Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
© 2010 Jones and Bartlett Publishers, LLC Chapter 3 Practical Disease Concepts in Epidemiology © 2010 Jones and Bartlett Publishers, LLC World Clock © 2010 Jones and Bartlett Publishers, LLC Objective: Define disease Disease is an interruption, cessation, or disorder of body functions, systems, or organs Diseases arise from infectious agents, inherent weaknesses, lifestyle, or environmental stresses Environment – all that is external to the human host (physical, biological, social, cultural, etc.) © 2010 Jones and Bartlett Publishers, LLC Causes of disease Identifying the causes of disease and the mechanisms by which they spread remains a primary focus in epidemiology The science and study of the causes of disease and their mode of operation is referred to as etiology © 2010 Jones and Bartlett Publishers, LLC Objective: Classify acute and chronic diseases according to infectivity and communicability When an infectious disease is contagious, or capable of being communicated or transmitted, it is called a communicable disease HIV/AIDS Cholera Influenza Cryptosporidiosis © 2010 Jones and Bartlett Publishers, LLC Objective: Identify various classifications of disease and their sources and modes of transmission Two types of transmission Vertical transmission refers to transmission from an individual to its offspring through sperm, placenta, milk, or vaginal Horizontal transmission refers to transmission of infectious agents from an infected individual to a susceptible contemporary © 2010 Jones and Bartlett Publishers, LLC Pathogens Organisms or substances such as bacteria, viruses, fungi, or parasites that are capable of producing diseases The ability to get into a susceptible host and cause disease is termed invasiveness The disease-evoking power of a pathogen is called virulence Toxins – kill pathogens by poisoning them. Antibiotics work against pathogens because of their toxicity © 2010 Jones and Bartlett Publishers, LLC Classifications of diseases 1. Acute – disorder with sudden onset, relatively severe, and short duration of symptoms 2. Chronic – less severe but of long and continuous duration, lasting over long time periods if not a lifetime © 2010 Jones and Bartlett Publishers, LLC Questions Are all infectious diseases communicable? What is an example of a chronic communicable disease? What is an infectious disease that is chronic? © 2010 Jones and Bartlett Publishers, LLC Examples of diseases according to selected classifications Communicable Acute Infectious Noninfectious Influenza/ pneumonia Lyme disease Mumps Measles Cholera Chronic Cancer Leprosy Polio Syphilis Tuberculosis Non-communicable Acute Chronic Tetanus Legionnaire s Anthrax Accidents Drug abuse Homicide Stroke Suicide Alcoholism Cancer Diabetes mellitus Heart diseases Paralysis © 2010 Jones and Bartlett Publishers, LLC Objective: Understand the major stages in the disease process Stages relevant to most health-related states or events 1. Stage of susceptibility 2. Stage of pre-symptomatic disease • • Incubation period Latency period 3. Stage of clinical disease 4. Stage of recovery, disability, or death © 2010 Jones and Bartlett Publishers, LLC Natural course of communicable disease © 2010 Jones and Bartlett Publishers, LLC Guinea Worm Guinea Worm (Dracunculiasis) © 2010 Jones and Bartlett Publishers, LLC Centers for Disease Control and Prevention, “Locally acquired neurocysticercosis— North Carolina, Massachusetts, and South Carolina, 1989–1991.” Morbidity and Mortality Weekly Report, Public Health Services, U.S. Department of Health and Human Services, Vol. 21, No. 1, Jan. 10, 1992, pp. 1–4. © 2010 Jones and Bartlett Publishers, LLC Breaking the cycle Viability – the capacity of the pathogen or disease-causing agent to survive outside the host and to exist or thrive in the environment. Viability – guinea worm is 1 year. Solution: Break the cycle for 1 year. © 2010 Jones and Bartlett Publishers, LLC Objective 5. Know the five major categories of disease Congenital and hereditary diseases Familial tendencies toward certain inborn abnormalities Injury to the embryo or fetus by environmental factors Examples – Down syndrome, hemophilia, heart disease at an early age Allergies and inflammatory diseases Body