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Transcript
ITA Fever Session (semester 1, week 8) Introduction Below you will find the four patient scenarios you have discussed in your small groups in week 7. Once again you will find a range of supplementary learning material in the ITA. The material should help you in your task. Tutors will also be present in the ITA session to answer any questions. During the first 50 minutes, please read and discuss questions at the end of all four scenarios and visit the ITA support material. After this time, your group will be allocated one of these scenarios to present to all the other groups in the final period of this ITA session. Please spend a further 25 minutes discussing your allocated scenarios (revisit the relevant ITA material and talk to the tutors) and arranging for one of you to talk for about 5 minutes to the full ITA group discussing the answers to the questions at the end of the scenario. For each of the scenarios, please also see how far you can get with answers to the following questions – and be prepared to discuss them in your feedback presentation. • What is the likely infection diagnosis (ie the clinical name given to this condition)? • What is the anatomical site of the infection? • What is the most likely micro-organism responsible – and what generic group do they belong to? • What clinical sample would you collect to confirm the infecting organism? • Analyse the symptoms and features of the illness into local and systemic manifestations (that’s the exercise you started with above) 1 Scenario 1: Mary McDonald aged 68 had previously been diagnosed with Type 2 diabetes and hypertension, and had been taking medication for both of these conditions for 10-15 years. She also had a chronic problem with athlete’s foot, and one of the cracks between her right toes became more infected, red and tender. Within a week this had spread up across the dorsum of her foot, which became red, swollen and painful. She then became hot and confused: her husband called the GP. Answer the questions below. When answering each question think about a) the basic principles underpinning your learning from this question and b) which curriculum outcome might be related to the question. What factors are responsible for swelling of an infected site? What factors made an infection site red and hot? What causes the white appearance of pus? (clue: think about the cells in the bloodstream) What factors in this patient might make infection more likely? 2 Scenario 2: Jenny Smith aged 32 presented to her GP as an emergency with a 48 hour history of increasing severe pain in her back on the left side. She reported a burning pain on passing urine, with increased frequency, producing only small amounts of urine on each occasion. In the previous 24 hours she had episodes of “burning up” and episodes of uncontrollable shivering lasting five minutes. She had vomited twice in the past 24 hours and found it difficult to keep more than sips of water down. On examination her temperature was 39◦C, pulse 120 per minute, respiratory rate 25 per minute, with marked tenderness in the left loin. Blood pressure was 120/80 mm Hg. Answer the questions below. When answering each question think about a) the basic principles underpinning your learning from this question and b) which curriculum outcome might be related to the question. Why did she develop pain in her back? What might have happened to make her more unwell and confused? What name is given to her uncontrollable shaking attack? What is happening to the thermal control centre of the hypothalamus while this feverish shivering is going on? What evidence of renal tract infection might be produced from dipstick testing? We forgot to tell you that the GP had earlier prescribed an antibiotic (amoxicillin) but it didn’t seem to help her. Try to think of reasons why a prescribed antibiotic might not work – in general, as well as in her case. 3 Scenario 3: Rory, a 17 year old student, was admitted to hospital with a 2 day history of fever, lethargy, vomiting, poor appetite and increasing headache. On examination he had a temperature of 39◦C: he was lucid but irritable, with a purplish-red non-blanching rash, which according to his flatmate was not present when he was seen earlier by the family practitioner. There was no neck stiffness. His pulse rate was 110 per minute, respiration rate 22 and blood pressure 100/70 mm Hg. Haemorrhages were also seen in the whites of his eyes (‘scleral haemorrhages’) Answer the questions below. When answering each question think about a) the basic principles underpinning your learning from this question and b) which curriculum outcome might be related to the question. In the management of this infection, which groups of professionals need to be involved? What samples should be collected to confirm the diagnosis? Before