- Email: [email protected]
THE PREVENTION OF DIPHTHERIA.
THE PREVENTION OF DIPHTHERIA.
Annotations. " Ne quid nimis."
PREVENTION OF DIPHTHERIA. diphtheria has a higher incidence and mortality than in almost any other European capital, and there seems to be no reason for supposing that its ravages will diminish under present conditions. This fact makes it necessary for the responsible authorities to give careful consideration to the modern methods of controlling the disease. In a preface to Dr. Graham Forbes’s recent report the Medical Research Council say that" the large body of evidence already available leaves no doubt that the disease and its often fatal consequences may now fairly be called avoidable " ; whilst Sir George Newman, in his report to the Ministry of Health for 1925, stated that " as antitoxin has proved itself the best method of treatment, so immunisation appears to be our best prophylactic." It is not surprising, therefore, that the London County Council should have decided to re-examine the need for taking fresh measures to combat diphtheria, and it would be regrettable if incomplete accounts of their Health Committee’s report should give rise to an impression that they are opposed to the active immunisation ,of school-children. This report was presented on Nov. 29th, and those who study its full text, as given in the Medical Officer for Dec. 3rd, will see that the Committee are by no means against Schick-testing and immunisation, though they that more evidence is wanted before these measures are applied to the school-children of London as a whole. They point out that there is as yet insufficient evidence to demonstrate their effect on the incidence of diphtheria in any given community in which the whole or the great majority of the child population has been protected ; for though in New York City over 600,000 children were tested and over 400,000 immunised between 1916 and 1926, the total number of children of school age is about 1,650,000, and the fact that until this year the disease has been steadily diminishing cannot with certainty be attributed to the use of toxin-antitoxin. On the other hand, the Committee point out that " according to authoritative American observers, as a result of observation over periods ranging from three to six years, no child who received the full immunising course, and had given a Schick-negative reaction, subsequently contracted THE
IN London
feelI
I
diphtheria."
Defence of the community against diphtheria does not imply protection of school-children alone, for, as the report remarks, the disease has its most fatal consequences on those who are less than 5 years old and have not yet come under the educational supervision of the London County Council. It is, moreover, the metropolitan boroughs, rather than the county authority, that are primarily responsible for measures to prevent infectious disease. In the City of Westminster and eight other boroughs, with a total population of a million and a half, preventive schemes are already in operation or are sanctioned. The extent to which these are used must depend largely on those who recommend immunisation to the public, as was emphasised at the meeting which we report on p. 1274, but the Council’s Health Committee obviously believe that local education, propaganda, and experiment are what is needed at the present time. " It would appear desirable," they say, " that all public health bodies, both voluntary and public, including hospitals, provided they are persuaded as to the soundness of the measure, should assist the borough councils, as far as possible, by the dissemination of authoritative information on the subject." Although it is considered premature for the County Council to introduce any measure of active immunisation among school-children until further experience is gained, there is apparently no objection to using the school organisation as a means of spreading
1247
information to parents who desire to be informed on the subject. In Holborn, Deptford, and Camberwell leaflets prepared by the borough medical officer of health are distributed through the schools, and these facilities will be extended to any other metropolitan boroughs which wish to adopt the same methods. The report recommends " that those parents who desire that their children should be protected by immunisation should be given every opportunity of satisfying their wishes." In conclusion, we may point out that the Council are responsible for a school population of well over 600,000 children. Before applying a comparatively novel method on so large a scale they are justified in awaiting evidence of the most definite kind, and although in the Medical Research Council’s publication there is cumulative favourable testimony to the benefit of toxinantitoxin in residential institutions and hospitals, yet the number of school-children immunised in this country-e.g., in Edinburgh and Aberdeen-has been relatively small. Until more is known of the incidence of the disease among the half million immunised children in New York City, no more than tentative deductions can be drawn about the eRect of the new methods on the incidence and mortality in a large
community.
____
THE ACTION OF LIGHT ON THE
EYE.
