RESUMO
OBJECTIVES: The aim of this work was to study the prevalence of anti-Trypanosoma cruzi in the blood donor population in Buenos Aires, to compare the relative sensitivity and specificity of the two screening tests used and to confirm the results with a third assay. MATERIAL AND METHODS: Between May 1995 and July 1999, 64,887 blood donor consecutive samples were screened with the following commercial tests: indirect hemagglutination (IHA) (Polychaco, Buenos Aires, Argentina) and enzyme-linked immunosorbent assay (ELISA) (40,222 with Chagatek, Organon Teknika, Buenos Aires, Argentina, and 24,665 with Chagas EIA, Abbott, São Paulo, Brazil). Repeatedly reactive samples in one or both tests were analyzed with a third method: dot blot (Bio Chagas, Gador, Buenos Aires, Argentina) or particle agglutination (Serodia, Fujirebio, Tokyo, Japan). Sera that reacted in at least two tests were considered positive. RESULTS: The seroprevalence was 2.66% (1744 samples were reactive for one or both screening tests), and 1.46% (949 samples) were confirmed positive. The ELISAs proved to be more sensitive (relative sensitivity: 99.67-99.71%) whereas 192 samples (0.47%) were IHA false-negatives (relative sensitivity: 79.77%). Relative specificity for EIA was 98.47--99.23% and for IHA 99.85%. CONCLUSIONS: Results suggest the need of performing two screening tests for Chagas disease in blood banks from endemic areas and the importance of a third confirmatory assay to avoid unnecessary medical counseling.
Assuntos
Anticorpos Antiprotozoários/sangue , Doadores de Sangue/estatística & dados numéricos , Trypanosoma cruzi/imunologia , Animais , Argentina/epidemiologia , Doença de Chagas/epidemiologia , Humanos , Sensibilidade e Especificidade , Estudos Soroepidemiológicos , Testes Sorológicos/normasAssuntos
Doadores de Sangue , Infecções por Deltaretrovirus/prevenção & controle , Infecções por HIV/prevenção & controle , Anticorpos Anti-Hepatite B/sangue , Antígenos do Núcleo do Vírus da Hepatite B/imunologia , Vírus da Hepatite B/imunologia , Hepatite B/prevenção & controle , Hepatite C/prevenção & controle , Programas de Rastreamento/métodos , Viremia/diagnóstico , Argentina/epidemiologia , Biomarcadores , Comorbidade , Anticorpos Antideltaretrovirus/sangue , Infecções por Deltaretrovirus/sangue , Infecções por Deltaretrovirus/epidemiologia , Anticorpos Anti-HIV/sangue , Soroprevalência de HIV , Hepatite B/sangue , Hepatite B/diagnóstico , Hepatite B/epidemiologia , Hepatite C/sangue , Hepatite C/epidemiologia , Anticorpos Anti-Hepatite C/sangue , Humanos , Prevalência , Sensibilidade e Especificidade , Estudos SoroepidemiológicosRESUMO
Blood transfusion is the second most common transmission route of Chagas' disease in endemic areas. Discrepancies between the available diagnostic kits are common, which indicates that a single test is not satisfactory. The aim of this work was to study the seroprevalence of anti-Trypanosoma cruzi markers, to compare sensitivity and specificity of the two screening assays currently in use and to confirm the results with a third test. A total of 20,860 volunteer blood donors were studied. Donations were screened with indirect hemagglutination assay (IHA) and enzyme immunoassay (EIA). Repeatedly reactive samples were assayed with an EIA carried out on strips, to which a mixture of T. cruzi antigens was applied as an horizontal line (DB). Sera that reacted in at least two tests were considered positive. A total of 576 samples were reactive for one or both screening tests (2.76%) and 391 of them (1.87%) were confirmed positive. EIA proved to be more sensitive, with no false negative results (100% sensibility), whereas 98 samples (0.47%) were IHA false negative (74.93% sensibility). Specificity for EIA was 99.3% and for IHA 99.8%. In our case, almost 0.9% of donated blood is discarded because of false reactive anti-T. cruzi results; two thirds correspond to false positive EIA and one third to false positive IHA. It is important to note that in our population we have not registered false negative results for EIA but there were false negative IHA. This fact implies that although the first method is less specific, it is much more sensitive. It is important to confirm the screening results in order to avoid unnecessary donor counselling and permit future donations. The DB test employed in our study results a useful alternative for this purpose.
