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CHAPTER 2: INFECTIOUS PROCESSES & HOST RESPONSE - Coggle Diagram
CHAPTER 2: INFECTIOUS PROCESSES & HOST RESPONSE
RESERVOIRS OF INFECTION
Sites where pathogens are maintained as a source of infection.
TYPES OF RESERVOIRS
Animal reservoir
Humans are usually dead-end host to zoonotic pathogens
Difficult to eradicate
Acquire zoonoses through various routes
Zoonoses
Human carriers
Asymptomatic infected individuals can be infective to others
Some individuals eventually develop illness whereas others never get sick
Healthy carriers may have defensive systems that protect them
Nonliving Reservoirs
Soil, water, and food can be reservoirs of infection
Presence of microorganisms is often due to contamination by feces or urine
THE INVASION & ESTABLISHMENT OF MICROBES IN HOSTS: INFECTION
Exposure to microbes
Infection
Organism evades body's external defenses, multiplies, and becomes established in the
body
Contamination
The mere presence of microbes in or on the body
Portals of Entry
Major pathways
Mucous membrane
Line the body cavities that are open to environment
Provide a moist, warm environment hospitable to pathogens
Respiratory tract is the most common site of entry
Gastrointestinal tract may be route of entry
Placenta
Typically forms effective barrier to pathogens
Pathogens may cross the placenta and infect the fetus
Can cause spontaneous abortion, birth defects and premature birth
Skin
Outer layer of dead skin cells act as barrier to pathogens
Some pathogens can enter through openings or cuts
THE NATURE OF INFECTIOUS DISEASE
Manifestations of Disease
Symptoms
Objective manifestations of disease observed or measured by others
Signs
Symptoms and signs that characterise a disease or abnormal condition.
Syndrome
Subjective characteristics of disease felt only by the patient
ETIOLOGY
Study the causes of the disease
Using Koch's postulates
Exceptions to Koch's postulates
VIRULENCE FACTORS AND PATHOGENICITY
Pathogenicity
Ability of a microorganism to cause disease
Virulence
Degree of pathogenicity
THE STAGES OF INFECTIOUS DISEASE
illness period (most severe signs & symptoms)
Decline period (declining signs & symptoms)
Prodromal period (general symptoms)
Convalescence period (recovery process)
Incubation period (no signs & symptoms)
THE NATURE OF INFECTIOUS DISEASE
Modes of transmission
Vector Transmission
Contact Transmission
Vehicle Transmission