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Three of the most significant medical advances of the last two centuries are sanitation, vaccination, and antibiotics. Each of these advances has engendered enormous positive social and economic impacts in developed societies. Sanitation has successfully impeded pathogenic growth in human living spaces, vaccines have protected humans from historically prolific diseases such as smallpox, and antibiotics have also saved countless human lives through daily sanitation and disease cure. However, the impact of these three advances has not been fully realized because they have not yet reached substantial portions of the developing world, vaccines for several prolific diseases continue to elude researchers, and misuse of antibiotics has led to resistant bacterial strains and other health hazards.
The rudiments of urban sanitation systems have been developed several times throughout human history but was nowhere near fully realized until the era of western industrialization in the 20h century. Once urbanization in the bronze age began to increase population densities in urban centers, increases in waste production required the use of outflowing systems like rivers to properly dispose of waste. The first documented system for sanitation was developed in the city of Mohenjo-Daro in 2600 BCE, and consisted of slits cut in the floors of houses to allow waste to drop into containers next to streets, and bath houses with covered channels that led to the nearby Indus River (“Mohenjo-Daro”). In addition, cities in the Roman Republic built the first documented sewer networks; for instance a massive combined sewer and storm drain called the Cloaca Maxima, or “The Great Drain” that carried waste and runoff water from Rome's civilian houses, public buildings, and bath houses to the Tiber River (Rich).
However, the era that followed the fall of the Roman Republic saw a regression in sanitation technology in which most of the world's civilizations operated without sanitation systems. For instance, the most common method to remove waste from living spaces in medieval Europe was to dump it into the street, where materials such as urine, feces, and wastewater from other domestic activities gathered and fostered bacterial, viral, and pest growth (Faria). Exponential growth of populations around industrializing centers without planned infrastructures made the immediate need for sewer systems evident. Citizens had heretofore relied either on dumping waste directly into waterways or simple cesspits, and the rapid growth of households using primitive sanitation methods increased the rate of contamination of groundwater, rivers, and other sources of fresh water. Stagnant sewage in cramped urban living conditions provided ideal conditions for growth of pathogens and caused outbreaks in many major cities in the mid-19th century; the most common were those of cholera and typhoid fever. It was clear that the need for advances in sanitation was imminent.
The most famous outbreak of the industrialization period is that of cholera linked to the London Broad Street water pump in 1854, in which a nearby cesspool had leaked sewage into groundwater and contaminated the well the water pump was drawing water from. The statistical analysis of cholera cases by physician John Snow that determined the connection between disease and contaminated water from the river provided irrefutable evidence that separating water resources and sewage is key to maintaining public health (Johnson). Outbreaks such as these in combination with the proliferation of the strong repulsive odor of sewage across all major industrialized cities prompted government authorities to take action and begin implementation of large sewer networks to isolate sewage from local water supplies.
Arguably the greatest advance in sanitation came about in 1908, when Jersey City Water Works began to add chlorine to its water supply network in a practice now called chlorination. The process involves the addition of chlorine to water to form an equilibrium solution composed of chlorine, Hydrochloric acid and Hypochlorous acid, the last of which plays the main role of disinfection. Systemic chlorination drastically decreased the incidence of water-borne illnesses such as typhoid and cholera (Kitsap Public Utility District). The final major advance came in the 1950s, when the United States government provided funds for states to build wastewater treatment plants, which resulted in the majority of U.S. cities discharging treated water into rivers and oceans instead of raw sewage, an important component of sanitation that minimizes re-uptake of water harboring harmful pathogens and microorganisms.
Development of modern sanitation systems has a significant effect on economic growth because its presence dramatically reduces the incidence of water-borne diseases and precludes their burden on worker productivity, student absenteeism, and medical costs. In addition, the reduction of sewage contamination in the developed world saves governments the cost of cleaning up environments to protect resources for human use. These benefits place in stark contrast the crude state of sanitation in parts of the developing world, who fail to reap these benefits because sanitation systems have not been implemented. In fact, according to the World Health Organization, investing in sanitation technology in developing countries is cost-beneficial and results in a “US$5 [to] US$11 economic benefit per US$1 invested” (Walter, and Hutton 39). Thus, cost-benefit analysis clearly favors investment by humanity for the whole of humanity.
