Serological studies on shistosomiasis mansoni in the Northeast Brasil

Tanabe, Masanobu; Okazaki, Mitsu; Okazaki, Masaichi; Kobayashi, Seiki; Kaneko, Nobuaki; Sekiguchi, Tsuneari; Tateno, Seiki; Motta, Severa R. N.; Takeuchi, Tsutomu

doi:10.1590/S0036-46651990000200010

Abstracts

Sera from the patients (N = 10) with schistosomiasis mansoni of the hospital of Federal University of Pernambuco, the Schistosoma mansoni egg-positive (N = 51) and -negative (N = 452) inhabitants in Cabo City area, out-patients (N = 37) of the IMIP hospital and Japanese immigrants (N = 127) in Petrolina City area of northeast Brazil as well as Japanese healthy subjects (N = 30) were examined by serological tests including an enzyme-linked immunosorbent assay with antigens prepared from eggs (ELISA-egg) and adult worms (ELISA-adult). The ELISA with egg or adult antigen correctly identified 100% of the uninfected individuals lived in non-endemic area of schistosomiasis. Moreover, when examined cross-reactivity of our ELISA with sera isolated from 78 subjects infected with various intestinal parasitic infections, only one of these sera reacted with the egg and adult antigens. On the examination of 51 sera from the egg-positive subjects, the ELISA-egg revealed the highest sensitivity (98.0%), whereas a large number of false negative reactions of ELISA-adult, Ouchterlony method using adult antigen, circumoval precipitation and immediate intradermal skin test were observed. A low sensitivity of these serologic tests except for ELISA-egg appears to be primarily due to their inability to detect antibody in the sera from egg-positive infantiles. There was no positive correlation between the absorbance values of these two types of ELISA among the sera isolated from ELISA-positive subjects. Rather, by the reactivity of these sera to egg or adult antigen, they could be divided into two subgroups; one reacted more positively with egg antigen and the other with adult antigen. Moreover, it was confirmed that the sera from young subjects (under 20 years old) appear to be highly reactive to the egg antigen than did aged ones. These data suggest that the ELISA with egg antigen, but not with the adult antigen, appears to be useful for the serological survey of schistosomiasis mansoni in the endemic area of northeast Brazil.

Schistosoma mansoni; Schistosomiasis mansoni; Intradermal skin test; Ouchterlony; Circumoval precipitation test; Enzyme-linked immunosorbent assay

Soros de pacientes com esquistosomíase mansônica do Hospital das Clínicas da Universidade Federal de Pernambuco (N = 10), de residentes da cidade do Cabo (PE) - 51 casos ovo-positivo e 452 casos ovo-negativo -, de pacientes do Hospital Instituto Materno Infantil de Pernambuco (IMIP) (N = 37), de imigrantes japoneses residentes na cidade de Petrolina (PE) (N = 127), assim como de japoneses supostamente saudáveis (N = 30) foram examinados sorologicamente através de testes como ELISA; os antígenos utilizados foram preparados a partir de ovos (ELISA-ovo) e de vermes adultos de Schistosoma mansoni (ELISA adulto). Em 100% dos soros de indivíduos não infectados residentes em áreas não endêmicas, tanto na ELISA-ovo como na ELISA-adulto os resultados foram negativos. No tocante a reações cruzadas, em 78 soros provenientes de indivíduos portadores de diferentes parasitas intestinais, apenas um apresentou reatividade frente aos antígenos de vermes adultos e ovos. O ELISA-ovo realizado com o soro de 51 indivíduos portadores de ovos de S. mansoni revelou uma alta sensibilidade (98% de casos ovo-positivos); contudo grande número de resultados falso-negativos foi observado em reações como ELISA-adulto, Ouchterlony usando antígeno de verme adulto, reação periovular e intradermoreação. Em casos de jovens portadores de ovos, uma baixa sensibilidade destes testes, exceto para ELISA-ovo, parece ser, em princípio, devido a uma incapacidade de detecção de anticorpos do soro destes pacientes. Parece não existir nenhuma correlação positiva entre os valores dos dois tipos de ELISA (ELISA-ovo e ELISA-adulto) dentre os soros isolados de indivíduos com ELISA-positivo. Não obstante, a reação destes soros com antígeno de ovos ou vermes adultos pode ser dividida em dois sub-grupos: em um a reação é mais positiva frente a antígenos de ovos do que frente a antígenos de vermes adultos. Tudo indica que os soros de jovens com menos de 20 anos são mais reativos aos antígenos de ovos do que os soros provenientes de indivíduos de outras faixas etárias. Estes dados sugerem que ELISA preparado com antígeno de ovos, e não de vermes adultos, pareça ser bastante útil em pesquisas sorológicas na esquistosomíase mansônica em áreas endêmicas tais como o nordeste do Brasil.

