RELATIVE PREVALENCE OF CONTAGIOUS DISEASES

IN CHILDREN OF SCHOOL AGE.*

By P. H. BRYCE, M.A., M.D., Ottawa.

Late Secretary Provincial Board of Health of Ontario, Medical Inspector of Immigration and of the Department of Indian Affairs for the Dominion Government.

To everyone, but especially to those interested in the care of the children of our public schools, the subject of this paper becomes of extreme importance.

We naturally are all interested in the question of the prevention of contagious diseases among children at all ages, and in the measures by which such prevention may be accomplished; and it is natural to inquire how far schools are an aid or hindrance to such prevention. In one sense our schools are both an aid to the dissemination, and a means of preventing the spread of contagious discase. They do aid in the dissemination of disease in the same way that infection spreads among crowds everywhere; but they are a means of prevention through the educational influences which spread often from the children to parents, in these days of general compulsory school attendance and instruction in hygiene. Not until the organization of the Department of Health under the local government board in England was there any systematized study of the causative influences of the spread of infectious diseases; but since the appointment of Dr. John Simon, its first medical officer, investigations have been pushed in every direction. This is illustrated in the following quotation from Dr. Clifford Allbutt's "System of Medicine":

"The influence of school attendance on the diffusion of diphtheria was noted almost as soon as skilled inquiry into the circumstances of the disease was instituted. This was pointed out by Mr. W. H. Power in 1876, and in the following year I had an opportunity of studying the matter during a maintained prevalence of diphtheria at Coggeshall in Essex. It was found practical to divide the 928 children in the village into age-groups, and then to ascertain within each group the relative amount of diphtheria, in

*Read at Conference on School Hygiene and Education, February 2nd, 1904.

those who attended school and those who did not. Under three years of age school attendance was not found to have materially influenced the number of attacks, but in the age period three to twelve years, the incidence of the disease was not far from 50 per cent. greater on school attendants than on others: and in the age period twelve to fifteen years the school attendants suffered nearly three times more than those who were not at school."

A similar result in the instance of scarlet fever is illustrated in the Annual Report of Dr. Murphy, Medical Officer of Health of London, England, for 1893, in connection with 17,704 cases. Of these there were: 5,279 cases under five years of age; 6,727 cases under ten years of age; 3,187 cases under fifteen years of age; or but 29 per cent. of the cases were under five years of age.

Dr. Murphy illustrated the fact in another way by showing how the prevalence of this disease declined with the summer vacation. Thus, under three years the decrease was 1 per cent.; under three to twelve years the decrease was 26 per cent.; over thirteen years the decrease was 13 per cent. Increase in succeeding months: under three years, 4 per cent. ; under three to thirteen years, 65 per cent; over thirteen years, 26 per cent.

Such is the experience of officers of health in England; but we are able to further illustrate the prevalence of infectious diseases from our own statistics.

During the first half of 1897, we had a serious prevalence of scarlet fever in Toronto. There were in all 1,138 cases and 63 deaths.

In the returns for May, and up to the 5th of the following June, there were in all 280 cases. Of these 198 attended school, or 70 per cent. of the whole were school children.

Such are the statistics of several outbreaks in which the details regarding cases have been available. We have, however, in addition to this, always available, the study of the death-returns from year to year for the whole province, and for particular municipali

ties.

The following table, from the Registrar-General's Report of 1900, supplies a number of interesting details, by which comparative results may be obtained. It gives the population of the province by age periods from nought to nineteen years, inclusive, by years for the first five-year period, and for the three succeeding quinquennia. It further gives the deaths for each of the several periods separately for scarlatina and for diphtheria.

From the columns of totals we find that for the first quinquennium, the deaths for both diseases together were 516, and for the period of five to twenty, the legal school period, they were 352, and in the five to nine period separately, 244.

It will be observed that the ratio of deaths in the first five years of life is about three times that in the second five-year period for scarlatina, and twice that for the same period in the case of diphtheria. We see in this an apparent disagreement from the foregoing statistics regarding the cases as reported in the different iflustrated statistics given.

There is, however, a natural explanation for this in the fact that the percentage mortality of scarlatina in England in 14,000 cases between 1888 and 1893 under five years was 16.8 per cent., while that for the five to nine year period was 5.6 per cent.

