LO epi; History of epidemiology, Ignaz Semmelweis

1)Define the term "health-care associated infection" (HCAI) and provide some appropriate statistics to illustrate the magnitude of the problem globally (Slide 1)

infection occurring in a patient during the process of care in a hospital or other health care facility which was not present or incubating at the time of admission. - can be acquired in health care settings eg. 2011, in europe 4.1 mill patients affected by 4.5 mill patients every year acquire HCAIs, in US econ. impact was 6 and 1/2 bill dollars in 2004, 1.7mill patients every year acquire HCAI

3)Outline the reasons why Semmelweis' work was greeted with hostility by the medical profession (Slides 8 - 11)

1) Semmelweis's observations were in conflict with the prevailing miasmatic hypothesis of disease. In fact, Semmelweis's immediate superior in the hospital believed that the reduction in maternal mortality rates that began in 1847 could be attributed to a new ventilation system at the hospital - an idea that fitted the then popular miasmatic theory of disease. 2) Another problem was the failure of Semmelweis to publish his work promptly; his research did not appear in print until 1860 (13 years after he first introduced his hand hygiene intervention) and the 500 page document was, in parts, badly written and incoherent. 3) Another reason why Semmelweis's findings were ignored was the fact that doctors were reluctant to admit that they were actually responsible for the deaths of many patients that were under their care. 4) A further problem would have been the lack of indoor plumbing at the time making it difficult to obtain access to fresh water. The practice of handwashing would also have been somewhat inconvenient for doctors and medical students at the time. 5) Another possible reason for the reaction to Semmelweis's work may have been the fact that he was a Hungarian in Austria at the time of a xenophobic backlash in Europe, been innately distrusted by his Austrian colleagues..

examples of public health implications of historical events- lack of acceptance & understanding of information

1. Cholera could be prevented before the causal bacterial agent was identified - 44 years between institution of preventive practices and identification of vibrio cholerae 2. The association between diet and scurvy was described and appropriate interventions initiated before vitamins were identified - Vitamin C (ascorbic acid) identified 175 years after use of oranges and lemons to treat scurvy. 3. Maternal deaths declined after sanitation procedures were initiated but before specific pathogens could be identified - Streptococcus not identified until 32 years later 4. The eradication of smallpox, the removal of the handle of the Broad Street Pump and the introduction of a 'handwashing policy' emphasise that the "organised efforts of society" are required to prevent disease and promote health 5. Smallpox could be prevented before the viral agent was identified and before basic immunology was understood - 160 years between 1st vaccination and identification of variola (smallpox virus)

2) Describe in detail the background to, the introduction of, and the aftermath of Semmelweis's hand hygiene intervention. You must be able to describe the series of events with reference to the progression of epidemiological reasoning (Slides 2 - 11)

Stage 1 observation: 1846; noticed that death rates for new mothers from 'childbed fever' was significantly higher in OB ward division 1, deliveries by doctors and medical students than the division 2, deliveries by midwives & midwifery students. Always consistently higher over 1841-1850. Unknown reason until 1847, his colleague Jakob Kolletchka died from infection due to cutting finger with blade whilst performing an autopsy. Stage 2; hypothesis formation; connection between performing autopsies and childbed fever; Childbed fever was caused by "cadaverous particles" transmitted from hands of doctors & medical students to the obstetrics ward, introducing more meticulous hand hygiene in division 1 could reduce maternal mortality rates from childbed fever Stage 3; testing hypothesis: a) introducing the handwashing intervention (mandatory hand scrub w chlorinated lime solution) b) collecting data following the introduction of the intervention c) comparing maternal mortality rates in Division I before and after the introduction of the intervention d) comparing maternal mortality rates between Division I and Division II before and after the introduction of the intervention. Stage 4; results of epi. research into public health action; opposition faced, misamatic hypotheiss of disease, his superior thought it was due to the ventilation system at hospital.

Explanatory work of Robert Koch

Work with anthrax, disovered anthrax bacillus, developed methods of isolating and cultivating disease producing bacteria & strategies for preventing their spread., Formulated Koch's postulates. March 24th 1883, discovered TB was caused by a germ; wondered if bovine TB was the same that was found in humans, campaigns for the pasteurization of milk (in case bovine TB was spread). Discovered old version of tubercillin, but was ineffective

4) Write explanatory notes on the work of Louis Pasteur

a) germ theory on the effects that microorganisms had on fermentation and putrefaction of organic matter Koch & pastuer worked well together to become fathers of medicine & surgery. Pasteur; owrked on alcoholic fermentation of yeast & lactic acid fermentation, dismisses spontaneous regeneration 1861 (bottleneck experiment). Germ theory; germs affected us too, defined how germs cna be harmful under bioloical conditions, investigated the role fo air, oxygen, dirtiness on germ growth & spread his knowledge

Explanatory note on the work of Joseph Lister

applied pasteurs germ theory in surgery Lister culminated his extraordinary work with the full acceptance of his antiseptic method. In spite of his well-recognized advances in the treatment of contaminated wounds, as we know it today, it took many years and even decades before everyone fully accepted his method. - virtues of antiseptics in preventing surgical wound sepsis, based on germ theory of disease (germs must be eliminated at all costs, but not all surgeons believed in the germ theory- difficult when surgeons didnt have scientific involvement).