LIST OF INVESTIGATIONS.
Anterior Poliomyelitis.

Fifteen epidemiological investigations of anterior poliomyelitis were made during the period Aug. 1, 1912 to Jan. 1, 1914, in ten counties. field work required nineteen days.

The

LIST OF INVESTIGATIONS.

Leprosy, Pellagra, Trichinosis and Miscellaneous Trips.

Fourteen trips as listed below, were made covering territory in ten
The field work required thirty-six days.

counties.

Trachoma, Independent School District No. 13, including schools in Aurora Village, Mesaba Village, Mesaba Township, part of White Township, St. Louis County, Oct. 8, 9, 10, 1913.

BY DR. W. P. GREENE

(All investigations are made upon order from, or with the approval of the Executive Officer of the State Board of Health.)

Reason To determine the prevalence of trachoma among school children in Independent District No. 13.

History-Dr. R. P. Pearsall. Health Officer, Aurora village, and medical supervisor of schools in Independent District No. 13, had found several adults with trachoma; had examined all pupils, finding a few with suspicious symptoms in certain schools. Inspector, with Dr. Pearsall, examined eyes of pupils as follows:

At Mesaba village, with Dr. P. S. Epperson, saw M. J. P., (m), 38; born in Marquette' Mich.; has acute exacerbation of old trachoma. Mrs. A. L., 38, is an old, inactive case; probably infected her boys; K. L., 8, has acute trachoma and E. L., 7, has suspected trachoma.

Results-In four schools, 5 active and 3 suspected cases of trachoma were found among 475 pupils. Cases are excluded from school and will be placed under treatment.

POLIOMYELITIS IN MINNESOTA SINCE 1910.

DR. W. P. GREENE.

INTRODUCTION.

In order to permit ultimately the compilation of uniform data from which deductions may be made the tables of Dr. Hill's "Epidemiologic Study of Anterior Poliomyelitis in Minnesota" of 1910 have been followed as far as possible in reviewing the data of cases reported since January 1, 1910. To obtain the data, the United States Public Health Service "Case Report of Acute Anterior Poliomyelitis" and the Minnesota State Board Laboratory Division "Spinal Fluid Data Sheet" have been sent to physicians reporting cases with the request that complete information be returned to the Division of Epidemiology for study. The first and only information was obtained from death certificates as follows:

In 1910 from 156 cases

In 1911 from 50 cases

In 1912 from 25 cases
In 1913 from 16 cases

These could not be included in this study.

The estimated number of cases calculated upon a death rate of 20 per cent would give 1910 a total of 1000 cases, 1911 a total of 285 cases, 1912 a total of 140 cases, and 1913 a total of 135 cases. The 1910 cases are regarded as part of the epidemic starting in 1909.

Dr. Hill's study covered 333 cases. He saw 161 suspected cases; of these he recorded 85 as poliomyelitis, 58 as not poliomyelitis, and 18 as doubtful.

This study covers 300 cases, but only 29 have been available for personal observation since the writer joined the Division in June, 1913. (See table 1.)

The 300 cases occurred in 134 sanitary districts in 56 counties. Hennepin County had 38 cases; St. Louis County had 33 cases. Of the 300 cases tabulated, 16 2-3 per cent occurred in the cities of Minneapolis and Winona,

In

while 83 1-3 per cent were scattered cases, chiefly in the rural districts. 1910 there was but one case from St. Louis County, but in 1911 when 40 cases were reported from the whole state 32 were St. Louis County cases, 11 being in Virginia and 10 in Proctor. The epidemic of 1909-1910 spared the earliest settled agricultural districts, where the majority of cases have developed since 1910. These cases were chiefly on farms well stocked with cows, horses, sheep and hogs. (See table 4.)

Contagiousness.

Nothing in this study implies that the contagiousness of poliomyelitis is other than as formerly believed, very slight indeed.

In 280 families 1,583 persons were exposed to 275 initial cases, only 25 developing poliomyelitis after the initial case appeared. A single case developed in each of 263 families; 2 cases developed in each of 14 families; 3 in each of 3 families; and none had more than 3 cases. (See table 2.)

Classification of the sick and well persons in affected families by age and sex gives no new information about susceptibility or sex and age incidence. Male infants under one year affected number 6, females 3. There were 22 males under one year of age exposed who remained well, and 26 females. The crude attack rate for males under 1 is 17, for females 8. (See table 1.)

In the age group 1 to 5, male patients number 91, female 55. Exposed well males number 123, females 131. The crude attack rate for males is 34, for females 23.

In age group 6 to 10 the male patients number 40, females 25. Exposed males remaining well 138, females 106. The crude attack rate for males is 18, for females 15.