THE retinal currents have often been investigated since their discovery many years ago by F. Holmgren, of Upsala, and they are a valuable index of the activity of the retina. They are due, however, to processes taking place in the eye rather than in the optic nerve, and they do not tell us how the results of the retinal activity are transmitted to the brain. During the past two years E. D. Adrian, by recording action-currents with the capilliary electrometer and an amplifying system, has investigated the impulses occurring in various types of peripheral sense-organ, and has found that there is a close agreement in the behaviour of the different kinds of end-organ and in the impulse discharges set up by them. In experiments (with Rachel Matthews), which have recently been recorded, he has broken new ground by using a special sense-organ, the eye of the conger-eel, and recording the discharge of impulses in the optic nerve, and its relation to the electric changes in the retina. The results of this research show that the activity of the optic nerve is in close agreement with that of sensory nerves, although the mechanism of the receptor apparatus of the eye is naturally far more complex than that of the peripheral senseorgans. By means of a capillary electrometer and valve amplifier, the action-currents of impulses in the optic nerve of the eel and frog were recorded when the retina was stimulated by light. It was found that the action-currents do not differ appreciably in time relations or in grouping from those in other sensory nerves, and their size is not affected by the strength of the stimulus (all-or-nothing relation). When the eye is illuminated, the discharge of impulses rises rapidly to a maximal frequency and then If declines at first rapidly and then more slowly. the illumination has lasted a second or more there is a renewed outburst of impulses when the light is turned off. Owing to the rapid decline in the discharge with steady illumination, a movement of light and shadow in the visual field is a much more effective stimulus than a steady pattern. When the retinal image does not exceed 1 mm. in diameter, the effects of an increase in the size of the image are the same as those of an increased intensity of illuminaBoth the latent period and the maximum frequency of the discharge are determined approximately by the quantity of light in unit time, and the frequency is not directly proportional to the area of the retinal image. The relation between area and threshold intensity for the human eye is of the same kind. When the retinal current and the optic nerve discharge are compared, it is found that the initial
tion.
1 Jour. of Physiology, Sept. 9th.
Annotations. " Ne quid nimis."
PREVENTION OF DIPHTHERIA. diphtheria has a higher incidence and mortality than in almost any other European capital, and there seems to be no reason for supposing that its ravages will diminish under present conditions. This fact makes it necessary for the responsible authorities to give careful consideration to the modern methods of controlling the disease. In a preface to Dr. Graham Forbes’s recent report the Medical Research Council say that" the large body of evidence already available leaves no doubt that the disease and its often fatal consequences may now fairly be called avoidable " ; whilst Sir George Newman, in his report to the Ministry of Health for 1925, stated that " as antitoxin has proved itself the best method of treatment, so immunisation appears to be our best prophylactic." It is not surprising, therefore, that the London County Council should have decided to re-examine the need for taking fresh measures to combat diphtheria, and it would be regrettable if incomplete accounts of their Health Committee’s report should give rise to an impression that they are opposed to the active immunisation ,of school-children. This report was presented on Nov. 29th, and those who study its full text, as given in the Medical Officer for Dec. 3rd, will see that the Committee are by no means against Schick-testing and immunisation, though they that more evidence is wanted before these measures are applied to the school-children of London as a whole. They point out that there is as yet insufficient evidence to demonstrate their effect on the incidence of diphtheria in any given community in which the whole or the great majority of the child population has been protected ; for though in New York City over 600,000 children were tested and over 400,000 immunised between 1916 and 1926, the total number of children of school age is about 1,650,000, and the fact that until this year the disease has been steadily diminishing cannot with certainty be attributed to the use of toxin-antitoxin. On the other hand, the Committee point out that " according to authoritative American observers, as a result of observation over periods ranging from three to six years, no child who received the full immunising course, and had given a Schick-negative reaction, subsequently contracted THE
IN London
feelI
I
diphtheria."
