Current Topics Flashcards
3 prime examples of vaccination working well
Problems with vaccines
* protection not complete (can still become infected and develop clinical signs of disease)
* Adverse events associated– generally mild (swlling, fever, aches, pain); severe side effects (allergic reaction, vaccine associated feline sarcomas)
* Many vaccines require a level of “herd immunity” for them to be effective- difficult to explain to people with no scientific background
* Some vaccines are expensive (e.g. Hendra virus vaccines $100-200 per horse, twice per year)– veterinary vaccines not subsidized by the government
Why are anti-vaccination sentiments re-emerging? Common themes with anti-vaccination?
People have never seen the diseases, if vaccination level drops below 75%, high risk of becoming ill
* social media facilitating dissemination of information (misinformation)
* safety concerns- toxins/ poisons, causing Autism
* concerns for effectiveness
* conspiracy theories– “big pharma”
* moral objections- against animal testing
* natural “alternatives”- homeopathy
What were the consequences of the Wakefield study?
Dangers associated with anti-vaccination sentiments?
Example of a vaccine concern in poultry?
What is influenza? Who does type A infect? Type B/C?
* An acute respiratory illness resulting from infection
* different strains have different severities
What does HA do? NA?
* HA- attach
NA- release
Where do influena A viruses come from?
* water birds- common
* all the ones in black have infected humans and can sustain themselves human to human (PANDEMIC)
* the ones in red- infected humans and caused severe disease but cannot transmit human to human
Influenza pandemics
Cytokine storms can cause the major deaths in a young population
Influenza epidemics
Important aspects of influenza that allow it to persist in the human population?
* can’t proof read and genetic segments
* Antigenic shift (pandemic)- avian and human virus able to infect the same cell–> when they replicate– they can mix genome segments
* Antigenic drift (epidemic- seasonal variation)- acquistion of point mutations over time
Impact of 1918 Spanish Flu pandemic (H1N1)?
* many died from bacterial infections
Why are we currently concerned about a influenza pandemic #1?
Why are we currently concerned about a influenza pandemic number 2?
What happened in 2009 with influenza?
How would you slow a pandemic?
How do the antiviral drugs work?
* M2 channel blockers- stop virus from getting out and replicating
* NA inhibitors- block the process of the virus getting out of the cell
Problems associated with using antiviral drugs to treat influenza infections?
Seasonal influenza vaccines
Dead viruses- cannot get influenza but can get a reaction
Problems with pandemic vaccination
* WHO tries to reach a consensus for what vaccine should have
Role of the Global Influenza Surveillance and Response System (GISRS)
What happens when a sample is received by the WHO Collaborating Centers (CC)?
How are the samples analyzed when they are received at a WHO CC?
How does influenza replicate?
How is influenza sampled?
How is influenza detected?
What Family is Ebola virus in? What is the mortality?
Filoviridae
Mortality 50-90%
Where do most African Ebola Outbreaks occur since 1976?
Ebola virus ecology?
Reservoir host- bats
* means of local enzootic (endemic) maintenance and transmission of the virus within bat populations is unknown
* Epizootics appear sporadically, producing high mortalities with non-human primates and duikers and may precede humans outbreaks
** Reston virus is the excepton as it does not produce detectable disease in humans
** HUman to human transmission is the predominant feature in epidemics following initial human infection through contact with infected bat or other wild animal
* Ebolaviruses: Ebola Virus, Sudan Virus, Tai Forest Virus, Bundibugyo virus, Reston virus (non-human)
What is the incubation of Ebola? Where is it most infectious at peak symptoms/death? How long can it persist in semen?
* Incubation 4-10 days- onset abrupt
* 10- 21 are peak symptoms/death
* Clinical recovery 20- 30 days
* Potential sexual transmission up to 82 days post recovery = 112 days
Ebola virus transmission
* Entry through mucous membranes and broken skin
* High titres in blood
* infectious dose 1-10 particles
* Found in many body fluids and excreta without blood contamination: saliva, tears, breast milk, faeces, semen, and sometimes urine
* Maximum days duration of RNA detection examples: blood (21), semen (101), conjunctival swabs (22), urine (23), rectal swabs (21)
* Propagation generally involves intimate contact: secondary attack rates 10-15%
* Transmission risk increases with contact
* 1976 Sudan e.g. Family members sharing sleeping quarters 23%, Active nursing care 81% transmission
Why is Ebola classified as a level 4 agent?
Basis of high CFR 50-90% and absence of therapeutics or vaccines
What is R naught? What is Ebolas?
The number of cases one case generates on average over teh course of its infectious period
Ebola = 1/2
What are the 7 basic rules of biosafety?
* Do not mouth pipette
* manipulate infectious fluids carefully to avoid spills and production of aerosols
* restrict the use of needles and syringes, use only if there is no alternative
* use PPE
* Wash hands following all laboratory activities, following removal of gloves and immediately after contact with infectious materials
* Decontaminate work surfaces before and after use, and immediately after spills
* Do not eat, drink, store food, smoke, take medications in teh laboratory
Steps in PC4 lab
