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Practical aspects of Chagas disease
Parasitology Today, vol.IO,no.8, I994
287
Practical Aspects of Chagas Disease A-0. Minas Gerais, Brazil November I993 For three days, all those interested in the practical aspects of Chagas disease gathered together at the new Conference Center of the Faculty of Medicine of the Triangulo Mineiro iI1 the city of Uberaba, a region which has a large number of chagasic patients as well as many investigators dedicated to this disease. More than 250 specialists attended this annual meeting, with a significant number from other Latin-American countries, and several participants from Europe and USA. Congenital Transmission The main topic covered was congenital transmission, a subject that had not been extensively covered before. Now that, in Brazil, control of Chagas disease transmitted by reduviid bugs (mainly Triatoma infestam) is being efficiently handled’r2, and the second most important means of transmission, transfusion, is under control in the main cities, congenital transmission is a strong candidate as a source of new cases. The prevalence for this means of transmission in different regions of the Americas varies from I to I I% of infected mothers. Investigators from Chile (Myriam Lorca, Facultad de Medicina, Universidad de Chile, Santiago), Bolivia (Esperanza Azogue, Centro National de Enfet-medades Tropicales, Santa Cruz), Argentina (Roberto Chuit, Ministerio de Salud y Action Social, Buenos Aires) and Uruguay (Wellington Saras,ua, Artigas) spoke of their experience in their countries, and discussed methods for diagnosis. Achilea Bittencourt (Univenidade Federal da Bahia, Salvador, Brazil) reported her vast experience as a pathologist. Diagnosis of congenitally acquired Chagas disease is not easy because patasites are sometimes not detectable the first (7-10) days after delivery. Weight at birth may be between normal limits in a high proportion of infected newborns, most cases have no symptoms and increased titres of IgM are not always 0
1994. Elsewer Science Ltd
Luquetti
present. Nevertheless, recommendations emerged for early diagnosis, since the majority of newborns treated with benzimidazole were found, by serological testing, to be free of parasites after a few months [Gabriel Schmunis, Pan American Health Organization (PAHO), Washington, USA]. Testing foetal antibody responses against a recombinant antigen (SAPA) was proposed by Lorca as a new tool for diagnosis. Other topics related to congenital transmission were highlighted during the meeting, such as the harmful effect of chagasic mothers to newborns in experimental models (Yves Carlier, University of Brussels, Belgium) and a higher risk that school-aged children be chagasic, when the mothers (but not when the fathers) were chagasic, providing evidence for congenital silent transmission (Ana Lucia Andrade, lnstituto de Patologia Tropical e Saljde Publica, Univenidade Federal de Goids, Goiania, Brazil). Malnutrition related to American trypanosomiasis and higher prevalence of cardiopathy in children were also referred to by this investigator. Chagas Disease in Non-endemic Areas There is considerable migration of chagasic individuals into and out of the Americas, and this is an important factor for the expansion of Chagas disease to areas that are not endemic. These individuals may be blood donors in countries whose blood banks do not perform serological tests for exclusion of American tt-ypanosomiasis. This leads to increased transmission by this route, as discussed by Louis V. Kirchhoff (University of Iowa, USA) As the overall prevalence is low, the cost:benefit ratio of serological screening of blood donors in a non-endemic area was considered too high to be practicable. A questionnaire for blood donors was proposed as an effective (and cheaper) altemative method to avoid transmission in non-endemic countries. The demonstration of human cases in the Amazonian Region (Jose R. Coura, lnstituto Oswald0 Cruz, Rio de Janeiro, Brazil) emphasized the importance of this disease in areas in which trans-
mission has hitherto sylvatic ecotopes.