infection this patient would need to be colonised with a virulent strain of the micro-organism. What does ‘colonisation’ mean, and where might be the site of colonisation? How might colonisation eventually lead to infection? What serious complication of infection is appearing in this scenario? How might this also relate to the fact that some severely affected patients with this condition (esp children) can eventually lose hands or feet? 4 Scenario 4: Tracy aged four had always been healthy and was a very happy and sociable member of her nursery school class. An illness seemed to be going round the class however, and early one morning Tracy was found to be hot and feverish, listless and uncooperative, bending up her knees with the pain in her tummy, and producing a couple of loose stools. She became worse during the day: painful diarrhoea continued, and her bowel motions were noted to contain fresh blood and mucus. Just as the GP was called out he received a report that stool samples from other affected children in the class had been found to be positive for Shigella organisms. Answer the questions below. When answering each question think about a) the basic principles underpinning your learning from this question and b) which curriculum outcome might be related to the question. The factors associated with the spread of this type of dysentery are said to be “the four Fs” . What do you think these might be? Antibiotic treatment for Tracy is probably much less important than the management of disordered body homeostasis. What aspects of body homeostasis likely to be most disturbed? Can you think of any reasons why it might not be a good idea to give anti-diarrhoeal treatments like Lomotil to Tracy? 5 Fever area 1/1 Other Infections Here is a nasty infection between the toes (Scenario 1) The right leg has signs of a spreading subcutaneous infection, typical of streptococcus. The red spots on the left leg are a common normal finding. This is a close up picture of quite a severe case of oral thrush – fungal infection at the rear of the palate. Fever area 1/2 Colony cultures of bacteria can be grown in Petri dishes containing appropriate nutrients Dip slide kits containing suitable nutrient material assist in the rapid identification of infecting organisms A rash like this with many small raised red spots or ‘papules’ can occur following a viral infection – this example is like the pattern occurring in measles, and is called ‘morbilliform’ after the latin name for measles. A morbilliform rash like this can also be caused by hypersensitivity to medication. This scan shows an enlarged kidney in a patient suffering from pyelonephritis Fever area 2/1 Meningitis This wee boy is severely ill with meningococcal septicaemia These pictures show examples of the rash which can appear as a consequence of meningococcal septicaemia This is a slide showing severe gram positive infection with diplococci – probably meningitis Fever area 2/2 This post-mortem brain has pus on its surface from inflammation of the meninges – i.e meningitis. Pus like this is perhaps more likely to be the result of pneumococcal meningitis than meningogoccal meningitis These are subconjunctival (scleral) haemorrhages in a case of meningitis, which are analogous to the ‘purpuric’ rash seen on the skin Fever Area 3/1 Fever and Sepsis REGULATION OF BODY TEMPERATURE Human body temperature normally varies throughout a 24 hour cycle, often varying between about 36.0º C or lower in the early hours of the morning to 37.5º C or more in the afternoon, so perfectly healthy individuals can at times have a body temperature higher than the “normal” value of 37.0º C Within this circadian rhythm, however, body temperature is closely regulated by homeostatic mechanisms that balance heat production and heat loss. Heat is a by-product of all metabolic processes; at rest, metabolic activity in the liver and heart produce much of the body’s heat. During exercise, skeletal muscle produces even more heat. Heat is normally lost via the skin - about 90 percent, with the lungs losing most of the remaining 10 percent. At rest, about 70 percent of the body’s heat is lost by radiation and 30 percent lost by insensible perspiration. When there is a rise in the surrounding temperature or when increased metabolism produces extra heat, then increased evaporation from skin, plus heat radiation from dilated blood vessels help to maintain heat balance. The thermal control centre is situated in the preoptic nucleus of the anterior hypothalamus in the brain. This maintains body temperature at a set value, the so-called hypothalamic thermal set point. In response to elevations in core body temperature, the hypothalamus stimulates the autonomic nervous system to cause dilatation of skin blood vessels and sweating. If core body temperature falls, the hypothalamus conserves heat by causing constriction