Chapter 14: Infection, Infectious Diseases, and Epidemiology.

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Microbes live in Symbiotic relationships.. what are the types?
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Mutualism (both members benefit) Parasitism (parasite benefits while the host is harmed) Commensalism (One member benefits while the other is relatively unaffected)
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Pathogen
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Any parasite that causes disease
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Noraml Microbiota
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organisms that live in and on the body. Some are resident and others are transient.
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Opportunistic Pathogens
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cause disease when the immune system is suppressed, when normal microbial antagonism (competition) is affected by certain changes in the body, and when a member of the normal microbiota is introduced into an area of the body unsual for that microbe.
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Reservoirs of infection
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Living and nonliving continous sources of infectious disease.
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zoonotic diseases (zoonoses)
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diseases of animals that may be spread to humans via direct contact with the animal or its waste products, or via an arthropod. Humans may be asymptomatic carriers.
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Nonliving reservoirs
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infection include soil, water, and inanimate objects.
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Microbial contamination
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refers to the mere presense of microbes in or on the body or object. They include harmless resident and transient members of the microbiota, as well as pathogens, which after a successful invasion cause an infection.
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Portals of entry of pathogens into the body
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skin, mucous membranes, the placenta, and the parenteral route, by which microbes are directly deposited into deeper tissues.
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Adhesion
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Pathogens attach to cells via a variety of structures or attachment proteins called adhesion factors. Some bacteria and viruses lose the ability to make a adhesion factors called adhesions and thereby become avirulent.
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Biofilm
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some bacteria interact to produce a sticky web of cells and polysaccharides that adheres to a surface.
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Morbidity
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AKA disease- a condition sufficiently adverse enough to interfere with normal functioning of the body.
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Symptoms versus Signs
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subjectively felt by patient / outside observable
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Syndrome
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a group of symptoms and signs that collectively characterizes a particular abnormal condition.
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Asymptomatic or subclinical infections
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may go unnoticed because of the absense of symptoms, even though clinical tests might reveal signs of disease.
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Etiology
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the study of the cause of a disease
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Kochs Postulates
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a series of essential conditions to prove the cause of infectious diseases. Some circumstances can make the use of these postulates difficult or even impossible.
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Pathogenicity
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a microorganisms ability to cause disease
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Virulence
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degree of pathogenicity.
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Virulence Factors affect the relative ability of a pathogen to infect and cuase disease. What are the factors?
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adhesion factors extracellular enzymes toxins antiphagocytic factors
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Toxemia
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the presense of poisons called toxins in the blood
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Exotoxins
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secreted by pathogens into their environment
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Endotoxins (lipid A)
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released from the cell wall of dead and dying Gram-negative bacteria and can cause fatal effects.
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Antitoxins
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antibodies the host forms against toxins
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Disease Process (stages of infectious diseases)
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incubation period prodromal period illness decline convalescence
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Portals of Exit
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(ex nose, mouth, and urethra) allow pathogens to leave the body and are of interest in studying the spread of disease.
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Direct Contact transmission
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person-to-person spread by bodily contact.
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Indirect Contact Transmission
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When pathogens are transmitted via inanimate objects (fomites)
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Doplet Transmission
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pathogens travel in droplets of mucus less than 1 meter to a new host as a result of speaking, coughing, or sneezing.
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Vehicle Transmission
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involves airborne, waterborne, and foodborne transmission.
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Aerosols
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clouds of water droplets, which travel more than 1 meter in airborne transmission.
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Fecal-oral Infection
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result from sewage contaminated drinking water or from ingesting fecal contaminants.
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Bodily Fluid Transmission
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spread of pathogens via blood, urine, saliva, or other fluids
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1. Vectors 2. Biological vectors 3. Mechanical vectors
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1. transmit pathogens between hosts. 2. animals (usually biting arthropods) serve as both host and vector pathogens. 3. not hosts to the pathogens they carry.
