*491
Epizootic Plague.
Plague in Rats.-Throughout the past year, the examination of rats, found dead, or caught alive, has been systematically carried out. 21,907 rats were sent for examination; of these, 993 were found plague infected. A general chart has been prepared giving the incidence of rat and human plague, and from it the following will be apparent :-
1. Rat plague is present to a greater or lesser extent throughout the
whole year.
2. It becomes epizootic about the beginning of April.
3. The epizootic reaches its maximum about the middle of June.
4. From this time onwards, the epizootic gradually abates, reaching its
lowest point about the end of October.
5. From the beginning of November, there is a tendency towards a
recrudescence of the epizootic.
6. Human plague becomes epidemic more or less suddenly about the middle of April, ie., about 1 week or 10 days after the commence- ment of the epizootić.
7. The epidemic reaches its highest point about the same time as the
epizootic.
8. If the ascent of both curves be examined carefully, it will be seen that sudden rises in the epizootic are followed closely by exacer- bations of the epidemic.
9. After the epidemic has reached its maximum it quickly fades, leaving
the epizootic still much in evidence.
10. The tendency towards a recrudescence of rat plague, is marked by
the re-appearance of human plague.
In general, it may be said that the curve for 1904 follows closely those given in my Special Report on lague for 1902 and 1903.
The interval between the outbreak of rat plague in epizootic form, and human plague. in epidemic form, has been maintained. During the progressive march in severity of both forms of plague, the disease in the rat always leads the way.
As already mentioned, the rise in rat plague towards the end of the year, was accompanied by the re-appearence of human plague. From my experience of past years, I conclude that should this rise in rat plague be continued during the early part of 1905 we may reasonably expect an early recurrence of the disease in epi- demic form.
In addition to rats, a number of other animals, sick or found dead, have been examined for the presence or absence of plague.
82 Fowls,
57 Ducks,...
2 Geese,
All negative.
Do. Do.
6 Cats,
D
1 Monkey,
1 Rabbi,...
•••
2 returned as infected. Negative.
Do.
Outbreak of Disease in Fowls.
In Hongkong and the surrounding country, outbreaks of a deadly disease are frequently found amongst fowls. During the past year, several of these epi- zootics were brought to my notice, and I had an opportunity of investigating the subject bacteriologically. In a certain number of cases, some account of the course of the disease was ascertainable. The usual tale is as follows:-In some particular district hundreds of fowls have died in a week. On observation the remark is usually made that the fowls look quite healthy one hour and are dead the next. They become weak, and are attacked with violent spasms. Diarrhoea is also fre- quently present, and there is a viscid discharge from the beak and nostrils. The comb and toes become dark red in colour.