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96 Cards in this Set
- Front
- Back
What is the term for a microorganism occupying and multiplying in the body?
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Colonization
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When does an opportunistic pathogen cause disease?
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When host defenses are down.
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What is the term for enhancing virulence in vivo and weakening virulence in vitro?
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attenuation
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What are four common portals of entry?
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Parenteral
Ingestion Inhalation Sexual Transmission |
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Punctures, injections, bites, cuts, wounds, etc are examples of what portal of entry?
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Parenteral
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What are two common ways that bacterial pathogens cause disease?
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Bacterial Colonization
Production of toxins. |
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What is ID50?
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It is the number of microorganisms required to cause infection in 50% of infected animals or humans.
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What is LD50?
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Lethal dose to kill half of animals experimentally inoculated.
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Which organism is more virulent? One that has an LD50 = 2 or LD50 = 20,000
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LD50 = 2 is more virulent.
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What are three factors that influence the manifestation of disease in a pathogen-host interaction?
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Virulence, Infectious dose, and immune status.
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What is a necessary stem for pathogenicity in bacteria?
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Adherence
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What do bacteria use for adherence?
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Adhesins or ligands located on pilli, fimbriae, flagella, or glycocalyx.
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Do both Gram positive and Gram negative bacteria have adhesins?
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Yes
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What does the binding of a pathogen trigger?
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Signal Transduction in both host and pathogen.
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What allows bacteria to resist phagocytosis?
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Their Capsules, or glycocalyx.
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In what bacterium does the M protein play a major virulence factor?
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Streptococcus pyogenes
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Name some of the bacterial enzymes that allow bacteria combat the immune system.
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Coagulase, kinase, hyaluronidase, collagenase, IgA protease.
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How does invasion take place in a bacteria?
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Invasins allow the rearrangement of cytoskeleton.
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What trace element is required for growth of most pathogenic bacteria?
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Iron
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What are toxins?
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poisonous substances that damage host cells
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What are the two pathways of toxins?
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Excreted directly, or released during bacterial lysis.
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What is the term that measures a bacterias capacity to produce toxins?
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Toxigenicity
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What is the term for toxins transported by the blood?
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Toxemia
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In which type of bacteria are exotoxins found? (Gram + or -?)
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Found in both G+ and G-
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What are exotoxins?
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They are toxins directly excreted from the bacteria to the host.
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How does the body respond to exotoxins?
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Creates antitoxins to combat these toxins.
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What type of toxin binds to the host cell surface but do not alter the cell?
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Type I
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What type of toxin is an A-B toxin? And which part of the protein has a toxic effect?
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Type III, the A portion has a toxic effect.
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What type of toxin acts on cell membranes to cause host cell death?
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Type II
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What type of bacteria can produce endotoxins? (G+ or G-)?
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Gram negative only.
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What are endotoxins?
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They are part of the LPS in gram- cell walls. Lipid A is toxic
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What is pyrogenic?
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Fever inducing
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What is shock?
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It is any life-threatening loss of blood pressure.
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What is septic shock?
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It is shock caused by reproducing bacteria in the blood
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What it it called when high levels of LpS, LTA, or peptidoglycan was found in the blood stream
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Systemic reaction.
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What is an acellular infectious agent consisting of nucleic acid enclosed in a protein coat?
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A virus
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What is a virus called with no additional covering other than a capsid?
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A naked virus
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Where does the viral envelope originate in an enveloped virus?
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The host cell's nuclear membrane.
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What are the four different types of viral nucleic acid makeups?
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Dbl Stranded DNA, dbl stranded RNA, Single Stranded DNA, Single Stranded RNA
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Do all viruses insert themselves into hosts genome?
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No
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Why are viruses considered non-living?
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They have no cell membrane, no metabolic activity, no ribosomes, and they cannot reproduce on their own.
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How are viruses classified?
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Morphology, Type of Nucleic Acid, and Presence of an envelope.
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Which viral species often cause epidemics/pandemics?
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Those that "Jump species"
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What determines the specificity of viruses?
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Specific attachment receptors and the availability of cellular factors for viral replication.
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What is the capsid made of?
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Protein Coat
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What is the viral envelope made of?
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Lipid Bilayer w/ proteins and carbohydrates
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What are spikes made of?
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Glycoproteins
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What functions do spikes serve on viruses?
