The highest primary admission rates for white and colored enlisted men combined occurred in Camps Jackson, S. C. (6.76 per 1,000), Beauregard, La. (6.40), and Funston, Kans. (2.72); and the numbers of cases in these camps were, respectively, 284, 132, and 153, or one-fifth the total number for the whole TABLE 30.-Cerebrospinal meningitis. By camps of occurrence, showing primary admissions and deaths, with annual ratios per 1,000 strength, white and colored enlisted men, United States Army; also case fatality rates, April, 1917, to December, 1919

country. It is obvious that the increased prevalence was not due entirely to the size of these camps, since other large camps such as Camp Dix, N. J., had much lower admission rates; furthermore, it can not be ascribed to climate or other similar local conditions, since the rates for different camps in a single State, or for different States in a given section of the country, varied considerably. For example, in South Carolina the primary admission rates per 1,000 were 6.76 for Camp Jackson, 2.45 for Camp Sevier, and only 0.63 for Camp

CEREBROSPINAL MENINGITIS, BY CAMPS
ADMISSIONS, WHITE ENLISTED MEN, U. S.

Wadsworth. A study of the mobilization charts indicates that the disease was most common in the camps which were made up mainly of men from the rural sections of the Southeastern States and from Kansas and Missouri, and that it was relatively infrequent in camps composed of troops drawn from States which had large urban populations.

Sporadic cases occurred in all of the other camps except Camp Forrest in Georgia, and Camp Syracuse in New York, which were relatively small camps, organized late in 1918.

The relatively high incidence of meningitis in certain of our camps was no doubt due mainly to the fact that large numbers of susceptible men from rural sections, under the strain and fatigue incident to intensive military training, were, for the first time, brought into close contact with meningococcus carriers and cases.

CAMP JACKSON, S. C.

This National Army cantonment which had 284 cases of meningitis and an admission rate of 6.76 per 1,000, drew a large percentage of its men from the rural sections of North Carolina, South Carolina, and Florida. Meningitis occurred in practically epidemic form during November and December, 1917, and was prevalent from that time on.

CAMP WADSWORTH, S. C.

Although located in South Carolina, only 20 cases occurred in this camp, and the admission rate was 0.63 per 1,000 strength. However, Camp Wadsworth was made up largely of troops from New York City and other thickly populated localities.3

CAMP BEAUREgard, La.

There were 132 cases, an annual primary admission rate of 6.40 per 1,000 in this camp, which drew troops mainly from Louisiana, Arkansas, and Mississippi, all of which States have a large rural population.

CAMP FUNSTON, Kans.

Including all troops in the State, 153 cases, or an admission rate of 2.72 per 1,000, were reported for Camp Funston. The men in this camp came mainly from Missouri and Kansas.5

IN EUROPE

Meningitis in the American Expeditionary Forces occurred sporadically rather than in extensive epidemics. A large percentage of the cases originated either in the base ports or on shipboard, and, as a rule, the incidence was highest in organizations from training camps with high rates in the United States. There were 1,848 primary admissions reported between June 1, 1917, and December 31, 1919, an annual admission rate of 1.11 per 1,000 strength, or 111 cases in every 100,000 men. Of these, 802 died, a case fatality of 43.3 per cent; the annual death rate was 0.48 per 1,000 strength. The first case was reported in June, 1917, and more cases occurred as the strength of the Army increased during the following months, until a peak was reached in January, 1918, with 59 cases and a rate of over 4 per 1,000. These cases were mainly due to outbreaks in organizations which had brought the infection with them from their training camps in the United States.

In October, 1918, when the strength was over a million and a half men, 222 cases occurred, or a rate of less than 2 per 1,000. This increase occurred just after the highest incidence of influenza, which possibly contributed, along with hardships, fatigue, and overcrowding of troops, to lowering the resistance of soldiers to meningitis. During demobilization the monthly number of cases decreased rapidly until there were only 9 in October, 1 in November, and none in December, 1919. The high admission rate of 5 per 1,000 in October, 1919, is not considered significant, as it is based on only 9 cases.

ETIOLOGY

While the experience during the World War added nothing entirely new to our knowledge of the etiology of cerebrospinal meningitis, it emphasized the relative importance of certain contributing factors.