Defence of the community against diphtheria does not imply protection of school-children alone, for, as the report remarks, the disease has its most fatal consequences on those who are less than 5 years old and have not yet come under the educational supervision of the London County Council. It is, moreover, the metropolitan boroughs, rather than the county authority, that are primarily responsible for measures to prevent infectious disease. In the City of Westminster and eight other boroughs, with a total population of a million and a half, preventive schemes are already in operation or are sanctioned. The extent to which these are used must depend largely on those who recommend immunisation to the public, as was emphasised at the meeting which we report on p. 1274, but the Council’s Health Committee obviously believe that local education, propaganda, and experiment are what is needed at the present time. " It would appear desirable," they say, " that all public health bodies, both voluntary and public, including hospitals, provided they are persuaded as to the soundness of the measure, should assist the borough councils, as far as possible, by the dissemination of authoritative information on the subject." Although it is considered premature for the County Council to introduce any measure of active immunisation among school-children until further experience is gained, there is apparently no objection to using the school organisation as a means of spreading
1247
information to parents who desire to be informed on the subject. In Holborn, Deptford, and Camberwell leaflets prepared by the borough medical officer of health are distributed through the schools, and these facilities will be extended to any other metropolitan boroughs which wish to adopt the same methods. The report recommends " that those parents who desire that their children should be protected by immunisation should be given every opportunity of satisfying their wishes." In conclusion, we may point out that the Council are responsible for a school population of well over 600,000 children. Before applying a comparatively novel method on so large a scale they are justified in awaiting evidence of the most definite kind, and although in the Medical Research Council’s publication there is cumulative favourable testimony to the benefit of toxinantitoxin in residential institutions and hospitals, yet the number of school-children immunised in this country-e.g., in Edinburgh and Aberdeen-has been relatively small. Until more is known of the incidence of the disease among the half million immunised children in New York City, no more than tentative deductions can be drawn about the eRect of the new methods on the incidence and mortality in a large
community.
____
THE ACTION OF LIGHT ON THE
EYE.
THE retinal currents have often been investigated since their discovery many years ago by F. Holmgren, of Upsala, and they are a valuable index of the activity of the retina. They are due, however, to processes taking place in the eye rather than in the optic nerve, and they do not tell us how the results of the retinal activity are transmitted to the brain. During the past two years E. D. Adrian, by recording action-currents with the capilliary electrometer and an amplifying system, has investigated the impulses occurring in various types of peripheral sense-organ, and has found that there is a close agreement in the behaviour of the different kinds of end-organ and in the impulse discharges set up by them. In experiments (with Rachel Matthews), which have recently been recorded, he has broken new ground by using a special sense-organ, the eye of the conger-eel, and recording the discharge of impulses in the optic nerve, and its relation to the electric changes in the retina. The results of this research show that the activity of the optic nerve is in close agreement with that of sensory nerves, although the mechanism of the receptor apparatus of the eye is naturally far more complex than that of the peripheral senseorgans. By means of a capillary electrometer and valve amplifier, the action-currents of impulses in the optic nerve of the eel and frog were recorded when the retina was stimulated by light. It was found that the action-currents do not differ appreciably in time relations or in grouping from those in other sensory nerves, and their size is not affected by the strength of the stimulus (all-or-nothing relation). When the eye is illuminated, the discharge of impulses rises rapidly to a maximal frequency and then If declines at first rapidly and then more slowly. the illumination has lasted a second or more there is a renewed outburst of impulses when the light is turned off. Owing to the rapid decline in the discharge with steady illumination, a movement of light and shadow in the visual field is a much more effective stimulus than a steady pattern. When the retinal image does not exceed 1 mm. in diameter, the effects of an increase in the size of the image are the same as those of an increased intensity of illuminaBoth the latent period and the maximum frequency of the discharge are determined approximately by the quantity of light in unit time, and the frequency is not directly proportional to the area of the retinal image. The relation between area and threshold intensity for the human eye is of the same kind. When the retinal current and the optic nerve discharge are compared, it is found that the initial
tion.
1 Jour. of Physiology, Sept. 9th.