Resumen: Se evaluó el efecto del tratamiento con aire caliente (35 °C/36 h) sobre nectarinas Big Top, previo a la conservación a 0 y 5 °C durante 6, 18 y 27 días seguidos de 6 días a 20 °C (vida de mostrador, vm). La actividad respiratoria en los frutos a 5 °C fue el doble (24 CO2 kg-1h-1) de la medida en los frutos a 0 °C durante el pico respiratorio. A 0 °C, los frutos tratados mostraron entre un 2 y un 5 % más actividad respiratoria. Los polifenoles totales no fueron afectados por temperatura ni tratamiento en conservación (0,22 y 0,24 mg equivalente ácido gálico g-1 pf), pero aumentaron casi el doble en vm, sobre todo en frutos procedentes de 0 °C. En algunos momentos de análisis la capacidad antioxidante total de los frutos no tratados a 0 °C (0,42 y 0,45 mg equivalente ácido ascórbico g-1 pf) duplicó a la de los tratados, aunque esta situación se revirtió en vm. La actividad de la superóxido dismutasa fue considerablemente mayor en frutos tratados a 0 °C (15-30 unidades de actividad mg-1 de proteína), contrariamente a lo que ocurrió a 5 °C. La actividad de la poligalacturonasa y pectinmetil esterasa, así como el desarrollo de harinosidad en vm y en frutos no tratados procedentes de 5 °C, indicaría que el tratamiento térmico tuvo un efecto protector, reduciendo la ocurrencia del daño. Sin embargo, la poca o nula respuesta observada en otras variables hace necesaria la confirmación del efecto en trabajos futuros.

Abstract: The effect of hot air treatment (35 °C / 36 h) on Big Top nectarines prior storage at 0 and 5 °C for 6, 18 and 27 days followed by 6 days at 20 °C (shelf life, sl) was evaluated. Respiratory activity was twice as much in fruits at 5 °C (24 mg CO2 kg-1h-1), compared to those kept at 0 °C during the respiratory peak. At 0 °C, the treated fruits showed between 2 and 5 % more respiratory activity. The total polyphenols were not affected by temperature or treatment (0.22 and 0.24 mg galic acid equivalent g-1 fw) but almost doubled in sl, especially in fruits from 0 °C. At some analysis moments, the total antioxidant capacity of untreated fruits stored at 0 °C (0.42 and 0.45 mg equivalent ascorbic acid g-1 fw) doubled the values of the treated ones, although this situation was reversed in sl. The superoxide dismutase activity was considerably higher in fruits treated and stored at 0 °C (15-30 units of activity mg-1 of protein), as opposed to the observed at 5 °C. The activity of polygalacturonase and pectinmethyl esterase, as well as the development of mealiness in sl and in untreated fruits from 5 °C, would indicate that the heat treatment had a protective effect reducing the occurrence of damage. However, the little or no response observed in other variables make it necessary to confirm the effect of heat treatment in future studies.

Discovered in 1909, Chagas disease was progressively shown to be widespread throughout Latin America, affecting millions of rural people with a high impact on morbidity and mortality. With no vaccine or specific treatment available for large-scale public health interventions, the main control strategy relies on prevention of transmission, principally by eliminating the domestic insect vectors and control of transmission by blood transfusion. Vector control activities began in the 1940s, initially by means of housing improvement and then through insecticide spraying following successful field trials in Brazil (Bambui Research Centre), with similar results soon reproduced in São Paulo, Argentina, Venezuela and Chile. But national control programmes only began to be implemented after the 1970s, when technical questions were overcome and the scientific demonstration of the high social impact of Chagas disease was used to encourage political determination in favour of national campaigns (mainly in Brazil). Similarly, large-scale screening of infected blood donors in Latin America only began in the 1980s following the emergence of AIDS. By the end of the last century it became clear that continuous control in contiguous endemic areas could lead to the elimination of the most highly domestic vector populations - especially Triatoma infestans and Rhodnius prolixus - as well as substantial reductions of other widespread species such as T. brasiliensis, T. sordida, and T. dimidiata, leading in turn to interruption of disease transmission to rural people. The social impact of Chagas disease control can now be readily demonstrated by the disappearance of acute cases and of new infections in younger age groups, as well as progressive reductions of mortality and morbidity rates in controlled areas. In economic terms, the cost-benefit relationship between intervention (insecticide spraying, serology in blood banks) and the reduction of Chagas disease (in terms of medical and social care and improved productivity) is highly positive. Effective control of Chagas disease is now seen as an attainable goal that depends primarily on maintaining political will, so that the major constraints involve problems associated with the decentralisation of public health services and the progressive political disinterest in Chagas disease. Counterbalancing this are the political and technical cooperation strategies such as the "Southern Cone Initiative" launched in 1991. This international approach, coordinated by PAHO, has been highly successful, already reaching elimination of Chagas disease transmission in Uruguay, Chile, and large parts of Brazil and Argentina. The Southern Cone Initiative also helped to stimulate control campaigns in other countries of the region (Paraguay, Bolivia, Peru) which have also reached tangible regional successes. This model of international activity has been shown to be feasible and effective, with similar initiatives developed since 1997 in the Andean Region and in Central America. At present, Mexico and the Amazon Region remain as the next major challenges. With consolidation of operational programmes in all endemic countries, the future focus will be on epidemiological surveillance and care of those people already infected. In political terms, the control of Chagas disease in Latin America can be considered, so far, as a victory for international scientific cooperation, but will require continuing political commitment for sustained success.

The control of the vector-borne transmission of Chagas disease in Brazil was organized as a national program in 1975, when two large entomological and sero-epidemiological surveys were conducted in the country in order to identify areas at highest risk of transmission and to guide inerventions regarding the chemical treatment of domestic vectors of the disease. The authors present the baseline data gathered through these studies and compare them with more recent data. The evaluation performed shows that the transmission by Triatoma infestans is virtually interrupted and that the transmission by other native species of triatominae from different regions of the country is possibly very low. It is emphasized the need to maintain permanent actions of entomological surveillance in order to prevent recurrent transmission.