EPIDEMICS^ PAST AND PEESENT. 
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Consort^ came to tlieir untimely end. It differs also from 
typlius in tffe circumstance that its origin and propagation 
are quite independent of overcrowding with defective ventila- 
tion_, and are so intimately connected with bad drainage^ that 
by some physicians the fever is now designated pythogenic, or 
fever born of putridity. It is asserted by some writers that 
the poison of enteric fever is never generated in obstructed 
drains_, but that the drains are merely the vehicle of trans- 
mission of the poison from an infected person. But if this 
were so^ enteric fever must needs be a most contagious 
disease^ whereas all experience goes to show that it rarely 
spreads^ even under the most favourable circumstances. The 
disease, in fact, is so slightly contagious that many excellent 
observers have doubted if it be so at all. It is probable that 
certain meteorological conditions, such as a high temperature, 
a defective supply of ozone, or a peculiar electrical state, may 
be necessary for the production of the poison of enteric fever ; 
and thus, nuisances which are offensive to the senses may 
exist for a long time without producing the disease. The 
necessity of a high temperature is undoubted, and is itself a 
strong argument against the view which makes dizains merely 
the vehicle of transmission of the poison. It is well known 
that enteric fever, like ordinary diarrhoea, becomes epidemic 
in this country every autumn, and almost disappears in spring, 
while the autumnal epidemics are always greatest in seasons 
remarkable for their high temperature. Enteric fever is 
much later in commencing and in attaining the acme of its 
autumnal prevalence than diarrhoea, showing* that a longer 
duration of hot weather is necessary for its production ; but, 
when once produced, a more protracted duration of cold 
weather seems necessary for its destruction. 
10. Cholera . — Epidemic cholera is generally described as 
having originated at Jessore, in the delta of the Ganges, in the 
year 1817, and as having spread thence over Hindustan, and 
ultimately to Europe. Since 1817, Europe has been visited 
by three great epidemics of cholera; viz., in 1832, in 1848-9, 
and in 1854 ; and at the present moment, it is threatened with 
a fourth. During the past autumn the disease has appeared 
at Ancona and Marseilles, and at many other places in the 
basin of the Mediterranean. In England and Wales, cholera 
destroyed 53,273 lives in 1849, and 20,097 in 1854. Although 
the great epidemics of cholera have appeared to take their 
origin in India and gradually to have spread to Europe, followiug 
often the lines of human intercourse, the evidence in favour 
of its being a very contagious malady is small. The attend- 
ants on the sick are rarely attacked ; and, on the other 
hand, the disease has often appeared in isolated localities. 
