PCVC-FVCC

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CHAGAS DISEASE DISCUSSION FORUM
FORO DE DISCUSIÓN DE ENFERMEDAD DE CHAGAS

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Web # 3 (21-30)

21
From: "Dr. Marcelo Bassino" <marbas@teletel.com.ar>
To: <chagas-pcvc@pcvc.sminter.com.ar>
Subject: Controversia sobre parasiticidas
Date: Tue, 2 Nov 1999 12:26:21 -0300

Indudablemente, la informacion a nuestra disposicion no avala la eficacia de los parasiticidas en el chagasico cronico. Datos mas precisos deberian provenir de un estudio aleatorio doble ciego multicentrico, cuya realizacion seria deseable, aunque presenta evidentes dificultades de disenio y financiacion. Por el momento, considero prudente abstenerse de su uso. Por otra parte, quisiera plantear el problema, que considero que ira haciendose predominante, del chagasico anioso. Como bien dice el Dr. Pinto Dias en su excelente conferencia del PCVC, habra un "desplazamiento de la curva de mortalidad hacia las edades mas avanzadas", con lo cual estoy totalmente de acuerdo. Me agradaria que se planteara el tema.
Dr. Horacio Romero Villanueva


There is no doubt at all that, according to the data we have, parasiticides are of no use in the chronic Chagas patient. We should try to get more information from a randomized double blind multicentric trial, which would be very useful, but difficult to design and to finance. Till then, I think it advisable not to use these drugs. On the other side, I would like to talk about the problem of the elderly Chagas patient, which is going to be more and more important as time goes by. Dr. Pinto Dias says it in his excellent FVCC conference: there is going to be a "displacement of the mortality curve towards older age", an affirmation which I thoroughly share. I would like to talk about this subject.
Horacio Romero Villanueva

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22
From: "Dr. Marcelo Bassino" <marbas@teletel.com.ar>
To: <chagas-pcvc@pcvc.sminter.com.ar>
Subject: Controversia sobre Parisiticidas .
Date: Wed, 3 Nov 1999 13:50:16 -0300

Estimados colegas:
Me agradaria saber acerca de los resultados de una investigacion multicentrica apoyada por el T.D.R. de la Organizacion Mundial de la Salud, tratando de demostrar la eficacia del allopurinol (parasiticida especial), en el chagasico cronico en tres centros de elevada endemia: Cordoba (Argentina)-Goiana (Brasil ) y Santa Cruz de la Sierra (Bolivia).
Muy agradecida .
Dra. Ana Maria Bosch


Dear colleagues
I would like to know about results of the multicentric research supported for T.D.R.
of the Health World Organization for the Allopurinol the effcacy to demostration in the chronic chagas patient (in three center of high endemia:Cordoba of Argentina Goiana of Brasil and Santa Cruz de la Sierra of Bolivia )
Thank you very much.
Dra. Ana Maria Bosch

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23
From: "Dr. Edgardo Schapacnik" <edgardo@schapachnik.com.ar>
To: chagas-pcvc@pcvc.sminter.com.ar
Subject: Controversia sobre parasiticidas
Date: Wed, 03 Nov 1999 14:49:54 -0300 (ART)

Queridos amigos:
El tema que estamos debatiendo es sumamente importante, ademas de apasionante. Yo, si fuera el titulo de una novela, la llamaria: "O" u "Y". ¿Por que plantear como contradiccion antagonica planificar erradicar ranchos e insectos, con la necesidad de hacer un estudio prospectivo multicentrico randomizado para determinar la real efectividad de los parasiticidas en fase cronica?. ¿Por que "o" en lugar de "y"?. ¿Por que uno u otro? ¿No pueden ser "ambos"?. ¿O acaso no se generaran gastos si hay que tratar empiricamente a 16 millones
de chagasicos o a los que vayan accediendo a la consulta?. ¿No es mas barato acaso decidir tomar una muestra de 2000 (por dar una cifra tentativa) y sacar correctas conclusiones, asi el esfuerzo lleve 20 anios? Todo se sintetiza en dos vocales y una consonante que suena como vocal (por lo menos en espaniol): ¿"o" u "y"?
Un abrazo
Edgardo