SEROEPIDEMIOLOGY

Serological studies on shistosomiasis mansoni in the Northeast Brasil⁽¹ (1 ) Department of Parasitology, School of Medicine, Keio University, Tokyo, Japan. (4) Department of Biophysics and Radiobiology, Universidade Federal de Pernambuco, Pernambuco, Brazil. ⁾

Estudo sorológico na esquistosomíase mansônica no nordeste do Brasil

Masanobu Tanabe^I; Mitsu Okazaki^II; Masaichi Okazaki^II; Seiki Kobayashi^I; Nobuaki Kaneko^I; Tsuneari Sekiguchi^I; Seiki Tateno^III; Severa R. N. Motta^I,II,III; Tsutomu Takeuchi

^IDepartment of Parasitology, School of Medicine, Keio University, Tokyo, Japan

^IISecretaria de Saúde, Pernambuco, Brazil

^IIILaboratório de Imunopatologia Prof. Keizo Asami, Universidade Federal de Pernambuco, Pernambuco, Brazil

^{Address for correspondence} Address for correspondence: Masanobu Tanabe, Ph. D. Department of Parasitology, School of Medicine, Keio University 35 Shinanomachi Shinjuku-ku, Tokyo, 160, Japan

SUMMARY

Sera from the patients (N = 10) with schistosomiasis mansoni of the hospital of Federal University of Pernambuco, the Schistosoma mansoni egg-positive (N = 51) and -negative (N = 452) inhabitants in Cabo City area, out-patients (N = 37) of the IMIP hospital and Japanese immigrants (N = 127) in Petrolina City area of northeast Brazil as well as Japanese healthy subjects (N = 30) were examined by serological tests including an enzyme-linked immunosorbent assay with antigens prepared from eggs (ELISA-egg) and adult worms (ELISA-adult). The ELISA with egg or adult antigen correctly identified 100% of the uninfected individuals lived in non-endemic area of schistosomiasis. Moreover, when examined cross-reactivity of our ELISA with sera isolated from 78 subjects infected with various intestinal parasitic infections, only one of these sera reacted with the egg and adult antigens. On the examination of 51 sera from the egg-positive subjects, the ELISA-egg revealed the highest sensitivity (98.0%), whereas a large number of false negative reactions of ELISA-adult, Ouchterlony method using adult antigen, circumoval precipitation and immediate intradermal skin test were observed. A low sensitivity of these serologic tests except for ELISA-egg appears to be primarily due to their inability to detect antibody in the sera from egg-positive infantiles. There was no positive correlation between the absorbance values of these two types of ELISA among the sera isolated from ELISA-positive subjects. Rather, by the reactivity of these sera to egg or adult antigen, they could be divided into two subgroups; one reacted more positively with egg antigen and the other with adult antigen. Moreover, it was confirmed that the sera from young subjects (under 20 years old) appear to be highly reactive to the egg antigen than did aged ones.

These data suggest that the ELISA with egg antigen, but not with the adult antigen, appears to be useful for the serological survey of schistosomiasis mansoni in the endemic area of northeast Brazil.

Key words: Schistosoma mansoni; Schistosomiasis mansoni; Intradermal skin test; Ouchterlony; Circumoval precipitation test; Enzyme-linked immunosorbent assay.

RESUMO

Soros de pacientes com esquistosomíase mansônica do Hospital das Clínicas da Universidade Federal de Pernambuco (N = 10), de residentes da cidade do Cabo (PE) 51 casos ovo-positivo e 452 casos ovo-negativo , de pacientes do Hospital Instituto Materno Infantil de Pernambuco (IMIP) (N = 37), de imigrantes japoneses residentes na cidade de Petrolina (PE) (N = 127), assim como de japoneses supostamente saudáveis (N = 30) foram examinados sorologicamente através de testes como ELISA; os antígenos utilizados foram preparados a partir de ovos (ELISA-ovo) e de vermes adultos de Schistosoma mansoni (ELISA adulto).