Assuntos
Anticorpos Antiprotozoários/sangue , Doadores de Sangue , Trypanosoma cruzi/imunologia , Animais , Argentina , Reações Falso-Negativas , Testes de Hemaglutinação , Humanos , Técnicas Imunoenzimáticas , Sensibilidade e Especificidade , Estudos SoroepidemiológicosRESUMO
Blood transfusion is the second most common transmission route of Chagas disease in endemic areas. Discrepancies between the available diagnostic kits are common, which indicates that a single test is not satisfactory. The aim of this work was to study the seroprevalence of anti-Trypanosoma cruzi markers, to compare sensitivity and specificity of the two screening assays currently in use and to confirm the results with a third test. A total of 20,860 volunteer blood donors were studied. Donations were screened with indirect hemagglutination assay (IHA) and enzyme immunoassay (EIA). Repeatedly reactive samples were assayed with an EIA carried out on strips, to which a mixture of T. cruzi antigens was applied as an horizontal line (DB). Sera that reacted in at least two tests were considered positive. A total of 576 samples were reactive for one or both screening tests (2.76
) and 391 of them (1.87
) were confirmed positive. EIA proved to be more sensitive, with no false negative results (100
sensibility), whereas 98 samples (0.47
) were IHA false negative (74.93
sensibility). Specificity for EIA was 99.3
and for IHA 99.8
. In our case, almost 0.9
of donated blood is discarded because of false reactive anti-T. cruzi results; two thirds correspond to false positive EIA and one third to false positive IHA. It is important to note that in our population we have not registered false negative results for EIA but there were false negative IHA. This fact implies that although the first method is less specific, it is much more sensitive. It is important to confirm the screening results in order to avoid unnecessary donor counselling and permit future donations. The DB test employed in our study results a useful alternative for this purpose.
Assuntos
Humanos , Masculino , Feminino , Adulto , Pessoa de Meia-Idade , Doadores de Sangue , Transfusão de Sangue , Anticorpos Antideltaretrovirus/sangue , Infecções por HTLV-I/transmissão , Infecções por HTLV-II/transmissão , Estudos Soroepidemiológicos , Bissexualidade , Heterossexualidade , Fatores de Risco , Infecções Sexualmente Transmissíveis , Abuso de Substâncias por Via Intravenosa , Transtornos Relacionados ao Uso de SubstânciasAssuntos
Humanos , Masculino , Feminino , Adulto , Pessoa de Meia-Idade , Anticorpos Antideltaretrovirus/sangue , Infecções por HTLV-I/transmissão , Infecções por HTLV-II/transmissão , Doadores de Sangue , Estudos Soroepidemiológicos , Transfusão de Sangue , Fatores de Risco , Heterossexualidade , Infecções Sexualmente Transmissíveis , Bissexualidade , Transtornos Relacionados ao Uso de Substâncias , Abuso de Substâncias por Via IntravenosaRESUMO
PURPOSE: The first human retrovirus, HTLV-I, was isolated in 1980; HTLV-II was described later. The former is endemic in southwestern Japan, the Caribbean and equatorial Africa; whereas the latter prevails in intravenous drug addicts, being also endemic in American indian populations. Both viruses are either sexually transmitted, from mother to child mainly by breast-feeding, by blood transfusion or by sharing contaminated needles. With regard to transmission, since they are intracellular viruses, it occurs only when whole blood or cellular components are transfused; this is not the case when either plasma or plasma derivatives are used. The likelihood of transmission decreases as the storage time increases. HTLV-I is associated, at least, with two diseases: adult T-cell leukaemia/lymphoma (ATLL), and the tropical spastic paraparesis (TSP) or HTLV-I-associated myelopathy (HAM). ATLL occurs after a latency period of 20 to 30 years; whereas the incubation period ranges from 3 to 5 years in the case of the neurological disease. Most individuals infected with the virus remain healthy; the risk of developing the hematological complication is 2-4% whereas it is below 1% in the case of TSP. No clear association of HTLV-II with any known disease has been reported as yet. In this study, we have assessed the prevalence of HTLV-I and HTLV-II in the sera of the blood donors who have come to our Division, with the aim of avoiding the spreading of this oncogenic virus by transfusion. This study could serve as a measure of the infection in the general population. MATERIAL AND METHODS: A total of 28,897 samples were analyzed from May 1993 to January 1995. Anti-HTLV-I/II antibodies were analyzed by the method of passive agglutination of gelatin participles (PA). Samples which reacted were tested again by the same method, and those reacting for the second time were further confirmed by Western blot (WBT), a method with the ability to differentiate between antibodies anti-HTLV-I and anti-HTLV-II. RESULTS: Of the 28,897 samples, 47 were repeatedly reactive by PA (0.16%). Analysis by WBT resulted in 10 reactive results with HTLV-I (0.035%), 2 reactive results with HTLV-II (0.007%); in one sample it could not be determined whether the anti-HTLV-I or anti-HTLV-II antibody was present. Of the remaining samples, 21 were non-reacting, whereas 13 were indeterminated. CONCLUSION: Prevalence of HTLV-I and HTLV-II seropositive blood donors is low and similar to that found in other non-endemic countries. We believe that routine evaluation of anti-HTLV-I and HTLV-II antibodies in blood donors would be warranted in our country, since transmission of the viruses by transfusion of blood components has been clearly shown. It is possible that the recipients of the reactive units do not develop the disease. Nevertheless, these individuals constitute an important source of virus dissemination, both during the perinatal period and by sexual intercourse. In fact, advise to seropositive donors would prevent transmission by these routes. Lastly, it should be noticed that investigation of anti-HTLV-I/II antibodies could result in a surrogate method for detecting other viral infections transmitted by these routes.