reacting to an invasion of or injury by a foreign object or substance Degenerative diseases Deterioration of body systems, tissue, and functions Metabolic diseases Cause the dysfunction, poor function, or malfunction of certain organs or physiological processes within the body leading to disease states. Example – cells may no longer utilize glucose normally causing diabetes Cancer Characterized by abnormal growth of cells that form a variety of tumors, both benign and malignant © 2010 Jones and Bartlett Publishers, LLC Common modes of entry into the body of infectious disease agents 1. Respiratory 2. Oral 3. Reproductive 4. Intravenous 5. Urinary 6. Skin 7. Gastrointestinal 8. Conjunctival 9. Transplacental © 2010 Jones and Bartlett Publishers, LLC Objective: Identify the role of zoonoses in communicable disease in humans Animals can be the host, vector, or source of certain infections and diseases. A zoonosis (plural zoonoses) is an infectious organism in vertebrate animals (e.g., rabies or anthrax) that can be transmitted to humans through direct contact, a fomite, or vector. The word comes from the Greek words zoon (animal) and nosos (ill). © 2010 Jones and Bartlett Publishers, LLC Common zoonotic diseases AIDS Amebiasis Anthrax Bovine papular stomatitis Brucellosis California encephalitis Cat-scratch fever Colorado tick fever Cowpox Dengue fever Dermatophilosis Leprosy Lyme disease Pasteurellosis Plague Q-fever Rabies Rat-bite fever Rickettsialpox Rocky mountain spotted fever Salmonellosis Shigellosis Streptococcus infections Tetanus Trichinosis Tularemia Yellow fever Zoonotic scabies © 2010 Jones and Bartlett Publishers, LLC Objective: Discuss notifiable disease reporting in the United States Notifiable diseases are those of considerable public health importance because of their seriousness. Such diseases Cause serious morbidity or death Have the potential to spread Can be controlled with appropriate intervention © 2010 Jones and Bartlett Publishers, LLC Objective: Immunity and immunizations against infectious diseases According to the Centers for Disease Control and Prevention, if fewer than 80% of the children in a given area have been inoculated for one of the contagious diseases, the danger of serious outbreaks or localized epidemics remains; every unvaccinated child is at risk © 2010 Jones and Bartlett Publishers, LLC Active and passive immunity Active immunity - the body produces its own antibodies. This can occur through a vaccine or in response to having a specific disease pathogen invade the body Passive immunity is acquired through transplacental transfer of a mother’s immunity from diseases to the unborn child © 2010 Jones and Bartlett Publishers, LLC Diseases for which vaccines are used Anthrax Cervical Cancer (HPV) Cholera Chickenpox Diphtheria German measles (rubella) Haemophilus influenzae type b (Hib) Hepatitis A Hepatitis B Influenza Japanese encephalitis Lyme disease Measles Meningitis Mumps Pertussis Plague Pneumonia Polio Rabies Smallpox Spotted fever Tetanus Tuberculosis Typhoid fever Typhus Whooping cough Yellow fever © 2010 Jones and Bartlett Publishers, LLC Smallpox If smallpox were introduced into our classroom… © 2010 Jones and Bartlett Publishers, LLC Herd immunity Viewed as the resistance a population has to the invasion and spread of an infectious disease Based on the notion that if a population or group is mostly protected from a disease by immunizations (say 80% or more) , then the chance of a major epidemic occurring is highly limited © 2010 Jones and Bartlett Publishers, LLC Estimated Herd Immunity thresholds for vaccine preventable diseases Diptheria 85% Polio 80-86% Measles 83-94% Mumps 75-86% Pertussis 92-94% Rubella 80-85% Smallpox 83-85% © 2010 Jones and Bartlett Publishers, LLC Objective: Identify the changing emphasis of epidemiologic study Increasing life expectancy in modern times and higher levels of chronic disease has produced a change in the emphasis of epidemiologic studies © 2010 Jones and Bartlett Publishers, LLC Percentage of deaths attributed to selected infectious and chronic diseases in the United States © 2010 Jones and Bartlett Publishers, LLC Host-related control and prevention Isolation applies to persons who are known to be ill with a contagious disease. It is