Topnotch Medical Board Prep Preventive Medicine & Public Health Main Handout - April 2024 PDF

TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or https://www.facebook.com/topnotchmedicalboardprep/ This handout is only valid for April 2024 PLE batch. This will be rendered obsolete for the next batch sin...

TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or https://www.facebook.com/topnotchmedicalboardprep/ This handout is only valid for April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. MATCH THE TERM TO THE ACTIVITY THAT BEST DESCRIBES IT. YOU SHOULD MATCH ONLY ONE TERM PER ACTIVITY. 1. Compare food histories between A. Distribution persons with Staphylococcus food B. Determinants poisoning and those without. C. Application 2. Compare frequency of brain cancer among anatomists with frequency in general population 3. Mark on a map the residences of all children born with birth defects within 2 miles of a hazardous waste site 4. Graph the number of cases of congenital syphilis by year for the country 5. Recommend that close contacts of a child recently reported with meningococcal meningitis receive Rifampin 6. Tabulate the frequency of clinical signs, symptoms, and laboratory findings among children with chickenpox in Cincinnati, Ohio Principles of Epidemiology in Public Health Practice Third Edition Answers: BBAACA HIGHLIGHTS IN THE HISTORY OF EPIDEMIOLOGY • Hippocrates (400BC): attempted to explain disease occurrence from a rational rather than a supernatural viewpoint • John Graunt (1662): First to employ quantitative methods in describing population vital statistics – recorded descriptive statistics of birth and death data • Edward Jenner (1796) discovered that it is possible to vaccinate against Small Pox using material from Cow Pox • John Snow investigated a cholera epidemic in mid-19th century in London – “Father of field epidemiology” • Koch (late 1800s): Some diseases are caused by living organisms! Koch’s Postulates! • Framing Heart Study (1949): Risk factors for coronary heart disease • Salk (1954): Polio Vaccine • Doll and Peto (Post WWII): Association between smoking and Lung CA • Eradication of small pox (1980) (Dr. Kurt’s notes, from Dr. Ofelia Saniel’s Intro to Epid Lecture, CPH, UPM) Principles of Epidemiology in Public Health Practice Third Edition • Punitive theory o disease was a punishment meted out by an outraged God for the sins of the individual or the race • Humoral theory o matter is made up of four elements – Earth, Air, Fire and Water and these elements have the corresponding qualities of being Cold, Dry, Hot and Moist o represented in the body by four humors – Phlegm, yellow bile, black bile and blood o According to this theory, the equilibrium among these humors characterizes health (eucrasia), and disequilibrium (dyscrasia) characterizes disease • Miasmatic theory o based on the inference that the air arising from certain kinds of ground, especially low, swampy areas, was a cause of disease • Contagion theory o based on the observation that persons could contract infections even if their humors are normally balanced o Contagion passes from one thing to another and is originally caused by infection of the imperceptible particles. Particles are called the seminaria (seeds or seedlets) of contagion Dr. Mann MODERN VIEWS • Germ Theory o proposed by Louis Pasteur (1822 –1895) and Robert Koch (1843 –1910) o postulates that every human disease is caused by a microbe or germ • BEINGS THEORY o Biologic factors and Behavioral factors o Environmental factors o Immunologic factors o Nutritional factors o Genetic factors o Services, Social factors, and Spiritual factors The acronym BEINGS can serve as a mnemonic device for the major categories of risk factors for disease • Genetic factors are among the most difficult to change • Immunologic factors are usually the easiest to change, if effective vaccines are available. Jekel's Epidemiology, Biostatistics and Preventive Medicine USES OF EPIDEMIOLOGIC STUDIES: • To identify the etiology or cause of the disease • To determine of natural history and prognosis of the disease • Identification of risk factors and high-risk groups • Determination of the extent of disease found in the community • Identification of health programs, adequate measures for diagnosis and treatment and prevention of diseases • Evaluation of effectiveness of existing health programs, therapy and preventive measures CLASSICAL VS. CLINICAL EPIDEMIOLOGY CLASSICAL CLINICAL • Population oriented • Study patients in health care settings rather that in • Studies the community community at large origins of health problems (infectious agents, • Goal is to improve the nutrition, environment, prevention, early detection, behavior, social, economic, diagnosis, treatment, and spiritual prognosis, and care of illness in INDIVIDUAL • Interested in discovering PATIENTS who are at risk risk factors that might be for, or already affected by, altered in a population to specific disease prevent or delay disease, injury, and death In community medicine, using a sociological and anthropological lens is highly encouraged, as compared to clinical medicine. Dr. Mann • MULTIPLE CAUSATION THEORY o >1 factor is required to cause the disease • EPIDEMIOLOGIC TRIANGLE/CHAIN/TRIAD o In this model, disease results from the interaction between the agent and the susceptible host in an environment that supports