In 1962 Sir McFarland Burnett stated, ‘By the end of the Second World War it was possible to say that almost all of the major practical problems of dealing with infectious disease had been solved.’ At that time, his statement was logical. Control and prevention measures had decreased the incidence of many infectious diseases, and with the ability to continue to identify new antibiotics, to handle new problems, and the ongoing development of appropriate vaccines, his statement appeared to be appropriate.
In the US, similar feelings were expressed and funding for infectious disease fellowships began to decline with federal resources being directed elsewhere.
The history of the world is intertwined with the impact that infectious diseases have had on populations. Evidence of smallpox has been found in 3000-year-old Egyptian mummies. Egyptian papyrus paintings depict infectious diseases such as poliomyelitis. Hippocrates wrote about the spread of disease by means of airs, water, and places, and made an association between climate, diet, and living conditions. Investigators described miasmas as the source of infections. Fracastoro discussed the germ theory in the 1500s and three routes of contagion were proposed—direct contact, fomites, and contagion from a distance (airborne). Epidemics of leprosy, plague, syphilis, smallpox, cholera, yellow fever, typhoid fever, and other infectious diseases were the norm.
The development of the microscope by Leeuwenhoek in the 1600s allowed scientists to visualize micro-organisms for the first time. The 1800s brought knowledge of the cultivation and identification of micro-organisms. Vaccines were developed and used which introduced specific methods to our storehouse of measures for control and prevention. Pasteurization was another important contribution to disease control. An appreciation of the environment and its relationship to infectious diseases resulted in implementation of broad control measures such as community sanitation, personal hygiene, and public health education. The importance of nutrition was appreciated for its impact on infectious diseases.
I would say this question is false.
1. change
The natural selection is a process that occurs as a direct consequence of the living conditions in the environment. When the environment starts to change though, the organisms that live in it face a big challenge. They either have to change, adapt to the new conditions, and thus survive, or if they are not able to do so, to die out. This is the biggest evolutionary pressure for the organisms, and while some come out as winners from it, many others die out .
2. variation
In order for the process of natural selection to occur, the population needs to have some genetic variation. The environment is the ultimate push factor, but if the population doesn't have genetic variation in it, than the species will die out. The genetic variation is very important as in that way the individuals choose who will they mate with, in accordance with their traits, so that only the advantageous traits can be passed on to the next generation, so that it can be more competitive in the environment.
3. traits
The natural selection is a very simple process. The individuals of a population, when choosing a mate, look for the individuals that exhibit traits that are advantageous for survival. Mating with individuals with traits that are advantageous guarantees that the offspring will inherit those traits, thus it will have higher chances to survive. The individuals that do not have advantageous traits though will be avoided as mating partners, and that would rapidly lead to their decline and elimination from the gene pool, as they will not have any offspring to continue their line.
