THE JOURNAL OF INFECTIOUS DISEASES. VOL. 140, NO.5. NOVEMBER 1979 © 1979 by The University of Chicago. 0022-1899/79/4005-0017$00.75
NOTES Prevalence of Antibodies to Toxoplasma gondii in Pregnant Women in Oregon Peter G. Beach
From the Oregon Public Health Laboratory, Department of Human Resources, Health Division, Portland, Oregon
Materials and Methods
There have been numerous reports on the prevalence of antibodies to Toxoplasma gondii in U.S. military recruits [1-3], in residents of various countries [4-7], and in pregnant women in Europe and North America [8-10], but no studies have covered large numbers of normal pregnant women in a program extending more than three years in the United States. On June 1, 1973, the Oregon State Public Health Laboratory began serologic screening of pregnant women for evidence of acute toxoplasmosis. We have tested 95,929 prenatal sera for evidence of toxoplasmosis by combining the indirect hemagglutination (IHA) test [11] and the indirect fluorescent antibody-IgM specific (IFA-IgM) test [12]. To determine the sensitivity and reliability of the IHA test, samples were also tested by the methylene blue dye (MBD) test (13] and by the indirect fluorescent antibody (IFA) test (11]. These data were analyzed by linear regression to determine the efficacy of the IHA test.
Specimen handling. Sera were collected for one of three reasons: prenatal syphilis screening as required by state law, prenatal rubella screening, or toxoplasmosis screening of pregnant women not covered by either of the first two categories. Specimens were tested daily as they were received or held at 4 C for testing the next day; they were frozen at - 60 C if they were stored for longer periods. Sera sent for consultative studies were mailed in leak-proof containers at ambient temperatures. IHA test. We used the microtitration method as described by Palmer et al. (11]. Sensitized sheep red blood cells (International Biological Laboratories, Rockville, Md.) were purchased in lots prescreened for uniform reactivity to the "Fried" control provided by the Parasitic Serology Section, Center for Disease Control (CDC), Atlanta, Ga. The "Fried" control has an IFA and IHA titer of 1:256 ± one tube-dilution. MBD test. The procedure of Sabine and Feldman (13] was performed in Professor Otto Thalhammer's laboratory in Vienna, Austria. An exchange of sera between our laboratories was arranged as two single-blind studies. IFA test. The procedure used was described by Palmer et al. (11]. The conjugated antiserum (lot W-5) was provided by the Parasitic Serology Section, CDC. IFA-IgM test. The technique used for the IFA-IgM test was originally described by Remington et al. (12]. Antigen-spotted slides and conjugated IA-chain-specific antisera were purchased
Received for publication February 15, 1978, and in revised form May 18, 1979. I thank Gatlin R. Brandon and William H. Stevenson, without whose perseverance and foresight this program would not exist. I also thank Dr. Kenneth Wall, Parasitic Serology Section, Center for Disease Control, and Dr. William H. Murphey, Manager-Director of the Oregon Public Health Laboratory for their guidance, and Dr. Otto Thalhammer for his assistance. Please address requests for reprints to Peter G. Beach, Oregon Public Health Laboratory, Department of Human Resources, Health Division, P.O. Box 275, Portland, Oregon 97207.
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Downloaded from http://jid.oxfordjournals.org/ at New York University on August 31, 2015
Sera from 95,929 pregnant women were screened for antibodies to Toxoplasm~ g~ndii with the indirect hemagglutination test (lHA) at a 1:64 dilution of the sera. An mdlTect fluorescent antibody-IgM specific test (lFA-IgM) was used on all sera found to have an IHA titer of ~1:256. From August 1973 to December 1976, 8.1070 of pregnant women had IHA titers of ~ 1:64. In addition, 129 (18.4070) of 700 pregnant women with IHA titers of ~1:256 had IFA-IgM titers of ~1:4. The IHA test was an acceptable test for mass screening of sera from pregnant women. In Oregon, one in every 200 women contracts toxoplasmosis during her pregnancy.