Em 100% dos soros de indivíduos não infectados residentes em áreas não endêmicas, tanto na ELISA-ovo como na ELISA-adulto os resultados foram negativos. No tocante a reações cruzadas, em 78 soros provenientes de indivíduos portadores de diferentes parasitas intestinais, apenas um apresentou reatividade frente aos antígenos de vermes adultos e ovos.

O ELISA-ovo realizado com o soro de 51 indivíduos portadores de ovos de S. mansoni revelou uma alta sensibilidade (98% de casos ovo-positivos); contudo grande número de resultados falso-negativos foi observado em reações como ELISA-adulto, Ouchterlony usando antígeno de verme adulto, reação periovular e intradermoreação. Em casos de jovens portadores de ovos, uma baixa sensibilidade destes testes, exceto para ELISA-ovo, parece ser, em princípio, devido a uma incapacidade de detecção de anticorpos do soro destes pacientes.

Parece não existir nenhuma correlação positiva entre os valores dos dois tipos de ELISA (ELISA-ovo e ELISA-adulto) dentre os soros isolados de indivíduos com ELISA-positivo. Não obstante, a reação destes soros com antígeno de ovos ou vermes adultos pode ser dividida em dois sub-grupos: em um a reação é mais positiva frente a antígenos de ovos do que frente a antígenos de vermes adultos.

Tudo indica que os soros de jovens com menos de 20 anos são mais reativos aos antígenos de ovos do que os soros provenientes de indivíduos de outras faixas etárias.

Estes dados sugerem que ELISA preparado com antígeno de ovos, e não de vermes adultos, pareça ser bastante útil em pesquisas sorológicas na esquistosomíase mansônica em áreas endêmicas tais como o nordeste do Brasil.

Full text available only in PDF format.

Texto completo disponível apenas em PDF.

ACKNOWLEDGEMENT

This study was supported in part by research grants from Ooyama Health Foundation, Chiyoda Mutual Life Foundation, Keio University, the Ministry of Education, Science and Culture (N? 01570221), and Japan International Cooperation Agency (JICA), Tokyo, Japan.

Recebido para publicação em 29/06/1989.

