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John Snow "Father of Modern Epidemiology"
John Snow "Father of Modern Epidemiology"

John Snow, born in 1813, was the son of a coal-yard laborer in York, England. Snow planned to become a physician, and at fourteen, he was apprenticed to Dr. William Hardcastle. During his early years as an apprentice, he filled notebooks with his thoughts and observations on scientific subjects. In the summer of 1831, when Snow was eighteen and in his fourth year as an apprentice, an epidemic of cholera struck London. The disease, which had already killed hundreds of thousands of people on the European continent, spread north to Newcastle in October. The first symptom of cholera was queasiness, followed by stomachache, vomiting, and diarrhea so profuse that it caused victims to die of dehydration.

Dr. Hardcastle had so many sick patients that he could not personally see them all, so he sent Snow to treat the many coal miners who had fallen sick at the Killingworth Colliery. There was little that Snow could do to help the stricken miners, because the usual treatments for disease- bleeding, laxatives, opium, peppermint, and brandy -- were ineffective against cholera. Snow continued to treat cholera patients until February of 1832, when the epidemic ended as suddenly and mysteriously as it had begun. By that time, it had left fifty thousand people dead in Great Britain.

During the next sixteen years, Snow earned an M.D. degree, moved to London, became a practicing physician, and distinguished himself by making the first scientific studies of the effects of anesthetics. By testing the effects of precisely controlled doses of ether and chloroform on many species of animals, as well as on human surgery patients, Snow made the use of those drugs safer and more effective. Surgeons who wished to anesthetize their patients no longer risked killing them by the unscientific application of chloroform-soaked handkerchiefs to their faces.

Snow began to do a lot of thinking about the possible causes of contagious diseases, and he came to the unconventional conclusion that they might be caused by invisibly tiny parasites. This was not an original idea, but it was an unpopular one during the first half of the nineteenth century. The "germ theory" of disease had first been proposed in ancient times, and the discovery of microscopic organisms in the late 1600s had made the theory seem plausible, but no one had ever proved that miniature organisms could make people sick.

In Snow's day most physicians believed that cholera was caused by "miasmas" -- poisonous gases that were thought to arise from sewers, swamps, garbage pits, open graves, and other foul-smelling sites of organic decay. Snow felt that the miasma theory could not explain the spread of certain diseases, including cholera. During the outbreak of 1831, he had noticed that many miners were struck with the disease while working deep underground, where there were no sewers or swamps. It seemed most likely to Snow that the cholera had been spread by invisible germs on the hands of the miners, who had no water for hand-washing when they were underground.

Title page of Snow's pamphlet

In August of 1849, during the second year of the epidemic, Snow felt obliged to share what he considered convincing evidence that cholera was being spread through contaminated water. At his own expense he published a pamphlet entitled On the Mode of Communication of Cholera. Thirty-nine pages in length, the essay contained both a reasoned argument and documentary evidence to support his theory. As one example he cited the case of two rows of houses in a London neighborhood that faced each other. In one row many residents became cholera victims, while in the other row only one person was afflicted. It was discovered, Snow wrote, that "in the former bowl the slops of dirty water, poured down by the inhabitants into a channel in front of the houses, got into the well from which they obtained their water." Snow realized that such conditions existed in many neighborhoods and that if cholera epidemics were ever going to be eliminated, wells and water pipes would have to be kept isolated from drains, cesspools, and sewers.

Snow's research remains extremely relevant today, necessitating sanitary septic infrastructure in any populated area. The pathogen Vibrio cholerae is not contagious from body to body but is easily spread through food and water sources that become contaminated with sewage. The conditions necessary to induce a cholera outbreak still exist in many countries where hygienic water sources are not readily available. The largest outbreak in modern history occurred months after the 2010 Haitian earthquake. 6,631 deaths were recorded among the 470,000+ reported cases. The Centers for Disease Control and Prevention (CDC) soon went to work, establishing guidelines for cholera treatment and avoidance as well as setting up sanitation facilities. $75 million has been spent by the US government in attempts to control the disease but Haiti will likely continue to have increased cholera transmissions far into the future. Educating people in hygienic practices can only go so far. Efficient water and sewage infrastructure is vital to reducing the impact of the disease. John Snow was the first to recognize the importance of a clean water supply after investigating the cholera outbreaks of 1800s London. His work was the first step into requiring strict government and city maintenance of water resource structures.