been
limited
to
Problems Following Eradication of Triatomo infestans in Brazil A ‘round table’ was held conceming ‘secondary’ vectors and their role in transmission (Chris Schofield, London School of Hygiene and Tropical Medicine, UK). Several important species were highlighted, including Ttiatoma sordida (lonizete G. Silva, lnstituto de Patologia Tropical e Saude Publica, Universidade Federal de Go&, Goiania, Brazil; Lileia Diotaiuti, lnstituto de Ciencias Biologicas, Universidade Federal de Minas Gerais, Belo Hotizonte, Brazil) and Tn’atoma rubrovoria (Roberto Salvatella, Progtama de Chagas, Ministerio de Salud Publica, Montevideo, Uruguay). The experience in S%o Paulo State, the first to have T. infestans under control, was presented by Dalva Wanderley (Superintendencia de Controle de Endemias, S%o Paulo, Brazil). It was clear that even if T in/&tans transmission could be controlled, these other species will still provide much interesting work to those devoted to vector control (Joao Carlos P. Dias, lnstituto Renee Rachou, Belo Horizonte, Brazil). The International Effort to Eradicate T. infestans A parallel meeting was organized by PAHO (Gabriel Schmunis, Coordinator of Transmissible Diseases Program, PAHO, Washington, USA). Twenty specialists from nine countries met in order to define indicators for the elimination of T. infestons from the south countries, This initiative started in I990 and was signed by public health authorities from Argentina, Bolivia, Brazil, Chile, Paraguay and Uruguay. It was demonstrated that the program was feasible, and cheaper than expected 2. Cardiopathy and the Autonomic Nervous System The subject included anatomical (Washington L. Tafuri, Universidade
Parasitology Today, vol. IO, no. 8, I994
288
Federal de Ouro Preto, Ouro Preto, Minas Gerais, Brazil), functional (LourenGo Gallo Jr, Hospital das Clinicas, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo, Brazil) and physiopathological (Luis F. Junqueira, Universidade de Brasilia, Brazil) aspects of the importance of the autonomic nervous system in chagasic cardiopathy. Even if variable degrees of denervation occur in the heart, evidence that these are responsible for the outcome of chagasic cardiopathy is still not clear, and further research is needed. The use of gangliosides for treatment of autonomic lesions of the heart was also discussed (Daniel loss, Centro Privado de Medicina, Cordoba, Argentina). Results of first trials are promising, but should be confirmed by additional controlled studies in other centres. Other Issues A course on molecular biology for clinicians was conducted by Bianca Zingales (Instituto de Quimica, Universidade de S?io Paulo, Sao Paulo, Brazil). The involvement of cytokines (mainly interferon-y) (Joao S. Silva, Faculdade de Medicina de Ribeirao Preto, Univer-
sidade de 90 Paulo, Ribeirao Preto, Sao Paulo, Brazil) in the protection of resistant animals, and the importance of natural killer cells as generators of these cytokines was stressed. Preliminary results with human macrophages are confirming these experimental data. The use of recombinant antigens for the diagnosis of Chagas disease (Jose F. da Silveira, Escola Paul&a de Medicina, Sao Paulo, Brazil) was also a subject of much interest. What to do about the chagasic blood donor, was considered by Vicente Amato Neto (Faculdade de Medicina da Universidade de Sao Paulo, Sao Paulo, Brazil) and different surgical techniques for dealing with megaesophagus and megacolon were discussed. The value of electrophysiology to handle cardiac-rhythm alterations was stressed by Sergio G. Rassi (Faculdade de Medicina, Universidade Federal de Go&, Goiania, Brazil) and indications for pacemaker implant in cardiac disease were covered in a ‘round table’ conducted by Anis Rassi (Faculdade de Medicina, Universidade Federal de Goids, Goiania, Brazil). Results from a national electrocardiographic survey were presented by Vanize Macedo (NQcleo de Medicina Tropical, Universidade de Brasilia, Brazil), by which the most characteristic elec-
trocardiographic alteration of chagasic cardiopathy, right bundle branch block, was present in 6.7% of chagasic individuals in the field. Acknowledgements The 9th Annual Meeting on applied research of Chagas disease, held in the city of Uberaba, State of Minas Get-k, Brazil, 4-6 November 1993, was organized by Alejandro 0. Luquetti. All subjects covered were published in a special issue of the Rev&o da Sociedade Brasileira de Medicina Tropical, Vol. 26 (Suppl. II), 1993. A number of guidelines (concerning congenital transmission, secondary vector bugs, autonomic nervous system derangement in cardiopathy and the decentralization of public health control), approved by participants and directed to public health authorities, were published in Ref. 4. References
I Dias, J.C.P. (1987) Parasitology Today 3. 336-34 I 2 Miles, M.A.M. (1992) Parasitology Today 8. 22 I-222 3 Frasch.A.A.C. and Reyes, M.B. ( 1990) Parasitoiogy Today 6, l37- I39 4 Anon. (I 994) Revista da Sociedade Brasileira de Medicina Tropical27, 5 I-59 Alejandro 0. Luquetti is at Parasitology, Institute fir and Public Health, Federal PO Box IO3 I, 7400 1-970
the Department of Tropical Pathology Univenity of Goibs, Goianio, Brazil.