of skin blood vessels. In extreme cold, the hypothalamus acts to increase heat production by stimulating muscular activity in the form of shivering; although this is mediated by the action of somatic nerves, shivering is automatic and involuntary. Fever Area 3/2 DISORDERS OF BODY TEMPERATURE Since antiquity, fever has been appreciated to be a cardinal feature of disease, but understanding of the pathophysiology of fever is much more recent. For more than 100 years, it has been known that pus is pyrogenic (ie causes fever), but only with the work of Dr. Paul Beeson in 1948 did it become clear that the ultimate cause of fever is not a bacterial product (a so-called exogenous pyrogen) but a product of host inflammatory cells (i.e., an endogenous pyrogen). We now know that this is produced by white cells in the bloodstream. The products of white cells which cause fever are called cytokines, and the names of important cytokines include interleukin-1 (IL-1), IL6,interferon gamma, and tumornecrosis factor(TNF). Abnormal elevation of body temperature, or pyrexia, can occur in one of two ways: hyperthermia or fever. In hyperthermia, control mechanisms fail, and heat production exceeds heat loss. In true fever, on the other hand, the hypothalamic thermal set point rises, and intact thermal control mechanisms are brought into play to bring body temperature up to the new set point. Hyperthermia Thermoregulatory homeostasis is influenced by increased heat production, decreased heat dissipation, or hypothalamic insult. During exercise, heat production can increase up to 20-fold, often overwhelming heat dissipation mechanisms. Heavy exercise in hot countries can cause life-threatening heatstroke in which body temperature can rise above 41º C. Some clinical disorders can also result in hyperthermia Treating high temperature So-called antipyretic drugs like aspirin and paracetamol (acetaminophen) can be used in fever because they lower the thermal set point. Fever and hyperthermia can both be treated with physical cooling methods – eg sponging with tepid water, or covering the patient with a wet sheet. Fever Fever is defined as an oral temperature greater than 38º C, although some authorities do not consider a fever significant until the temperature exceeds 38.5º C SEPSIS “Sepsis is an increasing and major health-care problem worldwide. Using data from 91 intensive care units collected between 1995 and 2000, there were estimated to be 51 cases of sepsis per 100,000 population in England, Wales and Northern Ireland over this period. It was also reported that 27% of all admissions to critical care suffered from severe sepsis within the first 24 hours. There was 47% hospital mortality among these patients and they occupied 45% of total hospital critical care bed-days. The incidence of sepsis also appears to be increasing: there has been a 53% increase in the UK between 1996-1997 and 2001-2002.” David Saunders and Simon Baudouin, Clinical Medicine 5: 431-439 2005. Intensive Care Medicine. Fever area 4/1 History Corner MEET YOUR DISTANT COUSINS! The theory of evolution (The Origin of Species, Charles Darwin, 1859) tells us that bacteria and humans had a common ancestor billions of years ago, so the diagram which was handed out last week in the microbiology practical session introduced you to the names of some of your (very) distant cousins. If you’re not sure about evolution, read some of Richard Dawkins’ books, such as “The Blind Watchmaker” and “The Ancestor’s Tale”, and read some of the essays by Stephen Jay Gould. The American biologist Lynn Margulis has argued that the origin of the eukaryotic cell is the result of bacteria being incorporated symbiotically into other bacteria. Mitochondria in animal cells and chloroplasts in plant cells contain their own unique DNA. So it is considered that organelles like mitochondria inside our cells represent a distant evolutionary symbiosis of different bacteria. Endosymbiosis: Lynn Margulis The Modern Synthesis established that over time, natural selection acting on mutations could generate new adaptations and new species. But did that mean that new lineages and adaptations only form by branching off of old ones and inheriting the genes of the old lineage? Some researchers answered no. Evolutionist Lynn Margulis showed that a major organizational event in the history of life probably involved the merging of two or more lineages through symbiosis. Symbiotic microbes = eukaryote cells? In the late 1960s Margulis (left) studied the structure of cells. Mitochondria, for example, are wriggly bodies that generate the energy required for metabolism. To Margulis and others hypothesized that chloroplasts Margulis, they looked remarkably like (bottom) evolved from cyanobacteria (top). bacteria. She knew that scientists had been struck by the similarity ever since the discovery of mitochondria at the