Dear friends:
The subject we are discussing is extremely important, as well as exciting. Personally, if it was the title of a novel, I would call it: "Or" or "And". Why do we pose as a conflicting contradiction, to plan to eradicate huts and insects, as opposed to the need to perform a prospective multicentric randomized study to determine the real effectiveness of parasiticides in chronic phase?. Why "or" instead of "and"?. Why one or the other? Why not "both"?. Or is it not that expenditures are generated if 16 million people infected with Chagas, or those that come to the office, have to be treated empirically? Is it not cheaper to decide to take a sample from 2000 (to provide an attempted figure) and to draw the right conclusions, even if the effort extends for 20 years?. It is all summarized in two vowels and a consonant that sounds like a vowel (at least in Spanish): "Or" or "and"? ("O" u "y"?)
Hugs,
Edgardo

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24
From: "Gustavo Oby" <gustavooby@3net.com.ar>
To: <chagas-pcvc@pcvc.sminter.com.ar>
Subject: SEROLOGIA PARA CHAGAS
Date: Wed, 3 Nov 1999 23:06:18 -0300

ESTIMADOS COLEGAS:
Desearia conocer una actualizacion sobre los criterios serologicos para el diagnostico de la Enfermedad de Chagas y cuales son las pruebas de Laboratorio necesarias y/o confiables para efectuar el mismo, al dia de la fecha.
Los saluda atte .
Dr Gustavo Oby


DEAR COLLEAGUES:
I would like to know about an updating on serology criteria for diagnosis of Chagas disease, and which are the necessary and/or reliable Lab tests to carry out the former, to date.
Greetings,
Dr Gustavo Oby

Index

25
From: Joao Carlos <jcpdias@cpqrr.fiocruz.br>
To: "'chagas-pcvc@pcvc.sminter.com.ar'"
Subject: Controversia sobre Parasiticidas
Date: Mon, 8 Nov 1999 09:19:44 -0200

Estimados amigos. Los 3 ultimos talleres internacionales de OPS y OMS indican formalmente el tratamiento especifico en algunos casos cronicos: baja edad (15 anos o menos), congenitos, transmision reciente (menos que 2 anos), quimioprofilaxia en accidentes y transplantes de organos con donante infectado. El Dr. Romero Villanueva esta absolutamente correcto en proponer los dos ensayos doble ciego. Los datos disponibles indican rasonable posibilidad de cura parasitologica en los casos arriba indicados. Hay tambien evidencias de beneficio clinico de largo plazo para cronicos indeterminados tratados correctamente. Asi, la decision para este tratamiento se queda formalmente en las manos del medico, quien debera evaluar y considerar con el paciente los beneficios y riesgos. Pragmaticamente, la tendencia actual es tratar - cuando no existan contra-indicaciones formales - regalando al paciente el "beneficio de la duda". Esto sera el panorama etico de la cuestion, mientras no llegan farmacos mejores.
Abrazos a todos.
Dr Joao Carlos  Pinto Dias.


Dear friends:
The last 3 international workshops from the PAHO and the WHO, formally indicate the specific treatment in some chronic cases: low age (15 years or less), congenital, recent transmission (less than 2 years), chemical prophylaxis in accidents and transplants of organs with infected donors. Dr. Romero Villanueva is absolutely right in proposing the two double blind trials. Available data indicate that the possibility of a parasitologic cure in the case mentioned above, is a reasonable possibility. There is also evidence of clinical benefits in long term for undetermined chronic patients treated properly. Thus, the decision for this treatment remains formally in the hands of the physician, who has to assess and consider together with the patient the benefits and risks. Pragmatically, the current tendency is to treat - when there are no formal contraindications - presenting the patient with the gift of the "benefit of doubt". This will be the ethical view of the matter, while better drugs do not arrive.
Hugs,
Dr Joao Carlos  Pinto Dias.

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26
From: Joao Carlos <jcpdias@cpqrr.fiocruz.br>
To: "'chagas-pcvc@pcvc.sminter.com.ar'"
Subject: Eficacia del Allopurinol . Estudio Multicentrico
Date: Mon, 8 Nov 1999 09:05:18 -0200

Rapidamente: el ensayo en Brasil y Bolivia ha resultado totalmente inefectivo, incluso con rapida re-positivisacion parasitologica.
Atentamente.
Dr  Joao Carlos Pinto Dias


Quickly: the trial carried out in Brazil and Bolivia, has turned out to be totally ineffective, even with quick parasitologic re-positivization.
Sincerely,
Dr  Joao Carlos Pinto Dias

