Parasitism and Disease

Ectoparasite

parasite that lives on the outside of an organism

Ectoparasite characteristics

constant threats of predation, inconsistent access to host, variable environment, easily dispersed, and limited exposure to host immune system

Endoparasite

parasites live inside organisms

Endoparasite characteristics

protected from external environment and predators, complex dispersal mechanisms, constant response to the host immune system, constant host access

Endoparasite Diversity

virus, fungus, bacteria, protist, flatworm/nematode/leeches, prions

Parasite load

number of protists of a given species that an individual host can harbor

Best intrest in parasite

host stays alive

Host provides

nutrients and/or cellular machinery for proliteration

Horizontal transmission

parasite moves between individual other than parents and their offspring

Vector

used to dispense one host to another

Vertical transmission

parasite is transmitted from a parent to its offspring

Accessing the host

open wound, inhalation ingestion, injection

Switching hosts

evolution of ability to infect alt host. Requires frequent exposure

Reservoir species

can carry a parasite but do not succumb to the disease that parasite causes in other species

Host response

immune system can target parasite it detected; immune system activation require exposure. Some parasites hide inside cell

Environment Variability

access to host, exposure to enemies, abiotic conditions

Vaccination of individuals

reduce host susceptibility and stimulates immune system

Susceptible-infected-resistant model

simplest model of infectious disease transmission that incorporates immunity

Parasite defense

zombie hosts, resistant to digestion, high genetic variation

Host defense

avoidance, cleaning, chemical defense, physical defense

Coevolution

reciprocal evolutionary change between interacting species, driven by natural selection