passed that it can be known whether or not there is regularity in United States was in Medford, Massachusetts, in 1806 (Clymer,

Transcription

1 A STUDY OF MENINGOCOCCI RECOVERED IN THE UNITED STATES SINCE 1930 SARA E. BRANHAM AND SADIE A. CARLIN National Institute of Health, Washington, D. C. Received for publication April 2, 1937 The first recorded outbreak of meningococcus meningitis in the United States was in Medford, Massachusetts, in 1806 (Clymer, 1872). Records since that time indicate a periodic return to epidemic proportions at intervals of approximately ten years. Hedrich (1931) has studied reported epidemics and has concluded that the interval falls oftenest between 6 and 12 years in length, though some localities may miss the wave, showing an interval of 20 to 25 years. The meningococcus was recognized as the cause of the disease by Weichselbaum (1887) but serological differences were not noted until the observations of Dopter (1909) and workable classifications were not available until the intensive work done during the World War by Gordon and Murray (1915) and Nicolle, Debains and Jouan (1918). Hence, the relation between the epidemic waves of meningitis and the predominance of various serological groups of meningococci could be studied only during the last twenty years, and it will not be until more decades have passed that it can be known whether or not there is regularity in the serological changes which occur, and what the epidemiological significance of such changes may be. This periodicity in return of epidemic conditions can be seen in table 1, which gives the total number of cases of meningococcus meningitis reported in the United States since These figures are not absolutely accurate since the number of States reporting is not the same for all years. The number of strains of 1 Information obtained from the Division of Sanitary Reports and Statistics, United States Public Health Service. 275

2 276 SAiRA E. BRANHIA AND SADIE A. CARLIN meningococci studied at the National Institute of Health for those years is also listed in this table. Peaks in incidence of cases occurred in 1918, 1929, and Thus far (March 1, 1937) there has not been an increased number of cases over The number of cultures of meningococci sent into the National Institute of Health for study during the endemic years has been small. Meningococci that were received during the years and 1921 and 1922 were studied and reported by Evans (1922) and TABLE 1 Number of cases of meningococcus meningitis reported in the United States for the years , inclusive, and number of strains studied at the National Institute of Health during those years STRAINS STRAINS NUMBER TOTAL STUDIED AT NUMBER TOTAL STUDIED AT YEAR OF STATES TAL NATIONAL YEAR OF STATES TAL NATIONAL INCLUDED INSTITUTE INCLUDED CASES INSTITUTE OF HEALTH OF HEALTH 1915? 1, , ? 1, , (?) 4, , (?) 5, , (?) 2, , , , , , , , , , , , , , those during the years by Branham, Taft, and Carlin (1931). The present report discusses especially those strains studied since In all of the studies referred to above, the meningococci were "typed" according to the Gordon-Murray (1915) classification. In and , Evans did this typing on the basis of standard type cultures received through the Rockefeller Institute. In our own studies of a preliminary typing was done on the basis of these same strains. It is well known that meningococci tend to "spread" antigenically after more or less long periods

3 MENINGOCOCCI RECOVERED IN UNITED STATES of laboratory maintenance and become less type specific, so Dr. Gordon's offer of the dried antigens which he had prepared from his original type strains in 1915 was welcomed. The typing of our strains was, therefore, checked with type sera made with Dr. Gordon's original preparations. Intensive studies were done with these strains and an analysis of their serologic patterns made in comparison with the original Gordon-Murray type preparations. On the basis of this study, new standard strains were chosen which seemed more closely to resemble the original type strains than any others. At first these were used in conjunction with the older ones, but as these newer strains proved more satisfactory than the old, they have been employed as a basis for "typing" ever since. Since January, 1931, we have typed approximately 500 strains of meningococci. These represent both endemic and epidemic years; the number received in each of these years is shown in table 1. When these cultures were first received they were examined for purity, their cultural characteristics and fermentation reactions were observed, and they were typed. Cultural characteristics were typical. The enormous colonies noted frequently during were not observed in any of the strains that came to us during these later years. Heretofore it has been our observation that all meningococci have ultimately produced acid in glucose and maltose media. In the present series there have been four strains with which fermentation of maltose has not been observed (one of Type I and three of Type II), and two strains which have not been proved to ferment glucose (both type I). Acid production is often both slight and very transient and can be easily overlooked. One strain began to ferment glucose after a year in the laboratory, so it is possible that these negative strains referred to above will ultimately ferment both glucose and maltose regularly. Sera for typing were prepared by injection of young rabbits with the standard type strains; viz., 331 (I), 173 (II), 302 (III), and 158 (IV). The cultures were grown for 18 hours on 0.5 per cent glucose agar slants, suspended in 0.85 per cent saline, diluted JOURNAL OF BACTERIOLOGY, VOL. 34, No

