ay now fairly say that
it has disappeared from our midst. It, however, still abounds in
Russia and her eastern provinces, and in Algeria, Tunis, and Morocco.
It is a disease of cold and temperate climates rather than of the
tropics.

In the last century typhus was distinguished definitely and clearly
from "typhoid" or "enteric" fever, and from "relapsing" or "famine"
fever, with which it had previously been confounded. The bacterial
germs causing enteric and relapsing fevers are now known, and have
been isolated and cultivated, and the mode in which they are conveyed
into the body of a previously healthy patient is ascertained. But
until the past year we knew neither the parasitic germ which causes
typhus fever nor the mode by which it passes from one individual to
another. A vague idea that it was spread through the air prevailed.
Typhus is remarkable for the frequency with which the nurses and
doctors attending a case become infected. About 20 per cent. of those
attacked by it die, but in persons above forty-five years of age the
mortality is much greater--about half succumb.

Dr. Nicole and his colleagues of the Institut Pasteur in Tunis have
recently had the opportunity of studying typhus there. They found that
the ordinary local monkey could not be made to take the disease. But a
drop of blood of a typhus patient injected into a chimpanzee (which is
far nearer akin to man) produced the disease after an incubation
period of three weeks. This fact was definitely established. From what
is now known as to relapsing fever, malaria, yellow fever, plague, and
sleeping-sickness, it seemed probable that some migratory insect must
be the carrier of the typhus infection from man to man. The typhus
patients brought into the hospital at Tunis were carefully washed
before admission, and no infection of other patients or nurses took
place in the wards, although the cases were not isolated, and bugs
were abundant. The only cases of infection which occurred were in
persons who had the duty of collecting and disinfecting the clothing
of the patients when admitted. This seems to exclude the bug as a
carrier. The flea is excluded by the fact that in the phosphate mines
of Tunis the flea is abundant, and bites both natives and Europeans.
Yet when typhus fever broke out among the miners--although all were
equally bitten by the fleas--no European was infected. The indication,
therefore, was that if any insect is the carrier, it is neit