The social benefits of effective sanitation are not as tangible as economic ones but are no less significant. Accessible facilities for private and sanitary hygienic activities preserves human dignity and encourages sanitary habits. The relationship between cleanliness and moral purity has been culturally accepted throughout human history, and scientific support that clean environments promote moral behavior is presented in an upcoming paper in Psychological Science (Elton). The social harmony that proper sanitation promotes supports the idea of implementing sanitation in the developing world to deal with social unrest and violence.
The second medical innovation, vaccination, is a more recent and specific advance in disease prevention. Its conceptual predecessor was inoculation, which was first documented credibly in 15th century China. The practice involved implantation of a disease agent such as pus from smallpox into a healthy individual who had never been infected to produce immunity (Needham 134). Vaccination replaced inoculation in 1796 when Edward Jenner used pus from a cowpox patient to inoculate a child; the child was then exposed to smallpox and subsequently did not exhibit infection with the virus. Shortly afterwards the British government mandated vaccination of children from smallpox, the first government push for mass vaccination in history; by 1800 “100,000 people had been vaccinated in Europe, and vaccination had begun in the United States” (Minna Stern, and Markel 613-614). In 1885, Louis Pasteur developed a rabies vaccine using samples obtained from dried infected rabbit tissue, which was the first to be manufactured from weakened microorganisms.
Further advances in biology and understanding of germs from the 19th century led to widespread research, development and implementation of vaccines to spread immunity from prolific diseases in the 20th century. A vaccine is now known as a preparation of attenuated or dead bacteria or viruses to stimulate production of antibodies in a patient. Although weakened pathogens carried a greater risk for infection than dead ones, they generally induce a stronger immune response and longer lasting immunity. A principal medical advance that allowed the production of durable vaccines is attenuation, the practice of passing the target virus through a nonhuman host to encourage adaptation through mutations when the virus replicated. Subsequent introduction into a human host to which the virus is not adapted to replicate allows the immune system to produce antibodies to recognize the same pathogen in future exposures.
The development of consistently effective vaccines led to systematic mass immunizations against several worldwide diseases such as smallpox starting in the 19th century and polio in the mid-20th century. Government oversight in cooperation with the World Health Organization (WHO) was essential to these worldwide efforts, and smallpox was in fact declared eradicated by the WHO in 1979 . Polio and measles are currently in the process of eradication (“Smallpox”).
However, not all viruses are created equal, and certain viruses have eluded attempts by scientists to engineer an effective vaccine. The HIV virus is one such example; its high mutability and genetic divergence complicate attempts to design a vaccine in the same fashion as that of historically successful ones. To address this need, research to develop new types of vaccines that utilize only protein subunits of pathogens or delivery of viral DNA is ongoing.
The elimination of globally endemic disease has been key to lowering mortality and raising life expectancy around the world, but has also engendered an interesting array of social and economic developments. For instance, the unequivocal success of vaccines against globally prolific viruses has undermined the economic motive for further production for vaccines for diseases more prevalent in the developing world. Because citizens in poorer nations cannot come close to affording the price of a vaccine in developed nations, pharmaceutical and biotechnology companies lack the financial incentive to expand their markets. Solutions to lack of economic incentives include academic research and government incentives for vaccine development.
Mass vaccination against the world's historically endemic viruses has altered social attitudes in many ways. For instance, during the Middle Ages life expectancy was short due to the rampant disease and epidemics; death was accepted as a necessary part of life, and often as an act of God (Dumond). The drastic drop in mortality due to diseases such as smallpox in the late 19th and 20th centuries raised the life expectancy of the average human and replaced the cultural acceptance of death with a cultural appreciation of life. In other words, living longer and delaying death is now a universal goal because disease has dramatically improved the prospect of living up to biological potential. Thus, the success of vaccines has cultured a social ignorance of the danger of viruses because deaths due to disease are so much rarer than in previous historical eras.