end of the 1800s. Some even suggested that mitochondria began from bacteria that lived in a permanent symbiosis within the cells of animals and plants. There were parallel examples in all plant cells. Algae and plant cells have a second set of bodies that they use to carry out photosynthesis. Known as chloroplasts, they capture incoming sunlight energy. The energy drives biochemical reactions including the combination of water and carbon dioxide to make organic matter. Chloroplasts, like mitochondria, bear a striking resemblance to bacteria. Scientists became convinced that chloroplasts (below right), like mitochondria, evolved from symbiotic bacteria — specifically, that they descended from cyanobacteria (above right), the light-harnessing small organisms that abound in oceans and fresh water. When one of her professors saw DNA inside chloroplasts, Margulis was not surprised. After all, that's just what you'd expect from a symbiotic partner. Margulis spent much of the rest of the 1960s honing her argument that symbiosis (see figure, below) was an unrecognized but major force in the evolution of cells. In 1970 she published her argument in The Origin of Eukaryotic Cells The genetic evidence In the 1970s scientists developed new tools and methods for comparing genes from different species. Two teams of microbiologists — one headed by Carl Woese, and the other by W. Ford Doolittle at Dalhousie University in Nova Scotia — studied the genes inside chloroplasts of some species of algae. They found that the chloroplast genes bore little resemblance to the genes in the algae’s nuclei. Chloroplast DNA, it turns out, was cyanobacterial DNA. The DNA in mitochondria, meanwhile, resembles that within a group of bacteria that includes the type of bacteria that causes typhus (see photos, right). Margulis has maintained that earlier symbioses helped to build nucleated cells. For example, spiral-shaped bacteria called spirochetes were incorporated into all organisms that divide by mitosis. Tails on cells such as sperm eventually resulted. Most researchers remain skeptical about this claim. Mitochondria are thought to have descended from close relatives of typhus-causing bacteria. It has become clear that symbiotic events have had a profound impact on the organization and complexity of many forms of life. Algae have swallowed up bacterial partners, and have themselves been included within other single cells. Nucleated cells are more like tightly knit communities than single individuals. Evolution is more flexible than was once believed. Phylogenetic analyses based on genetic sequences support the endosymbiosis hypothesis. text and images from http://evolution.berkeley.edu/evolibrary/article/0_0_0/history_24 Fever area 4/2 CLASSIFICATION OF GRAM POSITIVE ORGANISMS Strep. pneumoniae (pneumonia, meningitis) α-haemolytic Strep. “viridans” (endocarditis) Group A Strep (throat, skin infections) (aka Strep. pyogenes) chains - Streptococci β -haemolytic Group B Strep (neonatal meningitis) cocci non-haemolytic Enterococcus sp.(gut commensal, UTI) coagulase +ve Staph. aureus (wound, skin infections etc.etc) coagulase -ve Staph. epidermidis clusters - Staphylococci Aerobic Corynebacterium diphtheriae (diphtheria) Corynebacterium sp. small bacilli large cocci anaerobic streptococci bacilli Clostridium sp. Anaerobic Diphtheroids (skin commensals) Listeria monocytogenes. (meningitis) Bacillus cereus (food poisoning) Bacillus sp. Bacillus anthracis (anthrax) Cl. tetani (tetanus) Cl. perfringens (gas gangerene) Cl. difficile (antibiotic associated colitis) CLASSIFICATION OF GRAM NEGATIVE ORGANISMS Aerobic (strict) Legionella sp Pseudomonas aeruginosa bacilli Neisseria gonorrhoeae (gonorrhoea) cocci (diplococci) Neisseria meningitidis (meningitis) Aerobic Bordetella pertussis (whooping cough) small Haemophilus influenzae (exacerbation COPD) bacilli E(scherichia) coli gut commensals Klebsiella sp. large (coliforms) Proteus sp. Salmonella sp gut pathogens Shigella sp. E. coli O157 Microaerophilic Small curved bacilli Campylobacter sp Spiral bacilli Helicobacter sp. (gastritis) bacilli cocci (not relevant) Anaerobic (strict) bacilli Bacteroides sp. (gut commensal, wound infection) } }urinary tract infection } }wound infection } Fever area 4/4 SOME TIMELINES TIME EVENT 4,000 million yr ago Formation of the Earth 3,000 million yr ago RNA particles evolve into life forms 2,000 million yr ago First eukaryotic cells produced (cooperation between bacteria?) 1 million yr ago Evolution of mankind 1719 Leeuvenhoek’s single-lens ‘microscope’ – saw microbes from the mouth of an old man who’d never cleaned his teeth 1846 Ignaz Semmelweis (Austria) insisted on hand washing in his maternity unit to prevent ‘childbed fever’ (empirical observation) 1859 Charles Darwin’s ‘Origin of Species’ 1860s Louis Pasteur’s germ theory of disease, based on studies of fermentation in wine and beer, and diseases of silkworms 1870 Joseph Lister (Glasgow) read Pasteur’s theory and prevented gangrene by treating an open fracture with carbolic antiseptic 1880s Proof that diseases like anthrax, tuberculosis, cholera, diphtheria, rabies, were caused by microbial infection. 