MICROPARA Lesson 4: Disease and Immunology

Disease

is an abnormal state in which part or all of the body is not properly adjusted or is unable to carry out its usual functions

Infection

on the other hand is defined as pathogenic microorganisms invading the body

Communicable disease

infectious disease that is transmissible from one human to another (person to person)

Contagious disease

a communicable disease that can be easily transmitted from one person to another

Zoonotic disease

infectious disease that human acquire from animal source

Incidence rate

incidence of a particular disease is defined as the number of new cases of that disease in a defined population during a specific period

Period prevalence

number of cases of the disease existing in a given population during specific time period

Point prevalence

number of cases existing in a given population at a particular moment in time

Morbidity rate

rate for that particular disease which is usually expressed as the number of new cases of a particular disease that occurred during a specified time period per a specifically defined population

Mortality rate

ratio of the number of people who died of a particular disease during a specified time period

Sporadic disease

one that occurs only occasionally

Endemic disease

always present in a population

Pandemic

a disease that is occurring in epidemic proportions in many countries simultaneously—sometimes worldwide

Acute disease

develops rapidly but lasts for short period of time

Chronic disease

develops more slowly and occur for long period

Latent disease

causative organism remains inactive for a time but can become active and produce symptoms of disease

Virulence of the pathogen

Factors pertaining to pathogen

Mechanical

direct damage to tissue or surfaces

Chemical

bacteria produces chemicals and toxins

exotoxins

protein molecules that are released from bacterial cells

exotoxins

can cause disease or increase severity of disease

exotoxins

Act at tissue sites far from where the bacteria are growing

exotoxins

Bind to specific receptors on target cells

exotoxins

Ex: botulinum, tetanus, diphtheria and cholera toxins

Endotoxins

toxic substance associated with Gram negative bacteria

Endotoxins

Released when the outer membrane of the bacteria is disrupted

Endotoxins

Contribute to the severity of symptoms

Other toxins: Lipopolysaccharides (LPS)

asso with the cell wall of Gram-negative bacteria

Other toxins: Hemolysin

S. aureus strains

Other toxins: Leukotoxins

S. aureus strains

Other toxins: Exfoliative toxins

S. aureus strains

Other toxins: Enterotoxins

S. aureus strains

Other toxins: Toxic shock syndrome toxin-1 (TSST-1)

S. aureus strains

Immunologic

response of the immune system

Gram +

EXOTOXIN: Bacterial source

Metabolic product of growing cell

EXOTOXIN: Relation to microorganism

Affects cell functions, nerves, GIT

EXOTOXIN: Effect on the body

NO

EXOTOXIN: Fever producing

Gram -

ENDOTOXIN: Bacterial source

Present in the LPS of outer membrane of cell wall

ENDOTOXIN: Relation to microorganism

Fever, weakness, aches, shock

ENDOTOXIN: Effect on the body

YES

ENDOTOXIN: Fever producing

Incubation period

time interval between entry of microorganism and the first appearance of s/s

Prodromal period

mild symptoms of a disease which are non-specific (fever, cough, colds, malaise)

Period of illness

period of maximal invasion. The disease is most acute during this period

Carrier state

the patient does not show s/s but still continues to shed infecting microorganisms

Period of decline

period of defervescence; period in which s/s starts to subside; patient is vulnerable to secondary infections

Period of convalescence

patient regains strength, body returns to its pre-diseased state

Human carriers

most important reservoirs of human infectious disease are other humans – people with infectious disease as well as carrier

Carrier

is a person who is colonized with a particular pathogen, but the pathogen is not currently causing disease in that person.

Passive carrier

carry the pathogen without ever having had the disease

Incubatory carrier

a person who is capable of transmitting a pathogen during the incubation period of a particular infectious disease

Convalescent carrier

harbor and can transmit a particular pathogen while recovering from an infectious disease

Active carrier

have completely recovered from the disease, but continue to harbor the pathogen indefinitely

Active carrier

Animals

Active carrier

Vectors—mosquito, flies

Non-living reservoir

these are inanimate objects where pathogen can survive.

Non-living reservoir

Examples: water, soil, and air.

Non-living reservoir

Pathogens can survive in this reservoirs for varying time, sometimes by becoming dormant or resilient

Fomites

beddings, linen, doorknobs

Contact Transmission

can be direct contact, indirect contact or droplet

Vehicle transmission

can be food borne, air borne, or water borne

Presence of Pathogen (infectious agent)

Rapid and accurate identification of organisms

Presence of Pathogen (infectious agent)

Control or elimination of infectious agents (cleaning of water, mechanical action with or without detergent)

Reservoirs

Immunization

Reservoirs

Regular check ups

Reservoirs

Restriction from work of patient contact when infected with communicable disease

Portal of Exit

Practice aseptic precaution

Portal of Exit

Avoid talking directly into the client’s mouth to prevent the droplet infection

Portal of Exit

Wearing mask, careful handling of waste, and usage of disposable gloves

Means of Transmission

contact droplet and airborne precaution

Portal of Entry

Maintain integrity of skin and mucous membrane

Susceptible host

Regular oral hygiene

Susceptible host

Maintaining adequate water intake

Susceptible host

Encouraging deep breathing exercise

Susceptible host

Proper immunization

Disease

is described as an abnormal state where the body's functions are impaired

Infection

while infection involves the invasion of pathogenic microorganisms

Key epidemiologic terms

are defined, including communicable diseases, zoonotic diseases, and various rates of incidence and prevalence

Koch's Postulates

introduced as guidelines for establishing causative relationships between microorganisms and diseases, along with exceptions to these rules

Factors influencing infection occurrence

are discussed, including pathogen virulence, host health, and conditions

Mechanisms

by which microorganisms produce disease—mechanical, chemical, and immunologic—are outlined

Bacterial toxins

are categorized into exotoxins and endotoxins, highlighting their sources and effects on the body

Stages of infectious diseases

from incubation to convalescence, are described