The clinical trials of immunonutrition that we have undertaken have often been small, single centre studies. They have often been of limited statistical power and have often included patients with a variety of underlying disease states and at different points in the disease process. Three meta-analysis and a consensus statement in conjunction with a systematic review, have been performed in an attempt to overcome many of these limitations and understand further the clinical place for immunonutrition. However, there are still many questions regarding the place of immunonutrition in clinical practice that we still do not understand or have definitive answers to. For example, do we really know what is the optimal combination of nutrients and in what quantities they should be provided? Do we understand any potential interactions that might occur between these nutrients? What is the effect of the patients nutritional state? When and for how long should immunonutrition provided? What is the impact of the patients´ underlying disease process and how does this interact with the provision of immunonutrition? At the present time whilst there is some indication and evidence as to which patients might benefit most, and as to those who may not benefit or even suffer detrimental effects from immunonutrition, we still can not answer these questions with any definitive authority. It is essential now that we undertake large well designed, well controlled multicentre studies with adequate statistical power to answer these questions. The indications are that immunonutrition has the potential to help patients but its place must be more clearly defined before its widespread acceptance into clinical practice is based on sound scientific evidence.

Los ensayos clínicos sobre inmunonutrición que se han realizado han sido en general pequeños y unicéntricos. Su poder estadístico se ha visto limitado y con frecuencia se han incluido pacientes con situaciones patológicas subyacentes múltiples y en diferentes puntos del proceso de la enfermedad. Se han realizado tres meta-análisis y una valoración de consenso, junto con una visión sistemática en un intento de superar muchas de las limitaciones y para entender mejor las situación clínica de la inmunonutrición. Sin embargo, hay todavía gran número de incógnitas en relación con el papel de la immunonutrición en la práctica clínica, que todavía no entendemos y para los que no tenemos contestaciones definitivas. Por ejemplo, ¿conocemos en realidad cuál es la combinación óptima de nutrientes y qué cantidades deben ser administradas? ¿Entendemos las interacciones potenciales que pudieran suceder entre estos nutrientes? ¿Cuál es el efecto sobre el estado nutritivo del paciente? ¿Cuándo y durante cuánto tiempo debe ser administrada inmunonutrición? ¿Cuál es el impacto de la enfermedad subyacente y cómo interactúa ésta con la de immunonutrición? En el momento actual, hay alguna indicación y evidencia en relación con los pacientes que se benefician más y en relación con cuales no se benefician o incluso puedan sufrir efectos detrimentales de la immunonutrición, pero aún no podemos responder a estas preguntas con una autoridad definitiva. Es esencial que se lleven a cabo estudios multicéntricos controlados, bien diseñados con poder estadístico adecuado para responder a estas preguntas. La inmunonutrición tiene potencial para ayudar a los pacientes pero su lugar deberá ser clarificado aún más antes de su aceptación universal en la práctica clínica basada sobre una evidencia científica sólida.

O controle de triatomíneos é dificultado pela capacidade de reinvasão das casas por exemplares silvestres. Entre agosto/96 e dezembro/97 realizou-se, no Ceará, um estudo a respeito da reinfestação das casas após borrifação. Das 277 Unidades Domiciliares UD pesquisadas, 40,8% estavam infestadas (21,7% dos intradomicílios e 35,4% dos peridomicílios). Dos 433 triatomíneos capturados, 207 eram Triatoma brasiliensis (48,8% no intradomicílio, média de 1,8 insetos/casa) e 226 Triatoma pseudomaculata (97,3% no peridomicílio). Ocorre um único ciclo anual do T. brasiliensis, e dois ciclos anuais do T. pseudomaculata. Quatro meses após a borrifação, 9,7% das unidades domiciliares permaneciam positivas, principalmente no peridomicílio; 10,3% das UD foram positivas em todas as avaliações. O teste de suscetibilidade biológica à deltametrina revelou a persistência do inseticida no intradomicílio até nove meses após a borrifação. A prevalência global da infecção humana foi de 5,7%, tendo sido positivas cinco crianças menores de dez anos. Considerando-se a alta pressão de recolonização a partir de exemplares silvestres, propõe-se, como metodologia de controle, um sistema misto da avaliação tradicional e a vigilância epidemiológica.

Vector control strategies against indigenous species is not easy, due to their capacity to reinvade treated premises from sylvatic ecotopes. Between August 1996 and December 1997 we conducted a study on reinfestation of houses after spraying in a county in the State of Ceará. Of 277 houses examined, 113 (40.8%) were infested (21.7% intradomiciliary and 35.4% peridomiciliary). Of the 433 Triatominae collected, 207 were Triatoma brasiliensis (49% of which intradomiciliary, with a mean of 1.8 insects/house) and 226 were Triatoma pseudomaculata (97% peridomiciliary). The age structure of the two indicated a univoltine development cycle for T. brasiliensis and two cycles per year for T. pseudomaculata. Four months after spraying with deltamethrin SC 25mg ia/m², 9.7% of the houses were still positive, mainly with peridomestic infestations. Intradomiciliary wall bioassays showed persistence of the insecticide up to 9 months after spraying. Considering the high potential for recolonization of treated premises from sylvatic foci, we propose an operational strategy combining traditional evaluations and community-based surveillance with increased selective interventions and community education.

