U1.6 Flashcards
__________________ is determined by the type of infectious disease process acquired. Diseases are often classified in terms of how they behave within a host and within a given population.
Transmission to the host
Transmission to the host: What type?
- any disease that spreads from one host to another, either directly or indirectly
Communicable infectious disease
Transmission to the host: What type?
- a disease that is readily or highly transmissible especially through direct contact
Contagious infectious disease
Transmission to the host: What type?
- one which does not arise through transmission from host to host. This includes diseases acquired by contact with water or soil.
Non-communicable infectious disease
The causative agents of disease can be transmitted from the source or reservoir of infection to a susceptible host. There are four principal routes or modes of transmission: what are they?
- contact
- airborne
- vehicles
- vectors
What mode of transmission: Contact, airborne, vehicles or vectors?
This implies the coming together or touching of the source and the host.
Contact transmission
Contact transmission: What are the 3 mechanisms under it?
- Direct contact transmission (Horizontal transmission & Vertical transmission)
- Indirect contact transmission
- Droplet transmission
Contact transmission: What mechanism? Direct, Indirect or Droplet?
- the transmission of pathogens by contact of the portal of exit with the portal of entry, no intermediate object is involved
Direct contact transmission
Contact transmission: What mechanism? Direct, Indirect or Droplet?
- the transfer of pathogens from an
infected host, to an intermediary object or substance, to another
host.
Indirect contact transmission
Contact transmission: What mechanism? Direct, Indirect or Droplet?
- implies the transfer of
disease agents through droplets of saliva or mucus discharged into the air by coughing, sneezing, laughing, or talking. The route is through the air but because these particles are large (i.e., greater than 5 µ), they travel a short distance (less than 1 meter), and quickly settle out of air.
Droplet transmission
Direct Contact transmission: what specification? horizontal or vertical?
- also known as person-to-person
transmission. Disease transmission occurs by touching, kissing,
and sexual intercourse.
Horizontal transmission
Direct Contact transmission: what specification? horizontal or vertical?
- involves transmission of pathogens from the mother to an infant.
- Disease transmission may occur in two ways: Prenatal and Perinatal
Vertical transmission
Vertical Direct Contact transmission: what specification? Prenatal or Perinatal?
- implies transmission of the pathogen across the placenta.
Prenatal
Vertical Direct Contact transmission: what specification? Prenatal or Perinatal?
- occurs during passage through the first canal or during close contact between mother and infant in the first few days of life.
Perinatal
Indirect Contact Transmission:
- an inanimate object that harbors and transmits a pathogen
fomite
What mode of transmission: Contact, airborne, vehicles or vectors?
This occurs when a pathogen is suspended in air contained in dust or within droplet nuclei.
Air-borne transmission
What mode of transmission: Contact, airborne, vehicles or vectors?
It is the transmission of disease-causing agents by a common inanimate reservoir such as food, water, or blood.
Common vehicle transmission
Air-borne transmission:
- are small particles (1 µ to 4 µ in diameter) that represent what is left from the evaporation of larger droplet particles. They remain suspended in air and travel 1 meter or more from the source.
Droplet nuclei
What mode of transmission: Contact, airborne, vehicles or vectors?
It indicates the transmission of pathogens through the aid of a vector.
Vector-borne transmission
Vector-borne transmission:
It is an invertebrate (e.g., arthropod, or mollusk) that transmit an infectious agent from one host to another
vector
Vector-borne transmission: How? What type?
- during which the pathogen does not undergo morphological or physical changes within the vector (i.e., mechanical vector). That is, the vector is not important in the life cycle of the pathogen.
Harborage or mechanical transmission
Vector-borne transmission: How? What type?
- the pathogen goes through morphological or physical changes within the vector (i.e., biologic vector). The vector assists in the completion of the pathogen’s life cycle
Biological transmission
To initiate infection, a microbe enters the tissues through a characteristic route - _____________?
the portal of entry
This is usually a cutaneous or membranous boundary through which the microorganism enter the tissue.
portal of entry
Portal of entry: The microorganism may enter through what routes:
- Gastrointestinal tract
- Respiratory tract
- Skin and mucus membranes -
- Genito-urinary tract
- Blood
- Placenta
Portal of Entry: Which route? (Gastrointestinal tract, Respiratory tract, Skin and mucus membranes, Genito-urinary tract, Blood, or Placenta)
- is the portal of entry for pathogens contained in food, drinks and other ingested materials. Agents of diseases such as typhoid fever, cholera, dysentery, botulism enter by way of mouth.
Gastrointestinal tract
Portal of Entry: Which route? (Gastrointestinal tract, Respiratory tract, Skin and mucus membranes, Genito-urinary tract, Blood, or Placenta)
- the greatest number of pathogens enter by way of the nose and mouth. Infectious diseases with this total of entry include common colds, tuberculosis, pneumonia, measles.
Respiratory tract
Portal of Entry: Which route? (Gastrointestinal tract, Respiratory tract, Skin and mucus membranes, Genito-urinary tract, Blood, or Placenta)
- nicks, abrasions and punctures on this serve as portal of entry of many pathogens including those that cause boils, and impetigo.
Skin and mucus membranes
Portal of Entry: Which route? (Gastrointestinal tract, Respiratory tract, Skin and mucus membranes, Genito-urinary tract, Blood, or Placenta)
- is the portal of entry of pathogens that are contracted by sexual means (intercourse, intimate direct contact). Diseases such as gonorrhea, AIDS and syphilis, has been collectively known by a more descriptive term, sexually-transmitted infection (STI).
Genito-urinary tract
Portal of Entry: Which route? (Gastrointestinal tract, Respiratory tract, Skin and mucus membranes, Genito-urinary tract, Blood, or Placenta)
- agents of so-called blood borne diseases such as hepatitis, AIDS, syphilis, and malaria enter the body through blood transfusion, contaminated needles and syringes, and through blood-sucking insects.
Blood
Portal of Entry: Which route? (Gastrointestinal tract, Respiratory tract, Skin and mucus membranes, Genito-urinary tract, Blood, or Placenta)
- permits diffusion of dissolved nutrients and gases form the mother’s circulation to the growing fetus in her womb. Several diseases from the mother such as syphilis, AIDS, listeriosis, and toxoplasmosis can also be passed to the fetus by way of the placenta.
Placenta
Susceptible Host or the Infectious Agent
- the effectivity of the host’s defense mechanisms
Susceptible Host
Susceptible Host or the Infectious Agent
- the microbe’s pathogenicity and virulence
Infectious Agent
Microbial colonization and
dissemination is determined by two factors: what are they?
Susceptible Host and the Infectious Agent
It is usually but not always the same as the portal of entry. It is of importance since it determines how
pathogens spread in a population.
portal of exit
