Lecture 10 - Infectious diseases Flashcards
what is the disease triangle?
the interactions between the disease, the host and the environment
in terms of epidemiology, what is most important things about the microbe
type of microbe and virulence factors, route of transmission
in terms of epidemiology, what is most important things about the host
risk factors
what is a prion?
infectious proteins
what is a virus?
infectious particle that requires host cells to replicate and make new nucleic acid and proteins for new virus particles
what are parasites?
eukaryotes, may be multicellular.
what is an outbreak?
sudden increase in occurence
what is a pandemic?
outbreak that has spread across a wide region
what is an endemic?
case are at a baseline level in a geographic area
what is a pathogen?
a microbe capable of causing damage to a host
what is pathogenesis
the mechanism by which a disease develops
what is a faculative intracellular organism?
can live inside and outside cells
what is an obligative intracellular
not really alive until they invade a host cell
what is a reservior
aka source, where was the infectious agent caught from
what is the transmission
how the infectious agent gets from reservoir to point of infection
describe host carriage and restriction
host carriage is the ability of a host to carry a disease
host restriction is diseases that don’t work on one host but will on another animal
what are the most common transmission routes?
- airborne
- direct contact
- indirect contact (fomites)
- blood (bites and wounds)
- fecal-oral route
who is most at risk for disease?
people with:
- naiive or failing immunity
- compromised immune system
- unfortunate lifestyle/occupation/location
what can cause compromised immunity?
- drug users (and chemo)
- surgery or wound
- existing condidtion eg HIV
why are the very young and the very old at risk for diseases
due to naiive or failing immunity respectively
what is the general measure of infectiousness?
R0, the higher the number, the more people that can get infected from one person being infected
(R0 of 2-3 means 2-3 people get infected per other infected person on average)
what does R0 depend on?
microbe
dose
route of transmission
host susceptibility
on top of what R0 depends on, what does a superspreading event depend on?
environment
host infectiousness (people may make the disease easier to pass on)
what is the Reff?
the effective R
takes into account public health measures
- what actually happens even after public health measures
R0 is the __________ of a disease and Reff is?
capacity, what is actually does after public health measures e.g masks and vaccination
what is the incubation period?
time between exposure to infectious microbe and onset of symptoms
when are we typically most infectious?
when we are experiencing symptoms, but this does vary with different microbes and different hosts
why are diseases with no diseases during the first half of their infectious period hard to control?
because they are unknowingly infecting others while seeming perfectly fine
- infectious while in incibation period
what are the most important things to consider with symptoms?
- when (onset)
- what
- severity
- organism vs host, what is causing symptoms
what is the clinical disease rate?
the proportions of infected people who develop disease
what is the infection fatality rate?
the number of estimated deaths as a proportion of all infected
what is the case fatality rate?
the number of deaths as a proportion of confirmed cases
what is the immunity rate?
the proportion of people immune to reinfection
lifespan of an outbreak on a graph looks like?
a camel hump
- daily cases vs time since first case (may be a second hump if people begin to get reinfected)
what is ebola also known as?
EVD (ebola virus disease)
zaire virus
how does ebola happen?
Zaire virus attaches to TIM-1 receptors on epithelial cells in body orifices
viral RNA is released into the cell and replicated
new viruses bud from infected cell
what is the reservoir of ebola?
not humans, but usually fruit bats or other infected animal that touched a fruit bat.
how can ebola be spread?
through contact with an infected person or animal
contact with bodily fluids of the sick or even dead
contact with contaminated objects such as needles or bedding
describe the incubation period of ebola
2-21 days, no transmission during incubation period
what are the early symptoms of ebola?
fever, headache, sore throat
what are the severe symptoms of ebola?
severe diarrhoea, vomiting and bleeding
how does the risk of spread change with severity of the symptoms of ebola?
the more severe the symptoms, the higher the risk of spread
what part of traditions in africa made it difficult to contain the outbreak?
the families like to clean the bodies and prepare them before burial
what is the mortality rate of ebola
anywhere between 25-70%
what were the three main countries that were impacted in the 2014 western ebola outbreak?
guinea, liberia and sierra leone
which ebola virus is the main one nowadays
zaire
true or false: ebola coincides with the wet season
false, ebola often occurs more often during prolonged dry seasons and deforestation
true or false, ebola happens during civil war and political instability
true
what are the main treatments for ebola?
- monoclonal antibody treatments
- monitoring
- fluid resucitation
- treatment of coinfections and seizures
but not all countries have access
how many vaccines are there for prevention of ebola?
two
what ebola do the vaccines not work against?
sudan
what is the ERVEBO vaccine
1 intramuscular dose for 18+
- WHO recommends revaccinating if a contact >6 months after vaccination
what is the Zabdeno + Mvabea vaccine?
intramuscular and suitable for 1+
can get a zabdeno booster after 4 months if a contact
true or false, vaccines make a massive difference to the shortening of and outbreak
true
