. A new collaborative module using the Internet was started and is now in its third year, new European plans for distance learning are being developed. Possibilities for collaborative research have been identified and those involved developed a broader horizon and international contacts. The planned grant from the EU was 72,040 Euros. Staff time spent administering the project was much greater than time spent discussing curricula. This is the only publication. CONCLUSION: Although the aims were achieved, the opportunity costs were great, as methods of assessing European research do not value such work highly and the administrative burden of small EU grants is high. Once a network is established greater efforts should be put into electronic communication, but European programmes currently do not fund such 'remote' support. (+info)
Genotypic analysis of Staphylococcus aureus from milk of dairy cows with mastitis in Argentina.
(78/1356)
Staphylococcus aureus is the most prevalent pathogen causing mastitis of dairy ruminants. This study was developed to ascertain the genotypes and genealogical relationship among strains isolated from milk of bovines with mastitis in Argentina. Molecular epidemiological analysis of S. aureus was performed on 112 isolates from 21 districts. Clonality was assessed by SmaI pulsed-field gel electrophoresis (PFGE) typing, automated EcoRI ribotyping and restriction enzyme analysis of plasmid (REAP) DNA profiles. A total of 22 band patterns distributed in four clusters were found by SmaI PFGE analysis. The similarity of clusters 2, 3 and 4 with cluster 1 was 0.73, 0.69 and 0.33, respectively, and 101 of 112 isolates belonged in cluster 1. PFGE band patterns from 42 isolates within cluster I were indistinguishable from each other (type A). The second largest group of isolates with indistinguishable PFGE band patterns was subtype A11, which was composed of 19 isolates. Automated ribotyping assigned the 112 isolates into 13 ribotypes. Among these, the most prevalent ribotypes I and VI were composed of 49 and 35 isolates respectively. Although there was certain correspondence between PFGE genotypes and ribotypes, further discrimination was achieved by combining both methods. REAP DNA profile analysis was useful to provide even further discrimination between isolates with identical PFGE genotype and ribotype. The most prevalent S. aureus strains A/I and A11/VI were widely distributed in the country and were not restricted to individual nearby locations. Prevalence of these two strains varied consecutively within a period of 8 years. Whether the shift in type prevalence was due to selection of a phenotypic trait remains undisclosed. (+info)
Antibodies to Trypanosoma cruzi among blood donors in Buenos Aires, Argentina.
(79/1356)
OBJECTIVES: The aim of this work was to study the prevalence of anti-Trypanosoma cruzi in the blood donor population in Buenos Aires, to compare the relative sensitivity and specificity of the two screening tests used and to confirm the results with a third assay. MATERIAL AND METHODS: Between May 1995 and July 1999, 64,887 blood donor consecutive samples were screened with the following commercial tests: indirect hemagglutination (IHA) (Polychaco, Buenos Aires, Argentina) and enzyme-linked immunosorbent assay (ELISA) (40,222 with Chagatek, Organon Teknika, Buenos Aires, Argentina, and 24,665 with Chagas EIA, Abbott, Sao Paulo, Brazil). Repeatedly reactive samples in one or both tests were analyzed with a third method: dot blot (Bio Chagas, Gador, Buenos Aires, Argentina) or particle agglutination (Serodia, Fujirebio, Tokyo, Japan). Sera that reacted in at least two tests were considered positive. RESULTS: The seroprevalence was 2.66% (1744 samples were reactive for one or both screening tests), and 1.46% (949 samples) were confirmed positive. The ELISAs proved to be more sensitive (relative sensitivity: 99.67-99.71%) whereas 192 samples (0.47%) were IHA false-negatives (relative sensitivity: 79.77%). Relative specificity for EIA was 98.47--99.23% and for IHA 99.85%. CONCLUSIONS: Results suggest the need of performing two screening tests for Chagas disease in blood banks from endemic areas and the importance of a third confirmatory assay to avoid unnecessary medical counseling. (+info)
Contribution of environmental factors to the risk of male infertility.
(80/1356)
BACKGROUND: An increasing number of reports suggest that chemical and physical agents in the environment, introduced and spread by human activity, may affect male fertility in humans. We investigated the relationships between exposure to environmental agents and seminal characteristics, and the concentrations of reproductive hormones in the serum of men seeking infertility treatment. METHODS: We studied 225 male partners from consecutively recruited couples, who had their first infertility consultation between 1995 and 1998, in the Litoral Sur region of Argentina, one of the most productive farming regions in the world. RESULTS: A multivariate logistic regression model showed that exposure to pesticides and solvents is significantly associated with sperm threshold values well below the limit for male fertility. We also found that men exposed to pesticides had higher serum oestradiol concentrations, and that men exposed to solvents had lower LH concentrations than non-exposed men. All of these effects were greater in men with primary infertility than in men with secondary infertility. CONCLUSION: We have shown that environmental factors contribute to the severity of infertility, and that this may worsen the effects of pre-existing genetic or medical risk factors. (+info)