1880s Pasteur coined the word “virus” (Latin = “poison”) because he considered rabies to be transmitted by a non-living substance. 1884 Hans Christian Gram devised staining, +ve and –ve, based on cell wall structure – became useful 60 yr later in antibiotic selection 1891 First successful use of ‘antitoxin’, developed to cure diphtheria 1901 First Nobel prize - from the profits of dynamite - awarded to Emil von Behring (for diphtheria antitoxin serum therapy) 1910 Paul Ehrlich developed arsenical drugs which could cure syphilis 1918 ‘Spanish flu’ influenza pandemic 1930s ‘Sulphonamide’ antimicrobial drugs used to treat some infections 1940s Penicillin used to treat infections for the first time 1983 Peptic ulceration – a new infectious disease! (Barry Marshall is the 2005 Nobel prizewinner for medicine) 1983 Recognition of viral cause of of HIV infection and AIDS Fever Area 5/1 Antibiotic Treatment TAYSIDE AREA DRUG FORMULARY A drug formulary provides guidance on the appropriate use of medicines, which usually takes account of both clinical effectiveness and cost effectiveness. Here are a few pages copied from the Tayside Area Drug Formulary, which give some guidance on prophylaxis in contacts of a case of meningitis and recommendations for treatment of urinary tract infections Medical students can access this formulary on line from the MESMIS site (B) Haemophilus influenzae B Meningitis Give prophylaxis to household members only where there is a child aged 3 years or under in the same household as the index case. Treat all household members except pregnant or breast feeding women, any person with severe hepatic impairment and children under 3 months. 12 years and over 3 months -12 years Rifampicin 600mg orally, once daily for 4 days Rifampicin 20mg/kg (max. 600mg) orally, once daily for 4 days Meningitis Prophylaxis NB. Inform Consultant in Public Health Medicine (CPHM) with responsibility for the control of infectious disease, at the earliest opportunity. Do not wait for laboratory confirmation. Time is of the essence in contact tracing. In particular, where the clinical suspicion is of Meningococcal meningitis/septicaemia, telephone the CPHM and discuss. N.B. Treatment of the index case with rifampicin prior to discharge is unnecessary where ceftriaxone was used in the treatment of infection. (A) Meningococcal infection Establish a list of close (kissing) household contacts. Give chemoprophylaxis as outlined beloW. Caution is required with pregnancy,breastfeeding, children under the age of three months and any person with severe hepatic impairment. The CPHM can advise. 12 years and over 1-12 years under 1 year Rifampicin Rifampicin Rifampicin 600mg orally, twice daily for 2 days 10mg/kg orally, twice daily for 2 days 5mg/kg orally, twice daily for 2 days Patients taking rifampicin should be advised that it stains body secretions. The urine may turn yellow/orange in colour and soft contact lenses may be similarly discoloured. Also, rifampicin is a potent liver enzyme inducer which, theoretically at least, may enhance the metabolism of oestrogens contained in the combined oral contraceptive. Women taking the pill should be warned that additional precautions are required during their current cycle. In the case of pregnant women, ceftriaxone should be given in a dose of 250mg i.m. stat. The index case should be treated with rifampicin prior to discharge to eliminate carriage but only if ceftriaxone was not used in the treatment of infection. Note: Ciprofloxacin is also known to clear the organism from the throat. The dosage is 500mg orally stat. This Is for adults only. Ciprofloxacin is not licensed for use in children under 12 years. Fever Area 5/2 SELECTIVE TOXICITY Here is an astute observation made by a distinguished British scientist, T H Huxley, 20 years before the origin of chemotherapy and 60 years before the first clinical use of penicillin: “There can surely be no ground for doubting that, sooner or later, the pharmacologist will supply the physician with the means of affecting, in any desired sense, the functions of any physiological element of the body. It will, in short, become possible to introduce into the economy a molecular mechanism which, like a very cunningly contrived torpedo, shall find its way to some particular group of living elements, and cause an explosion among them, leaving the rest untouched. The search for the explanation of diseased states in modified cell life; the discovery of the important part played by parasitic organisms in the etiology of disease; the elucidation of the action of medicaments