In the same way diphtheria which, between 1895 and 1899, had 25.6 per cent. of deaths in cases of children under five years, had 14.6 per cent. of deaths for the five to nine period. Or there were 1,536, as compared with 695. What is very pleasing to notice, however, in this study of English statistics, is the relatively great decrease in recent years, not only of the total cases and total mortality, but also of the lessening percentage in school children, due doubtless to the closer inspection of school children, and the very general removal of first cases to the isolation hospitals.

To conclude this reference to the relative prevalence in the two periods through illustrative statistics, I shall take the returns of our two largest cities, Toronto and Ottawa, for 1903. Except for the first three months of the year, the following are the number of cases, as well as deaths, for the year 1903. We find that for the ten months from March to December, Toronto had 418 cases of scarlet fever and 62 deaths, and 806 cases of diphtheria, with 100 deaths. The deaths for the whole year by ages are seen in the following table:

Comparing cases with deaths as given, we find that the percentage death rate was 14.7 for scarlatina, and that for diphtheria was 11.7. I have not the figures enabling us to determine the death-rate at different periods, but we may assume that the relative rates would be much the same as in other years and places.

We find for scarlet fever that in the nought to five period the deaths were 44, while those for the school period, five to nineteen, were exactly the same. Applying the rate in the London Report, this means that there were three times as many cases among children of school age as in those from nought to five years.

For diphtheria it would appear that the record for children of school age is more favorable. Assuming that the London rates prevailed of two to one for the two periods, we find the prevalence in the schools to have a ratio only 50 per cent. greater than that for the nought to five year period.

The following table illustrates the relative prevalence in the city of Ottawa:

From the figures here given for scarlet fever, we similarly conclude that the prevalence of cases among the school children was three times as great in the five to nine period as in the nought to five year period; but we find that in the matter of diphtheria there is by no means the same relation, there being twenty-two deaths in the nought to five period, and but five in the five to nine period.

These figures are of extreme interest since they represent the results of a year's work, where for nine months all cases of diphtheria were removed to the isolation hospital so soon as diagnosed, and the school children of the rooms, where cases had been, were inspected till the period of incubation was over. The very considerable number of cases which occurred during the year (320 of scarlatina and 351 of diphtheria) removes the element of incorrect deductions which may result from a small number of cases.

The history of these Ottawa figures as a statistical study is most interesting. For years the city had an unenviable reputation in the matter of contagious diseases. In 1902, there were in all 689 cases of scarlet fever and 234 of diphtheria. In February, 1903, a new well-equipped isolation hospital was opened, and after March all cases of the diseases occurring in the city were sent to the hospital. Of the 320 of scarlet fever, 198 were treated in the new hospital during the eleven months; the balance, 102, were treated else

where, or after the complete removal to hospital of all cases began, there were for the nine latter months of the year but 159 cases compared with 161 in the first three months.

Of the diphtheria cases (251 cases), 69 occurred in the first three months of the year, and 182 in the latter nine months, during which all cases were treated in the hospital. While not directly bearing on this subject, it is pleasing to remark that the total deaths for the nine months from scarlet fever were but three, while those from diphtheria were nine, or 1.52 per cent., and 4.9 per cent. of the cases. Such a low record of deaths for so large a number of cases has, so far as I know, never hitherto been obtained. But the other important point is the effect of the removal to hospitals of first cases in lessening the prevalence of the disease. In 1902 there were 689 cases of scarlet fever in Ottawa with thirty-nine deaths, and 487 cases of diphtheria. As a matter of fact, there has resulted from the more effective methods adopted in 1903, a reduction of over 50 per cent. in the cases of scarlatina and 85 per cent. of deaths, and 41 per cent. in the cases of diphtheria, and 54 per cent. of deaths.

But little more, I think, need be said on the subject, as the methods for dealing with infectious diseases in schools will be dealt with in another paper. To me, and I think to every one, it must be apparent that practically there is no limit to the economic and lifesaving results which public health work, moving along the lines of experimental science, is capable of. What it is apparent is necessary is:

I. A conviction arrived at by such statistics as have been cited that disease is disseminated in such ways as I have indicated.

2. That we be convinced by the results of such methods as have been especially illustrated by the Ottawa statistics, that an enormous saving of cases of disease and deaths is possible.

3. That we possess scientific methods so certain when persistently and systematically carried out, that they will suppress outbreaks of epidemic disease almost with the same certainty as the demonstrated amount of work which a properly constructed machine will perform with the combustion of a definite weighed quantity of fuel. All that is further required is to educate the public that such work is life-saving and patriotic, and that, like all other philanthropic work, the results are not only good to the receiver, but also to the giver. As Sir Launfal, in his search for the Holy Grail, came to realize :