transmission of the agent from a source à host o Consist of: § Host § Environment § Agent Principles of Epidemiology in Public Health Practice Third Edition • COMPONENT CAUSES AND CAUSAL PIE o An individual factor that contributes to cause disease is shown as a piece of a pie. § Component cause – Individual factors (a piece of pie) § Sufficient cause – The complete pie § Necessary causes – It is component cause or a piece of pie that appears in every pie, because without it disease does not occur Dr. Tan CONCEPTS OF DISEASE TRANSMISSION CONCEPTS ON CAUSATION DISEASES ANCIENT VIEWS • Demonic theory o evil spirit entering the body directly and pursuing nefarious action https://sphweb.bumc.bu.edu TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or email us at [email protected] This handout is only valid for the April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. Page 2 of 77 TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or https://www.facebook.com/topnotchmedicalboardprep/ This handout is only valid for April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. • WEB OF CAUSATION o effects never depend on single isolated cause but rather develop as a result of causation in which each link is the result of a complex genealogy and antecedents SUPPLEMENT: Factors of disease causation Q: In the setting po ba of a patient with HIV/AIDS na admitted due to Pneumonia, is the state of having HIV/AIDS po ba considered as a Predisposing factor, reinforcing factor, or a risk factor? If ever po we’re given a question where we have to choose only 1 option A: Best ang Predisposing factor. Again defining it, predisposing factors are the factors which create a state of susceptibility, making the host vulnerable to the agent. Both risk factors and predisposing factors are associated with an increased likelihood of health-related outcomes, the key difference lies in modifiability. Risk factors can often be modified through lifestyle changes or interventions, while predisposing factors are inherent and typically cannot be changed. In the case of having HIV and AIDS unfortunately it is non-modifiable. Dr. Mann https://www.nhp.gov.in/causation-of-diseases_mtl pitt.edu • THE WHEEL THEORY o de-emphasizes the agent as the sole cause of disease o emphasizes the interplay of physical, biological and social (production) environments. It also brings genetics into the mix o visualizes human disease in the form of a wheel, which has a central hub representing the genetic components and the peripheral portion representing the environmental component. o the outer part (environmental component) has spokes (3 in this model) and the environmental component is thus divided into 3 sub components, representing the social, biological and physical components of the environment COMMUNICABLE DISEASES INFECTIOUS DISEASE • a disease caused by a microorganism and therefore potentially infinitely transferable to new individuals. • May or may not be communicable. o Example of non-communicable: disease caused by toxins from food poisoning or infection caused by toxins in the environment, such as tetanus. COMMUNICABLE DISEASE • an infectious disease that is contagious and which can be transmitted from one source to another by infectious bacteria or viral organisms. CONTAGIOUS DISEASE • a very communicable disease capable of spreading rapidly from one person to another by contact or close proximity Wheel model of human-environment interaction. (Redrawn from Mausner JS, Kramer S: Mausner and Bahn epidemiology: an introductory text, ed 2, Philadelphia, 1985, Saunders.) • LEVER OR BALANCE o Environment is the fulcrum. o Any shift in the lever caused by either factor will result in disequilibrium (disease) PHASES OF A COMMUNICABLE DISEASE PRE-PATHOGENIC PHASE PATHOGENIC PHASE Phase before man is involved; Course of disorder in man preliminary interaction of from the first interaction with potential agent, host and the disease, provoking stimuli environmental factors in to the changes in form and disease production function which result or until equilibrium is reached or Everyone is in the period of recovery, defect, disability or pre-pathogenesis death ensues Process in environment Process in man REQUIREMENTS FOR SUCCESSFUL AGENT INVASION • Conditions in the environment must be favorable to the agent. • Suitable reservoir • Susceptible host • Satisfactory portal of entry • Accessibility of portal of exit from the host • Appropriate means of dissemination and transmission to a new host Factors of disease causation • Predisposing factors are the factors which create a state of susceptibility, making the host vulnerable to the agent. These are age, sex and previous illnesses. • Enabling factors are those which assist in the development of (or in recovery from) the disease, e.g., housing conditions, socio-economic status. • Precipitating factors are those which are associated with immediate exposure to the disease agent or onset of disease, e.g., drinking contaminated water, close contact with a case of pulmonary TB. • Reinforcing factors are those which aggravate an already existing disease, e.g. malnutrition, repeated exposures. • Risk factors are the conditions, quality or attributes, the presence of which increases the chances of an individual to have, develop or be adversely affected by a disease process. The risk factor need not necessarily cause the disease but does increase