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Serve to attach virus to specific receptors on host cells.
Also serve for evasion of immune response of host. |
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What are the four basic capsid structures?
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Helical
Polyhedral Enveloped Complex |
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What is an example of a helical virus?
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Ebola
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What is an example of a polyhedral virus?
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Adenovirus
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What is an example of an enveloped virus?
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Influenzavirus
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What is an example of a complex virus?
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Bacteriophage
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Parvoviridae, Papovaviridae, Adenoviridae, Herpesviridae, Hepadnaviridae, and poxviridae have which nucleic acid in common?
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DNA
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Reoviridae, Retroviridae, orthomyxoviridae, and paramyxoviridae all have what type of Nucleic acid in common?
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RNA
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What part of the bacteriophage enters the bacterial cell?
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Only the nucleic acid.
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In an animal cell, which part of the virus enters the cell?
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The whole virus enters by endocytosis or fusion of envelope.
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What are the five main stages of the viral life cycle?
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Attachment,
Penetration, Viral Synthesis, Assembly and packaging, Virus release |
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Where does replication usually take place in DNA viruses?
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In the host nucleus. (Exception is Poxviruses)
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Where do RNA viruses usually replicate?
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In the cytoplasms (Except for Influenza Virus)
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Which type of bacteriophage will lyse the cell after replication?
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Lytic Phages
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Which type of bacteriophage will not kill the cell?
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Lysogenic Phages
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How are viral plaques formed?
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They form from the lysed infected bacterial cells.
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Can lysogenic phages transform into a lytic phage?
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Yes
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Can cells be reinfected with the same phage?
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No
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What is a prophage?
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It is the viral DNA incorporated into the hosts chromosome.
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What two things must a virus replicate for survival?
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Viral DNA/RNA, and Viral Proteins
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What is the main difference in animal virus lifestyle with that of the bacteriophage?
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Uncoating must occur in animal viruses in between penetration and viral synthesis.
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Which viruses have higher rates of mutation?
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RNA Viruses
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Which strand of RNA can host machinery translate?
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+ strand only
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What is - strand RNA used for?
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It serves as the template for the creation of the + strand RNA
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List the characteristics of the influenza virus.
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Enveloped, Single Stranded, Segmented, RNA
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List the characteristics of HIV virus.
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Enveloped, single stranded, + segmented RNA virus
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List the characteristics of the Herpes virus.
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Enveloped, double stranded DNA virus.
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What are the two surface proteins that the flu virus is named from?
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Hemaglutinin, and Neuraminidase.
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Where does RNA replication and mRNA synthesis occur with the Influenza A virus?
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Nucleus
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What is the term with the recombination of genes between different viruses?
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Antigenic Shift
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What is the term for mutations in viral genome that allow for changes of the antigen?
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Antigenic drift
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Who is the natural host for all influenza A viruses?
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Birds
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How are viruses grown that are produced for vaccines?
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In eggs
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Which enveloped RNA virus reproduces via a DNA intermediate?
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HIV
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What are normal genes that if altered can make normal cells cancerous?
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Proto-oncogenes
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What is an already altered gene that can produce a protein that can make a cell cancerous?
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Oncogene
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What is an oncogenic Virus?
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A virus that is capable of inducing tumors.
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What is a prion?
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It is an incorrectly folded protein that is acquired through contaminated food.
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Mad cow disease, Creutzfeldt-Jakob disease, sheep and goat scrapie, kuru, Gerstmann-Straussler-Scheinker syndrome and fatal familial insomnia all result from which infectious agent?
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Prions
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What is a viroid?
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A single piece of RNA
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What is a viroids main host?
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Plants
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What is the term for the cause of disease?
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etiology
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What baseline is used to determine if a particular pathogen causes a disease?
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Koch's Postulates
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What is an exception to Koch's first postulate?
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Some pathogens are found in both healthy and sick hosts. Like Helicobacter pylori
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What is an exception to Kochs second postulate?
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Not all pathogens can be grown in vitro on a pure culture. For example Mycobacterium leprae.
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What is an endemic disease?
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A disease that is constantly present.
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What is the fraction of the population contracting a disease per time period?
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Incidence
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What is the fraction of the population having a disease as a specific time?
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Prevalence
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What is a subclinical infection?
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One that does not cause any noticeable illness (carrier)
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