Infectious Diseases

MC #2

Acute infection fever

7-10 days

Sepsis and ongoing infections fever

>10 days-3 wks

Infection

An organism establishes a parasitic relationship with its host; begins with transmission of an infectious organism

What a pathogen may do

• Contaminate the body surface and be destroyed by 1st-line defenses

• A subclinical infection may occur causes immune response of the host

• A clinically apparent infection- 1 or more clinical symptoms- infectious disease

Colonization

pathogen present in host but host asymptomatic

Incubation period

Time btw pathogen entering host and appearance of clinical symptoms

Latent infection

After microorganism has replicated but remains inactive in host

Period of communicability

This tume period when an organism can be shed and infect others through directs or indirect contact

Viruses

• subcellular organisms made up of a RNA or a DNA nucleus covered with proteins

• not susceptible to antibiotics

Mycoplasmas

Are unusual, self-replicating bacteria that have no cell wall components and very small genomes

Bacteria

single-celled microorganisms with well-defined cell walls that can grow independently on artifical media wo/ the need for other cells

Rickettsiae

primarily animal pathogens transmitted through bite

Chlamydiae

Require host cells for replication contain DNA and RNA

Protozoa

single cell unit or a group of nondifferentiated cells loosely held together and not forming tissues

Fungi

Unicellular to filamentous organisms possessing hyphae (filamentous outgrowths) surrounded by cell walls and containing nuclei (eukaryocyte)

Prions

Proteinaceous, infectious particles consisting of proteins but wo/ nucleic acids

HAIs

• Healthcare aquired infection (nosocomial infections)

• aquired during hospitalization

• 1/31

Principal pathogens

regularly cause disease in people w/ apprently intact defense systems

Opportunist pathogens

do not cause disease in people w/ intact host defense systems but can clearly cause devastating disease in many hospitalized and immunocompromised clients

Pathogenicity

the ability of the organism to induce disease, depends on the organism’s speed of reproduction in the host, the extent of damage it causes to tissues, and the strength of any toxin released by the pathogen

Virulence

Refers to the potency of the pathogen in producing severe disease and is measured by the case fatality rate

Reservoir

An environment in which an organism can live and multiply

The portal of exit

Place where parasite leaves reservoir (secreations, fluids, excretions)

Mode of transmission

Routes: contact, airborne, droplet, vehicle and vector borne

Portal of entry

Ingestion, inhalation, bites, through contact w/ mucous membranes, percutaneously or transplacentally

Host susceptibility- 3 lines of defense

• external

• inflammatory process

• immune response