by the methods and the data of experimental physiology – appear to me to be the greatest steps which have ever been made towards the establishment of medicine on a scientific basis. I need hardly say they could not have been made except for the advance of normal biology” T H Huxley The connexion of the biological sciences with medicine. Lancet 1881 ii 272 SELECTIVE TOXICITY - “MAGIC BULLETS” The expression ‘magic bullet’ has been used to illustrate the concept of selective toxicity of drugs like antibiotics – ideally killing the invading microorganism without harming the host. Antibiotics like penicillin have a uniquely selective effect on the bacterial cell wall – which does not exist in mammalian cells; but other antibiotics which influence protein synthesis inside the cell are perhaps more likely to interfere with similar cellular mechanisms in humans, so can be considered potentially more toxic than penicillin. The term ‘magic bullet’ probably came into public imagination following the appearance of the opera by Carl Maria von Weber called “Die Freischutz” , first performed in 1824, which is a story about a forester/huntsman who obtained magic bullets from the devil to help him to shoot more accurately. All drugs have toxicity problems, so in real life it is the ratio between the effective dose and the toxic dose which matters. This ratio is sometimes called the “therapeutic index” of a drug Increased selective toxicity is of course also the aim of cancer chemotherapy – but it’s even more difficult to kill cancer cells and spare normal cells, but newer treatments continue to refine the management of malignant disease. PSYCHOSOCIAL PRINCIPLES Scenario 1 Remember the original scenario... Mary Mc Donald aged 68 had previously been diagnosed with Type 2 diabetes and hypertension, and had been taking medication for both of these conditions for 10-15 years. She also had a problem with “athlete’s foot” and one of the cracks between her toes became more infected, red and tender. Within a week this had spread up across the dorsum of her foot, which had become red, swollen and painful. She then became hot and confused: her husband called the GP. BUT - you could go further... Mrs Mc Donald is usually well and active and the main carer for her husband who had a “stroke” 5 years ago and has been in a wheelchair since then. They have one daughter who lives and works in the USA. Consider this extended scenario, and think about the problems Mary’s illness may cause not only for her, but also for her family. What factors might the Primary Care Team have to consider with regard to Mary, her husband and her daughter when managing Mary’s condition? The duties of a doctor registered with the General Medical Council are described below. Patients must be able to trust doctors with their lives and well-being. To justify that trust, we as a profession have a duty to maintain a good standard of practice and care and to show respect for human life. Which of the duties listed below must be considered when managing Mary’s illness? In particular as a doctor you must: v make the care of your patient your first concern; v treat every patient politely and considerately; v respect patients' dignity and privacy; v listen to patients and respect their views v give patients information in a way they can understand; v respect the rights of patients to be fully involved in decisions about their care; v keep your professional knowledge and skills up to date; v recognise the limits of your professional competence; v be honest and trustworthy; v respect and protect confidential information; v make sure that your personal beliefs do not prejudice your patients' care; v act quickly to protect patients from risk if you have good reason to believe that you or a colleague may not be fit to practise; v avoid abusing your position as a doctor; v work with colleagues in the ways that best serve patients' interests. Source: GMC Good Medical Practice, third edition 2001) PSYCHOSOCIAL PRINCIPLES Scenario 2 Scenario 2 asks you to consider the case of Jenny: Jenny Smith aged 32 presented to her GP as an emergency with a 48 hour history of increasing severe pain in her back on the left side. She reported a burning pain on passing urine, with increased frequency, producing only small amounts of urine on each occasion. In the previous 24 hours she had episodes of “burning up” and episodes of uncontrollable shivering lasting five minutes. She had vomited twice in the past 24 hours and found it difficult to keep more than sips of water down. On examination her temperature was 39?C, pulse 120 per minute, respiratory rate 25 per minute, with marked tenderness in the left loin. Blood pressure was 120/80 mm Hg. However, Jenny’s past history may be just as revealing as the results of the tests reported above. Previous to this episode Jenny had a history of recurrent