often conducted on an inpatient basis in hospitals or nursing homes. Most state laws as well as accrediting organizations require one or two beds to be kept, designated, and equipped in a hospital or nursing home as isolation beds. © 2010 Jones and Bartlett Publishers, LLC Host-related control and prevention Quarantine applies to persons who have been exposed to a contagious disease but may or may not become ill. These people may not know whether they have been exposed to a disease or they may have the disease but not manifest clinical symptoms (e.g., Typhoid Mary). Quarantine may also refer to situations where a building, cargo, conveyance, or animal may be believed to be exposed to a dangerous contagious disease and is, therefore, closed or kept apart from others in order to prevent the spread of disease. Quarantine has been used throughout history to stop the spread of disease. Quarantine was probably the first public health measure to show a marked level of effectiveness in controlling the spread of disease. In the late 1800s and early 1900s, quarantine activities became an organized effort by government officials, and this had a major impact on improving the health status of the community, especially with regard to mortality statistics. In modern times, quarantine measures are still in use. Currently, the WHO invokes quarantine measures for three diseases: cholera, plague, and yellow fever. © 2010 Jones and Bartlett Publishers, LLC Objective: Be familiar with common nutritional deficiency diseases and disorders Malnutrition - a condition that arises when the body does not get the right amount of vitamins, minerals, and other nutrients to maintain healthy tissues and proper organ function. Malnutrition occurs in people experiencing either undernutrition or over-nutrition. © 2010 Jones and Bartlett Publishers, LLC Malnutrition syndromes Kwashiorkor (protein deficiency) Marasmus (protein-calorie malnutrition, chronic undernutrition) Iron-deficiency anemia Folic acid-deficiency anemia Vitamin B12-deficiency anemia Xerophthalmia (vitamin A deficiency) Endemic goiter (iodine deficiency) Beriberi (thiamine deficiency) Ariboflavinosis (riboflavin deficiency) Pellagra (niacin and amino acid tryptophan deficiency) Scurvy (vitamin C deficiency) Rickets (vitamin D deficiency) Tetany (mineral deficiency) Osteomalacia and osteoporosis (impaired calcium and phosphorus metabolism affecting bone formation) © 2010 Jones and Bartlett Publishers, LLC Undernutrition A consequence of consuming too little essential vitamins, minerals, and other nutrients or excreting them faster than they can be replenished. Inadequate intake may result from excessive dieting, severe injury, and serious illness. Excessive loss may result from diarrhea, heavy sweating, heavy bleeding, or kidney failure. © 2010 Jones and Bartlett Publishers, LLC Overnutrition The consumption of too much food, eating too many of the wrong things, too little physical activity and exercise, or taking too many vitamins or dietary supplements. © 2010 Jones and Bartlett Publishers, LLC Objective: Be familiar with selected chronic diseases and conditions Cardiovascular disease, cancer, chronic obstructive pulmonary disease, diabetes mellitus, and mental health disorders Chronic diseases are not typically caused by an infectious agent (pathogen), but result from genetic susceptibility, lifestyle, or environmental exposures Some exceptions are cancers of the cervix, liver, and stomach © 2010 Jones and Bartlett Publishers, LLC Characteristics of chronic diseases The latency period for chronic diseases is typically more difficult to identify than is the incubation period for acute infectious diseases This explained by the multifactorial etiology which characterizes many chronic diseases Multifactorial Nature of Chronic Disease © 2010 Jones and Bartlett Publishers, LLC Disability Umbrella term for impairments, activity limitations, and participation restriction Impairments - any loss or abnormality of psychological, physiologic, or anatomic structure or function Activity limitations are difficulties an individual may have in executing activities Participation restrictions are problems an individual may experience in involvement in life situations © 2010 Jones and Bartlett Publishers, LLC