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This is succeeded by a reappearance of the epidemic during the first and second weeks of June. Subsequent to this date, a peculiar alteration of circum- stances takes place.
Up to the middle of June, the epizootic has always preceded the epidemic by about a fortnight.
Subsequent to this period, a complete overthrowal of the order of events takes place.
The epidemic does not vanish in a week or two after the fall in epizootic plague. Cases frequently occur, maintaining the human plague curve above that of the epizootic.
The rat plague becomes extinct for a week in the presence of human plague.
In a week or so, rat plague reappears as pronounced as ever. By this time human plague has disappeared for a week. But after this recrudescence of rat plague has lasted a week, human plague reappears and persists for a week subsequent to the disappearance of the epizootic recrudescence. A week later rat plague again appears but is not followed by any marked epidemic. Subsequently brief outbursts of the epizootic occur during the last quarter of the year. No epidemic occurs. A possible explanation of this, will be given under a separate heading.
The Conclusions drawn from District No. 1.
1. The epizootic preceded the epidemic at the beginning.
2. The interval between both averages a fortnight.
3. Towards the middle of the epidemic, the continued elevation of the human plague curve, would appear to occasion an elevation of the epizootic curve, the latter again calling forth a recrudescence of the epidemic.
4. The recrudescence of the epidemic would again occasion an outbreak
of the epizootic, etc.
5. The curves show that during the early stages of the epizootic and epidemic, rat plague and human plague are distinct. The former is regularly succeeded by the latter. During the height of both each would appear to occasion the other. The epidemic may occasion the epizootic, the latter again stimulating the advent of the epidemic.
6. The commencement of the epidemic would appear to be the result of
the epizootic.
7. During the height of the disease, the epidemic and the epizootic
would appear to share equally the continuance of the disease.
The History of Health District No. 2 in 1902.
On the 8th of April, the epizootic is thoroughly established and maintains itself until the end of May. No epidemic was existent on the 8th of April. It appeared a fortnight later.
With the continued rise in the epizootic during this period, the epidemic was established. The epidemic reaches its highest point one week after the apex of the epizootic.
Towards the end of May both fall. The epizootic becomes extinct. The epidemic falls slightly, and subsequently rises to nearly its former height. As already mentioned, there is no rat plague at this period.
The epidemic now continues more or less constantly. This being so, the epizootic reappears, gradually rising to a higher level than the epidemic. Subse- quently the epidemic would appear to follow the epizootic and vice versa. The epidemic stopped on the 26th of August. The epizootic continued more or less throughout the year..
A rise in the epizootic towards the end of the year is well marked. Conclusions drawn from District No. 2.
1. The course of the disease is an excellent example of the relationship
between the epidemic and the epizootic.
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