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27
From: "Dr. Edgardo Schapachnik" <edgardo@schapachnik.com.ar>
To: chagas-pcvc@pcvc.sminter.com.ar
Subject: Serologia para Chagas
Date: Mon, 08 Nov 1999 14:58:18 -0300 (ART)

En relacion a la pregunta del Dr. Gustavo Oby, referente a los criterios serologicos para el diagnostico de Enfermedad de Chagas en su fase cronica, el mismo se basa en por lo menos la positividad de dos reaaciones que investiguen antigenos o fracciones antigenicas del parasito, distintas. Teniendo en cuenta la sensibilidad y especificidad, las reacciones
recomendables serian:
a)Inmunofluorescencia indirecta: es una de las reacciones mas sensibles y especificas y mas precoces en positivizarse en la fase aguda, siendo que al cuarto mes ya presenta una sensibilidad del 100%. Debe considerarse "reactivo" un suero con titulos por encima de 1/32, dado que por debajo puede tratarse de una reaccion cruzada

b) Hemoaglutinacion Indirecta: es tambien ua reaccion muy sensible y especifica, de bajo costo y facil lectura, util para ser usada como metodo de "screening". Tambien deben considerarse titulos de la misma por sobre 1/32

c) Inmunoensayo enzimatico: es una de las tecnicas conocidas como ELISA (enzime linked immunosorbent assay) equiparable a la inmunofluorescencia en cuanto a la sensibilidad y especificidad.

d) Aglutinacion directa con y sin 2 mercaptoetanol: esta es una reaccion tambien muy asequible, de muy facil realizacion y bajo costo, que permite inferir acerca de la presencia de anticuerpos anti IgG o IgM. El agregado de 2 mercapetanol a una reaccion de aglutinacion directa, al romper los puentes disulfuro de las moleculas de IgM, permite inferir -de producirse una caida significativa de los titulos- que los anticuerpos detectados eran IgM y por lo tanto sospechar que los mismos son debidos a un proceso agudo.
Cordialmente
Edgardo


About the question by Dr. Gustavo Oby, regarding serology criteria for diagnosis of Chagas disease in its chronic stage, they are based in at least the positivity of two different reactions that research antigens or antigen fractions of the parasite. Taking into consideration sensitivity and specificity, the advisable reactions would be:

a) Indirect immunofluorescence: is one of the most sensitive and specific reactions, and most early in becoming positive in the acute phase, since in the fourth month there is already a sensitivity in a 100%. A serum must be considered "reactive" with titers above 1/32, given that underneath can be considered a cross reaction.

b) Indirect hemoagglutination: is also a very sensitive and specific reaction, of low cost and easy reading, useful to be used as a method for screening. Its titers should also be considered above 1/32.

c) Enzymatic immunoassay: is one of the techniques known as ELISA (enzyme linked immunosorbent assay) that can be compared to immunofluorescence regarding sensitivity and specificity.

d) Direct agglutination with and without 2 mercapetanol: this is a reaction very accessible,
very easy to perform, and of low cost, that permits inferring about the presence of antibodies
anti IgG or IgM. The aggregate of 2 mercapetanol to a reaction of direct agglutination, by
breaking disulfide bridges of IgM molecules, permits to infer -if a significant decrease of
titers should happen- that the detected antibodies were IgM, and therefore suspect that the
latter are due to an acute process.
Cordially,
Edgardo

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28
To: chagas-pcvc@pcvc.sminter.com.ar
From: Medicina Tropical <a_prata@mednet.com.br>
Subject: Serologia para Chagas/Serology for Chagas
Date: Tue, 09 Nov 1999 10:24:42 -0200

Prezado Senhor:
Em relação a sua pergunta informo-lhe que habitualmente se usa duas dentre as três provas de laboratório para o diagnóstico sorológico da doença de Chagas:
- Hemaglutinação indireta (títulos de 1/32 ou maiores)
- Imunofluorescência indireta (títulos de 1/80 ou maiores)
- Teste imunoenzimático (ELISA) (resultados de 1,2 ou superiores).
Atenciosamente,
Aluízio Prata


Dear Sir:
About your question I inform you that usually it is used two out of three lab tests for serology diagnosis for Chagas disease:
- Indirect hemoagglutination (titers from 1/32 or above)
- Indirect immunofluorescence (titers from 1/80 or above)
- Immunoenzymatic test (ELISA) (results from 1.2 or above).
Sincerely,
Aluízio Prata

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