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Questions and Answers
What is the primary factor that determines the length of the incubation period?
What is the primary factor that determines the length of the incubation period?
What is the characteristic of a localized infection?
What is the characteristic of a localized infection?
During which period of a disease is the patient most contagious?
During which period of a disease is the patient most contagious?
What is the characteristic of a subacute disease?
What is the characteristic of a subacute disease?
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What is the term for a disease that is not producing symptoms?
What is the term for a disease that is not producing symptoms?
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What is the period of time during which the patient recovers from a disease?
What is the period of time during which the patient recovers from a disease?
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What is the typical time frame for the symptoms of the secondary stage of syphilis to arise after the spirochete enters the bloodstream?
What is the typical time frame for the symptoms of the secondary stage of syphilis to arise after the spirochete enters the bloodstream?
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What is the term for the stage of syphilis where the patient has few or no symptoms?
What is the term for the stage of syphilis where the patient has few or no symptoms?
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What is the name of the open lesion that appears during the primary stage of syphilis?
What is the name of the open lesion that appears during the primary stage of syphilis?
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What is the term for the destruction of organs in the body caused by the spirochetes during the tertiary stage of syphilis?
What is the term for the destruction of organs in the body caused by the spirochetes during the tertiary stage of syphilis?
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What is the name of the pathogen that causes syphilis?
What is the name of the pathogen that causes syphilis?
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What is the term for a disease that occurs when one infection is followed by another infection caused by a different pathogen?
What is the term for a disease that occurs when one infection is followed by another infection caused by a different pathogen?
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What is the main function of neurotoxins?
What is the main function of neurotoxins?
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What is the purpose of molecular mimicry in pathogens?
What is the purpose of molecular mimicry in pathogens?
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What is the result of the pathogen's surface antigens being shed and new ones appearing in their place?
What is the result of the pathogen's surface antigens being shed and new ones appearing in their place?
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What is the function of IgA protease in pathogens?
What is the function of IgA protease in pathogens?
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What is the 2nd line of defense in the host's defense mechanism?
What is the 2nd line of defense in the host's defense mechanism?
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What is the purpose of adult schistosomes coating themselves with host proteins?
What is the purpose of adult schistosomes coating themselves with host proteins?
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What is the primary function of cilia present on epithelial cells in the respiratory tract?
What is the primary function of cilia present on epithelial cells in the respiratory tract?
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What is the approximate pH of the stomach that helps protect the gastrointestinal tract from bacterial colonization?
What is the approximate pH of the stomach that helps protect the gastrointestinal tract from bacterial colonization?
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What is the primary function of bile in the gastrointestinal tract?
What is the primary function of bile in the gastrointestinal tract?
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What is the outcome of damage to ciliated epithelial cells in the respiratory tract?
What is the outcome of damage to ciliated epithelial cells in the respiratory tract?
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What is the term for substances that trigger an immune response and the production of antibodies?
What is the term for substances that trigger an immune response and the production of antibodies?
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What is the term for the physical attributes or properties of pathogens that enable them to escape various host defense mechanisms and cause disease?
What is the term for the physical attributes or properties of pathogens that enable them to escape various host defense mechanisms and cause disease?
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Which type of pathogen must live within host cells to survive and multiply?
Which type of pathogen must live within host cells to survive and multiply?
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What is the function of bacterial fimbriae?
What is the function of bacterial fimbriae?
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What is the term for the molecule on the surface of a host cell that a particular pathogen is able to recognize and attach to?
What is the term for the molecule on the surface of a host cell that a particular pathogen is able to recognize and attach to?
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Which of the following pathogens has an adhesin called Protein F?
Which of the following pathogens has an adhesin called Protein F?
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What is the term for the enzyme produced by certain pathogens, such as S. aureus, that helps them to clot blood?
What is the term for the enzyme produced by certain pathogens, such as S. aureus, that helps them to clot blood?
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Study Notes
Virulence Factors
- Physical attributes or properties of pathogens that enable them to escape host defense mechanisms and cause disease
- Examples: attachment, receptors and adhesins, bacterial fimbriae, coagulase, obligated intracellular pathogens
Attachment
- Type of cells to which the pathogen is able to attach
- Receptors and adhesins: molecules on the surface of host cells and pathogens that recognize and bind to each other
- Example: Streptococcus pyogenes cells have an adhesin called Protein F
Bacterial Fimbriae (Pili)
- Long, thin, hair-like, flexible projections composed of proteins called pilin
- Enable bacteria to attach to surfaces, including tissues within the human body
- Example: Fimbriated strains of Neisseria gonorrhoaea attach to inner walls of the urethra and cause urethritis
Obligated Intracellular Pathogens
- Must live within host cells to survive and multiply
- Examples: Rickettsia, Chlamydia, certain sporozoan protozoa (e.g. Plasmodium spp. that cause human malaria)
Toxins
- Exotoxins: produced by pathogens and released into the host environment
- Neurotoxins: affect the central nervous system (CNS)
- Enterotoxins: affect the gastrointestinal tract, causing diarrhea and vomiting
- Examples: Clostridium tetani and Clostridium botulinum produce neurotoxins, causing tetanus and botulism
Camouflage and Molecular Mimicry
- Adult schistosomes (trematodes) conceal their foreign nature by coating themselves with host proteins
- Molecular mimicry: pathogen's surface antigens closely resemble host antigens, making them unrecognizable as foreign
Destruction of Antibodies
- Some bacterial pathogens produce an enzyme (IgA protease) that destroys IgA antibodies
Host Defense Mechanisms
- Nonspecific host defense mechanisms:
- 1st line of defense: intact skin and mucous membranes
- 2nd line of defense: inflammation, phagocytosis
- Specific host defense mechanisms: the immune system (3rd line of defense)
Immune System
- Produces antibodies in response to foreign substances (antigens)
- Antibodies recognize and bind to specific antigens
Gastrointestinal Tract (GIT) Defense
- Digestive enzymes
- Acidity of the stomach (approx. pH 1.5)
- Bile, which lowers the surface tension and causes chemical changes in bacterial cell walls and membranes
Disease Progression
- Incubation period: time between arrival of the pathogen and onset of symptoms
- Prodromal period: early signs and nonspecific symptoms of a disease
- Period of illness: patient experiences typical symptoms associated with the disease
- Convalescent period: patient recovers
Infection Types
- Localized infection: affects only one body part or organ
- Systemic infection: affects multiple parts of the body
- Acute disease: rapid onset, usually followed by rapid recovery
- Subacute disease: comes on more suddenly than a chronic disease but less suddenly than an acute disease
- Chronic disease: long-lasting or recurring
Symptomatic and Asymptomatic Diseases
- Symptomatic disease: patient experiences symptoms
- Asymptomatic disease: patient is unaware of the disease because they are not experiencing symptoms
Syphilis
- Primary stage: patient has an open lesion called a chancre, which contains the spirochete Treponema pallidum
- Secondary stage: symptoms include rash, fever, and mucous membrane lesions
- Latent stage: patient has few or no symptoms
- Tertiary syphilis: spirochetes cause destruction of organs in which they have been hiding, leading to death
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Description
Learn about the different stages of disease progression, including the incubation period, prodromal period, and convalescent period. Understand the factors that influence the length of the incubation period and the characteristics of each stage.
