Methods for the Prevention of Secondary Contact Infection in Influenza and Pneumonia
The methods at present in vogue for preventing the spread of contagion in wards devoted to the care of patients with influenza and pneumonia may be briefly enumerated: The separation of patients by means of sheet or screen cubicles, the wearing of masks and gowns by the ward personnel and to some extent by convalescent patients who are up and about the ward, and in some hospitals the separation of streptococcus carriers from noncarriers as determined by throat culture at time of admission. That these methods are of some value in preventing spread of infection cannot be denied, and it is probable that they are fairly effective under ordinary conditions when conscientiously carried out. That they inevitably break down in the presence of an overwhelming epidemic when hospital wards become overcrowded is only too evident. Under such conditions the sheets hung between the beds are constantly being displaced and are slight proof against a patient’s curiosity as to the identity and condition of the man in the adjoining bed; masks cannot be worn by patients seriously ill with pneumonia, during the very time when they are most dangerous and in greatest danger and those worn by the ward personnel are very rarely sufficiently well made to prevent spread of contagion by droplet infection as the studies of Haller and Colwell[[54]] and Doust and Lyon[[55]] have shown; the separation of streptococcus carriers from noncarriers as at present carried out cannot keep pace with the ever increasing influx of patients nor with the rapidity of the spread of the hemolytic streptococcus, in part because of the time required to make the bacteriologic diagnosis, in part because the amount of work involved cannot be accomplished by the laboratory personnel available. That this is so will be shown in data presented below. Not only do these methods break down in the face of an epidemic, but they often provide a false sense of security.
In searching for a solution of the problem it is essential to have the following considerations clearly in mind. Every patient with influenza must be considered a potential source of pneumococcus or hemolytic streptococcus infection for his neighbor until he is proved otherwise by bacteriologic examination. Every person engaged in the care of patients with respiratory diseases must also be regarded as a potential source of danger. Pneumonia cannot be regarded as one disease but must be looked upon as a group of different diseases, with more or less similar physical signs and symptoms, it is true, but caused by a considerable variety of bacteria, infection with any one of which not only provides no protection against infection with another, but may even render the individual more susceptible to secondary infection. Therefore, every patient with pneumonia must be regarded as an actual source of danger to his neighbor, at least until it is established that he has the same type of infection. All these considerations are especially true in the presence of influenza, for it has become evident that many organisms readily gain access to the lung and produce pneumonia in patients with influenza which under ordinary circumstances fail to cause disease of the respiratory organs.
Since secondary infection in respiratory disease is undoubtedly spread in large part by droplet and contact infection, the prevention of secondary infection must depend upon the elimination of these methods of transmission. Three solutions present themselves: (1) Ward treatment with absolute elimination of overcrowding and much wider separation of patients than has hitherto been deemed necessary; (2) segregation of patients according to type of bacterial infection; (3) effective individual isolation of every patient.
It has been clearly shown that treatment of influenza and pneumonia in overcrowded wards even with the use of such precautions to prevent transfer of infection as cubicles, masking of attendants and patients, etc., is attended by serious danger of contact infection and that such infection will almost inevitably occur. This is not at all surprising when it is remembered that we are treating in the same ward, in the case of pneumonia, a group of what are in reality entirely different diseases, all of which may be transmitted from one patient to another, and in the case of influenza a group of individuals who carry a variety of potentially pathogenic bacteria. No one would expect to treat cases of scarlet fever, measles, and diphtheria together in a hospital ward without having contact infection result. Among patients ill with influenza and postinfluenzal pneumonia, certainly streptococcus pneumonia and to some extent pneumococcus pneumonia may be transmitted quite as readily as any of these diseases. In view of these considerations it must be apparent if ward treatment of these diseases is to be continued without respect to type of bacterial infection, not only that overcrowding is absolutely contraindicated but also that much wider separation of patients than has hitherto been regarded as necessary is imperative. Furthermore, beds should be separated by permanent cubicles that cannot readily be displaced. Patients should be confined to their cubicles until thoroughly convalescent and when up and about should not be allowed to enter cubicles occupied by patients still sick. Medical officers, nurses and attendants who come into contact with the patients should use the same rigid precautions that are used in the care of patients with typhoid or erysipelas or meningitis with the additional use of means to prevent droplet infection of the patients, always bearing in mind that the respiratory tract in patients with influenza or postinfluenzal pneumonia is as susceptible to secondary infection as the postpartum uterus or an open surgical wound. In other words, the most rigid aseptic technic should be maintained. The recognition of a case of streptococcus pneumonia in a ward should be an indication for immediate quarantine of the ward until it has been shown by bacteriologic examination that there is no longer danger of spread of streptococcus contagion. This is done in the case of meningitis or diphtheria, neither of which diseases is comparable with streptococcus pneumonia in rapidity of spread or in resulting fatality.
