EXAM 3 STUDY GUIDEChapter 14: Principles of Disease and Epidemiology: Lecture 20- Define pathology, etiology, infection, and disease.o Pathology is the scientific study of disease.o Etiology is the cause of disease.o Infection is the invasion or colonization of the body by pathogenic microorganisms.o Disease occurs when an infection results in any change from a state of health, partor all of the body is not functioning normally.- Define normal, transient microbiota, and opportunistic infections.o Normal microbiota are microorganisms that establish more or less permanent residence in the body (colonize) but that do not produce disease under normal conditions.o Transient microbiota may be present in the body for several days, weeks, or months and then disappear.o Opportunistic infections ordinarily do not cause disease in their normal habitat in a healthy person but may do so in a different environment.- Compare commensalism, mutualism, and parasitism.- Commensalism: only one benefits, other is not harmed (most microbes in our body)- Mutualism: Both host and parasite could benefit from each other (hermit crab)- Parasitism: host is harmed, microbes take advantage (virus)- Understand Koch’s postulates and the exceptions.o Used the prove the cause of an infectious disease- The same pathogen must be present in every case of the disease- The pathogen must be isolated from the disease host and grown in pure culture- The pathogen from the pure culture must cause the disease when it is isolated into a healthy, susceptible laboratory animal- The pathogen must be isolated from the inoculated animal and must be shown to be the original organism- Exceptions: Some microbes has unique culture requirements, the bacterium causing syphilis has never been cultured on artificial media. - EXCEPTIONS: Treponema pallidum causes syphilis but cant be plated. Mycobacterium leprae causes leprosy and has never been grown on artificial media. Some cant be plated, some cause several disease conditions, some pathogens cause different diseases, also it would mean some people could be inoculated with infectious diseases/- Sometimes several different pathogens cause the same signs and symptoms- Some pathogens cause several different disease conditions- Pathogens that cause disease in humans and no other known host (AIDS)- Some take years to develop (HPV takes years to cause cancer due to mutations that must take place)- Understand predisposing factors for disease.o A predisposing factor is one that makes the body more susceptible to a disease and may alter the course of the disease. These are gender, genetic background, climate and weather, inadequate nutrition, fatigue, age, environment, habits, lifestyle, occupation, preexisting illness, chemotherapy, and emotional disturbances.- Define reservoir of infection.o Reservoir of infection: continual source of the disease organisms, living organism or inanimate object that provides a pathogen with adequate conditions for survivaland multiplication and an opportunity for transmission (human, animal, or nonliving) o Human Reservoirs: can harbor pathogens and transmit to others. - Carriers have unapparent infections for which no signs or symptoms are ever exhibited- Play an important role in the spread of diseases such as AIDs, diphtheria typhoid fever, hepatitis, gonorrhea, amoebic dysentery, and streptococcal infectionso Animal Reservoirs: - Both wild and domestic - Diseases transmitted from animals to humans called zoonoseso Rabies, lyme diseaseo Direct contact with infected animalo Directed contact with domestic animal wasteo Contamination of food and watero By air (hides, fur or feathers)o Infected animal products (food)o Insect vectorso Nonliving Reservoirs- Soil and watero Fungi (ringworm)o Gastrointestinal diseaseso Botulism, tetanus - Food that has been improperly stored or prepared (salmonella)- Explain three methods of disease transmission.- Three principal routes: contact, vehicles, vectorso Contact Transmission is the spread of an agent of disease by direct contact, indirect contact, or droplet transmission.o Direct contact transmission: (person-to-person) is the direct transmission of an agent by physical contact between its source and a susceptible host. No intermediate object. Touching, kissing, sexual intercourse Respiratory tract infections, staph infections, hepatitis A, measles, scarlet fever, STIs, AIDSo Indirect: when the agent if disease is transmitted from its reservoir to a susceptiblehost by means of a nonliving object (fomite) Tissues, towels, bedding, drinking cups, toys, money, contaminated syringes (AIDS)- Tetanuso Droplet: microbes are present in droplet nuclei that travel only short distances Coughing, sneezing, laughing, talking Not regarded as airborne Influenza, pneumonia, pertussis- Vehicles: transmission by an inanimate reservoir o Water, food, airo Blood, other body fluids, drugso Waterborne: untreated or poorly treated sewage Cholerao Foodborne: incompletely cooked, poorly refrigerated, unsanitary conditions Food poisoning, tapewormo Airborne: droplet nuclei in dust (more than 1 meter) Discharged from mouth and nose Measles, tuberculosis Dust particles, fungi spores- Vectors: animals that carry pathogens from one host to anothero Arthropodso Mechanical transmission: passive transport of the pathogen on the insect’s feet orother body parts Contacts with host’s food Houseflies Typhoid fever, dysenteryo Biological Transmission: an active process Arthropod bites and infected person or animal and ingests some of infected blood (fleas, ticks, mosquitoes) Pathogens reproduce in the vector and increase the number of pathogens Some parasites reproduce in gut of arthropod, passed with feces- Defecates or vomit while biting potential host, parasite can enter wound- If parasites migrate to salivary glands of arthropod and directly injected into bite- Define epidemiology.o Epidemiology is the science that studies when and where diseases occur and how they are transmitted in populations.- Know the contribution of John Snow, Ignaz Semmelweis, and Florence Nightingale.- Epidemiology: science that studies when and where diseases occur and how they are transmitted in populationso Relationship between human and agento Epidemicso Occurrence, distribution, control and prevention- John Snow: mapped the occurrence of cholera in Londono Concluded that contaminated water
View Full Document
Unlocking...