4 278 SA2RA. E. BRANHAM AND SADIE A. CARLIN to approximately 1,000,000,000 meningococci per cc., and injected immediately. It has been found by workers in our laboratory2 that rabbits respond better to Types I and III if the first injection is given intracutaneously. Thus, an initial intracutaneous injection of about 400,000,000 meningococci, followed by four intravenous injections on successive days, usually gave a satisfactory typing serum. With Types II and IV it was desirable to repeat the series after a week of rest. A brief period of immunization usually resulted in sera which were more type specific than those obtained by longer immunization, though the agglutinin titer was somewhat less high. TABLE 2 Type distribution of strains of menitgococci from active cases since 1930 TZAR I- III I I AND m U IV NTPED STA per cent per cent per cent per cent per cent per cent per cent , All years Typing was by simple agglutination, the technique used being the same as that described by the authors in earlier reports (1931). Absorption of agglutinins was not done. It has been shown by one of us (Branham, 1932) that Types I and III are so closely related that even absorption of agglutinins will not "type" some strains. Scherp and Rake (1933, 1934, 1936) have shown the specific polysaccharide of these two types to be the same. For routine purposes it seems impracticable to spend time in trying to separate all strains of this I-III group into the two types I and III. In these present studies we have designated strains as Type I or Type III if they seemed definitely to be one or the 2 Observations made by Pabst and confirmed by Pittman.

5 MENINGOCOCCI RECOVERED IN UNITED STATES other; but in cases where the overlapping was great we have designated them as belonging to group I-III. In table 2, the type distribution is shown for each of the years since The results are expressed in percentage, and the total number of strains studied during each year is also given. No "carrier TABLE 3 Type II meningococci from active cases since 1930 YEA~iR ACTUAL NUMBER OF TYPE II (AL TYPES) STRAINS TOTAL STRAINS TABLE 4 Serological grouping of all strains reported at since 1918 the National Institute of Health NUMBER OF YER 1IV N. FLAVES- NOT IN THESE YEAR STRAINS II CENN TYPES per cent cent per cen pe cent per cent strains" are included in this table, but only strains from spinal fluid or blood. The year 1931 may be considered the end of the epidemic period which began in 1928, and the year 1935 represents a return of epidemic conditions. During the endemic years of 1932, 1933, and 1934 the percentage of Type II strains in cases of

6 280 SARA E. BRANHAM AND SADIE A. CARLIN meningitis studied rose from 4 per cent in 1931 to 32.0 per cent in 1932, and 43.0 per cent and 40.0 per cent in 1932 and 1933, respectively, falling to 13.2 per cent when epidemic conditions returned in The actual number of cases studied during the endemic years was very small, but the fact that so many of them proved to be of Type II seems to be not without significance. Table 3 shows the actual number of Type II strains identified during these years. The slight increase in number during 1935 and 1936 seems insignificant when compared with the increase in the total number of strains studied. Table 4 shows the type distribution of all meningococci reported from the National Institute of Health since Reference to this table indicates that Type II, which was abundant in the epidemics during the World War, has played a very insignificant r6le in the United States during the last two epidemic waves, and that Type IV seems to have dropped out of the picture altogether. The epidemic conditions occurring during these years have been due almost entirely to a very great increase in the I-III group of meningococci. In table 2 the total number of strains in the I and III group is expressed as a whole in the fifth column. These are subdivided into I, I-III, and III, in columns two, three, and four. This analysis shows that the Type III strains were predominant at the end of the epidemic of , comprising 64 per cent of all studied. During 1935, the first year of the latest epidemic wave, there was approximately an equal number of I strains, III strains, and strains which we designate as I-III because they were agglutinated equally well by both I and III type serums. During 1936 there was a steady shift in serological pattern toward Type I, and this trend has been even more marked among the meningococcus cultures received to date during the first two months of Of the total strains reported in this paper, only 20 are known definitely to have been isolated from blood; 16 of these fell into 'Of 34 strains studied in these last two months, 20 (or nearly 60 per cent) have been of Type I; 5 (or 13.7 per cent) have been of Type III; 6 (or 17.6 per cent) have been of I-III: and 3 (or 8.8 per cent) of Type II.

7 MENINGOCOCCI RECOVERED IN UNITED STATES the I-III group, and 4 were of Type II. These Type II strains comprised 20 per cent of the strains from septicemic cases without meningeal involvement, which is a high proportion when the low number of total Type II strains is considered. It has seemed best to consider the 42 carrier strains separately, since most of these were obtained under circumstances which made them not comparable to those from active cases. All except one of these 42 nasopharyngeal strains were received by us during the spring of Five were found among the contacts of active cases of meningitis in a CCC camp. Thirty-four were isolated during a carrier survey made in the same camp a few days later. The other three were from people in scattered localities who were in contact with active cases. The results of typing these strains may be seen in table 5. The predominance of Type II strains among these carriers gives support to the impression gained by TABLE 5 Types of strains of meningococci found in carriers III ~~~~NOT IN KNOWN TOTAL NUMBER 9(21.4%) 3I (7.1%) 24(57%) 6(14%)2TYPES 9 (21.4%) 3 (7.1%) 24 (57%) 6 (14%) Gordon and Murray (1915) and by Scott (1918) during the World War that Type II was more common among carriers than among active cases. A similar preponderance of Type II among carrier strains has been found by Rake (1934). The 24 Type II strains reported in table 5 were all found among the 35 strains obtained in the carrier survey made in the CCC camp; all strains obtained from persons in contact with active cases were of the same type as those isolated from the patients, none of whom were infected with Type II organisms. DISCUSSION AND SUMMARY Records of the occurrence of meningococcus meningitis in the United States since the first reported outbreak in 1806 indicate that this disease has a tendency to reach a peak in incidence at intervals which approximate 10 years.

