Rubella 1974 and its aftermath, congenital rubella syndrome Ruth S. Faulkner,
ph
d; Douglas A.
Gough,
rt
epidemic of rubella reached its peak in the Atlantic provinces in 1974, subsiding in early 1975. With the exception of Quebec the remainder of Canada showed a reverse trend, with a large increase in the numbers of cases reported in the first 41/2 months of 1975. The Halifax virus laboratory reported 106 serologically
An
of rubella in 1974, 44 of them in pregnant In the aftermath of the epidemic many infants were born with the congenital rubella syndrome (CRS). A study carried out from Sept. 1, 1974 through Apr. 30, 1975 showed an 80% correlation between clinical diagnosis and the presence of rubella-specific IgM antibodies in 35 of these infants. Of the 23 infants in whom the diagnosis of CRS was made by laboratory or clinical findings or both, laboratory criteria were met in 20 (87.0%), clinical criteria in 19 (82.6%) and both laboratory and clinical criteria in 16 (69.6%j. proven
cases
women.
Une
epidemie de rubeole
a
atteint
son sommet aux
provinces Atlantiques en 1974 et s'est apaisee au debut de 1975. A I'exception du Quebec, dans le reste
du Canada la tendance etait inversee, en ce sens qu'une forte augmentation du nombre de cas signales s'est produite durant les 41/2 premiers mois de 1975. Le laboratoire des virus de Halifax a rapporte en 1974 106 cas de rubeole serologiquement prouves, dont 44 survenus chez des femmes enceintes. Dans le sillage de I'epidemie, de nombreux nourrissons sont nes porteurs des malformations rubeoleuses congenitales (MRC). II ressort de l'etude entreprise du ler septembre 1974 au 30 avril 1975 qu'il y avait une correlation de 80% entre le diagnostic clinique et la presence d'anticorps IgM specifiques de ia rubeole chez 35 de ces nouveau-nes. Chez 23 des nouveau-nes ou le diagnostic de MRC avait ete pose d'apres les resultats laboratoire ou clinique, ou par les deux, les criteres du laboratoire etaient respectees chez 20 (87.0%), les criteres cliniques chez 19 (82.6%) et les criteres des deux sources chez 16 (69.6%).
From the department of microbiology, Victoria General Hospital, Halifax Reprint requests to: Dr. R.S. Faulkner, Department of microbiology, 5788 University Ave., Halifax, NS B3H 1V8
Rubella was made a notifiable disease in Canada in 1969. In Nova Scotia the number of reported cases declined be¬ tween 1969 and 1973 (260, 276, 185, 67 and 64, respec¬ tively), increased sharply in 1974 (727) and decreased sharply early in 1975. From Jan. 1 to May 17, 1974 the number of cases reported in Nova Scotia was 403, and in Canada as a whole, 3607; in the same period of 1975 the number of cases reported in Nova Scotia decreased to 47, while the Canadian total more than doubled, to 7380.1 The incidence pattern in these two 4 Vi -month periods was similar in New Brunswick and Newfoundland, the num¬ bers of cases decreasing from the first to the second period from 28 to 4 in New Brunswick and from 150 to 21 in Newfoundland. The number of cases reported in Quebec decreased slightly, from 984 in 1974 to 906 in 1975. The trend was reversed, however, in Ontario, Manitoba, Saskat¬ chewan, Alberta and British Columbia, with a large increase in numbers of cases in 1975 compared with 1974. Prince Edward Island did not report.1 Thus, it seems that a rubella epidemic in the Atlantic provinces in 1974 had subsided considerably by early 1975, whereas in the five western provinces the disease was much more prevalent in 1975 than in 1974. In the fail of 1974 the virus laboratory at Victoria Ge¬ neral Hospital in Halifax began testing for rubella-specific IgM antibodies in the serum of infants considered to have congenital rubella syndrome (CRS). We had previously found that the use of 2-mercaptoethanol2 for this purpose was unsatisfactory in our hands, and that titration of hemagglutination-inhibiting (HI) antibody after sucrose gradi¬ ent fractionation of the serum gave more reliable results. In this paper we report the findings of a study carried out from Sept. 1, 1974 through Apr. 30, 1975 to assess the correlation between clinical diagnosis and results of virologic studies, especially the presence or absence of rubellaspecific IgM antibodies.