the probability that the person exposed to the factor may get the disease easily. SUPPLEMENT: Na tanong ito nung nakaraan, yan ang chika so I included this sa handout, try to understand lang the different factors in causation Real life question/scenario ELEMENTS OF A COMMUNICABLE DISEASE © Topnotch Medical Board Prep I - AGENT • Any element, substance, or force whether living or non-living, the presence or absence of which can initiate or perpetuate a disease process. TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or email us at [email protected] This handout is only valid for the April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. Page 3 of 77 TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or https://www.facebook.com/topnotchmedicalboardprep/ This handout is only valid for April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. PHYSICAL /MECHANICAL PHYSICAL: Can disorganize function within cells, tissues, organs and the body as a whole; light; sound; heat; cold; radiation MECHANICAL: Chronic friction & other forces which add unusual stress to body CLASSIFICATION OF AGENTS CHEMICAL AGENTS NUTRIENT AGENTS EXOGENOUS: Chemical substances needed to Arise outside of the host sustain life (CHO, CHON, fats, vitamins, • Inhalation of pollutants water) • Ingestion of contaminants, drugs alcohol • Skin Contact BIOLOGIC AGENTS Living Disease Agents: • Bacteria • Virus • Fungi • Protozoa ENDOGENOUS Produced in human • abnormal products- uremia • Serum cholesterol • Hormone disturbance CHARACTERISTICS OF A LIVING AGENT • INHERENT o Physical make up o Chemical component o Antigenic characteristic – ability of an agent to oppose the effect of chemotherapeutic or antibiotic substance • BIOLOGIC o Viability – ability to withstand adverse environmental influence o Growth Requirements – availability of appropriate nutrition, temperature, etc. o Host range – spectrum of animals’ which an agent can invade or infect CHARACTERISTICS OF AGENTS DIRECTLY RELATED TO MAN (HOST): • INFECTIVITY o ability of the agent to invade and multiply (to produce infection; the minimum number of particles or agents required to establish infection in 50% of a group of hosts of the same species (ID50); depends on the following factors: § Viability § Portal of entry § Susceptibility of the host § Susceptible tissues § Body defenses of the host • PATHOGENICITY – capacity of an agent to induce disease which is clinically apparent in an infected host • VIRULENCE – Ability of an agent to produce serious illness; measured in terms of fatality • IMMUNOGENICITY – The ability of an agent to induce immunity, or to stimulate the host to produce defense mechanism • ANTIGENICITY – the ability to combine specifically with the products or effectors of the immune response CONCEPT OF THE “CHAIN OF INFECTION” • traditional epidemiologic triad model holds that infectious diseases result from the interaction of agent, host, and environment • transmission occurs when the agent leaves its reservoir or host through a portal of exit, is conveyed by some mode of transmission, and enters through an appropriate portal of entry to infect a susceptible host 1. A Causative or etiologic agent ( Infectious agent) 2. A reservoir or source of the causative agent ( Reservoir) 3. A mode of escape from the reservoir ( Portal of Exit) 4. A mode of transmission from the reservoir to the potential new host 5. A mode of entry into the new host ( Portal of Entry) 6. A susceptible host a. Interruption in any stage of the chain, the disease will not develop b. The reservoir and source are identical when transfer is direct from a reservoir to host c. Period of communicability - refers to the time during which an infectious agent can be transmitted directly or indirectly from an infected person to another person, from an infected animal to humans, or from an infected person to animals ✔GUIDE QUESTION Ability of an agent to produce serious illness; measured in terms of fatality A. Immunogenicity B. Antigenicity C. Pathogenicity D. Virulence Mnemonic: “VIRU"lence – Hindi na “BIRU” kasi serious na siya = serious illness. Dr. Virata CHARACTERISTICS OF AGENT DIRECTLY RELATED TO ENVIRONMENT: • RESERVOIR OF INFECTION – man, animals, plants, soil or inanimate organic matter in which an infectious agent multiplies; essential component of the cycle by which an infectious agent maintains and perpetuates itself. • SOURCES OF INFECTION – transfer is often direct from reservoirs à host in which the reservoir is also the source of infection • Carrier status – an infected person who does not have apparent clinical disease but is, nevertheless, a potential source of infection to others • Types of carrier: o Asymptomatic or passive or healthy carriers - those who never experience symptoms despite being infected o Incubatory carriers – those who can transmit the agent during the incubation period before clinical illness begins o Convalescent carriers – those who have recovered from their illness but remain capable of transmitting to others o Chronic carriers – those who continue to harbor a pathogen such as hepatitis B virus or Salmonella Typhi © Topnotch Medical Board Prep SUPPLEMENT: ISOLATION separates sick people with a contagious disease from people who are not sick Isolation would last for the period of communicability of the illness, which varies by disease and the availability of specific treatment. One of