 

 

Sources:

Father of Epidemiology

Haitian Cholera Outbreak

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Human epidemiology is the study of disease, its contributions and disparities, and potential ways to help stop the spread of disease. Among the West, there are many different diseases, viruses, prions, and other contagions that are incurable. Even among all the technology, in-depth research, and major complex studying among control variables, the West is still highly undeveloped; or, at least this is what one is lead to believe. However, there are many treatments, remission possibilities, and rehabilitation methods available. Among the many incurable diseases, Crohn’s disease has begun to resurface. This reappearance however, has been among children and teenagers not adults as witnessed in the past.

In the article entitled, “Pediatric Crohn’s Disease: Epidemiology, and Emerging Treatment Options”, Kansal and Smith explore Crohn’s disease and its affects globally on children ranging from 0-14 years of age. Crohn’s disease was first described as a clinical entity by Burrill B Crohn and colleagues in the USA in 1932 and has traditionally been regarded as a disease of the Western world. It is currently believed that Crohn’s disease occurs as part of interplay between environmental and immunological factors in a genetically susceptible host.  A rising incidence in both adults and children has been observed in recent years, with some studies suggesting a ten-fold to 20-fold increase in children over three decades. Crohn’s disease currently affects about 700,000 people in the USA and about a million in Europe. It’s a disease that affects the gastrointestinal tract (gut), which eventually causes bone degradation and/or abnormal growth among young children. Researchers have even reported it to relate to IBD (inflammatory bowel disease). It would make sense seeing as if the gut includes the small intestine which assists in digesting nutrients to be distributed throughout the body. Moreover, if the first initial site of absorption is interrupted, proper bowel movement, as well as building healthy bones in development suffer traumatically.

While the peak age of new diagnosis for Crohn’s disease overall is between the second and fourth decades, the average age in pediatric practice is about 11 years. A study from Scotland reported a doubling of the incidence of pediatric Crohn’s disease over the 15-year period to 1995, with an overall averaged standardized incidence rate of 2.5 cases per 100,000 populations for the period. Marked increases in pediatric diagnoses have also been confirmed in other parts of Europe, such as Sweden, Czechoslovakia, and the UK, while elsewhere, such as Canada and the USA, they appear to have plateaued after previously documented increases.

One of the most interesting conclusions is that genetic susceptibility for Crohn’s disease is defined as how the host interacts with its microbiota. The search for a microbial trigger for Crohn’s disease has been carried out in two ways, either a specific transmissible agent or a dysbiosis involving the gastrointestinal microbial milieu. With this, researchers have found many treatment options. Most treatment options have been reared toward inflammation. Traditionally, the Step-Up treatment option was used for adults, but history of the disease along with uprising epidemic, a  new method known as Top-down therapy is being administered to help with prevention of structural damage by achieving mucosal healing with this past use of immunosuppressants and biologicals. As mentioned, there is no cure for Crohn’s disease, but therapeutic interventions are designed to relieve symptoms, improve the quality of life, and avert-long-term complications.

Shavani Kansal, Anthony J. Smith (2014). Pediatric Crohn’s disease: epidemiology and emerging treatment options. Pediatric Health, Medicine and Therapeutic. University of Melborne.

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Carol Worthman received her PhD at Harvard in 1978, after first attending Pomona College for her BA in Botany and biology, and subsequently the University of California at San Diego Medical School and Massachusetts Institute of Technology. Her interests include biological anthropology, human reproduction, human development, biocultural and life history theory, and developmental epidemiology. These interests are bioculturally focused. She also has worked with the University of Alabama's own Dr. Jason DeCaro on various projects concerning stress and developmental biology.

