Principle of Disease and Epidemiology – Flashcards
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| Pathology |
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| Study of disease |
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| Etiology |
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| Study of the cause of a disease |
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| Pathogenesis |
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| Development of disease |
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| Infection |
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| Colonization of the body by pathogens |
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| Disease |
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| An abnormal state in which the body is not functioning normally |
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| Normal Microbiota Human eye - conjunctiva |
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| Staph; Streptococci;Coagulase-neg Staph; Haemophilus spp |
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| Normal Microbiota (Nose) |
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| Viridians Strep;Coagulase-neg Staph; Nesseria spp.; Haemophilus spp |
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| Normal Microbiota (Stomach) |
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| Staph; Strep;Lactobacillus;Peptostrep |
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| Normal Microbiota (Large intestine) |
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| Staph; Fusobac spp;Klesiella; Escherichia coli |
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| Normal Microbiota (Urethra) |
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| Myco spp; Coagulase-neg staph; Peptostrep;Diphtheroids |
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| Normal Microbiota (Outer ear) |
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| Pseudomonas spp; Enterobac; Diphtheroids; |
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| Normal Microbiota (Mouth and Oropharynx) |
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| Viridians Strep; Fusobac spp; Actinomyces spp; Candida spp |
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| Normal Microbiota (small intestine) |
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| Clostridium spp; Entero;Lacto Myco spp |
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| Normal Microbiota (Vagina) |
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| Candida spp; Garnerella vaginulis; Bacteriodes spp; Lacto spp |
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| Normal Microbiota (Skin) |
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| Malassezia furfur; Bacillus spp; Staph Au; Candida |
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| Respiratory tract |
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| 1) Normally, no microbiota 2) Action of ciliated epithelial cells 3) Alveolar macrophages |
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| Oral Cavity |
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| Bacteria present; Streptococcus ; Neisseria ; Actinomyces ; Veillonella ; Lactobacillus ; Some yeasts |
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| Stomach |
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| Low microbial content (<10/g) due to acid (pH2-3) |
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| Large intestine |
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| High microbial content (1012/g) Many anaerobes Many facultative anaerobes (Escherichia) |
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| Genitourinary tract |
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| 1) Upper regions (kidneys, ureters, and urinary bladder) are usually free of microbes 2) A few bacteria present in distal portion of urethra 3) Adult female genital tract has complex microbiota 4) Plays a significant role in health -- Lactobacillus acidophilus (Doderleins bacilli) keep pH of vagina low |
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| Koch's Postulates |
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| are used to prove the cause of an infectious disease. It must be isolated from the host and grown in pure culture. It must reproduce the original disease when introduced into a susceptible host. It must be found in the experimental host so infected. |
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| Symptom |
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| A change in body function that is felt by a patient as a result of disease |
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| Sign |
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| A change in a body that can be measured or observed as a result of disease. |
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| Syndrome |
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| A specific group of signs and symptoms that accompany a disease. |
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| Communicable |
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| A disease that is easily spread from one host to another. |
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| Incidence |
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| Fraction of a population that contracts a disease during specific time. |
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| Prevalence |
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| Fraction of a population having a specific disease at a given time. |
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| Sporadic disease |
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| Disease that occurs occasionally in a population. |
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| Endemic disease |
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| Disease constantly present in a population. |
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| Epidemic disease |
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| Disease acquired by many hosts in a given area in a short time. |
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| Pandemic disease |
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| Worldwide epidemic. |
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| Herd immunity |
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| Immunity in most of a population. |
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| Acute disease |
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| Symptoms develop rapidly |
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| Chronic disease |
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| Disease develops slowly |
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| Subacute disease |
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| Symptoms between acute and chronic |
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| Latent disease |
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| Disease with a period of no symptoms when the patient is inactive |
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| True pathogens |
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| capable of causing disease in healthy persons with normal immune defenses |
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| Opportunistic pathogens |
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| cause disease when the host’s defenses are compromised or when they grow in part of the body that is not natural to them. ex P. sp & candida albicans |
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| Toxemia |
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| Toxins in the blood |
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| Viremia |
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| Viruses in the blood |
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| Primary infection |
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| Acute infection that causes the initial illness |
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| Secondary infection |
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| Opportunistic infection after a primary (predisposing) infection |
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| Subclinical disease |
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| No noticeable signs or symptoms inapparent infection) |
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| Local infection (Host) |
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| Pathogens limited to a small area of the body |
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| Systemic infection (Host) |
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| An infection throughout the body |
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| Focal infection |
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| Systemic infection that began as a local infection |
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| Bacteremia |
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| Bacteria in the blood |
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| Septicemia |
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| Growth of bacteria in the blood |