Material, methods and patients Sucrose gradient fractionation The method was basically that of Vesikari and Vaheri,3 with the following modifications, recommended by Cadham Public Health Laboratories in Winnipeg (W. Stackiw: per¬ sonal communication, 1972): (a) the volume of serum was CMA JOURNAL/JANUARY 24, 1976/VOL. 114 115
increased from 0.2 ml of a 1:5 dilution (untreated) to 0.3 ml of undiluted serum previously incubated at 4°C for 2 hours with packed chick erythrocytes; (b) the number of serum fractions was reduced from 12 or 14 to 8; and (c) the ultracentrifugation time was increased from 14V^ to 16 hours. Titration of HI antibody Each of the eight fractions was titrated and plated un¬ diluted and in doubling dilutions from 1:2 to 1:1024. Antigen was obtained commercially. The method was that of Ste wart and coworkers,4 with the following modifications: (a) the chicks bled were up to 48 hours old instead of less than 24 hours old, and 0.25% suspensions of chick erythro¬ cytes were used instead of 0.16% suspensions;5 (b) the antiserum-antigen mixtures were incubated at 4CC for 1 hour rather than at 36°C for 15 minutes; and (c) serum was not pretreated to remove nonspecific inhibitors because remains at the top of the gradient and is thus ^-lipoprotein separated from the IgM during fractionation. Virus isolation Specimens were inoculated to primary cultures of African green monkey kidney cells; the presence of virus was in¬ dicated by interference with propagation of subsequently inoculated echovirus ll.6 Neutralization tests with rubellaspecific antiserum identified the isolates. Urine and throat swabs were the commonest types of specimens submitted, but cerebrospinal fluid (CSF), placental tissue and rectal swabs were also received, and fluid from the ears and lens material from cataract operations are now being received.
Clinical assessment In assessing the clinical data we used the criteria for diagnosis of CRS specified by the Center for Disease Con¬
trol, Atlanta, Georgia7 (Table I).
Patients A total of 44 infants with suspected congenital anomalies, or whose mothers were known or thought to have had rubella during pregnancy, were studied in the 8-month period Sept. 1, 1974 to Apr. 30, 1975. Five were from New Brunswick and the other 39 from hospitals in Halifax; the residence of 3 of the 39 was in Prince Edward Island. Subsequently five infants were removed from the study when they were shown to have abnormalities other than CRS. Results The data for the 39 infants are summarized in Table II. Neither sex predominated. November was the commonest month of birth of infants with CRS diagnosed clinically or by laboratory methods or both.
Rubella-specific IgM antibodies Of the 39 infants 17 had rubella-specific IgM antibodies, in 2 the test results were equivocal, and the remaining 20 had no demonstrable IgM antibodies. Testing was carried out at ages ranging from less than 24 hours to 6 months. The three oldest babies (4, 5 and 6 months) all had demon¬ strable antibodies; two had the clinical features of CRS and the third (patient 13) had a hearing loss and her mother had a history of rash, fever and sore throat when 2Vi months pregnant. Titres of HI antibody Unfractionated serum from only 14 babies was tested, but even this small number of tests showed that a high serum antibody titre alone is not diagnostic: titres of 1:64, 1:128 and 1:256 were found in both "positive" and "nega¬ tive" babies. Total IgM values Total IgM values tended to be higher in babies with rubella-specific IgM antibodies than in those without, but no statistical comparison was made. Most of these tests were done at the time of sucrose gradient fractionation but a few had been done at the referring hospitals. Isolation of virus Rubella virus was isolated from 8 of the 26 babies from whom specimens for culture were received; 5 of the 8 had rubella-specific IgM antibodies. Specimens were collected infrequently from these 26 infants and were never collected from the other 13. Clinical status In 19 of the infants CRS was diagnosed clinically. In another infant (patient 20) the diagnosis was questionable: she had hepatosplenomegaly, and an early radiograph of the long bones showed minimal linear densities; however, when seen by her family physician at 7 months of age she was considered normal. Her mother had a history of rubella when 2 months pregnant; her HI antibody titre increased from < 1:8 to 1:256. Nineteen of the babies were con¬ sidered clinically not to have CRS, and for one no clinical information was available. Correlation of clinical and laboratory diagnosis Of the 17 infants with rubella-specific antibodies a clin¬ ical diagnosis of rubella was made in 13; 3 had milder abnormalities (patient 13, loss of hearing; patient 15, low birth weight, small head circumference and laryngeal stridor; patient 4, hepatomegaly and a faint systolic mur¬ mur); and 1 (patient 11) was apparently normal, although his mother had had an increase in HI antibody titre from < 1:8 to 1:512 when VA months pregnant. For two infants test results for rubella-specific IgM anti¬ bodies were equivocal that is, a low titre was detected in only the last fraction of IgM. Both mothers were known to have had rubella during pregnancy; this had been con¬ firmed by increases in antibody titre. Patient 18 had hepatosplenomegaly and patient 19 appeared to be normal. Of the 20 infants with no demonstrable rubella-specific IgM antibodies 12 were clinically normal, the diagnosis was doubtful in 1, and 6 were clinically positive. Of the last six, virus was isolated in three, cultures were negative in two, and no specimens for culture were received from the other infant. There was insufficient information about one infant (patient 26) for comparison. Omitting patients 26, 18, 19 and 20 (in the last three either the clinical findings or the laboratory results were inconclusive) there was an 80% correlation between clinical and laboratory findings (28 out of 35 infants). Of the other seven infants four .