1. ASAMI, K.; MIURA, S.; YOKOGAWA, M.; OYA, H.; AOKI, T. & KOJIMA, S. Prevalence of parasites in school children of Săo Lourenço Village, Pernambuco, Brazil in 1975 and 1979. In: REPORT OF OVERSEAS SCIENTIFIC EXPEDITION. Clinico-pathological and immunological investigations on schistosomiasis mansoni in northeast Brazil. Tokyo, Keio University, 1980. p. 17-28.
2. BARBOSA, F.S. Cross-sectional studies on Schistosoma mansoni infection in northeastern Brazil. Ann. trop. Med. Parasit., 69: 207-216, 1975.
3. BOROS, D.L. & WARREN, K.S. Delayed hypersensitivity-type granuloma formation and dermal reaction induced and elicited by a soluble factor isolated from Schistosoma mansoni eggs. J. exp. Med., 132: 488-507, 1970.
4. CAMARGO, S. The impact of the country development in the expansion of schistosomiasis. Rev. Inst. Med. trop. S. Paulo, 22 (suppl. 4): 2-4, 1980.
5. CERRI, G.G.; ALVES, V.A.F. & MAGALHĂES, A. Hepatosplenic schistosomiasis mansoni: Ultrasound manifestations. Radiology, 153: 777-780, 1984.
6. CHAFFEE, E.F.; BAUMAN, P.M. & SHAPIRO, J.J. Diagnosis of schistosomiasis by complement fixation. Amer. J. trop. Med. Hyg., 3: 905-913, 1954.
7. COKER, C.M. & LICHTENBERG, F. A revised method for isolation of Schistosoma mansoni eggs for biological examination. Proc. Soc. exp. biol. Med. (N. Y.), 92: 780-782, 1956.
8. FARAG, H.F. & BARAKAT, R.M.R. - The enzyme-linked immunosorbent assay in the diagnosis of human bilharziasis. Tropenmed. Parasit., 29: 12-14, 1978.
9. HILLYER, G.V. & FRICK, L.P. Immunoprecipitins in Schistosoma mansoni infections. I. Mouse Infections. Exp. Parasit., 20: 321-325, 1967.
10. HILLYER, G.V. & GOMEZ DE RIOS, I. The enzyme-linked immunosorbent assay (ELISA) for the immuno-diagnosis of schistosomiasis. Amer. J. trop. Med. Hyg., 28: 237-241, 1979.
11. HILLYER, G.V.; RAMZY, R.M.R.; EL ALAMY, M. & CLINE, B.L. The circumoval precipitin test for the serodiagnosis of human schistosomiasis mansoni and haematobia. Amer. J. trop. Med. Hyg., 30: 121-126, 1981.
12. HILLYER, G.V.; RUIZ-TIBEN, E.; KNIGHT, W.B.; GOMEZ DE RIOS, I. & PELLEY, R.P. Immunodiagnosis of infection with Schistosoma mansoni: Comparison of ELISA, radio immunoassay, and precipitation tests performed with antigens from eggs. Amer. J. trop. Med. Hyg., 28: 661-669, 1979.
13. KAMIYA, H.; YAMASHITA, K.; ISHIGOOKA, S.; YOSHIMURA, K. & BLAS, B.L. Enhancement of circumoval precipitin reactivity by sonication in the paraformaldehyde-fixed eggs of Schistosoma mansoni and S. japonicum. Jap. J. Parasit., 34: 21-26, 1985.
14. LEWERT, R.M.; YOGORE, M.G. & BLAS, B.L. Seroepidemiology of schistosomiasis japonica by ELISA in the Philippines. II. Unreliability of stool examination in the assessment of incidence. Amer. J. trop. Med. Hyg., 33: 872-881, 1984.
15. LOWRY, O.H.; ROSEBROUGH, N.J.; FARR, A.L. & RANDALL, R.J. Protein measurement with Folin phenol reagent. J. biol. Chem., 193: 265-275, 1951.
16. MACHADO, P.A. The brazilian program for schistosomiasis control, 1975-1979. Amer. J. trop. Med. Hyg., 31: 76-86, 1982.
17. MADDISON, S.E. Schistosomiasis. In: WALLS, K.W. & SCHANTZ, P.M. Immunodiagnosis of parasitic diseases. V. 1 Helminthic diseases. London, Academic Press, 1986. p. 1-37.
18. MADDISON, S.E. The present status of serodiagnosis and seroepidemiology of schistosomiasis. Diagn. Microbiol. infect. Dis., 7: 93-105, 1987.
19. MATSUDA, H.; TANAKA, H.; BLAS, B.L.; NOSENAS, J.S.; TOKAWA, T. & OHSAWA, S. Evaluation of ELISA with ABTS, 2,2'-azino-di-(3-ethylbenzthiazoline sulfonic acid), as the substrate of peroxidase and its application to the diagnosis of schistosomiasis. Jap. J. exp. Med., 54: 131-138, 1984.
20. McLAREN, M.; DRAPER, C.C.; ROBERTS, J.M.; MINTER-GOEDBLOED, E.; LIGTHART, G.S.; TEESDALE, C.H.; AMIN, M.A.; OMER, A.H.S.; BARTLETT, A. & VOLLER, A. Studies on the enzyme linked immunosorbent assay (ELISA) test for Schistosoma mansoni infections. Ann. trop. Med. Parasit., 72: 243-253, 1978.
