Dale Carnegie has inspired a lifetime of learning and change, through the many books and
Research and development in the late 20th century
Research and development in the late 20th century
Epidemics
In the medical field, many diseases were discovered to be caused by micro-organisms and often the diseases had no specific treatment. Early in the 20th century, a researcher called Edwin Chadwick, working at the Lister Institute in England, helped to establish the germ theory of disease, and this became the basis for the treatment of many diseases, such as sexually transmitted diseases and infections of the gastrointestinal tract. The discovery of penicillin in 1928 brought hope of new antibiotics, which were effective for a long time, before the development of new strains of disease-causing bacteria that were resistant to the antibiotics.
Historically, epidemics have been a constant threat to the health of all peoples, and have left indelible marks on the societies in which they occurred. The Bubonic plague, which infected roughly one out of every five people who contracted it, struck much of Europe during the 14th and 15th centuries, killing approximately 50 percent of those affected. Another example is the Black Death, which, beginning in Europe in 1347, spread to the rest of the world, killing approximately 50 percent of the people infected. An excellent example of this is the Plague of Athens in 430 BCE, which struck more than half of the population of Athens at one point and resulted in the collapse of the Greek city-state.
In the later 20th century, there were many epidemics that struck the United States and the world, including SARS, the Avian Flu, the Swine Flu, and the H1N1 pandemic. The 2001 anthrax attacks, which began in September of 2001, exposed the vulnerability of the nation's critical infrastructure to bioterrorism. Although there were many scares over the past century, none had an impact comparable to the AIDS pandemic, which struck the United States in the 1980s. AIDS in America had a far more devastating effect on public health than any other epidemic since the Black Death. The official death toll for AIDS in the United States was approximately 40 percent of the number of people infected; this does not include the unknown number of people who have died without being counted.
Starting in the 1970s, research on AIDS was undertaken by scientists around the world, and then in 1981, the causative agent of AIDS, a retrovirus, was ac619d1d87
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