Anthelmintic-resistant Nematodes in the EU G.C. Coles, F.H.M. Borgsteede Brussels, Belgium November I993 A two-day conference was held to establish the extent of the problem of anthelmintic-resistant nematodes in farm animals in the I2 countries of the European Union (EU), and to determine what strategies should be adopted to prevent the situation deteriorating further. The meeting started with a worldwide overview of the problem of anthelmintic-resistant nematodes in the four major groups of farm animals: sheep and goats, cattle, pigs and horses. A Potential Time Bomb The situation is worst in sheep and goats because resistant nematodes are
and S. Geerts
present on all continents where sheep and goats are maintained. Currently, the greatest problems are in South Africa, New Zealand and Australia. Fred Borgsteede (Central Veterinary Institute, Lelystad, The Netherlands) cited the warning from Peter Waller about the ‘potential time bomb of resistant nematodes in sheep in South America. The sheep and goat industries in Europe also need to be aware of the problem. Christian Bauer (justus-LiebigUniversitat, Giessen, Germany) reviewed the widespread occurrence of benzimidazole resistance in the small strongyles (cyathostomes) of horses: I3 species have been shown to be resistant to benzimidazoles. Resistant nematodes in horses are common in many countries of the world; more so in thoroughbred studs than in private yards and riding stables, and worse where anthelmintics are used more frequently, and where
benzimidazoles have continued to be used. There have been relatively few reports of anthelmintic-resistant nematodes in cattle (Stanny Gee&, Prince Leopold Institute of Tropical Medicine, Antwerp, Belgium), and almost no surveys, but existing cases demonstrate that several species of cattle nematodes can become resistant to benzimidazoles and to levamisole. It would be interetiing to know what effect, if any, the use of boluses will have on the development of resistance. The EU has the distinction of being the only area in the world where anthelmintic-resistant nematodes have been confirmed in pigs. Henrik Bjom (Royal Veterinary and Agricultural University, Copenhagen, Denmark) reported that a recent field survey in Denmark had found resistance to benzimidazoles, levamisole/morantel and 0
1994. Elsewr
Smnce
Ltd
287
Practical Aspects of Chagas Disease A-0. Minas Gerais, Brazil November I993 For three days, all those interested in the practical aspects of Chagas disease gathered together at the new Conference Center of the Faculty of Medicine of the Triangulo Mineiro iI1 the city of Uberaba, a region which has a large number of chagasic patients as well as many investigators dedicated to this disease. More than 250 specialists attended this annual meeting, with a significant number from other Latin-American countries, and several participants from Europe and USA. Congenital Transmission The main topic covered was congenital transmission, a subject that had not been extensively covered before. Now that, in Brazil, control of Chagas disease transmitted by reduviid bugs (mainly Triatoma infestam) is being efficiently handled’r2, and the second most important means of transmission, transfusion, is under control in the main cities, congenital transmission is a strong candidate as a source of new cases. The prevalence for this means of transmission in different regions of the Americas varies from I to I I% of infected mothers. Investigators from Chile (Myriam Lorca, Facultad de Medicina, Universidad de Chile, Santiago), Bolivia (Esperanza Azogue, Centro National de Enfet-medades Tropicales, Santa Cruz), Argentina (Roberto Chuit, Ministerio de Salud y Action Social, Buenos Aires) and Uruguay (Wellington Saras,ua, Artigas) spoke of their experience in their countries, and discussed methods for diagnosis. Achilea Bittencourt (Univenidade Federal da Bahia, Salvador, Brazil) reported her vast experience as a pathologist. Diagnosis of congenitally acquired Chagas disease is not easy because patasites are sometimes not detectable the first (7-10) days after delivery. Weight at birth may be between normal limits in a high proportion of infected newborns, most cases have no symptoms and increased titres of IgM are not always 0
1994. Elsewer Science Ltd
Luquetti
