Micro CH 11 Flashcards
Signs vs. Symptoms
Signs: Objective indicators of disease that can be measured or observed (e.g., fever, rash).
Symptoms: Subjective experiences reported by the patient (e.g., pain, fatigue).
Types of Reservoirs
Reservoirs are places where pathogens live and multiply.
Human Reservoirs: Infected humans (can be symptomatic or asymptomatic).
Animal Reservoirs: Animals or insects that carry pathogens (e.g., Zoonoses).
Environmental Reservoirs: Soil, water, or other environmental sources.
Vectors, Fomites, Carriers
Vectors: Organisms (usually insects) that transmit pathogens (e.g., mosquitoes for malaria).
Fomites: Non-living objects that can carry infectious agents (e.g., doorknobs, towels).
Carriers: Individuals who harbor pathogens but do not show symptoms (e.g., Typhoid Mary).
“-emia” Suffix Meaning
-emia: Refers to the presence of a substance in the blood.
Bacteremia: Presence of bacteria in the blood.
Viremia: Presence of viruses in the blood.
Septicemia: Presence of infectious agents and their toxins in the blood.
Types of Pathogens (ex. Opportunistic)
Opportunistic Pathogens: Normally harmless microorganisms that cause disease in compromised hosts (e.g., Candida albicans in immunocompromised individuals).
Primary Pathogens: Can cause disease in healthy individuals (e.g., Mycobacterium tuberculosis).
Obligate Pathogens: Require a host to complete their life cycle (e.g., HIV).
Factors That Impact Host Defenses
Age: Young and elderly are more susceptible.
Genetic Factors: Genetic makeup can influence susceptibility to infections.
Nutritional Status: Malnutrition weakens the immune system.
Immunocompetence: The ability of the immune system to respond to pathogens.
Environmental Factors: Pollution, hygiene, and living conditions.
Normal Biota Colonization of the Human Body
The normal microbiota are microorganisms that reside on the body without causing disease.
Locations: Skin, gastrointestinal tract, respiratory tract, genitourinary tract.
Role: Help with digestion, immune system development, and prevention of pathogenic microorganism colonization.
Calculation of Infectious Dose
The infectious dose is the number of pathogens required to cause infection in a host. A lower infectious dose means the pathogen is more virulent (i.e., requires fewer microorganisms to establish an infection).
Stages of Infectious Disease
Incubation: Time between exposure and the first symptoms.
Prodromal: Early, non-specific symptoms (e.g., mild fever, malaise).
Illness: Full-blown symptoms of the disease.
Decline: Symptoms begin to subside as the immune system fights off the infection.
Convalescence: Recovery period, where tissue repair and healing occur.
Features of Infectious Disease
Contagion: Ability to spread from one host to another.
Pathogenicity: The ability of a microorganism to cause disease.
Virulence: The degree of harmfulness of a pathogen, often measured by its ability to invade and damage tissues.
Transmission: How the pathogen spreads from one host to another.
Virulence Factors
Characteristics of pathogens that enhance their ability to cause disease, such as:
Adhesion factors: Help pathogens stick to host tissues (e.g., fimbriae).
Enzymes: Help pathogens invade tissues (e.g., hyaluronidase).
Toxins: Damage host tissues (e.g., exotoxins, endotoxins).
Pathogenicity
The ability of a microorganism to cause disease. Factors that contribute to pathogenicity include:
Host factors (immune status, age).
Microbial factors (virulence, adaptability).
Host Defense Mechanisms
Physical Barriers: Skin, mucous membranes.
Chemical Barriers: Acids in the stomach, enzymes in saliva.
Innate Immune System: Non-specific defense mechanisms (e.g., inflammation, phagocytosis).
Adaptive Immune System: Specific immune response involving T and B cells.
Endogenous vs. Exogenous
Endogenous: Infections caused by microorganisms already present in or on the body (e.g., UTIs from normal gut flora).
Exogenous: Infections caused by microorganisms from outside the body (e.g., foodborne illness, infections from wounds).
Types of Microbial Transmission
Direct Transmission: Person-to-person contact (e.g., kissing, sexual contact).
Indirect Transmission: Through a fomite or vector (e.g., touching contaminated surfaces, mosquito bites).
Droplet Transmission: Through respiratory droplets (e.g., coughing, sneezing).
Airborne Transmission: Pathogens in the air (e.g., tuberculosis).
Vehicle Transmission: Through contaminated food, water, or blood.
