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Search Results: 1 - 10 of 689 matches for " Schofield CJ "
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Trypanosoma cruzi -- the vector-parasite paradox
Schofield, CJ;
Memórias do Instituto Oswaldo Cruz , 2000, DOI: 10.1590/S0074-02762000000400016
Abstract: trypanosoma cruzi and the majority of its insect vectors (hemiptera, reduviidae, triatominae) are confined to the americas. but while recent molecular studies indicate a relatively ancient origin for the parasite (~65 million years ago) there is increasing evidence that the blood-sucking triatomine vectors have evolved comparatively recently (<5 mya). this review examines the evidence for these ideas, and attempts to reconcile the apparent paradox by suggesting that marsupial opossums (didelphidae) may have played a role, not just as original reservoir hosts, but also as original vectors of the parasite.
Trypanosoma cruzi the vector-parasite paradox
Schofield CJ
Memórias do Instituto Oswaldo Cruz , 2000,
Abstract: Trypanosoma cruzi and the majority of its insect vectors (Hemiptera, Reduviidae, Triatominae) are confined to the Americas. But while recent molecular studies indicate a relatively ancient origin for the parasite (~65 million years ago) there is increasing evidence that the blood-sucking triatomine vectors have evolved comparatively recently (<5 mya). This review examines the evidence for these ideas, and attempts to reconcile the apparent paradox by suggesting that marsupial opossums (Didelphidae) may have played a role, not just as original reservoir hosts, but also as original vectors of the parasite.
Control of Chagas disease vectors
Ramsey,JM; Schofield,CJ;
Salud Pública de México , 2003, DOI: 10.1590/S0036-36342003000200010
Abstract: most latin american countries are making dramatic progress in controlling chagas disease, through a series of national and international initiatives focusing on elimination of domestic populations of triatominae, improved screening of blood donors, and clinical support and treatment of persons infected with trypanosoma cruzi. some countries, particularly uruguay, chile and brazil, are sufficiently advanced in their programmes to initiate detailed planning of the subsequent phases of chagas disease control, while others such as peru, ecuador, and mexico, are currently applying only the initial phases of the control campaigns. in this review, we seek to provide a brief history of the campaigns as a basis for discussion of future interventions. our aim is to relate operational needs to the underlying biological aspects that have made chagas disease so serious in latin america but have also revealed the epidemiological vulnerability of this disease.
Control of Chagas disease vectors
Ramsey JM,Schofield CJ
Salud Pública de México , 2003,
Abstract: Most Latin American countries are making dramatic progress in controlling Chagas disease, through a series of national and international initiatives focusing on elimination of domestic populations of Triatominae, improved screening of blood donors, and clinical support and treatment of persons infected with Trypanosoma cruzi. Some countries, particularly Uruguay, Chile and Brazil, are sufficiently advanced in their programmes to initiate detailed planning of the subsequent phases of Chagas disease control, while others such as Peru, Ecuador, and Mexico, are currently applying only the initial phases of the control campaigns. In this review, we seek to provide a brief history of the campaigns as a basis for discussion of future interventions. Our aim is to relate operational needs to the underlying biological aspects that have made Chagas disease so serious in Latin America but have also revealed the epidemiological vulnerability of this disease.
The evolution of Chagas disease (American Trypanosomiasis) control after 90 years since Carlos Chagas discovery
Dias JCP,Schofield CJ
Memórias do Instituto Oswaldo Cruz , 1999,
Abstract:
The impact of Chagas disease control in Latin America: a review
Dias, JCP;Silveira, AC;Schofield, CJ;
Memórias do Instituto Oswaldo Cruz , 2002, DOI: 10.1590/S0074-02762002000500002
Abstract: 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 s?o 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 socia
Comparison of intervention strategies for control of Triatoma dimidiata in Nicaragua
Acevedo, F;Godoy, E;Schofield, CJ;
Memórias do Instituto Oswaldo Cruz , 2000, DOI: 10.1590/S0074-02762000000600022
Abstract: the effectiveness of three operational strategies for the control of triatoma dimidiata was compared by a field trial in the department of madriz, nicaragua. one strategy involved full pretrial evaluation, followed by spraying of all houses irrespective of whether or not they had been found to be infested. the second strategy minimised the pretrial evaluation by considering the locality infested as soon as one house was found to be positive, followed by spraying all houses. the third strategy involved full pretrial evaluation, followed by spraying only those houses found to be positive. evaluation after twelve months indicated that all three strategies were similarly effective, since all sprayed houses remained free of infestation. however, comparative estimates of the unit intervention costs indicated that strategies 1 and 2 were substantially less efficient than the third strategy of spraying only positive houses.
Triatominae as a model of morphological plasticity under ecological pressure
Dujardin, JP;Panzera, P;Schofield, CJ;
Memórias do Instituto Oswaldo Cruz , 1999, DOI: 10.1590/S0074-02761999000700036
Abstract: the use of biochemical and genetic characters to explore species or population relationships has been applied to taxonomic questions since the 60s. in responding to the central question of the evolutionary history of triatominae, i.e. their monophyletic or polyphyletic origin, two important questions arise (i) to what extent is the morphologically-based classification valid for assessing phylogenetic relationships? and (ii) what are the main mechanisms underlying speciation in triatominae? phenetic and genetic studies so far developed suggest that speciation in triatominae may be a rapid process mainly driven by ecological factors.
The impact of Chagas disease control in Latin America: a review
Dias JCP,Silveira AC,Schofield CJ
Memórias do Instituto Oswaldo Cruz , 2002,
Abstract: 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 S o 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
Triatominae as a model of morphological plasticity under ecological pressure
Dujardin JP,Panzera P,Schofield CJ
Memórias do Instituto Oswaldo Cruz , 1999,
Abstract: The use of biochemical and genetic characters to explore species or population relationships has been applied to taxonomic questions since the 60s. In responding to the central question of the evolutionary history of Triatominae, i.e. their monophyletic or polyphyletic origin, two important questions arise (i) to what extent is the morphologically-based classification valid for assessing phylogenetic relationships? and (ii) what are the main mechanisms underlying speciation in Triatominae? Phenetic and genetic studies so far developed suggest that speciation in Triatominae may be a rapid process mainly driven by ecological factors.
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