Segregation of patients in wards according to type of bacterial infection while theoretically an improvement over the indiscriminate mixing of patients with many different types of infection presents many practical difficulties which make it impossible to carry out in the presence of an overwhelming epidemic. It is quite obvious that grouping of influenzal patients on the basis of the types of pneumococci that they carry in their mouths is impossible since the great majority of mouth pneumococci belong to Group IV and comprise a heterologous immunologic group. The separation of influenza patients who carry S. hemolyticus from those who do not would appear to offer a more hopeful field. Since we cannot make an immediate distinction between streptococcus carriers and noncarriers by inspection of the patient, this procedure requires the taking of throat cultures at time of admission to the hospital, the holding of patients for eighteen to twenty-four hours in receiving wards until the bacteriologic diagnosis has been made, and their subsequent distribution to streptococcus and nonstreptococcus wards. This is feasible when the admission rate is low and the number of streptococcus carriers found at time of admission is small. In the presence of an influenza epidemic it immediately becomes impossible to carry out in base hospitals as now constituted, since the demand for beds under such conditions at once converts a large part of the hospital into a group of receiving wards with little room remaining for subsequent separation of patients. The amount of bacteriologic work involved at once becomes prohibitive and the time required to make the bacteriologic diagnosis defeats its purpose since it allows the spread of hemolytic streptococcus to occur in the receiving wards during the interval.
The foregoing statements are based on results obtained in an attempt to separate streptococcus carriers from noncarriers in a limited group of cases of influenza at Camp Pike, the investigation being conducted during a secondary wave of influenza between November 27 and December 5. A special group of five wards consisting of one receiving ward and four distributing wards were set aside for the study. Cubicles, masks and gowns were in use and the wards were not crowded. The personnel on these wards did not carry S. hemolyticus in their throats. Patients entering the receiving ward were assigned to beds in rotation. Throat cultures were made on blood agar plates at time of admission. The plates were examined promptly the next morning, the diagnosis of S. hemolyticus being made by the characteristic hemolytic colonies and microscopic examination of stained smears. By this method a report reached the receiving ward at 9:30 a.m. and patients were promptly evacuated to the streptococcus and nonstreptococcus wards, where they were again assigned to beds in rotation, remaining confined in bed until convalescent. Confirmation of all strains of hemolytic streptococcus was subsequently carried out by isolation in pure culture, bile solubility test, and hemolytic test with washed sheep corpuscles. All cases free from hemolytic streptococci at time of admission who were sent to the “clean” wards were recultured daily throughout the period of study, those acquiring a hemolytic streptococcus being transferred to a streptococcus ward as soon as the bacteriologic diagnosis was made. The results are shown in Table XXVI.
