Lecture 7: Activities of pathogens Flashcards
What are six questions to ask when someone presents with an illness?
- What has caused this illness?
- How did the symptoms develop?
- Where did it come from?
- How is this illness diagnosed?
- How is this illness treated?
- How is the illness prevented?
What causes the symptoms of an upper respiratory tract infection?
Inflammation of the throat and nasal airspace =
- Redness
- Swelling
- Pain/irritation
- Purulence
- Mucosa in airways
What causes upper respiratory tract infections?
Rhinovirus (1/3) cases of common cold… more than 100 sub types.
Always caused by virus
Where did the upper respiratory tract illness come from?
The virus has to make contact with the cells lining the airways (Only have receptors for airways, specificity)
Human to human
Virus embedded in mucous, resp droplets contain virus, direct contact and indirect.
How is upper respiratory tract infection diagnosed?
- Diagnosis is clinical, based on symptoms, signs and lack of other illness.
i. e check lungs for pneumonia
i. e check for allergic rhinitis
Lab tests are not useful for common cold
What treatment is required for the common cold?
All (almost) get better on their own.
- Nasal decongestants
- Sedating anti-histamines, NSAIDS for COUGH
Cough occurs because cell chemokines stimulate nocioceptors
How can common cold be prevented?
Exercise and hand hygiene are sensible and have other health benefits.
Whats the evidence of Vit C in common cold?
No robust evidence for vit c, zinc, probiotics etc for use in treatment of common colds.
What is a virus? What cant they do?
A nucleic acid wrapped in a protein shell formed from viral proteins.
Unable to self replicate, protein synthesise, derive energy, nucleic acid.
Describe the features of virus’
Nucleic acid (DNA or RNA)
Protein caspid
Pre-packaged Proteins/enzymes
Surface viral proteins
Possibly; Enveloped (Comes from host cell during replication)
How can viruses be classified and whats the best method?
- Structural (Not helpful)
- Disease (Clinically meaningful)
- Transmission (Clinically meaningful and best method)
Whats the viral cycle of the cell (NOTE VERY EXAMINABLE)?
- Binding
- Cell entry
- Uncoating
- Replicate proteins and nucleic acid
- Assembly
- Exit
How do virus’ cause damage?
A virus causes disease by activating the immune system and/or damaging human cells
i.e activate the immune system which causes the damage.
Specific diseases are often the result of viral tropism, what does this mean?
Respiratory viruses bind to molecules on the surface of respiratory epithelial cells
i. e rhinovirus binds to either icam-1 or the LDL receptor of cells.
i. e Glycoprotein 120 on surface of HIV specifically binds to CD4 receptor.
What can trigger the immune system?
- Chemicals (Cytokines) released by virus as it exits
- Viral proteins
- Cells displaying surface proteins that indicate viral infection or withdrawl of surface proteins i.e MHC-1 that indicates cell stress.