8 282 SARA E. BRANHAM AND SADIE A. CARLIN A correlation of these increases in incidence with the serological classification of the meningococci involved has been possible only during the last 20 years or so-a period which involves three recrudescences in which the disease reached epidemic proportions. Serological studies of the meningococci received at the National Institute of Health have been reported for the periods and In the present report those strains received since 1930 are described. During the years four hundred and fifty-one strains of meningococci have been typed according to the Gordon-Murray classification. As found in previous studies, Type I and Type III are so closely related that it is often unprofitable to attempt to separate them; every possible intergradation seems to occur. Many strains have been definitely I or definitely III, but others have been agglutinated equally by both I and III sera. Absorption of agglutinins has not been done with these strains except for purposes of special research. For routine work this technique has seemed to be a waste of time. Such strains have been classified as I-III. In most of the tables included in this report we have grouped all I and III strains together as I-III, but in table 2 this group has been resolved into I, III, and I-III, in order that the present trend in changing serological pattern of prevalent strains from Type III (1931) to Type I (1936) may be seen. For practical purposes we may consider that we have met two groups of meningococci during the last decade; viz., groups I-III and II. We have encountered no strain of IV or of Neisseria flavescens, both of which played an important role in Chicago in Study of the five tables included in this report will show that the I-III group of meningococci has been responsible for most of the active epidemic cases. Type II has been more frequently found in carriers, and its relative incidence in cases has been greater during the endemic years. Whether Type II is to be considered as generally less virulent than the meningococci of the I-III group, or whether this minor role which it seems to play in our present epidemics is merely characteristic of this last decade, can only be determined in the future.

9 MENINGOCOCCI RECOVERED IN UNITED STATES 283 CONCLUSIONS In this report, 409 strains of meningococci from spinal fluid and blood of persons with meningococcus infection, and 42 strains from carriers, received since 1930, have been "typed" according to the classification of Gordon and Murray. Of the strains from active cases, 352 (or 86.0 per cent) fell into the I-III group (including types I and III, and strains agglutinated equally well by both serums); 48 (or 11.7 per cent) were of Type II. Of 42 carrier strains, 24 (or 57.0 per cent) were of Type II, and 12 (or 28.5 per cent) were of group I-III. Of these twelve I-III strains, 8 were from individuals who were in immediate contact with cases due to that type of meningococcus. Apparently Type II has been relatively unimportant as a cause of epidemic meningitis in the United States during the last decade. On the other hand, the prevalence of Type II strains among the carriers studied, and the relatively greater occurrence of this type in active cases during the endemic years of 1932 to 1935, throws some light on the possible significance of this group. It is impossible to judge at this time whether the epidemiological differences noted between groups I-III and II are a rule, or if they are an accident of this decade. REFERENCES BRANHAM, S. E Serological diversity among meningococci. Jour. Immunol., 23, BRANHAM, S. E., TAFT, C. E., AND CARLIN, S. A Studies on meningococci isolated in the United States, Serological classification and geographic distribution. U. S. Pub. Health Repts., 46, CLYMER, MEREDITH 1872 Cerebro-spinal meningitis. Philadelphia, 59 pp. DOPTER, CH Etude de quelques germes isoles du rhinopharynx, voisins du meningocoque (parameningococcus). C. R. Soc. de Biol., 67, EVANS, A. C The serological grouping of meningococcus strains isolated in New York City in 1921 and U. S. Pub. Health Repts., 37, GORDON, M. H., AND MURRAY, E. G. D Identification of the meningococcus. Jour. Roy. Amer. Med. Corps, 25, HEDRICH, A. W The movements of epidemic meningitis, U. S. Pub. Health Repts., 46, NICOLLE, M., DEBAINS, E., AND JOUAN, C Etudes sur les meningocoques et les serums antimeningococciques. Ann. l'inst. Past., 32,

10 284 SARA E. BRANHAM AND SADIE A. CARLIN RAKE, G. W Studies on meningococcus infection. VI. The carrier problem. Jour. Exper. Med., 59, RAKE, G. W., AND SCHERP, H. W Studies on meningococcus infection. III. The antigenic complex of the meningococcus-a type specific substance. Jour. Exper. Med., 58, RAKE, G. W., AND SCHERP, H. W Studies on meningococcus infection. VIII. The Type I specific substance. Jour. Exper. Med., 61, SCHERP, H. W., AND RAKE, G. W A type-specific substance from the meningococcus. Proc. Soc. Exper. Biol. and Med., 31, SCOTT, W. M A further study of the serological reactions of meningococci from the spinal fluid and the naso-pharynx with special reference to their classification and to the occurrence of the latter among normal persons. Jour. Hyg., 17, WEICHSELBAUM, A Ueber die Aetiologie der akuten meningitis cerebrospinalis. Fortschr. d. med., 5,