| Table XXVI | ||||||
|---|---|---|---|---|---|---|
| S. Hemolyticus in Cases of Influenza | ||||||
| DATE | PATIENTS ADMITTED TO RECEIVING WARD | THROAT CULTURES ON ADMISSION. S. HEMOLYTICUS: | “CLEAN” CASES ACQUIRING S. HEMOLYTICUS IN THE HOSPITAL | |||
| + | − | WHILE IN REC. WARD | WHILE IN “CLEAN” WARD | TOTAL | ||
| Nov. 27 | 12 | 4 | 8 | 0 | 2 | 2 |
| Nov. 28 | 8 | 2 | 6 | 0 | 1 | 1 |
| Nov. 29 | 17[[56]] | 8 | 9 | 1 | 2 | 3 |
| Nov. 30 | 11 | 2 | 9 | 3 | 0 | 3 |
| Dec. 1 | 10 | 5 | 5 | 0 | 0 | 0 |
| Dec. 2 | 37 | 16 | 21 | 1 | 1 | 2 |
| Dec. 3 | 21 | 8 | 13 | 0 | 2 | 2 |
| Dec. 4 | 32[[56]] | 11 | 21 | 4 | 2 | 6 |
| Dec. 5 | 17 | 10 | 7 | 5 | 0 | 5 |
| Totals | 165 | 66 | 99 | 14 | 10 | 24 |
One hundred and sixty-five cases were admitted to the receiving ward during the period of study as cases of influenza. Of these, 137 had influenza; 4 of those with influenza had pneumonia at time of admission, 23 had acute follicular tonsillitis, 3 epidemic cerebrospinal meningitis, 1 scarlet fever, and 1 Vincent’s angina. Sixty-six cases (40 per cent) showed hemolytic streptococcus in the throat at time of admission and were sent to the streptococcus wards; 99 cases (60 per cent) were negative for hemolytic streptococcus on admission, and of these 91 were sent to the “clean” influenza wards. Twenty-four of these clean cases subsequently became positive for S. hemolyticus. It is especially noteworthy that 14 of them acquired a hemolytic streptococcus during the short period that they were held in the receiving ward awaiting the report of the culture taken at time of admission, the first culture taken shortly after admission to the “clean” wards being positive. This result was undoubtedly due to the fact that these cases were unavoidably associated in the receiving ward with many carriers of hemolytic streptococcus. It is evident that cases which were supposedly free from streptococci but which in reality had picked up the organism in the receiving ward were constantly being sent to the “clean” wards. It is furthermore evident that if the precaution had not been taken of reculturing all clean cases on day of admission to the “clean” wards and daily thereafter these wards would soon have become saturated with hemolytic streptococci. Even under these conditions, 10 cases, after varying periods in the “clean” wards, acquired the organism in their throats. When it is stated that it required the full time of two men under very special conditions to carry out this work in a very limited number of cases and that it failed to keep “clean” wards free from hemolytic streptococci, it is only too apparent that the efficient separation of carriers from noncarriers in the presence of an epidemic of influenza is an impossible task.
The segregation of pneumococcus pneumonias following influenza according to type of infection is obviously impossible, since they are caused by an almost unlimited variety of immunologic types as far as present knowledge goes.
Even the efficient separation of streptococcus pneumonias from pneumococcus pneumonias would require a considerable team of workers and the closest cooperation between laboratory and ward staffs, so that no case of pneumonia would be sent to a pneumonia ward until the bacteriologic diagnosis had been made. In our experience this is rarely considered feasible even under ordinary conditions, and in the presence of an epidemic is nearly impossible because of the volume of work involved and the delay necessitated by bacteriologic methods. It is, nevertheless, absolutely essential if highly fatal ward epidemics of streptococcus pneumonia are to be prevented.
In view of the considerations discussed above, it is believed that the clear and most fundamental indication for the management of epidemic respiratory diseases in the army is to scatter patients as widely as possible instead of following the time-honored custom of concentrating them. In brief, abandon open ward treatment and adopt effective individual isolation of every case, maintaining as strict a quarantine as is demanded in other highly contagious and infectious diseases. The adoption of a strict aseptic technic in the handling of these patients is an evident corollary. Only by this means can the serious and highly fatal secondary hospital infections, which occur in influenza and pneumonia when these diseases are present in epidemic form, be prevented.
The prevention of secondary infection, prior to admission to the hospital, is another and more difficult problem. That opportunity for secondary contact infection in cases of influenza before patients reach the hospital is great seems unquestionable, since many cases have already developed these infections at time of admission. During the epidemic patients were crowded in regimental infirmaries, in ambulances, and in the receiving office of the hospital with every opportunity for droplet infection present. No study has been made of this question, but it seems reasonable that the same methods of prevention should apply, namely, effective separation of patients.
It is not within the scope of this paper to discuss details of method, but anything that is possible becomes feasible as soon as sufficient evidence can be brought to bear that it is a necessity. In the present instance it would seem that any means that can be used to reduce materially the terrific toll taken by respiratory diseases is an absolute necessity.