Brandon Kohrt is an assistant professor at Duke Global Health Institute and Department of Psychiatry and Behavioral Sciences. He conducts global mental health research focusing on populations affected by war-related trauma and chronic stressors of poverty, discrimination, and lack of access to healthcare and education. His research is conducted in Nepal, and he has worked closely with the Transcultural Psychosocial Organization (TPO) Nepal, the Carter Center Mental Health Liberia Program, and was a co-founder of the Atlanta Asylum Network for Torture Survivors. His interests include culture, health economics, health systems, and mental health.

Worthman and Kohrt are concerned with how our current approach to public health is dissonant with contemporary health concerns. They call this phenomenon a "paradox of success," which is characterized by historical accomplishments in public health perpetuating paradigms which cannot be applied globally or to recent emerging health concerns. Sometimes these paradigms result in negative effects on health, which I will explain below. According to multiple sources, only 2-60% of health outcome variation is explained by the models we currently use in public health (see Worthman & Kohrt 2005). In order to evaluate and adjust public health models, Worthman and Kohrt identify five paradoxes stimulating morbidity instead of expected success.

  1. Unmasking is characterized by changes in morbidity patterns. Advances in health care have created an epidemiologic transition from infectious disease to chronic degenerative and mental illnesses. Think cancer, Alzheimer's, etc... The example used in the article was depression, although the rise in mental illness could also be a result of historically unreliable data.
    What other examples of unmasking can you think of?

    Simplified model of epidemiological transition.


  2. Localization is an important paradox resulting from globalization of public health paradigms. It is becoming increasingly evident that biological function and regulation are heavily dependent on context. Vaccinations sometimes fail as a result of locally derived immunocompetence. Fetal/childhood development also play a role, as shown by the relationship between breastfeeding/birth spacing and infant survival/health.
    The article talked about fetal programming as a factor of localization. What about research in fetal programming is relevant here (in the article or outside)?

    Anti-vaccine propaganda. Success of vaccination can be affected by malnutrition, pathogen load, stress, and immune development of individual.


  3. Socialization in this context applies to the enhancement or diminishing of vulnerability to disease based on cultural factors. HIV/AIDS prevalence in African countries are exacerbated by cultural attitudes toward sex and the availability of sex education, as opposed to Western countries.
    What are some examples of cultural practices that perpetuate disease?

    Fast food culture... you can find these anywhere!

     

  4. Re/emerging disease is a resurgence of disease patterns, sometimes in more virulent forms. Tuberculosis is an important example, responsible for 3% of all mortality in 1999. Diabetes and asthma are other examples, although literature on  re-emergence of non-infectious disease is currently limited.
    What factors contribute to re/emergent diseases?

    Travel is just one factors contributing to re/emerging disease.
  5. Savage inequity adds fuel to the previously mentioned paradoxes. Poverty, inequality, and inequity are all included under this paradox. Global media especially perpetuates inequity and can be the cause of varying psychosocial factors that contribute to morbidity.
    What is the difference between inequality and inequity, and what are the health implications of each?

    Link between risk factors and income levels.

I thought about tuberculosis as an historical disease until I had to take my TB test before entering college. I wasn't positive, but the test indicated that I had been in contact with the disease at some point. I didn't realize that our health practices were, in a way, catalyzing the resurgence of antibiotic-resistant tuberculosis. Savage inequity is also a concept the resonates with me. Intuitively, I know that mental health is just as important as physical health, but this knowledge conflicts with what I've observed in medicine and health research. I only recently realized that this is a problem with the paradigm, not my understanding or health.

I also think it's important to note that, although socialization and local biology seem obvious contributing factors to health in our class, we are anthropology students. It appears to me that medical students are vastly under-educated regarding biocultural models of medicine. I won't pretend to know how to change education policies in medical school, but it is important to recognize that a global public health paradigm isn't going to satisfy our global health needs.

 

EDITED 12-9-2013