6
Infection.
16. The commonest history of the infection of a village was that a person had arrived
there suffering from plague. The next event
was an epidemic among rats, and this within
a period varying most commonly between a week and a fortnight was succeeded by an
outbreak among human beings.
Influence of climatic conditions, soil, &c.
17. The only climatic condition which can be said to have affected the course of the
epidemic was the seasonal variation in tem-
perature, the effect of which has already been
noticed. It may be pointed out that the first lull in the epidemic corresponded with the
coldest part of the season, a time during which the people remained most largely indoors.
That a lull does occur at this period is therefore an indication that the cold reduces the
virulence of the plague bacillus. In this connection it is of interest to note that the
epidemic in the Siálkot District, which was a much milder one than that of the previous
season, appeared to be held in check, till the end of January, by the severity of the
winter, which was such that the sugarcane crop was destroyed.
Some very interesting investigations were made in the Ambala District with a view
to determining the relation of the soil to the incidence of the disease and to the liability to
infection and recrudescence. The results tended to show that plague affects villages situated
in sandy tracts less than others, but the results must be accepted with reserve, as it is
probable that the variation in incidence of the disease is due less to variation in the soils
than to variation in density of the population located thereon. It is stated that in the
Hoshiárpur District the epidemic raged as severely in the hilly part of the district as in the
plains. That a certain amount of immunity is conferred on a community by a previous
epidemic is indicated by the course of the present epidemic in the Ludhiána District. In
the Ambala District it was noticed that those parts of the district which had suffered severely
during the previous season escaped lightly during the present. Also in the Nawashahr
Tahsil of the Jullundur District it was observed that the mortality was distinctly lower than
in the more recently infected parts of the district.
Plague among rats and other animals.
18. In some districts, in addition to rats, dogs, cats, squirrels and birds also were
observed to die during the height of the epi-
demic. In some places it was noticed that
crows left the neighbourhood of a village when the epidemic was at its height to return again
after it had ceased, but no crows were ever observed to die from the disease.
Some attempts were made to get rid of rats, but without success. Many Hindús have
religious scruples against taking animal life, and these would not consent to any measure
involving the destruction of rats. In Amritsar, however, rats were caught and kept in
captivity in which they usually soon died, but the measure was not adopted with any vigour
and was soon discontinued.
When the people had no objection trial was made of various methods for destroying
and catching rats. Among them were the placing of a mixture of flour and plaster of Paris
near rat-holes, the stuffing of these holes with a mixture of tar and sulphuric acid, and
the setting of traps.
The mixture of flour and plaster of Paris is said to have been used wih success in
France, where rats were said to eat it greedily with fatal effect.
From experiments made at Jullundur, however, it appeared that rats could survive
for more than a week on an exclusive diet of this mixture.
The method of stopping rat-holes with a mixture of tar and sulphuric acid is stated
to have been effective in Southern India. The method, however, is a very troublesome one ,
requiring careful supervision ; and the fumes of the mixture are very disagreeable.
One form of trap which was found to be useful in the Gurgaon District was a chatty
half full of water sunk in the ground to the level of its mouth which was covered over with
a very thin layer of dough on which a bait was placed ; when trodden upon by rats the dough
was supposed to give way and precipitate the rat into the water. When carefully carried
out, the method of catching rats appears to have been effective, but it involves a little trouble,
and this the people were not disposed to take.
Type of plague.
Classes attacked.
19. The bubonic type of plague vastly preponderated, though some cases of the
pneumonic and septic forms of plague were
observed in most districts. It is reported that
in parts of the Shahpur District and in some
villages in the Amritsar District outbreaks of