urinary tract infections causing a burning pain on passing water and to need to pass urine frequently. They usually resolved when she treated herself by drinking cranberry juice, and she didn’t usually bother the doctor with these symptoms. Jenny felt she could control her symptoms, and didn’t want to waste the doctor’s time as as she didn’t feel she had an illness. ILLNESS OR DISEASE? Illness can be a synonym for disease or it can be a person’s perception of having poor health. Disease is an actual, physical, pathophysiological, diagnosable process which can cause an abnormal condition of the body or mind. Illness and disease are therefore not necessarily the same, and some conditions illustrate clearly the differences (see the box below). This case gives us an opportunity to explore what is meant by disease and illness. Most people who have a disease will feel ill, while others will feel perfectly healthy. A third group (alILLNESS NO ILLNESS though small) may claim illness although they do not actually have a disease. Acute MI HIV DISEASE Influenza Early Cancer Rabies Jenny’s current symptoms, and previous symptoms she has experienced with the same disease are different. What do you think may have have caused Undiagnosable Jenny to experience more illness ths time? Or NO DISEASE Psychosomatic conditions Jenny works from home so doesn’t find needing to pass urine frequently too inconvenient and is happy to give the cranberry juice time to work. J But what if that were not the case. Consider the effects which some of the symptoms of Jenny’s recurrent urinary tract infections would have on her ability to work if she was, for example, a bus driver or a teacher. How do you think this difference in occupation might affect her perception of urinary tract infections as an illness? PSYCHOSOCIAL PRINCIPLES Scenario 3 Preventative Care Rory was a fit young adult probably much like yourself until a few days ago. However he is now seriously unwell with major sepsis. Could this have been avoided? Who else is at risk? Can you think of two distinct strategies that apply here? It is possible that his decisions and behaviour have contributed to him becoming unwell. Many people carry infections but remain well. Why might his risk increase at this time of life? Understanding the whole person The Patient-Centered model (see box on right) suggests that we need to consider not simply the disease/illness but also the person and their context. Look in particular at the area inside the green box, labelled Understanding the whole person. What sort of personal or contextual factors might favour or deter appropriate preventative health in a young student of this age? Can you relate this to the Health Belief Model which you were introduced to in ITA before? The PatientPatient-Centered Clinical Clinical Method Method 1 - Exploring Both Disease and Illness Experience History Physical Lab Person Illness 3 - Finding Common Ground Proximal Context Distal Context • problems • goals • roles 4 - Incorporating Prevention and Health Promotion 6 - Being Realistic Mutual Decisions 5 - Enhancing the PatientPhysician Relationship Perceived severity Perceived benefits Disease Feelings Ideas Function Expectations Perceived susceptibility Demographic variables 2 - Understanding The Whole Person Cues & Prompts Behaviour The Health Belief Model (see box on left) proposes that people will be motivated to carry out protective health behaviours in response to a perceived threat to health. The perceived benefits of a course of action are weighed against the perceived barriers. It also proposes that a trigger event is often necessary to make a person change their behaviour. Perceived barriers Cues to action Self care What is the relevance of this to you? What preventative health options are open to you at present and which have you taken up? Does this differ between you all? Why? PSYCHOSOCIAL PRINCIPLES Scenario 4 Tracy’s illness, whilst potentially serious for her, is a good illustration of how an acute infection of an indivdual patient can be a part of a much bigger picture. In the case of many infectious diseases, it is required that doctors notify cases to a central system of disease surveillance and communication. In Scotland the central agency is The Scottish Centre for Infection and Environmental Health (SCIEH), which is a part of Health Protection Scotland. The sort of data which SCIEH records is illustrated in the box below. Laboratory isolates of Shigella spp. in humans reported to HPS, 1993-2004* Year 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004* Sh sonnei Sh flexneri Sh boydii Sh dysenteriae 613 376 522 150 81 83 65 62 62 61 46 70 34 56 34 24 33 20 20 24 19 13 21 31 18 4 13 7 3 8 3 3 7 3 7 2 0 5 5 1 2 3 0 1 2 0 2 1 *Data for 2004 remain provisional . Source: Health Protection Scotland/SCIEH The information which SCIEH receives is used to