21. McLAREN, M.L.; LONG, E.G.; GOODGAME, R.W. & LILLYWHITE, J.E. Application of the enzyme-linked immunosorbent assay (ELISA) for the serodiagnosis of Schistosoma mansoni infections in St. Lucia. Trans. roy. Soc. trop. Med. Hyg., 73: 636-639, 1979.
22. MOTT, K.E. Diagnostic tools for Schistosoma japonicum in control programs. Arzneimittel-Forsch, 34: 1217-1220, 1984.
23. OKAZARI, M.; OKAZAKI, M.; MIRANDA, P.; NETO, J.; DIEGUES, V.; ALVES, J.; CAUAS, M.; TANABE, M.; KOBAYASHI, S.; KANEKO, N.; NAGAKURA, K.; KOBAYASHI, M.; MOTTA, S.; TATENO, S. & TAKEUCHI, T. Parasitological and serological studies on amoebiasis and other intestinal parasitic infections in Recife and its suburban area, northeast Brazil. Rev. Inst. Med. trop. S. Paulo, 30: 313-321, 1988.
24. OYA, H.; AOKI, T.; ASAMI, K.; MIURA, S.; YOKOGAWA, M.; KOBAYASHI, M. & KOJIMA, S. Hemoglobin-specific protease from Schistosoma mansoni and Schistosoma japonicum; Antigenic properties for radio-allergo-sorbent test and applications to field trial. In: REPORT OF OVERSEAS SCIENTIFIC EXPEDITION. Clinico-pathological and immunological investigations on schistosomiasis mansoni in north-east Brazil. Tokyo, Keio University. 1980. p. 49-67.
25. PELLEY, R.P.; WARREN, K.S. & JORDAN, P. Purified antigen radioimmunoassay in serological diagnosis of schistosomiasis mansoni. Lancet, 2: 781-785, 1979.
26. PESSOA, S.B. Helmintologia. In: PESSOA, S.B. Parasitologia médica. Rio de Janeiro. Guanabara Koogan, 1972. p. 419-735.
27. RUIZ-TIBEN, E.; COX, P.M. & GREENBERG, E.R. Simplified criteria for interpretation of the schistosomiasis skin test. Ann. trop. Med. Parasit., 67: 341-348, 1973.
28. RUIZ-TIBEN, E.; HILLYER, G.V.; KNIGHT, W.B.; GOMEZ DE RIOS, I. & WOODALL, J.P. Intensity of infection with Schistosoma mansoni: its relationship to the sensitivity and specificity of serologic tests. Amer. J. trop. Med. Hyg., 28: 230-236, 1979.
29. SCHINSKI, V.D.; CLUTTER, W.C. & MURRELL, K.D. Enzyme and ¹²⁵I-labelled anti-immunoglobulin assays in the immunodiagnosis of schistosomiasis. Amer. J. trop. Med. Hyg., 25: 824-831, 1976.
30. SPEISER, F. & WEISS, N. Comparative evaluation of 7 helminth antigens the enzyme-linked immunosorbent assay (ELISA). Experientia, 35: 1512-1513, 1979.
31. TRACY, J.W.; DOMINGO, E.O. & MAHMOUD, A.A.F. Evaluation of purified Schistosoma japonicum glycoprotein egg antigen for the immunodiagnosis of infection in man. Amer. J. trop. Med. Hyg., 34: 92-95, 1985.
32. TSANG, V.C.W.; HANCOCK, K.; MADDISON, S.E.; BEATTY, A.L. & MOSS, D.M. Demonstration of species-specific and cross-reactive components of the adult microsomal antigens from Schistosoma mansoni and S. japonicum (MAMA and JAMA). J. Immunol., 132: 2607-2613, 1984.
33. TSANG, V.C.W.; TSANG, K.R.; HANCOCK, K.; KELLEY, M.A.; WILSON, B.C. & MADDISON, S.E. Schistosoma mansoni adult microsomal antigens, a serologic reagent. I. Systematic fractionation, quantitation, and characterization of antigenic components. J. Immunol., 130: 1359-1365, 1983.
34. WARREN, K.S.; KELLERMEYER, R.W.; JORDAN, P.; LITTELL, A.S.; COOK, J.A. & KAGAN, I.G. Immunologic diagnosis of schistosomiasis. I. A control study of intradermal (immediate and delayed) and serologic tests in St. Lucians infected with Schistosoma mansoni and in uninfected St. Vincentians. Amer. J. trop. Med. Hyg., 22: 189-198, 1973.
35. YOKOGAWA, M.; KOBAYASHI, M.; KOJIMA, S.; OYA, H.; AOKI, T.; ASAMI, K. & MIURA, S. Intradermal tests with antigens of proteolytic enzyme and veronal buffered saline extract of Schistosoma mansoni. In: REPORT OF OVERSEAS SCIENTIFIC EXPEDITION. Clinico-pathological and immunological investigations on schistosomiasis mansoni in north-east Brazil. Tokyo, Keio University, 1980. p. 29-48.

