Lecture 3 Flashcards
Define prion
Unusual infectious agents which appear to only consist of protein without any genetic material
Define viruses
Very small intracellular parasites that require a living host for replication
Define bacteria
Unicellular organisms that do not require living tissue to survive
Define Fungi
Single to multi-cellular, diverse range of yeasts and moulds
Define parasite
An organism that lives on or in a host, at the expense of the host (a non-mutual relationship)
Name and explain the three types of parasites
Protozoa - unicellular organisms with no cell wall
Helminths - multi-cellular organisms (worms)
Arthropods - insects
Name the 5 modes of transmission
Contact, airborne, water-borne, food borne, vector (transmission by a carrier)
4 potential sources of infection
- Socioeconomic factors (eg. hygiene), 2. nosocomial (originating in a hospital), 3. Iatrogenic (caused by medical examination or treatment). 4. Zeoonotic (exposure to animals).
Name 4 portals of entry for microbes
Skin (e.g mucosal surfaces, ears, lacrimal glands, puncture wounds), Respiratory tract (e.g. inhaled aerosols/spores or droplets), GIT (eg. contaminated food/water), Genitourinary system (e.g. urethra - contaminated from faecal route, STD, urinary retention).
Name 7 portals of exit for microbes
Sputum and mucosal secretions, saliva, semen and vaginal secretions, urine, faeces, blood.
Name five stages of infection
Incubation, prodromal illness, acute/invasive phase, decline, convalescence.
What is the incubation period?
The time interval between exposure of the infectious agent and the onset of symptoms of infection.
What is the incubation period of food posioning?
12-36 hours
What is the incubation period of tuberculosis?
4-12 weeks
What is the incubation period of influenza?
2-3 days
What is the prodromal period?
The onset of disease symptoms, signals the beginning of the disease. As the pathogen multiplies, non-specific disease symptoms emerge such as headache, nausea, general malaise.
What is the acute/invasive stage?
Period of acute disease (specific signs and symptoms relative to the disease are observed). Pathogen invades and damages host tissue.
What are characteristics of the acute/invasive stage?
Fever and chills caused by the release of pyrogens.
What symptoms may emerge during the prodomal period?
Headache, nausea, general malaise (non specific disease symptoms).
What are the two outcomes of infection?
Recovery or death
Depends on the ability of the host to overcome the invasive phase
What is the decline phase?
The immune system overcomes the effects of the pathogens and symptoms subside, and patient begins to recover.
What is the convalescence phase?
The time when the body repairs itself and regains strength.
What are the signs of infection?
Inflammation, pain or tenderness, swelling, redness, warmth, purulent exudate-bacterial, serous exudate - viral.
What are the symptoms of infection?
Fever, fatigue, weakness, headache, nausea, skin rashes