alert community healthcare teams to potential outbreaks of infectious disease - such as the Shigella infection mentioned here. The local Health Board’s Public Health directorate will also issue periodic advice, and will send out emergency alerts if necessary. This case also emphasises the importance of working as a part of a wider healthcare team in responding to cases of infectious disease. Rapid communication of the results of the other children’s tests will help the GP in this case to diagnose Tracy’s infection more quickly - he now knows that Shigella is one thing to look for! SCIEH (Data on occurrence and locations of Shigella infections) Health Board Public Health Directorate (Local information and guidance for health professionals) GP and other members of the primary care team It will also make it easier for them to tell all the other parents to look out for symptoms, and to take extra precautions with their children’s personal hygiene, thus helping to prevent the spread of the infection. (reporting cases, treating patients, advising patients and families) Tracy SOME KEY MESSAGES FROM THE ‘FEVER’ ITA SESSION Here is a summary of some of the important learning issues which emerged to varying degrees during discussion in the ITA sessions on ‘fever’: 1. The micro-organisms responsible for the infection in three of the scenarios (cellulitis, urinary tract infection and meningitis) are quite often found as colonising commensals sharing the body of healthy individuals – respectively Staphylococcus aureus/Streptococcus pyogenes, Escherichia coli and Neisseria meningitidis (meningococcus). These three infections occurred as a result of an unfavourable balance between host defence on the one hand, and microbial numbers and their infectivity (“pathogenicity”) on the other, after the organisms have penetrated a part of the body where they don’t ‘normally’ live. 2. We discussed some of the factors which might lead to infective penetration of these three organisms – eg breach of skin integrity (and diabetes) in the case of cellulitis; inadequate hygiene and/or perhaps more motile types of E coli in the case of urinary tract infection; and flu/colds/smoking/changes in pathogenicity in the case of meningitis. 3. In the fourth scenario of bacillary dysentery the Shigella organism is an out-andout pathogen and isn’t found as a commensal organism sharing a healthy body – again transmitted as a result of poor hygiene via faeces/fingers/food/flies/fomites (this fifth ‘F’ means items in the environment which are touched and shared). 4. We discussed the important clinical signs which indicate that an infection is becoming more serious – in other words, no longer localised and on the way towards dangerous septic shock. These clinical signs include increasing fever, rising pulse rate, rising respiratory rate and falling blood pressure. Septic shock happens when inflammation and toxicity of the infection has made the circulation collapse – once blood vessels dilate all through the body, the response of the heart is to increase cardiac output by beating faster, to maintain the circulating blood pressure – so a rising pulse even without an observed fall in blood pressure may be an important danger sign that eventually the cardiac output won’t be able to keep up. 5. We discussed the fact that resetting of the hypothalamus – resulting in fever - is the result of endogenous substances released from the body’s white cells, not from micro-organisms themselves. 6. We pointed out that successful antibiotic treatment illustrates the concept of “selective toxicity” – hitting the infection without harming the host. But an antibiotic has to penetrate via the blood stream to where the infection lies, so if an infection is isolated, for example in a large abscess, effective treatment may also need surgical treatment and drainage as well. Now please take a little time to look at the following: Here are some features of a suspected case of severe meningitis. Look at the list below and decide which of the twelve curriculum outcomes is the most immediately applicable to each situation: You observe a skin rash You know you must see whether the rash blanches under a glass tumbler You palpate the pulse rate You measure the blood pressure You send a sample of cerebrospinal fluid to the microbiology laboratory You realise that you need to inform the public health consultant You realise that the clinical features of meningitis, together with a high temperature, increased respiratory rate, rapid pulse rate and low blood pressure are all leading to a diagnosis of septic shock You administer intravenous penicillin You add your findings to the case notes The nurse tells you that you forgot to wash your hands after completing the examination Meningitis is confirmed and the public health consultant arranges for ‘kissing contacts’ to receive antibiotic treatment