Rat flea (Xenopsylla cheopis), the vector for bubonic plague

It was in this period that the great discoveries in microbiology of the late Nineteenth Century were beginning to be put to practical use through improvements in public health.  At the same time, there were major advances in diagnosis, in treatment, in surgery, in medical education and training, in organization, and in many areas of  medical knowledge.  The rise of psychology and psychiatry was underway as well.  Medicine was taking on something like a modern appearance.

But what’s most striking is what had not changed.  In this decade, millions were still carried away by epidemics and pandemics of plague, cholera, sleeping sickness, yellow fever, tuberculosis, smallpox, typhoid, and other communicable diseases.  Many more were killed or crippled by easily preventable dietary deficiencies like beriberi or rickets.

(1) Medicine: 1904-1908
(2) Medicine: 1909-1914

Regional headers are color-coded: 
North America - Western Europe - Central Europe - Russia.
Africa - Islam and South Asia - East Asia and the Pacific - Latin America

Sources include:
Alexander Hellemans and Bryan Bunch. The Timetables of Science.  1988
(American Red Cross)
(American Society for Microbiology)
(Dave’s Homepage: A Chronology of Significant Historical Developments in the Biological Sciences)
(Hell & Good Evening - History of Psychology Headlines 1650-1959)
(History of Psychology Timeline)
George C. Kohn, editor.  Encyclopedia of Plague and Pestilence.   1995.
Roy Porter.  The Greatest Benefit to Mankind: A Medical History of Humanity.  1997
Jan Romein.  The Watershed of Two Eras: Europe in 1900.  1978.
Walter I. Trattner.  From Poor Law to Welfare State: A History of Social Welfare in America, 6th Ed.  1999