Assuntos
Doadores de Sangue , Anticorpos Antideltaretrovirus/sangue , Infecções por HTLV-I/epidemiologia , Infecções por HTLV-II/epidemiologia , Vírus Linfotrópico T Tipo 1 Humano/imunologia , Vírus Linfotrópico T Tipo 2 Humano/imunologia , Adolescente , Adulto , Idoso , Testes de Aglutinação , Argentina/epidemiologia , Biomarcadores , Feminino , Infecções por HTLV-I/sangue , Infecções por HTLV-I/prevenção & controle , Infecções por HTLV-II/sangue , Infecções por HTLV-II/prevenção & controle , Humanos , Masculino , Programas de Rastreamento , Pessoa de Meia-Idade , Prevalência , Estudos SoroepidemiológicosRESUMO
HTLV-I and HTLV-II are two related retroviruses that are transmitted by sexual contact, breast feeding, blood transfusion and needle sharing. In this study the prevalence of HTLV-I and HTLV-II was evaluated in voluntary blood donors as a measure of the infection in the general population. Samples were tested by a gelatine particle agglutination test and repeatedly reactive samples were confirmed by Western blot tests (WBT), enriched with recombinant rgp21, rgp461 y rgp4611 proteins, which differentiates HTLV-I and HTLV-II antibodies. Of 19,426 samples, 40 were repeatedly reactive by particle agglutination (0.21%). When analyzed by WBT, 6 met the criteria for HTLV-I (0.036%), 2 for HTLV-II (0.01%) and 1 for HTLV-I/II, 13 samples were indeterminate and 18 were negative. The prevalence is low and comparable to that from non endemic countries. Screening for anti HTLV-I/II antibodies is necessary to prevent transmission through blood transfusions.
Assuntos
Infecções por HTLV-I/transmissão , Infecções por HTLV-II/transmissão , Adolescente , Adulto , Idoso , Testes de Aglutinação/métodos , Argentina , Doadores de Sangue , Western Blotting , Feminino , Anticorpos Anti-HTLV-I/análise , Anticorpos Anti-HTLV-II/análise , Vírus Linfotrópico T Tipo 1 Humano/imunologia , Vírus Linfotrópico T Tipo 2 Humano/imunologia , Humanos , Masculino , Pessoa de Meia-Idade , PrevalênciaRESUMO
HTLV-I and HTLV-II are two related retroviruses that are transmitted by sexual contact, breast feeding, blood transfusion and needle sharing. In this study the prevalence of HTLV-I and HTLV-II was evaluated in voluntary blood donors as a measure of the infection in the general population. Samples were tested by a gelatine particle agglutination test and repeatedly reactive samples were confirmed by Western blot tests (WBT), enriched with recombinant rgp21, rgp461 y rgp4611 proteins, which differentiates HTLV-I and HTLV-II antibodies. Of 19,426 samples, 40 were repeatedly reactive by particle agglutination (0.21
). When analyzed by WBT, 6 met the criteria for HTLV-I (0.036
), 2 for HTLV-II (0.01
) and 1 for HTLV-I/II, 13 samples were indeterminate and 18 were negative. The prevalence is low and comparable to that from non endemic countries. Screening for anti HTLV-I/II antibodies is necessary to prevent transmission through blood transfusions.