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| Infectious disease |
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| a departure from the normal state of health due to the presence or growth of a microorganism |
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| Pathogen |
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| a parasite that causes disease |
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| Virulence |
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| the ability to cause disease Low virulence - common cold High Virulence -rabies |
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| Invasiveness |
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| ability of the pathogen to spread to adjacent or other tissues |
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| Infectivity |
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| the ability of an organism to establish a focal point of infection |
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| Toxigenicity |
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| is the pathogens ability to produce toxins |
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| LD50 or ID50 |
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| Lethal dose 50 or infective dose 50 |
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| Incubation period |
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| No sign or symptoms |
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| Prodromal period |
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| Mild signs or symptoms |
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| ID (Infectious Dose) |
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| -minimum number of microbes required for infection to proceed -microbes with small IDs have greater virulence 1 rickettsial cell in Q fever 10 bacteria in TB, giardiasis 10 to 9 bacteria in cholera - Lack of ID will not result in infection |
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| Portal of entry |
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| Skin GI tract Respiratory tract Urogenital tract |
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| Contact Transmission of Disease |
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| Direct (close assoc) Indirect (by fomites) Droplet (via airborne) |
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| Vehicle (Transmission of Disease) |
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| Transmission by an inanimate reservoir (food, water) |
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| Vector (Transmission of Disease) |
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| Arthropods, especially fleas, ticks, and mosquitoes |
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| Mechanical (Transmission of Disease) |
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| Arthropod carries pathogen on feet |
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| Biological (Transmission of Disease) |
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| Pathogen reproduces in vector |
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| Nosocomial Infections |
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| are the infections acquired during hospital stay |
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| UTI (Nosocomial Inf) |
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| Most common, about 34% of all nosocomial inf. related to urinary catheterization |
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| Cutaneous Nosocomial Inf |
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| Least common but have high rate in newborns |
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| Morbidity |
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| incidence of a specific notifiable disease |
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| Mortality |
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| deaths from notifiable diseases |
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| Morbidity rate |
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| number of people affected/total population in a given time period |
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| Mortality rate |
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| number of deaths from a disease/total population in a given time |
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| LD50 |
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| Lethal dose (of a toxin) for 50% of the test population |
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| ID50 |
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| Infectious dose for 50% of the test population |
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| Mechanism of adhesion |
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| fimbrae, flagella, adhesive slimes or capsules Cilia, Suckers, Hooks ,barbs Nonspecific adhesion due to hydrophilic interactions, |
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| exoenzymes (virulence factor) |
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| digest epithelial tissues & permit invasion of pathogens |
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| endotoxins |
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| lipid A of LPS of gramnegative bacteria |
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| exotoxins |
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| proteins secreted by grampositive and gram-negative bacteria |
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| antiphagocytic factors |
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| help bacteria to kill or avoid phagocytes, include leukocidins and capsules |
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| Coagulase (enzyme) |
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| Coagulate blood |
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| Kinases |
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| Digest fibrin clots |
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| Hyaluronidase |
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| Hydrolyses hyaluronic acid |
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| Collagenase |
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| Hydrolyzes collagen |
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| IgA proteases |
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| Destroy IgA antibodies |
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| Siderophores |
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| Take iron from host iron- binding proteins |
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| Antigenic variation |
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| Alter surface proteins |
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| Toxin |
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| Substances that contribute to pathogenicity |
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| Toxigenicity |
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| Ability to produce a toxin |
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| Toxemia |
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| Presence of toxin in the host's blood |
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| Toxoid |
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| Inactivated toxin used in a vaccine |
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| Antitoxin |
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| Antibodies against a specific toxin |
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| A-B toxins |
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| Superantigens Cause an intense immune response due to release of cytokines from host cells |
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| Membrane-disrupting toxins or type II toxins |
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| Lyse host’s cells by: • Making protein channels in the plasma membrane (e.g., leukocidins, hemolysins) |
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| Portals of Exit |
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| Resp tract -coughing, sneezing GI tract -feces, saliva Genitourinary tract -urine, vaginal secretions Skin Blooc -biting arthropods, needles/syringes |
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| localized infection |
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| microbes enters body & remains confined to a specific tissue |
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| systemic infection |
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| infection spreads to several sites and tissue fluids usually in the bloodstream |
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| focal infection |
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| when infectious agent breaks loose from a local infection and is carried to other tissues |
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| Endotoxins |
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| are part of the outer potion of the cell wall (lipd A) of gram - bacteria. They are liberated when the bacteria die and the cell wall breaks apart. |