Table I.Clinical criteria* for
syndrome (CRS)
diagnosis of congenital rubella B
Cataracts Loss of hearing disease: Congenital heart patent ductus arteriosus,
peripheral pulmonic stenosis, atrial septal defect or ventricular septal defect Congenital glaucoma
Purpura Hepatosplenomegaly Neonatal jaundice
Microcephaly
Mental retardation
Radiolucent bone lesions *To be classed as clinically positive a child must have either two of the defect listed under A or one from A and one from B.7 116 CMA JOURNAL/JANUARY 24, 1976/VOL. 114
Table II.Summary of data for the 39 infants with suspected CRS Patient no.
Sex
Birth date*
Serum HI titre
Total
Agef
IgM (mg/dl)
(whole)
Virus culture
Mother's history of rubella
during pregnancy
Clinical
CRSt
Infants with rubella-specific IgM antibodies
2/9/74
17
2/4/75
5x/2 weeks
21 days
Infants with equivocal
350 100 54 145 (cord) ND ND 59 69 ND 132 120 150 41 220 25 500 220
1:128
1:64 ND 1:256 ND ND 1:256 ND ND 1:64 1:2048 (cord) 1:128 1:128 1:64 ND ND ND
test results
+
Contact at 10 weeks
+
Rash? Rubella zXV/z months Rash. High titre in 1st trimester Rubella Rash in 1st month Rash at 8 weeks. 7-globulin given Rash at 6 weeks
(throat)
(throat) +
(urine) + (throat)
Contact at llA months. Titre,
ph
d; Douglas A.
Gough,
rt
epidemic of rubella reached its peak in the Atlantic provinces in 1974, subsiding in early 1975. With the exception of Quebec the remainder of Canada showed a reverse trend, with a large increase in the numbers of cases reported in the first 41/2 months of 1975. The Halifax virus laboratory reported 106 serologically
An
of rubella in 1974, 44 of them in pregnant In the aftermath of the epidemic many infants were born with the congenital rubella syndrome (CRS). A study carried out from Sept. 1, 1974 through Apr. 30, 1975 showed an 80% correlation between clinical diagnosis and the presence of rubella-specific IgM antibodies in 35 of these infants. Of the 23 infants in whom the diagnosis of CRS was made by laboratory or clinical findings or both, laboratory criteria were met in 20 (87.0%), clinical criteria in 19 (82.6%) and both laboratory and clinical criteria in 16 (69.6%j. proven
cases
women.
Une
epidemie de rubeole
a
atteint
son sommet aux
provinces Atlantiques en 1974 et s'est apaisee au debut de 1975. A I'exception du Quebec, dans le reste
du Canada la tendance etait inversee, en ce sens qu'une forte augmentation du nombre de cas signales s'est produite durant les 41/2 premiers mois de 1975. Le laboratoire des virus de Halifax a rapporte en 1974 106 cas de rubeole serologiquement prouves, dont 44 survenus chez des femmes enceintes. Dans le sillage de I'epidemie, de nombreux nourrissons sont nes porteurs des malformations rubeoleuses congenitales (MRC). II ressort de l'etude entreprise du ler septembre 1974 au 30 avril 1975 qu'il y avait une correlation de 80% entre le diagnostic clinique et la presence d'anticorps IgM specifiques de ia rubeole chez 35 de ces nouveau-nes. Chez 23 des nouveau-nes ou le diagnostic de MRC avait ete pose d'apres les resultats laboratoire ou clinique, ou par les deux, les criteres du laboratoire etaient respectees chez 20 (87.0%), les criteres cliniques chez 19 (82.6%) et les criteres des deux sources chez 16 (69.6%).