6

As stated above, since 1887 it has been known that the disease is a specific infection caused by the meningococcus. In 1909 Dopter differentiated two types of meningococci which he designated "normal" and "para." Gordon? divided meningococci isolated from cases of meningitis, which occurred in British troops during the World War, into four serological types, which he called I, II, III, and IV. His types I and II corresponded with Dopter's "para" and "normal" types, while III and IV were irregular or intermediate in their serological reactions. The relative frequency of these types in the British Army is indicated by the following table:8

9

In 1917, Flexner investigated the subject and agreed with Dopter by dividing the meningococci into normal, para, and intermediate types.

In the United States Army the typing of meningococci was not a routine procedure; however, it was done in a great many instances. The information obtained sometimes aided in the selection of therapeutic serum for individual cases or in tracing the relationship between cases or carriers. The reports from certain organizations indicate that the normal type (II) predominated; that the para type (I) was about half as frequent, and that a relatively small percentage of the intermediate types (III and IV) were found.

It is now generally believed that the normal habitat of the meningococcus is the posterior nasopharynx of man. In susceptible individuals the organism may invade the body and produce meningitis, while in resistant or immune persons infection does not occur. These latter, apparently normal "carriers," may harbor meningococci in their throats for long periods of time and spread them to their associates. While it has been estimated that about 1 to 3 per cent of the population are carriers, fortunately relatively few persons are susceptible to the infection. Conditions which increase the contact between carriers and susceptible individuals favor the spread of meningitis. The tendency of the disease to greater prevalence in the winter and early spring is, no doubt, due to the fact that people live indoors and are therefore closer together

during the cold months. The higher incidence among recruits, especially those from rural localities, in mobilization camps points to the importance of contact between these relatively susceptible persons and carriers. Other infections, fatigue, and hardship may also help to lower the resistance of soldiers.

DIAGNOSIS

The specific diagnosis of cerebrospinal meningitis depends upon the isolation and identification of the meningococcus from the cerebrospinal fluid. During the World War, spinal punctures usually were performed on all patients with symptoms of meningeal irritation or inflammation; and the diagnosis was based entirely on the bacteriological examination of the spinal fluid. Wegeforth and Latham,10 however, warned against the indiscriminate use of spinal puncture as a diagnostic procedure in human septicemia, stating that the release of spinal fluid was an important factor in the development of meningitis. This observation was preceded by the investigations of Weed, Wegeforth, Ayer, and Felton," who showed that in animals suffering with an experimentally produced bacteriemia, spinal puncture was invariably followed by meningitis. It was therefore recommended that careful consideration be given to the bacteriological study of the blood before attempting puncture of the spinal canal. However, in spite of the fact that cases were observed in which the spinal fluid obtained at the first puncture was sterile and from later punctures infected, this was usually considered only an indication of the normal progress of the infection; and it was quite generally believed that diagnostic spinal puncture in meningitis was not attended by any serious results.

The observations of previous workers that meningococci may invade the blood stream were confirmed during the World War by Herrick.12 He reported that in a comparatively large percentage of the cases at Camp Jackson, S. C., the organism was isolated in cultures made of the blood before the appearance of meningeal symptoms; and, as a consequence, he advocated the more general use of blood cultures as an aid to early diagnosis, and proposed that the term "meningococcus sepsis" be used.

In most cases it is possible to isolate the meningococcus from the upper respiratory tract, and nasopharyngeal cultures may be helpful, when meningococci in a turbid spinal fluid escape detection. During the World War nasopharyngeal cultures were used mainly in the detection of carriers, but occasionally as an aid in the diagnosis of cases.

The symptomatology of cerebrospinal meningitis observed during the World War did not differ materially from that already recognized as characteristic of the disease. Naturally, differences occurred in the percentage of severe and mild cases in the various camps, resulting in variations in the predominant clinical signs and symptoms.

TREATMENT

Polyvalent antimeningococcic serum was used routinely for treatment. The gross case fatality for primary admissions in the whole Army was about 38 per cent. In the American Expeditionary Forces about 43 per cent of the cases died, while in the United States the percentage was about 34. Also the