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Diseases can be descibed as 1. acute 2. subacute 3. chronic 4. latent
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1. disease develops rapidly but lasts only a short time (common cold) 2. have durations and severities that lie somewhere between acute and chronic. (endocarditis, a disease of heart valves) 3. develop slowly and are continual or recurrent. (mononucleosis, hep C, TB, leprosy) 4. a pathogen remains inactive for a long period of time before becoming active. (Herpes)
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Communicable disease
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infectious disease comes either directly or indirectly from another host.
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Contagious disease
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a disease that is easily transmitted from a reservoir or patient.
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Noncommunicable disease
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arise from either outside of hosts or from normal microbiota.
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Epidemiology
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study of where and when diseases occur and how they are transmitted within populations.
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Epidemiologists track the Incidence/ prevalence of a disease
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number of new cases/ total number of cases
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classification of disease outbreaks as 1. endemic 2. spiradic 3. epidemic 4. pandemic
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1. usually present 2. occasional 3. more cases than usual 4. epidemic or more than one continent
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Decriptive epidemiology
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the careful recording of data concerning a disease; it often includes detection of the index case.
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index case
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the first case of the disease in a given area or population
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Analytical epidemiology
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seeks to determine the probable cause of a disease.
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Eperimental epidemiology
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involves testing a hypothesis resulting from analytical studies
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Nosocomial infections and nosocomial diseases
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acquired by patients in health care facilities
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exogenous
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acquired from the health care environment
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endogenous
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derived from normal microbiota that become opportunistic while in the hospital setting
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iatrogenic
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induced by treatment or medical procedures
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World Health Organization
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use epidemiological data to promulgate rules and standards for clean, potable water and safe food, to prevent disease by controlling vectors and animal reservoirs, and to educate people to make healthy choices concerning the prevention of disease.
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In which type of symbiosis do both members benefit from their interaction?
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mutualism
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An axenic environment is one that
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contains only one species
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which of the following is false concerning microbial contaminants?
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most microbal contaminants will eventually cause harm
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The most frequent portal of entry for pathogens is
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the respiratory tract
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The process by which microorganisms attach themselves to cells is
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adhesion
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Which of the following are most likely to cause disease?
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highly virulent organisms
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The nature of bacterial capsules
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affects the virulence of these bacteria
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When pathogenic bacterial cells lose the ability to make adhesions, they
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become avirulent
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A disease in which a pathogen remains inactive for a long period of time before becoming active is termed a(n)
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latent disease
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Which of the following statements is the best definition of a pandemic disease?
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It is an epidemic that occurs on more than once continent at the same time.
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Which of the following types of epifemiologists is most like a detective?
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an analytical epidemiologist
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An animal was infected with a virus. A mosquito bit the animal, was contaminated with the virus, and proceeded to bite and infect a person. which was the vector?
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The mosquito
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A patient contracted athletes foot after long term use of a medication. His physician explained that the malady was directly related to the medication. Such infections are termed:
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iatrogenic infection
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Which of the following phrases describes a contagious disease?
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a disease that is easily passed from host to host in aerosols.
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A microbe that causes disease is called a ___.
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pathogen
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Infections that may go unnoticed due to the absence of symptoms are called _____ infections.
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asymptomatic
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The study of the cause of a disease is___.
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etiology
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The study of where and when diseases occur and how they are transmitted within populations is____.
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epidemiology
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Diseases that are naturally spread from their usual animal hosts to humans are called___.
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zoonoses
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Nonliving reservoirs of disease, such as a toothbrush, drinking glass, and needle, are called ____
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fomites
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____ infections are those acquired by patients or staff while in health care facilities.
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nosocomial
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To total number of cases of a disease in a given area is its ___
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prevalence
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An animal that carries a pathogen and also serves as host for the pathogen is a ____ vector.
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biologocal
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Endotoxin is the part of the cell wall of a Gram-negative bacterium know as ___.
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Lipid A

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