From the department of microbiology, Victoria General Hospital, Halifax Reprint requests to: Dr. R.S. Faulkner, Department of microbiology, 5788 University Ave., Halifax, NS B3H 1V8
Rubella was made a notifiable disease in Canada in 1969. In Nova Scotia the number of reported cases declined be¬ tween 1969 and 1973 (260, 276, 185, 67 and 64, respec¬ tively), increased sharply in 1974 (727) and decreased sharply early in 1975. From Jan. 1 to May 17, 1974 the number of cases reported in Nova Scotia was 403, and in Canada as a whole, 3607; in the same period of 1975 the number of cases reported in Nova Scotia decreased to 47, while the Canadian total more than doubled, to 7380.1 The incidence pattern in these two 4 Vi -month periods was similar in New Brunswick and Newfoundland, the num¬ bers of cases decreasing from the first to the second period from 28 to 4 in New Brunswick and from 150 to 21 in Newfoundland. The number of cases reported in Quebec decreased slightly, from 984 in 1974 to 906 in 1975. The trend was reversed, however, in Ontario, Manitoba, Saskat¬ chewan, Alberta and British Columbia, with a large increase in numbers of cases in 1975 compared with 1974. Prince Edward Island did not report.1 Thus, it seems that a rubella epidemic in the Atlantic provinces in 1974 had subsided considerably by early 1975, whereas in the five western provinces the disease was much more prevalent in 1975 than in 1974. In the fail of 1974 the virus laboratory at Victoria Ge¬ neral Hospital in Halifax began testing for rubella-specific IgM antibodies in the serum of infants considered to have congenital rubella syndrome (CRS). We had previously found that the use of 2-mercaptoethanol2 for this purpose was unsatisfactory in our hands, and that titration of hemagglutination-inhibiting (HI) antibody after sucrose gradi¬ ent fractionation of the serum gave more reliable results. In this paper we report the findings of a study carried out from Sept. 1, 1974 through Apr. 30, 1975 to assess the correlation between clinical diagnosis and results of virologic studies, especially the presence or absence of rubellaspecific IgM antibodies.
Material, methods and patients Sucrose gradient fractionation The method was basically that of Vesikari and Vaheri,3 with the following modifications, recommended by Cadham Public Health Laboratories in Winnipeg (W. Stackiw: per¬ sonal communication, 1972): (a) the volume of serum was CMA JOURNAL/JANUARY 24, 1976/VOL. 114 115
increased from 0.2 ml of a 1:5 dilution (untreated) to 0.3 ml of undiluted serum previously incubated at 4°C for 2 hours with packed chick erythrocytes; (b) the number of serum fractions was reduced from 12 or 14 to 8; and (c) the ultracentrifugation time was increased from 14V^ to 16 hours. Titration of HI antibody Each of the eight fractions was titrated and plated un¬ diluted and in doubling dilutions from 1:2 to 1:1024. Antigen was obtained commercially. The method was that of Ste wart and coworkers,4 with the following modifications: (a) the chicks bled were up to 48 hours old instead of less than 24 hours old, and 0.25% suspensions of chick erythro¬ cytes were used instead of 0.16% suspensions;5 (b) the antiserum-antigen mixtures were incubated at 4CC for 1 hour rather than at 36°C for 15 minutes; and (c) serum was not pretreated to remove nonspecific inhibitors because remains at the top of the gradient and is thus ^-lipoprotein separated from the IgM during fractionation. Virus isolation Specimens were inoculated to primary cultures of African green monkey kidney cells; the presence of virus was in¬ dicated by interference with propagation of subsequently inoculated echovirus ll.6 Neutralization tests with rubellaspecific antiserum identified the isolates. Urine and throat swabs were the commonest types of specimens submitted, but cerebrospinal fluid (CSF), placental tissue and rectal swabs were also received, and fluid from the ears and lens material from cataract operations are now being received.
Clinical assessment In assessing the clinical data we used the criteria for diagnosis of CRS specified by the Center for Disease Con¬
trol, Atlanta, Georgia7 (Table I).
Patients A total of 44 infants with suspected congenital anomalies, or whose mothers were known or thought to have had rubella during pregnancy, were studied in the 8-month period Sept. 1, 1974 to Apr. 30, 1975. Five were from New Brunswick and the other 39 from hospitals in Halifax; the residence of 3 of the 39 was in Prince Edward Island. Subsequently five infants were removed from the study when they were shown to have abnormalities other than CRS. Results The data for the 39 infants are summarized in Table II. Neither sex predominated. November was the commonest month of birth of infants with CRS diagnosed clinically or by laboratory methods or both.