The last of the three medical innovations, antibiotics, has been used since humans have experimented with chemicals and substances from plants to discover remedies for diseases. Disinfection typically involved use of either plants believed to have healing properties or chemicals known to inhibit or kill organisms. Arsenic was one such remedy, and its broad toxicity meant that patients would also suffer serious side effects. Thus, the discovery of substances with high specificity and few side effects in humans was one of the great historical developments in modern medicine.
The first discovery in modern antibiotics was of penicillin in 1928 by Alexander Fleming due to a coincidence now famous in science: a Staphyloccocus sample mistakenly left in the open had been growth-inhibited by a Penicillium mold. However, a German scientist named Gerhard Domagk was the first to develop a commercial antibiotic called Prontosil with broad action against Gram-positive cocci.
Mass production of antibiotics was simple and relied on fermentation in large containers of growth medium for the target organism to produce the secondary metabolite. Modern development of partially synthetic or entirely synthetic antibiotics involves either chemical modification of metabolites after fermentation or synthesis from a naturally occurring skeleton.
Unfortunately, the misuse of antibiotics is leading to increasing prevalence of resistant strains of bacteria around the world. Incorrect diagnosis, improper administration, improper disposal, and overuse in livestock often lead to antibiotic resistance because bacteria can perform horizontal gene transfer through plasmid exchange. Thus, resistance genes can rapidly proliferate in a population of bacteria once one has genetically mutated and become immune to a particular antibiotic. For example, if a patient using a prescribed antibiotic stops taking it before the infection is completely eradicated, horizontal gene transfer will allow the few bacteria who have developed resistance throughout the duration of the infection to pass on the resistance gene and prolong the infection. One of the most alarming cases of resistance is that of Staphylococcus aureus, or the staph infection; the bacterium has shown historically to be extremely adaptable. For example, 40% of patients with staph infections were resistant to administration of penicillin by 1950, less than 10 years after the antibiotic was introduced (Chambers 178). Staphyloccocus aureus is now also resistant to a variety of other antibiotics such as tetracycline and methicillin. Although this problem has traditionally been isolated to hospitals, Community-acquired MRSA is now expanding in urban communities, and is responsible for several fatal conditions such as necrotizing fasciitis, or flesh eating disease.
The economic benefits of antibiotics, which are similar to vaccines because it deals with pathogens through a direct biological pathway, are complicated by the rise of bacterial resistance. However, this has also provided economic impetus to invest in development of synthetic antibiotics as demand for alternatives rises. More specifically, the threat of antibiotic-resistant bacteria like MRSA has spurred the development of oxazolidones, a newer class of antibiotics against Gram-positive bacteria. The first generation of this class of antibiotics is Linezolid, which disrupts the protein synthesis of Gram-positive bacteria; its mechanism for disruption occurs at a much earlier step than most other protein inhibitor antibiotics (Brickner 175). Linezolid is currently utilized as a last resort against MRSA and resistance has been low ever since its introduction in 1999 (Jones, Ross Castanheira, and Mendes 424). It is likely that research into synthetic drugs, the newest development in the antibiotic industry, will continue as long as antibiotic resistance persists.
The widespread use of antibiotics in medicines, soaps, and household cleaning supplies has created the social perception of a sterile domestic environment for human activities. This perception is partially justified in that regular use in daily routines and sicknesses has dramatically reduced illness and engendered a social paradigm shift away from the concept of death comparable to that of vaccination. In fact, use of antibiotics may have brought about a complacency towards bacterial threats to the human body because its use is ingrained in human hygienic habits. However, the recent revelation of superbugs like MRSA has also brought about a social awareness of antibiotic resistance, and this may result in another shift towards understanding how to handle antibiotics responsibly.
In sum, sanitation, vaccination, and antibiotic implementation has drastically reduced the prevalence of classic diseases in modern society. Previous scourges of humanity such as smallpox, cholera, and the black plague that ravaged human life are now essentially historical footnotes in the chronology of human medical achievements. Medical advances have brought about generally positive economic and social changes through reduction of health care through prevention, and a culture less concerned with death on a daily basis. However, these advances have not been distributed equally among all peoples of the world; many citizens of developing countries without effective sanitation, medical supplies, and access to vaccines of antibiotics continue to be at the mercy of the aforementioned scourges of humanity.
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