O controle de triatomíneos é dificultado pela capacidade de reinvasão das casas por exemplares silvestres. Entre agosto/96 e dezembro/97 realizou-se, no Ceará, um estudo a respeito da reinfestação das casas após borrifação. Das 277 Unidades Domiciliares UD pesquisadas, 40,8% estavam infestadas (21,7% dos intradomicílios e 35,4% dos peridomicílios). Dos 433 triatomíneos capturados, 207 eram Triatoma brasiliensis (48,8% no intradomicílio, média de 1,8 insetos/casa) e 226 Triatoma pseudomaculata (97,3% no peridomicílio). Ocorre um único ciclo anual do T. brasiliensis, e dois ciclos anuais do T. pseudomaculata. Quatro meses após a borrifação, 9,7% das unidades domiciliares permaneciam positivas, principalmente no peridomicílio; 10,3% das UD foram positivas em todas as avaliações. O teste de suscetibilidade biológica à deltametrina revelou a persistência do inseticida no intradomicílio até nove meses após a borrifação. A prevalência global da infecção humana foi de 5,7%, tendo sido positivas cinco crianças menores de dez anos. Considerando-se a alta pressão de recolonização a partir de exemplares silvestres, propõe-se, como metodologia de controle, um sistema misto da avaliação tradicional e a vigilância epidemiológica.

Vector control strategies against indigenous species is not easy, due to their capacity to reinvade treated premises from sylvatic ecotopes. Between August 1996 and December 1997 we conducted a study on reinfestation of houses after spraying in a county in the State of Ceará. Of 277 houses examined, 113 (40.8%) were infested (21.7% intradomiciliary and 35.4% peridomiciliary). Of the 433 Triatominae collected, 207 were Triatoma brasiliensis (49% of which intradomiciliary, with a mean of 1.8 insects/house) and 226 were Triatoma pseudomaculata (97% peridomiciliary). The age structure of the two indicated a univoltine development cycle for T. brasiliensis and two cycles per year for T. pseudomaculata. Four months after spraying with deltamethrin SC 25mg ia/m², 9.7% of the houses were still positive, mainly with peridomestic infestations. Intradomiciliary wall bioassays showed persistence of the insecticide up to 9 months after spraying. Considering the high potential for recolonization of treated premises from sylvatic foci, we propose an operational strategy combining traditional evaluations and community-based surveillance with increased selective interventions and community education.

During the period 1980-1986, we captured triatomine bugs and mammalian reservoir hosts from sylvatic and domestic situations in different municipalities of the State of Minas Gerais. Trypanosoma cruzi was isolated from captured bugs, mammals and patients. After cultivation in LIT medium, the electrophoretic enzyme profiles were determined. We obtained atotal of 32 parasite isolates from regions with active domestic transmission, and 24 isolates form areas under control. For the first areas the results suggest introduction of T. cruzi from sylvatic habitats, through incursion of infected opossums and/or sylvatic T. sordida, which appears to have given rise to at least one acute human infection. Of particular interest is the finding of sylvatic opossums and a T. sordida nymph infected with ZB, that could indicate return of parasites from chronic human infections to sylvatic transmission cycles. For the areas under control we also interpret the results as interaction between sylvatic and domestic cycles of transmission, here through the invasion of houses by bugs carrying the Z1 zymodeme from the sylvatic environment. The Multivariate Correspondence Analysis gives a spatial description between the different parasite isolates and confirms the existence of a bridge in the opposite direction in the region with active vectorial transmission including the exporting of Z2 through the peridomestic environment into the sylvatic cycle. For the others areas this bridge corresponds especially to Panstrongylus megistus, importing Z1 into the domestic environment.

Because of the relative epidemiological significance of Triatoma sordida, T. guasayana and T. patagonica, and the need to resolve doubts about their taxonomic validity, we report here a detailed taxonomic comparison of the three species using multivariate analysis of morphometric measures combined with comparisons of their genitalia and antennal structures. From the 17 metric variables studied, the length of the second segment of the rostrum and the anteocular length provided a discrimination function able to separate without error T. sordida from T. guasayana and T. patagonica. The multivariate discriminant functions classified T. guasayana and T. patagonica with an error of 2.44%. Comparison of the male genitalia of T. guasayana and T. sordida showed that there are minor differences in the articulatory apparatus, the median process of the pygophore, the phallosome support and the vesica, with bigger differences in the endosomal process and the phallosome. However, the already described male genitalia of T. patagonica is very similar to that of T. sordida. Analysis of antennal structure by scanning electron microscope showed that sensilla distribution around the pedicel is slightly different in the three species and sensilla density is highest in T. sordida and lowest in T. patagonica. The study showed that the three species form a closely related group. The results confirm the earlier classification of sordida and guasayana as separate species, but they raise some doubts about the taxonomic status of T. patagonica.

Chagas disease transmission can be effetively interrupted by insecticidal control of its triatomine bug vectors. We present here a simple model comparing the costs and benefits of such a programme, designed to eliminate domestic populations of Triatoma infestans throughout its known area of distribution over the seven southernmost countries of Latin America. The model has been simplified to require only four financial estimates relating to the unit cost of housing spraying and benefits due to avoidance of premature death in the acute phase of the disease, avoidance of supportive treatment and care in the chronic phase of the disease, and avoidance of corrective digestive and cardiac surgery. Exceptfor these direct medical costs, al other potential benefits have been ignored. Nevertheless, the model shows that the direct financial benefits of such a programme would far outweigh the costs, and the project would support a remarkably high internal rate of return under the least optimistic estimates.