Parasitism and Infectious diseases`

what are the two types of parasites

ectoparasites and endoparasites

where do ectoparasites reside

on the outsides of organisms

what are the advantages of ectoparasites

• easily move between hosts

• not exposed to host immune system

what are the disadvantages of ectoparasites 

• exposed to the environment 

• exposed to predators and parasites 

what are endoparasites and where do they reside

they live on the insides of organisms and can be intracellular (like viruses, that live and replicate inside host cell) or extracellular (like intestinal worms, that live and replicate between host cells)

what are the advantages of endoparasites

• safe from the external environment

• hosts rarely have internal, physical defenses to prevent feeding

what are the disadvantages of endoparasites

• exposed to the host immune system

• hard to move between hosts

t/f: parasites cause population cycles of hosts

true

what are emerging infectious diseases

newly evolved strains of diseases, where some mutations allow a pathogen to jump to a new host species or become a more virulent strain

what is white-nose syndrome in bats

a disease caused by a fungus that causes a large number of bats to die

what are zoonotic diseases 

those that jump from non-human animals to humans and are the main source of emerging infectious diseases in humans, resulting in many epidemics 

what are zoonotic epidemics related to

habitat fragmentation and climate change

what is the S-I-R model

the simplest way to model the transmission of an infectious disease (i.e., if an epidemic will happen or not) that incorporates immunity of the host

what is S in e S-I-R

susceptible to the pathogen

in the S-I-R model what percent of individuals begin as S 

100%

what is I in S-I-R

infected

of the susceptible individuals, some percentage become

infected

of the infected individuals some percentage develop

resistance via immunity

what is R in S-I-R

resistance via immunity 

what model does this graph represent

S-I-R model

What is the equation for N, the total population size

S+I+R

I —> R is

the recovery rate (g)

S—→ I is what 

transmission rate (beta)

S—→ R is

immunization

for most endoparasites (viruses and bacteria) what is counted instead of individual parasites

the number of hosts infected with parasites

what is Rnot

the basic reproductive number of an infectious disease (i.e. the number of new hosts who are infected by a single infectious host in an entirely susceotible population)

t/f: R0 is not a per captia growth rate 

false 

when the transmission rate is greater than the recovery rate what happens

disease spreads

what does it mean when R0 > 1

the infection will continue to spread through the population (potential epidemic)

what does it mean when R0 < 1

the infection will not spread (on average, each infected individual fails to infect another individual)

what is a spillover event

occurs when a disease that exists in a reservoir host population is transmitted to ahuman

what all can direct effects be caused by 

predation, parasitism and other types of interactions 

indirect effects are always a reault of what

multiple direct effects