Address for correspondence:

Masanobu Tanabe, Ph. D.

Department of Parasitology, School of Medicine, Keio University

35 Shinanomachi

Shinjuku-ku, Tokyo, 160, Japan

(1

) Department of Parasitology, School of Medicine, Keio University, Tokyo, Japan.

(4) Department of Biophysics and Radiobiology, Universidade Federal de Pernambuco, Pernambuco, Brazil.

Publication Dates

Publication in this collection
13 Sept 2006
Date of issue
Apr 1990

History

Received
29 June 1989

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

[1] 1. ASAMI, K.; MIURA, S.; YOKOGAWA, M.; OYA, H.; AOKI, T. & KOJIMA, S. Prevalence of parasites in school children of Săo Lourenço Village, Pernambuco, Brazil in 1975 and 1979. In: REPORT OF OVERSEAS SCIENTIFIC EXPEDITION. Clinico-pathological and immunological investigations on schistosomiasis mansoni in northeast Brazil. Tokyo, Keio University, 1980. p. 17-28.

[2] 2. BARBOSA, F.S. Cross-sectional studies on Schistosoma mansoni infection in northeastern Brazil. Ann. trop. Med. Parasit., 69: 207-216, 1975.

[3] 3. BOROS, D.L. & WARREN, K.S. Delayed hypersensitivity-type granuloma formation and dermal reaction induced and elicited by a soluble factor isolated from Schistosoma mansoni eggs. J. exp. Med., 132: 488-507, 1970.

[4] 4. CAMARGO, S. The impact of the country development in the expansion of schistosomiasis. Rev. Inst. Med. trop. S. Paulo, 22 (suppl. 4): 2-4, 1980.

[5] 5. CERRI, G.G.; ALVES, V.A.F. & MAGALHĂES, A. Hepatosplenic schistosomiasis mansoni: Ultrasound manifestations. Radiology, 153: 777-780, 1984.

[6] 6. CHAFFEE, E.F.; BAUMAN, P.M. & SHAPIRO, J.J. Diagnosis of schistosomiasis by complement fixation. Amer. J. trop. Med. Hyg., 3: 905-913, 1954.

[7] 7. COKER, C.M. & LICHTENBERG, F. A revised method for isolation of Schistosoma mansoni eggs for biological examination. Proc. Soc. exp. biol. Med. (N. Y.), 92: 780-782, 1956.

[8] 8. FARAG, H.F. & BARAKAT, R.M.R. - The enzyme-linked immunosorbent assay in the diagnosis of human bilharziasis. Tropenmed. Parasit., 29: 12-14, 1978.

[9] 9. HILLYER, G.V. & FRICK, L.P. Immunoprecipitins in Schistosoma mansoni infections. I. Mouse Infections. Exp. Parasit., 20: 321-325, 1967.

[10] 10. HILLYER, G.V. & GOMEZ DE RIOS, I. The enzyme-linked immunosorbent assay (ELISA) for the immuno-diagnosis of schistosomiasis. Amer. J. trop. Med. Hyg., 28: 237-241, 1979.

[11] 11. HILLYER, G.V.; RAMZY, R.M.R.; EL ALAMY, M. & CLINE, B.L. The circumoval precipitin test for the serodiagnosis of human schistosomiasis mansoni and haematobia. Amer. J. trop. Med. Hyg., 30: 121-126, 1981.

[12] 12. HILLYER, G.V.; RUIZ-TIBEN, E.; KNIGHT, W.B.; GOMEZ DE RIOS, I. & PELLEY, R.P. Immunodiagnosis of infection with Schistosoma mansoni: Comparison of ELISA, radio immunoassay, and precipitation tests performed with antigens from eggs. Amer. J. trop. Med. Hyg., 28: 661-669, 1979.

[13] 13. KAMIYA, H.; YAMASHITA, K.; ISHIGOOKA, S.; YOSHIMURA, K. & BLAS, B.L. Enhancement of circumoval precipitin reactivity by sonication in the paraformaldehyde-fixed eggs of Schistosoma mansoni and S. japonicum. Jap. J. Parasit., 34: 21-26, 1985.