present. Nevertheless, recommendations emerged for early diagnosis, since the majority of newborns treated with benzimidazole were found, by serological testing, to be free of parasites after a few months [Gabriel Schmunis, Pan American Health Organization (PAHO), Washington, USA]. Testing foetal antibody responses against a recombinant antigen (SAPA) was proposed by Lorca as a new tool for diagnosis. Other topics related to congenital transmission were highlighted during the meeting, such as the harmful effect of chagasic mothers to newborns in experimental models (Yves Carlier, University of Brussels, Belgium) and a higher risk that school-aged children be chagasic, when the mothers (but not when the fathers) were chagasic, providing evidence for congenital silent transmission (Ana Lucia Andrade, lnstituto de Patologia Tropical e Saljde Publica, Univenidade Federal de Goids, Goiania, Brazil). Malnutrition related to American trypanosomiasis and higher prevalence of cardiopathy in children were also referred to by this investigator. Chagas Disease in Non-endemic Areas There is considerable migration of chagasic individuals into and out of the Americas, and this is an important factor for the expansion of Chagas disease to areas that are not endemic. These individuals may be blood donors in countries whose blood banks do not perform serological tests for exclusion of American tt-ypanosomiasis. This leads to increased transmission by this route, as discussed by Louis V. Kirchhoff (University of Iowa, USA) As the overall prevalence is low, the cost:benefit ratio of serological screening of blood donors in a non-endemic area was considered too high to be practicable. A questionnaire for blood donors was proposed as an effective (and cheaper) altemative method to avoid transmission in non-endemic countries. The demonstration of human cases in the Amazonian Region (Jose R. Coura, lnstituto Oswald0 Cruz, Rio de Janeiro, Brazil) emphasized the importance of this disease in areas in which trans-
mission has hitherto sylvatic ecotopes.
been
limited
to
Problems Following Eradication of Triatomo infestans in Brazil A ‘round table’ was held conceming ‘secondary’ vectors and their role in transmission (Chris Schofield, London School of Hygiene and Tropical Medicine, UK). Several important species were highlighted, including Ttiatoma sordida (lonizete G. Silva, lnstituto de Patologia Tropical e Saude Publica, Universidade Federal de Go&, Goiania, Brazil; Lileia Diotaiuti, lnstituto de Ciencias Biologicas, Universidade Federal de Minas Gerais, Belo Hotizonte, Brazil) and Tn’atoma rubrovoria (Roberto Salvatella, Progtama de Chagas, Ministerio de Salud Publica, Montevideo, Uruguay). The experience in S%o Paulo State, the first to have T. infestans under control, was presented by Dalva Wanderley (Superintendencia de Controle de Endemias, S%o Paulo, Brazil). It was clear that even if T in/&tans transmission could be controlled, these other species will still provide much interesting work to those devoted to vector control (Joao Carlos P. Dias, lnstituto Renee Rachou, Belo Horizonte, Brazil). The International Effort to Eradicate T. infestans A parallel meeting was organized by PAHO (Gabriel Schmunis, Coordinator of Transmissible Diseases Program, PAHO, Washington, USA). Twenty specialists from nine countries met in order to define indicators for the elimination of T. infestons from the south countries, This initiative started in I990 and was signed by public health authorities from Argentina, Bolivia, Brazil, Chile, Paraguay and Uruguay. It was demonstrated that the program was feasible, and cheaper than expected 2. Cardiopathy and the Autonomic Nervous System The subject included anatomical (Washington L. Tafuri, Universidade
Parasitology Today, vol. IO, no. 8, I994
288
Federal de Ouro Preto, Ouro Preto, Minas Gerais, Brazil), functional (LourenGo Gallo Jr, Hospital das Clinicas, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo, Brazil) and physiopathological (Luis F. Junqueira, Universidade de Brasilia, Brazil) aspects of the importance of the autonomic nervous system in chagasic cardiopathy. Even if variable degrees of denervation occur in the heart, evidence that these are responsible for the outcome of chagasic cardiopathy is still not clear, and further research is needed. The use of gangliosides for treatment of autonomic lesions of the heart was also discussed (Daniel loss, Centro Privado de Medicina, Cordoba, Argentina). Results of first trials are promising, but should be confirmed by additional controlled studies in other centres. Other Issues A course on molecular biology for clinicians was conducted by Bianca Zingales (Instituto de Quimica, Universidade de S?io Paulo, Sao Paulo, Brazil). The involvement of cytokines (mainly interferon-y) (Joao S. Silva, Faculdade de Medicina de Ribeirao Preto, Univer-