In age group 11 to 15 there is a noticeable difference. The male patients number 18, females 13. The exposed well males number 88, females 72. The crude attack rate for males is 14, for females 12.

Age group 16 to 20 number about the same in patients as the 11 to 15 group, the males being 17 and females 9, while the exposed well males number 44 and exposed well females 59. The crude attack rate for males is 20, for females 11. (See tables 1 and 5.)

All males with poliomyelitis over 20 years number 14, females 7. The exposed well males number 289 and the exposed well females 290. The crude attack rate for this group is 4.6 for males, 2.3 for females.

The interval between the development of initial cases and so-called secondary cases in the same family varies from a few hours to 23 days, but 4-5 of the 25 so-called secondaries appeared within 8 days after the initial cases. (See table 10.)

The so-called secondary cases compared with the initial or so-called primary cases have been tabulated by age and sex groups and compared with Chapin's figures for the same groups in diphtheria and scarlet fever. The result for poliomyelitis is that in each 100 cases 9 were so-called secondaries, while Chapin's figures show that of each 100 diphtheria cases 50 are secondaries, and of each 100 cases of scarlet fever 40 are secondaries. The fatality rate of the poliomyelitis cases studied was 21, in comparison with Capins fatality rate of 15.5 in diphtheria and 8.3 in scarlet fever. (See table 7.)

Abortive Cases.

In many families a history was obtained of cases with general gastrointestinal or respiratory symptoms, slight retraction of the head, sore throat, even slight limping or transitory paresis, but with no true paralysis. While there can be no doubt that abortive cases occur and there is good reason to

believe that well persons may carry the active virus of poliomyelitis, only those cases with flaccid atrophic type of paralysis are included in these tabulations.

Differential Diagnosis.

Laboratory tests often assist in establishing the diagnosis in suspected cases. A toxic neuritis characterized by a paralysis, which may occur in an infectious disease (for instance, typhoid or diphtheria) may be diagnosed by the usual laboratory tests. Examination of cerebrospinal fluid may assist in other diseases simulating poliomyelitis. Between January, 1908, and December, 1913, inclusive, 92 specimens of spinal fluid were examined by the laboratory division. In 45 cases the final diagnosis was epidemic cerebro-spinal meningitis; in 13 of these the diagnosis was established by demonstrating Diplococcus intracellularis meningitidis. In 12 cases the final diagnosis was tuberculous meningitis; B. tuberculosis was demonstrated in 8 cases. Or 10 cases of meningitis the cause was found by laboratory examination to be Diplococcus pneumoniae in 5, Streptococcus in 1, Staphylococcus in 3; the other case being finally diagnosed as syphlitic meningitis. In 25 cases polioymelitis was finally diagnosed, the spinal fluid specimens being entirely free of organisms.

Modes of Transmission.

Experimental work undertaken to determine the nature of virus, the infective media, the modes of transmission, etc., are matters of common knowledge, and mention is made only of certain points brought up in Minnesota work relating to the theories and conclusions of other investigators. Perhaps more attention has been paid to special questions, but the epidemiological work as a whole has not been and in fact scarcely could be more careful or inclusive than formerly. Neither has the control of the disease been affected by experimental conclusions. Isolation in screened rooms, disinfection of all discharges, private funerals, fumigation of sick rooms, observation of exposed persons, etc., have been advocated from the first and still are used. School association seems to play no part in the spread of the disease. The maximum number of cases in this study occurred in August. In Dr. Hill's study the maximum number of September. Of the 296 primary cases 27 are reported to have had direct contact with other cases. Three had direct contact through a third party. One case attended school where other cases developed and three are reported to have played with children who were later taken with the disease. In one case there was another child sick in the neighborhood and in 3 cases there were children sick with pol iomyelitis in adjoining apartments, making a total of 38 in which there was a history of direct or indirect contact, while 258 cases had no history whatsoever of contact. (See table 3.)

Clinical Characteristics.

The clinical characteristics of the cases studied were as follows. In 264 paralyzed cases the paralysis occurred within the first six days of the disease; about 48 per cent of the cases on the first and second day. Sixty-five of the 300 cases in this series terminated fatally. The time relation of death to onset of disease was tabulated and it is found that 75 per cent died on or before the sixth day of the disease, while the time relation of death to paralysis shows that 80 per cent died on or before the sixth day following the onset of paralysis. Partial recovery occurred in 68 per cent, complete recovery in 10 per cent. Fever was reported in 94 per cent of the cases, headache and pain in 83 per cent, tenderness in 73 per cent, constipation in 66 per cent, vomiting in 65 per cent, retraction of the head in 52 per cent, and sore throat in 33 per cent. Eighty-one per cent of the patients were in good health when attacked by the disease. (See tables 1, 13, 16 and 17.)