Week 6 Flashcards
What is epidemiology?
The study of how diseases in different groups of people and why
How is epidemiology studied?
Drawing on knowledge of specfic cases
Applies that knowledge across a population
What is the key in the aplication of epidemiology?
Is considering the population risk and how different populations react
Applying relevant data
What is an endemic disease?
Disease that is constantly present in a certain population or region, with relatively low spread or periods with no spreaf when it doesn’t affect people at all (if it is only in the environement)
What is an epidemic disease?
When there is a sudden increase in cases through a large population like a country
What is the different between outbreak and epidemic disease?
An outbreak is similar but usually covers a smaller geographic area
What is a pandemic?
When there is a sudden increase in cases spreading through several countries, continents or the whole world
What is etiology?
The cause of a disease
What is Prevalence?
The number of existing cases of a given disease at a given point in time
What is incidence?
The number of new cases of a given disease over a specific time period
What is virulence?
The severity of a disease
What is mortality rate?
The death rate (number of deaths in a given time period due to particular disease)
What is R0?
The basic reproductive rate for a disease. A proxy measure for how contagious a disease is
What is R1?
The number of cases that any given case could case. R0 = 1 every case leads to 1 case
What is morbidity?
The rate of disease in a population (useful for low case-fatality diseases)
What are the 5 questions to study epidemiology at a population level?
The 5 W’s
What is the health concern? (e.g causative pathogen)
Who is it affecting? (Determine who your population is)
Indentify a sample (hopefully represents your population)
Surveillance - Moniter for patterns and changes over time and space
What is requred for studying parasite/pathogens?
The pathogen
The host
Any vectors or intermidiate host
The context/environment
What are the 3 not all’s of studying pathogens?
Not all pathogens are equal
Not all pathogens are parasites
Not all hosts are equal
What is a key case study involving the same disease but in different hosts?
TB in meerkats, the more social the meerkat the higher probability of testing positive for TB
Badgers: The less social the Badger the higher risk of testing positive for TB
What is a key case study involving the closely related parasites in the same host
Plasmodium relictum lowers reproductive sucess for blue tit
Plasmodium circumflexum results in lower survival for blue tit
What is the 2 major scales for studying pathogens/parasites?
Temporal scale and Spatial
What is temporal scale?
If you sample seasonally but your pathogen kills your host quickly (within a season), your sampling is inaccurate
What is spatial scale?
Consider your landscape, e.g tick-born Lyme disease at a small scale shows a positive link between human disease risk (amplification effect) and biodivserity but at a larger scale shows the opposite (dilution efffect)
What rules do you need to apply to study the principles of pathogen ecology?
Understand your species (pathogen, host and any vectors)
Understand their habitat (the context)
Monitor the populations
Respond to populations changes (manage your population)
Repeat
What are Zoonoses?
Disease that comes from an animal
What are prion diseases?
Prion diseases occur when the prion protein found on the cell surface of many proteins becomes abnormal and clumps in the brain causing damage
What makes a pathogen sucessful?
Pathogens that can manipulate their hosts
What 3 things are required for a pathogen to be spread?
Needs to be transmissible to allow it to spread between hosts
Needs the host to survive and be well enough to continue transmission
Ideally wants host to respond to infection that maximises transmission
What is the R number, minimum vaccination for herd immunity and case-fatality rate for Bordetella patois (whooping cough)?
12-17
92-94%
4%
What is the R number, minimum vaccination for herd immunity and case-fatality rate for Measles?
12-18
83-94%
0.1-0.2%
What is the key feature of Yersina pestis?
Intracellular obligate bacterium
What is the life cycle of Yersina pestis?
Infections of rodents and fleas but can infect any mammalian host
What is Yersina pestis commonly called?
Bubonic plague
What is surprising about Yersina pestis with human infections?
Not well suited to human hosts expect in human-human transmission (pneumonic plague) as the flea can’t reproduce on human blood
What is ironic bubonic plague?
It was a evolutionary disaster
How many people have died from Yersina pestis?
Roughly 100 million since 6th century
What is fatality rate of Yersina pestis?
90%
What is the minimum infective dose of Yersina pestis?
10 cells
What is the R number for Yersina pestis?
1.5 to 1.9
What is the urban cycle for Yersina pestis?
Domestic rodent is bitten by infected flea which then may go on to bite another rat. Then a flea may go from rat to person
What is the Sylvatic cycle?
Same as the urban cycle but with wild animals
How did Yersina pestis to become better at propergating in humans?
Mutation to 1 amino acid 1500 years ago
Switching from primarily respiatory pathogen to a more invasive one
What are the new methods allowing Yersina pestis become more effective at targeting humans?
A multipronged attack including adhesins which help the pathogen become established within the target host tissue.
They have proteins called Yop effector proteins which disrupt cell signalling and trigger apoptosis
How many types of Influenza are there?
4
(A,B,C and D)
What are the key features of influenza?
Obligate intracellular pathogen
Zoonotic
Big impact on humans not necessarily deaths
Variable fatility rate
How many people die a year from the Flu?
Roughly 600,000
How many people were killed by the spanish flu?
Around 40 million
What is special about the Influenza A surface proteins?
H1-18 and N1-11
High mutation rates
Influenza A virus can undergo antigenic shift and antigenic drift
What 2 types of Influenza spike proteins?
Hemagglutinin (18 types)
Neuraminidase (11 types)
What is antigenic shift?
Rapid, big change in a subtype. Result from spillover event and lead to new virus subtype. Virus combination
What is antigenic drift?
Gradual changes in membrane proteins resulting from mutations during virus replication
Why do mutations occur quickier in Influenza A?
RNA genome lacks any proofreading mechanisms thus mutations can accumulate
What is significant about Influenza virus A?
All have animal reservoirs like birds, bats, equiene and pigs
What is one health?
Preventing major outbreaks but helping treating animals and the general environment