sidade de 90 Paulo, Ribeirao Preto, Sao Paulo, Brazil) in the protection of resistant animals, and the importance of natural killer cells as generators of these cytokines was stressed. Preliminary results with human macrophages are confirming these experimental data. The use of recombinant antigens for the diagnosis of Chagas disease (Jose F. da Silveira, Escola Paul&a de Medicina, Sao Paulo, Brazil) was also a subject of much interest. What to do about the chagasic blood donor, was considered by Vicente Amato Neto (Faculdade de Medicina da Universidade de Sao Paulo, Sao Paulo, Brazil) and different surgical techniques for dealing with megaesophagus and megacolon were discussed. The value of electrophysiology to handle cardiac-rhythm alterations was stressed by Sergio G. Rassi (Faculdade de Medicina, Universidade Federal de Go&, Goiania, Brazil) and indications for pacemaker implant in cardiac disease were covered in a ‘round table’ conducted by Anis Rassi (Faculdade de Medicina, Universidade Federal de Goids, Goiania, Brazil). Results from a national electrocardiographic survey were presented by Vanize Macedo (NQcleo de Medicina Tropical, Universidade de Brasilia, Brazil), by which the most characteristic elec-
trocardiographic alteration of chagasic cardiopathy, right bundle branch block, was present in 6.7% of chagasic individuals in the field. Acknowledgements The 9th Annual Meeting on applied research of Chagas disease, held in the city of Uberaba, State of Minas Get-k, Brazil, 4-6 November 1993, was organized by Alejandro 0. Luquetti. All subjects covered were published in a special issue of the Rev&o da Sociedade Brasileira de Medicina Tropical, Vol. 26 (Suppl. II), 1993. A number of guidelines (concerning congenital transmission, secondary vector bugs, autonomic nervous system derangement in cardiopathy and the decentralization of public health control), approved by participants and directed to public health authorities, were published in Ref. 4. References
I Dias, J.C.P. (1987) Parasitology Today 3. 336-34 I 2 Miles, M.A.M. (1992) Parasitology Today 8. 22 I-222 3 Frasch.A.A.C. and Reyes, M.B. ( 1990) Parasitoiogy Today 6, l37- I39 4 Anon. (I 994) Revista da Sociedade Brasileira de Medicina Tropical27, 5 I-59 Alejandro 0. Luquetti is at Parasitology, Institute fir and Public Health, Federal PO Box IO3 I, 7400 1-970
the Department of Tropical Pathology Univenity of Goibs, Goianio, Brazil.
Anthelmintic-resistant Nematodes in the EU G.C. Coles, F.H.M. Borgsteede Brussels, Belgium November I993 A two-day conference was held to establish the extent of the problem of anthelmintic-resistant nematodes in farm animals in the I2 countries of the European Union (EU), and to determine what strategies should be adopted to prevent the situation deteriorating further. The meeting started with a worldwide overview of the problem of anthelmintic-resistant nematodes in the four major groups of farm animals: sheep and goats, cattle, pigs and horses. A Potential Time Bomb The situation is worst in sheep and goats because resistant nematodes are
and S. Geerts
present on all continents where sheep and goats are maintained. Currently, the greatest problems are in South Africa, New Zealand and Australia. Fred Borgsteede (Central Veterinary Institute, Lelystad, The Netherlands) cited the warning from Peter Waller about the ‘potential time bomb of resistant nematodes in sheep in South America. The sheep and goat industries in Europe also need to be aware of the problem. Christian Bauer (justus-LiebigUniversitat, Giessen, Germany) reviewed the widespread occurrence of benzimidazole resistance in the small strongyles (cyathostomes) of horses: I3 species have been shown to be resistant to benzimidazoles. Resistant nematodes in horses are common in many countries of the world; more so in thoroughbred studs than in private yards and riding stables, and worse where anthelmintics are used more frequently, and where
benzimidazoles have continued to be used. There have been relatively few reports of anthelmintic-resistant nematodes in cattle (Stanny Gee&, Prince Leopold Institute of Tropical Medicine, Antwerp, Belgium), and almost no surveys, but existing cases demonstrate that several species of cattle nematodes can become resistant to benzimidazoles and to levamisole. It would be interetiing to know what effect, if any, the use of boluses will have on the development of resistance. The EU has the distinction of being the only area in the world where anthelmintic-resistant nematodes have been confirmed in pigs. Henrik Bjom (Royal Veterinary and Agricultural University, Copenhagen, Denmark) reported that a recent field survey in Denmark had found resistance to benzimidazoles, levamisole/morantel and 0
1994. Elsewr
Smnce
Ltd