parasitism Flashcards
What are parasites?
Parasites are organisms that derive their nourishment from another organism, it’s host, which is harmed in the process
Why do parasites tend to have a narrow niche?
Because they are ‘host specific’ - they are only able to live based on the conditions the host can provide to them
What is transmission?
Transmission is the spread of a parasite to a host
What is virulence?
The potential of a parasite to cause harm to a host
Factors which can increase transmission?
overcrowding of hosts in high density populations
The use of vectors
Fomities (any object or substance capable of carrying infectious organisms)
Food and water
What can the parasite do to the host in order to gain benefit?
Exploit the host’s behaviour by changing it to increase transmission rates
What behaviour’s of the host can the parasite alter?
movement, sexual behaviour, habitat choice and anti-predator behaviour
The host behaviour becomes…
The extended phenotype of the parasite
Parasites can…
suppress the immune system of their host, suppress the reproductive system of the host, modify host size and affect specific organs
Sexual phases…
Allow rapid evolution of the parasites
Asexual phases
Allow rapid build-up of the population
What do endoparasites do in order to evade the immune system?
mimic host antigens to avoid being recognised by the host’s immune system,
Change host’s immune response to avoid its destruction
Evolve fast enough (by changing their antigenic markers) for them to be one step ahead of host memory cells
How does the control of the parasite benefit the human population?
More energy can be used for growth and development
Reduction in child mortality
