Microbiology 5-6 Flashcards
How can viruses be transmitted?
- Respiratory (droplets)
- Faecal-oral tract
- Contact
- Zoonoses
- Blood
- Sexual contact
- Maternal-neonatal
- Germ-line
What is iatrogenic transmission?
Passed on by a healthcare worker.
What is nosocomial transmission?
Caught in hospital (hospital-acquired infection)
What is horizontal transmission?
From person to person.
What can persistent infections lead to?
Oncogenesis/cancer.
Where do persistent infections normally reside?
Hard-to-reach places such as the skin and nervous system.
e.g. Varicella-zoster virus resides in the dorsal root ganglions
How does cancer develop from persistent infections?
Viruses can interfere with the cell cycle to enhance their own replication. This can cause unregulated growth, leading to tumour growth.
e.g. HPV (cervical cancer) and Hep C (hepatocellular carcinoma)
What does HTLV-1 cause?
Adult leukaemia
What can the Epstein-Barr virus cause?
Burkitts and Hodgkins lymphoma (confection with other viruses)
Where does the EPV remain latent?
B cells (95% of the population are infected with this virus)
What factors affect the outcome of a viral infection?
- Age
- Gender
- Host genetics
- Other medications
- Viral load
- Viral sequence (strain)
- Host immune response stays
- Host co-morbidity
- Co-infections
What is prophylaxis?
Preventing disease before the aetiological agent infects the host.
Why was the eradication of smallpox a success?
- No animal reservoir so easier to isolate
- Easily recognisable disease
- No latent or persistent infection
- No resistance to vaccine
- Lost cost
- Heat stability of vaccine
- Easy administration of vaccine
What is attenuated vaccine?
A live virus that is initially injected into monkey to promote mutations so that it loses its ability to fully induce disease in humans when injected.
What is a fractionated vaccine?
Non-recombinant, purified subunits of a vaccine. Only safe/effective for short durations.
