Effects on Individuals and Populations Flashcards
What is who’s definition of health?
A state of complete, physical, mental and social well-being and not merely the absence of disease or infirmity.
Definition of disease?
Any impairment that interferes with or modifies the performance of normal functions
What are two forms of Costs?
Direct
Indirect
Examples of direct costs
Mortality Injury that has to be repaired Injury that results in less efficiency Direct loss of resources Loss or reproduction
Examples of indirect cost
Avoidance
Resistance - Ab production
Increased vulnerability to other harmful factors
What is the currency used to measure “cost”
Energy
Energy pathway
Ingested Energy –> Assimilated Energy
Assimilated Energy prongs into
- Respiration, maintenance, thermoreg, defense
- Production, growth, reproduction
- Storage - storage can return to assimilated
2 basic rules about energy
An animal cannot use more energy than it can assimilate
If an animal uses more energy for one purpose, there is less available for another
How can disease affect ingested energy?
Super occupied with disease that they dont eat as often
How can chinchilla: dental abnormality affect the chinchilla
Teeth grow funny and cant eat well
Cow: Johne’s disease
Malabsorption
What is life time success measured in?
Fitness
What is fitness determined by?
Combination of survival and fecundity
Where does all disease begin?
Cellular level
- interference with cell’s energy or resource supply
- damage to the cell’s membrane
4 forms of resistance
Avoidance
Physical barriers
Innate resistance
Acquired resistance
Example of avoidance
If sheep are healthy they will not eat lush feed when near or covered in feces
If sheep are sick they will eat lush grass even though feces are present
3 physical barriers
Intact skin
Gastric pH
Flow of urine
What is the most important component of innate resistance?
Inflammation
Two forms of repair
Regeneration - complete return of function
Scarring - Replacement with CT, diminish function
What is the cause for most of the actual injury?
Body’s reaction to the agent
~inflammation
~immune response
~Repair and scarring
What is a population
A group of individuals of the same species that live together in an area of sufficient size to permit normal dispersal and or immigration behavior and in which numerical changes are largely determined by birth and death processes
5 Important features of a pop?
Size Rate of contact Spatial distribution Sex and age composition Rate of turnover (replacement)
How doe effects of disease act at the population level?
Influencing survival or reproduction
Two types of survival?
Direct mortality
Indirect mortality
3 ways of indirect mortality?
Increased susceptibility to predation
Increased susceptibility to other diseases
Increased susceptibility to physical factors
3 ways disease can affect repro
Injury to reproductive organs
Injury to fetus
Interference with reproductive behavior
A population consists of 3 types of individuals with respect to any disease caused by a microparasite
Susceptible animals
Infected animals
Resistant animals
3 results to infection
Recover and become resistant
Remain chronically infected
Die
What is Ro?
The basic reproductive number (rate) of a disease
- the avg # of secondary infections that arise from introduction of one infected individual into a fully susceptible population
What is Ro determined by?
Frequency of contacts
Proportion of contacts that result in transmission
What must Ro = in order to become established in a pop?
Ro should = at least 1.
On avg, each infected individual has to infect at least on new individual or the disease will not become established
Who was the most famous super-shedder?
Typhoid Marry
What occurs as disease spreads within the pop?
The proportion of contacts that are with susceptible animals decreases
Ro no longer applies, uses Reff now
Of maintenance, spillover and dead-end, which host do you want to target most?
Maintenance
2 ways in which we manage or control disease?
Reduce the exposure to the agent or risk factor
Increase resistance