Rubella-specific IgM antibodies Of the 39 infants 17 had rubella-specific IgM antibodies, in 2 the test results were equivocal, and the remaining 20 had no demonstrable IgM antibodies. Testing was carried out at ages ranging from less than 24 hours to 6 months. The three oldest babies (4, 5 and 6 months) all had demon¬ strable antibodies; two had the clinical features of CRS and the third (patient 13) had a hearing loss and her mother had a history of rash, fever and sore throat when 2Vi months pregnant. Titres of HI antibody Unfractionated serum from only 14 babies was tested, but even this small number of tests showed that a high serum antibody titre alone is not diagnostic: titres of 1:64, 1:128 and 1:256 were found in both "positive" and "nega¬ tive" babies. Total IgM values Total IgM values tended to be higher in babies with rubella-specific IgM antibodies than in those without, but no statistical comparison was made. Most of these tests were done at the time of sucrose gradient fractionation but a few had been done at the referring hospitals. Isolation of virus Rubella virus was isolated from 8 of the 26 babies from whom specimens for culture were received; 5 of the 8 had rubella-specific IgM antibodies. Specimens were collected infrequently from these 26 infants and were never collected from the other 13. Clinical status In 19 of the infants CRS was diagnosed clinically. In another infant (patient 20) the diagnosis was questionable: she had hepatosplenomegaly, and an early radiograph of the long bones showed minimal linear densities; however, when seen by her family physician at 7 months of age she was considered normal. Her mother had a history of rubella when 2 months pregnant; her HI antibody titre increased from < 1:8 to 1:256. Nineteen of the babies were con¬ sidered clinically not to have CRS, and for one no clinical information was available. Correlation of clinical and laboratory diagnosis Of the 17 infants with rubella-specific antibodies a clin¬ ical diagnosis of rubella was made in 13; 3 had milder abnormalities (patient 13, loss of hearing; patient 15, low birth weight, small head circumference and laryngeal stridor; patient 4, hepatomegaly and a faint systolic mur¬ mur); and 1 (patient 11) was apparently normal, although his mother had had an increase in HI antibody titre from < 1:8 to 1:512 when VA months pregnant. For two infants test results for rubella-specific IgM anti¬ bodies were equivocal that is, a low titre was detected in only the last fraction of IgM. Both mothers were known to have had rubella during pregnancy; this had been con¬ firmed by increases in antibody titre. Patient 18 had hepatosplenomegaly and patient 19 appeared to be normal. Of the 20 infants with no demonstrable rubella-specific IgM antibodies 12 were clinically normal, the diagnosis was doubtful in 1, and 6 were clinically positive. Of the last six, virus was isolated in three, cultures were negative in two, and no specimens for culture were received from the other infant. There was insufficient information about one infant (patient 26) for comparison. Omitting patients 26, 18, 19 and 20 (in the last three either the clinical findings or the laboratory results were inconclusive) there was an 80% correlation between clinical and laboratory findings (28 out of 35 infants). Of the other seven infants four .
Table I.Clinical criteria* for
syndrome (CRS)
diagnosis of congenital rubella B
Cataracts Loss of hearing disease: Congenital heart patent ductus arteriosus,
peripheral pulmonic stenosis, atrial septal defect or ventricular septal defect Congenital glaucoma
Purpura Hepatosplenomegaly Neonatal jaundice
Microcephaly
Mental retardation
Radiolucent bone lesions *To be classed as clinically positive a child must have either two of the defect listed under A or one from A and one from B.7 116 CMA JOURNAL/JANUARY 24, 1976/VOL. 114
Table II.Summary of data for the 39 infants with suspected CRS Patient no.
Sex
Birth date*
Serum HI titre
Total
Agef
IgM (mg/dl)
(whole)
Virus culture
Mother's history of rubella
during pregnancy
Clinical
CRSt
Infants with rubella-specific IgM antibodies
2/9/74
17
2/4/75
5x/2 weeks
21 days
Infants with equivocal
350 100 54 145 (cord) ND ND 59 69 ND 132 120 150 41 220 25 500 220
1:128
1:64 ND 1:256 ND ND 1:256 ND ND 1:64 1:2048 (cord) 1:128 1:128 1:64 ND ND ND
test results
+
Contact at 10 weeks
+
Rash? Rubella zXV/z months Rash. High titre in 1st trimester Rubella Rash in 1st month Rash at 8 weeks. 7-globulin given Rash at 6 weeks
(throat)
(throat) +
(urine) + (throat)
Contact at llA months. Titre,