[14] 14. LEWERT, R.M.; YOGORE, M.G. & BLAS, B.L. Seroepidemiology of schistosomiasis japonica by ELISA in the Philippines. II. Unreliability of stool examination in the assessment of incidence. Amer. J. trop. Med. Hyg., 33: 872-881, 1984.

[15] 15. LOWRY, O.H.; ROSEBROUGH, N.J.; FARR, A.L. & RANDALL, R.J. Protein measurement with Folin phenol reagent. J. biol. Chem., 193: 265-275, 1951.

[16] 16. MACHADO, P.A. The brazilian program for schistosomiasis control, 1975-1979. Amer. J. trop. Med. Hyg., 31: 76-86, 1982.

[17] 17. MADDISON, S.E. Schistosomiasis. In: WALLS, K.W. & SCHANTZ, P.M. Immunodiagnosis of parasitic diseases. V. 1 Helminthic diseases. London, Academic Press, 1986. p. 1-37.

[18] 18. MADDISON, S.E. The present status of serodiagnosis and seroepidemiology of schistosomiasis. Diagn. Microbiol. infect. Dis., 7: 93-105, 1987.

[19] 19. MATSUDA, H.; TANAKA, H.; BLAS, B.L.; NOSENAS, J.S.; TOKAWA, T. & OHSAWA, S. Evaluation of ELISA with ABTS, 2,2'-azino-di-(3-ethylbenzthiazoline sulfonic acid), as the substrate of peroxidase and its application to the diagnosis of schistosomiasis. Jap. J. exp. Med., 54: 131-138, 1984.

[20] 20. McLAREN, M.; DRAPER, C.C.; ROBERTS, J.M.; MINTER-GOEDBLOED, E.; LIGTHART, G.S.; TEESDALE, C.H.; AMIN, M.A.; OMER, A.H.S.; BARTLETT, A. & VOLLER, A. Studies on the enzyme linked immunosorbent assay (ELISA) test for Schistosoma mansoni infections. Ann. trop. Med. Parasit., 72: 243-253, 1978.

[21] 21. McLAREN, M.L.; LONG, E.G.; GOODGAME, R.W. & LILLYWHITE, J.E. Application of the enzyme-linked immunosorbent assay (ELISA) for the serodiagnosis of Schistosoma mansoni infections in St. Lucia. Trans. roy. Soc. trop. Med. Hyg., 73: 636-639, 1979.

[22] 22. MOTT, K.E. Diagnostic tools for Schistosoma japonicum in control programs. Arzneimittel-Forsch, 34: 1217-1220, 1984.

[23] 23. OKAZARI, M.; OKAZAKI, M.; MIRANDA, P.; NETO, J.; DIEGUES, V.; ALVES, J.; CAUAS, M.; TANABE, M.; KOBAYASHI, S.; KANEKO, N.; NAGAKURA, K.; KOBAYASHI, M.; MOTTA, S.; TATENO, S. & TAKEUCHI, T. Parasitological and serological studies on amoebiasis and other intestinal parasitic infections in Recife and its suburban area, northeast Brazil. Rev. Inst. Med. trop. S. Paulo, 30: 313-321, 1988.

[24] 24. OYA, H.; AOKI, T.; ASAMI, K.; MIURA, S.; YOKOGAWA, M.; KOBAYASHI, M. & KOJIMA, S. Hemoglobin-specific protease from Schistosoma mansoni and Schistosoma japonicum; Antigenic properties for radio-allergo-sorbent test and applications to field trial. In: REPORT OF OVERSEAS SCIENTIFIC EXPEDITION. Clinico-pathological and immunological investigations on schistosomiasis mansoni in north-east Brazil. Tokyo, Keio University. 1980. p. 49-67.

[25] 25. PELLEY, R.P.; WARREN, K.S. & JORDAN, P. Purified antigen radioimmunoassay in serological diagnosis of schistosomiasis mansoni. Lancet, 2: 781-785, 1979.

[26] 26. PESSOA, S.B. Helmintologia. In: PESSOA, S.B. Parasitologia médica. Rio de Janeiro. Guanabara Koogan, 1972. p. 419-735.

[27] 27. RUIZ-TIBEN, E.; COX, P.M. & GREENBERG, E.R. Simplified criteria for interpretation of the schistosomiasis skin test. Ann. trop. Med. Parasit., 67: 341-348, 1973.

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