Toxoplasma Antibodies in Oregon Mothers
Results
Of 95,929 prenatal sera tested by the IHA test, 7,791 (8.1070) were positive with titers of ;;?;1:64. The overall distribution of titers within the prenatal population is given in table 1. Among 88,138 pregnant women found seronegative (titers,
NOTES Prevalence of Antibodies to Toxoplasma gondii in Pregnant Women in Oregon Peter G. Beach
From the Oregon Public Health Laboratory, Department of Human Resources, Health Division, Portland, Oregon
Materials and Methods
There have been numerous reports on the prevalence of antibodies to Toxoplasma gondii in U.S. military recruits [1-3], in residents of various countries [4-7], and in pregnant women in Europe and North America [8-10], but no studies have covered large numbers of normal pregnant women in a program extending more than three years in the United States. On June 1, 1973, the Oregon State Public Health Laboratory began serologic screening of pregnant women for evidence of acute toxoplasmosis. We have tested 95,929 prenatal sera for evidence of toxoplasmosis by combining the indirect hemagglutination (IHA) test [11] and the indirect fluorescent antibody-IgM specific (IFA-IgM) test [12]. To determine the sensitivity and reliability of the IHA test, samples were also tested by the methylene blue dye (MBD) test (13] and by the indirect fluorescent antibody (IFA) test (11]. These data were analyzed by linear regression to determine the efficacy of the IHA test.
Specimen handling. Sera were collected for one of three reasons: prenatal syphilis screening as required by state law, prenatal rubella screening, or toxoplasmosis screening of pregnant women not covered by either of the first two categories. Specimens were tested daily as they were received or held at 4 C for testing the next day; they were frozen at - 60 C if they were stored for longer periods. Sera sent for consultative studies were mailed in leak-proof containers at ambient temperatures. IHA test. We used the microtitration method as described by Palmer et al. (11]. Sensitized sheep red blood cells (International Biological Laboratories, Rockville, Md.) were purchased in lots prescreened for uniform reactivity to the "Fried" control provided by the Parasitic Serology Section, Center for Disease Control (CDC), Atlanta, Ga. The "Fried" control has an IFA and IHA titer of 1:256 ± one tube-dilution. MBD test. The procedure of Sabine and Feldman (13] was performed in Professor Otto Thalhammer's laboratory in Vienna, Austria. An exchange of sera between our laboratories was arranged as two single-blind studies. IFA test. The procedure used was described by Palmer et al. (11]. The conjugated antiserum (lot W-5) was provided by the Parasitic Serology Section, CDC. IFA-IgM test. The technique used for the IFA-IgM test was originally described by Remington et al. (12]. Antigen-spotted slides and conjugated IA-chain-specific antisera were purchased
Received for publication February 15, 1978, and in revised form May 18, 1979. I thank Gatlin R. Brandon and William H. Stevenson, without whose perseverance and foresight this program would not exist. I also thank Dr. Kenneth Wall, Parasitic Serology Section, Center for Disease Control, and Dr. William H. Murphey, Manager-Director of the Oregon Public Health Laboratory for their guidance, and Dr. Otto Thalhammer for his assistance. Please address requests for reprints to Peter G. Beach, Oregon Public Health Laboratory, Department of Human Resources, Health Division, P.O. Box 275, Portland, Oregon 97207.
780
Downloaded from http://jid.oxfordjournals.org/ at New York University on August 31, 2015
Sera from 95,929 pregnant women were screened for antibodies to Toxoplasm~ g~ndii with the indirect hemagglutination test (lHA) at a 1:64 dilution of the sera. An mdlTect fluorescent antibody-IgM specific test (lFA-IgM) was used on all sera found to have an IHA titer of ~1:256. From August 1973 to December 1976, 8.1070 of pregnant women had IHA titers of ~ 1:64. In addition, 129 (18.4070) of 700 pregnant women with IHA titers of ~1:256 had IFA-IgM titers of ~1:4. The IHA test was an acceptable test for mass screening of sera from pregnant women. In Oregon, one in every 200 women contracts toxoplasmosis during her pregnancy.
Toxoplasma Antibodies in Oregon Mothers
Results
Of 95,929 prenatal sera tested by the IHA test, 7,791 (8.1070) were positive with titers of ;;?;1:64. The overall distribution of titers within the prenatal population is given in table 1. Among 88,138 pregnant women found seronegative (titers,