the best-known examples of a long-term/chronic carrier was Typhoid Mary, who carried Salmonella typhi. • ISOLATION VS. QUARANTINE QUARANTINE separates and restricts the movement of people who were exposed to a contagious disease to see if they become sick Lasts only as long as necessary to protect the public by: (1) providing public health care (such as immunization or drug treatment/prophylaxis) (2) ensuring that quarantined persons do not infect others if they have been exposed to a contagious disease = known incubation period Dr. Mann TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or email us at [email protected] This handout is only valid for the April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. Page 4 of 77 TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or https://www.facebook.com/topnotchmedicalboardprep/ This handout is only valid for April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. MODE OF TRANSMISSION: • Direct Transmission (person to person) o Direct contact (Touching, biting, kissing & Sexual intercourse) o Droplet spread (spray with relatively large, short-range aerosols produced by sneezing, coughing, or even talking o Contact with soil o Inoculation into skin or mucosa o Transplacental (vertical) • Indirect Transmission o Vehicle borne - objects, food, water, biologic products o Vector borne - mosquitoes, fleas, and ticks o Airborne - dust, droplets carried in air o Fomites VECTORS Vector Aedes sp. Anopheles Culex Sand flies Triatome bugs Lice-body louse Tse-tse flies Blackflies Ticks Mites Synanthropic flies Cockroaches Rodents Snails Pigs Fleas © Topnotch Medical Board Prep Regarding sa transmission of different pathogens, there can be more than 1. Example is covid-19, pwedeng airborne, fomites and even shedding of the virus from the stool. In rabies, it can be BOTH placed in direct contact (dog bite) or through inoculation into skin or mucosa (dog licks a broken wound or though mucous membranes in the eyes, nose or mouth). In Leptospirosis, exposure can also be BOTH direct contact by skin to skin with an infected animal (this explains why occupations such as veterinarian, farm workers, and those who handles animals in laboratories are at risk) or inoculation into the skin or mucosa (when the urine from the infected animals gets in contact to a human). In the exam, the answer would depend on how is it asked (if it’s a casebased question). Pwede ang rabies both for direct contact and inoculation, for leptospirosis applicable for direct contact and inoculation. Dr. Mann • DROPLETS VS. AIRBORNE TRANSMISSION Distance Size of droplets Suspended in air • Droplets Shorter (hence considered direct contact) >5μm No Airborne Longer <5μm Yes Dr. Virata EXAMPLES OF MODE OF TRANSMISSION Vector Disease Direct Transmission Sexually transmitted diseases (STD), Direct contact HIV, Leprosy , Leptospirosis Tuberculosis, Whooping cough, Droplet spread Diphtheria, and respiratory infections Contact with soil Tetanus, Hookworm larvae Inoculation into Rabies and Hepatitis B skin or mucosa TORCH (Toxoplasma, Rubella, Transplacental or Cytomegalovirus, Herpes virus), vertical Hepatitis B, Coxsackie B, HIV, Syphilis, and Varicella Indirect transmission Water – typhoid fever, cholera, polio, hepatitis A Vehicle born Blood- Hepatitis B, malaria, syphilis Organ transplantation cytomegalovirus Vector-borne See table for vector-borne diseases Tuberculosis, influenza, chicken pox, Airborne measles, and Q fever Diphtheria, typhoid fever, bacillary Fomites dysentery, hepatitis A Disease Dengue, Chikungunya, filariasis, zika Malaria Filariasis, Japanese encephalitis, west Nile fever Leishmaniasis Chagas disease (American trypanosomiasis) Typhus fever Sleeping sickness (African trypanosomiasis) Onchocerciasis Lyme disease, rickettsial diseases (spotted and Q fever) Scabies Dysentery, yaws Diarrheal diseases, Intestinal, skin and eye infections Leptospirosis Intermediate host for schistosomiasis Trichinosis Bubonic plague FACTORS AFFECTING COMMUNICABILITY OF BACTERIA • Site of lesion of infected host • Size of inoculum • Chance/ accident of coming in contact with bacterial species or strain • Survival capacity in immune subjects • Ability to survive outside animal body • Ability to multiply and survive in intermediate host or vector • Size of reservoir of infection II – HOST • Individual or other living animal exposed to the agent that affords subsistence or lodgment. • Final outcome may vary from complete recovery to death of the host. STAGES IN THE NATURAL HISTORY OF DISEASE • STAGE OF SUSCEPTIBILITY: o Disease has not developed but the groundwork has been laid by the presence of factors that favor its occurrence o Portal of entry o Risk factors • STAGE OF PRE-SYMPTOMATIC DISEASE: o No manifestation of the disease yet but pathogenic changes have started to occur o Incubation period o Ex: Atherosclerotic changes in coronary vessels prior to any signs and symptoms • STAGE OF CLINICAL DISEASE: o End organ damage has occurred so that there are recognizable signs or symptoms of the disease o The clinical horizon • STAGE OF DISABILITY: o Any limitation in a person’s activities including psychosocial role © Topnotch Medical Board Prep TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or email us at [email protected] This handout is only valid for the April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. Page 5 of 77