Communicable Diseases - is an illness due to an infectious agent or its toxic products which is easily transmitted or communicated directly or indirectly from one person or animal to another
Contagious Disease - disease that easily spreads directly from one person to another
Infectious Disease - disease not transmitted by ordinary contact but require a direct inoculation of pathogenic agents (microbes). On the other hand, all contagious diseases are infectious.
Carrier – is an individual who harbors the organism and is capable of transmitting it to a susceptible host without showing manifestations of the disease.
Contact - is any person or animal who is in close association with an infected person, animal, or freshly soiled material
Classification of Infectious Diseases:
Based on Occurrence of Disease:
Sporadic Disease
Endemic Disease
Epidemic Disease
Pandemic Disease
Classification of Infectious Diseases
Based on Severity or Duration of Disease
Acute Disease
Chronic Disease
Latent Disease
Classification of Infectious Diseases
Based on State of Host Resistance:
Primary Infection
Secondary Infection
Subclinical/Inapparent Infection
Based on Occurrence of Disease
Sporadic Disease - disease that occurs only occasionally & irregularly with no specific pattern (tetanus, botulism)
Based on Occurrence of Disease
Endemic Disease - constantly present in a population, country or community (malaria)
Based on Occurrence of Disease
Epidemic Disease - = patient acquire the disease in a relatively short period of time ; greater than normal number of cases in an area within a short period of time (cholera, typhoid)
Acute Disease - develops rapidly (rapid onset) but lasts only a short time (measles, mumps, influenza)
Based on Severity/Duration of Disease
Chronic Disease - develops more slowly (insidious onset) disease likely to be continual or recurrent for long periods (tuberculosis, leprosy)
Based on Severity/Duration of Disease
Latent Disease - causative agent remains inactive for a time but then becomes active to produce symptoms of the disease (chicken pox > shingles)
Based on State of Host Resistance
Primary Infection - acute infection that causes the initial illness.
Based on State of Host Resistance
Secondary Infection - one caused by an opportunistic pathogen after primary infection has weakened the body’s defenses
Based on State of Host Resistance
Subclinical Infection - does not cause any noticeable illness
Stages of Disease
Incubation Period
Prodromal Period
Period of Illness
Period of Decline
Period of Convalescence
Stages of Disease
Incubation Period - time interval between the initial infection and the 1st appearance of any s/sx
Stages of Disease
Prodromal Period - early, mild appearance of symptoms of the disease.
Stages of Disease
Period of Illness - •Time of greatest symptomatic experience (pt. is sick)• overt s/sx of disease •WBC may increase or decrease •Can result to death if immune response or medical intervention fails •Communicable disease are most easily transmitted during this phase
Stages of Disease
Period of Decline - s/sx subside and pathogen replication is brought under control and vulnerable to secondary infection
Stages of Disease
Period of Convalescence - Replication of pathogenic organisms is stopped regains strength and the body returns to its pre diseased state.
Pathogenicity – ability to cause disease
Chain of Infection
Source of Infection
Reservoir
Portal of exit
Mode of transmission
Portal of entry
Susceptiblehost
Types of Carriers
Passive Carrier - carry the pathogen without ever having had the disease. They are said to be asymptomatic. can also be uninfected but can transfer infectious agents from infected persons to uninfected ones by hand and instrument contact
Types of Carrier
Incubatory Carrier - a person who is capable of transmitting a pathogen during the incubation period of a particular infectious disease.
Types of Carrier
Convalescent Carrier - can harbor and can transmit a particular pathogen while recovering from an infectious disease
Types of Carrier
Active Carrier - completely recovered from the disease, but continue to harbor the pathogen indefinitely.
Mode of Transmission
Droplet Contact - occurs within 3 ft from source (from coughing, sneezing or talking to an infective person)
Mode of Transmission
Contact Transmission
Direct Transmission - immediate direct transfer of microorganism from person to person
Mode of Transmission
Contact Transmission
: Indirect Transmission
by Vehicle route
Fomites
by Vector route
Mode of Transmission
Airborne Transmission
DropletNuclei - residue of evaporated droplets that remain suspended in air
Infection Control: 1st line of Defense
FirstLine
HandHygiene
Handwashing
IMMUNITY - is the condition of being secure against any particular disease, particularly the power which a living organism possesses to resist and overcome infection also the resistance that an individual has against disease
ImmuneSystem - protection against infective or allergic diseases by a system of antibodies, immunoglobulins and related resistance factors.
Antibody - a specific immune substance produced by the lymphocytes of the blood of tissue juices of man or animal in response to the introduction into the body of an antigen
IMMUNOGLOBULINS
IgG - most prevalent antibody 80%, produced later in the immune response, only Ig that can cross placenta
IgA - found in colostrum, tears, saliva, sweat
IgM - principal antibody of blood, quickly produced in response to an antigen, responds to artificial immunization
IgE - responds to allergic reaction
IgD - unknown, antigen receptor, found in the surface of the cells
Antigen - triggering agent of the immune system; foreign substance introduced into the body causing the body to produce antibodies