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cases studied by Dr. Gale the Medical Officer of Health (to whom I am indebted for various charts which she will publish in detail, separately) the peaks of the curve of incidence according to age are from infancy to 5 years of age and at 173 years, the latter especially for males. It is apparent then that the susceptible elements of the population are children and young adult males.
(d) Influence of meteorological conditions.-The temperature, the mean as well as the wet-bulb (temperature of saturation), had a marked influence on the incidence of the disease. In general terms it may be stated that when there occurred a sudden drop of temperature the number of cases increased and when there was a rise in temperature, the incidence of epidemic meningitis declined. From a chart prepared by Dr. Gale, one will note this relationship, as shown by the following table:-
Date.
Effect of Drop of Temperature upon Incidence.
February 14-18 ..............
Degree of drop (Temperature of Saturation.)
No. of cases (Increase
over previous low level.)
Time clapsed between drop of temperature and increase of cases.
Febr. 27-March 2
March 10-12
March 25-27
April 9-11
ca. 13°C
ca.
11°C
Gal.
9°0
ca.
12°C
ca.
14°C
11
4 days
8
4 days
4
2 days
15
5 days
5
5 days
Effect of Rise of Temperature upon Incidence.
Degree of rise (Temperature of saturation.)
Date:
February 18-27
ca. 20°C
March 15-24
No. of cases (Decrease
over precious low level for week.)
Time elapsed between rise of temperature and decrease of cases.
8 days
March 31-April 9.
(gradual rise.)
Ca. 17°C (gradual rise.) ca. 13°C
8 days
4 days
Subsequently as the temperature rose, there was a corresponding decrease in the number of cases.
From this table it will be seen that, as a rule, about four days after a sudden drop of temperature there was a great increase in the number of cases reported. other hand it will be noted that rising temperature was usually followed by an ameliora- tion of the epidemic.
The influence of sunshine also made an impression upon the number of cases. Reversely, the lack of sunshine, showed an increase in the returns. For example, February 28th and March 1st, showed practically no sunshine, March 2nd, 44 hours, March 3rd, 1 hour; in other words, 5 hours of sunshine in 4 days. Three days later twenty-three cases were reported, the greatest number reported for a day with the excep tion of one. There was practically no sunshine for 4 days from March 26th, on the fourth day after this period twenty-one cases were reported, although from five to fifteen cases were the rule for the previous week. Thus we see that the lack of sunlight shows a relationship to the increase in number of cases.
It is doubtful whether humidity or rainfall by themselves have any bearing on the number of cases. January and February were extremely dry months. Indeed the rainfall was considerably behind the average for several years. Yet February saw increasing numbers of cases and March, with relatively small amount of rainfall, showed the greatest number. Recently rainfalls were heavy but the corresponding number of cases was not influenced.
(e) Pre-epidemic infectious disease.-It is a matter of common knowledge amongst the practitioners, although no official records are available, of the great number of cases of influenza and sore throat prevalent in the Colony during the period preceding the epidemic (November and December, 1917). The Principal Civil Medical Officer states that an unusual number have come to his attention. This is attested by Dr. Jordan, the