CSIM 1.18 - Viruses and Diseases Flashcards
Define ‘viral transmission’ and provide examples?
The route a virus takes to cause infection
Horizontal - respiratory, sexual, faecal-oral
Vertical - mother to baby
Give an example of a virus that is transmitted through the respiratory route and causes localised infections?
Rhinovirus (common cold)
Give an example of viruses that are transmitted through the respiratory route and cause generalised infections?
Measles
Varicella-zoster
Chicken pox
Name the virus that is endemic in Pakistan, Afghanistan and Nigeria that is transmitted through faecal-oral route?
Polio
Name two viruses that are transmitted vertically that produce specific congenital syndromes?
Rubella - congenital rubella syndrome
Parvovirus B19 - foetal hydrops
Define the term pathogenicity?
Severity of a disease caused by a virus (more pathogenic = more severe the disease)
Define the term virulence?
Severity of a disease caused by different strains of the same virus
Define the term dissemination?
Viral spread once inside the body (evaded immunity) to other sites within the body
Describe primary and secondary viraemia?
Once a virus enters the body and migrates to a lymph node and then the blood stream = Primary viraemia
The virus then travels to organs/tissues where it multiplies, once enough of a viral load is produced it re-enters the bloodstream = Secondary viraemia
Define the term incubation period?
The time interval between being infected (viral exposure) and the onset of illness (symptoms and signs)
Define the term generation time?
The time period between being infected (viral exposure) and the individual becoming infectious to others
Define the term reproduction number (Ro)?
The number of subsequent infections in a population caused by a viral illness in ONE individual during the infectious period
What is the reproduction number for small pox?
Ro = 2
What is the reproduction number for influenza?
Ro = 4
What is the reproduction number for measles?
Ro = 11-18
