![]() nutrient thievery, food entering ps instead of host find a dead host teaming with parasite, not sure if they were the cause or not Parasite and Host Metabolism Look at the effect of parasite on host metabolism, parasites eat and obtain nutrients from their host. Cautions, problem in detecting a particular host. schistosome, parasitic barnacle, hook wormĥ. Variation in effects is associated with variation in host exploitation strategies. Variation in effects is associated with variation i many other factors (context dependent)Ĥ. Dicrocelium in sheep and cows, Winter tick in Moose and deerģ. The same species of parasite can have very different effects on different hosts. parasite if Daphnia, have multiple parasites within but few effect it negativelyĢ. Different parasites have contrasting effects on the same host. *wormy hosts have a predisposition to infections Effect on Host Individuals 1. Immunity that is triggered by parasite (antigen?) numbers Density Dependent Mechanisms - Competition for space Factors such as humidity, moisture etc. Applied epidemiology: diagnosis and treatment of hosts at right side of FD Abiotic Factors Temp-dependent transmission, growth, survival in.= mutual stability & regulation of host and parasite.linked to distribution of parasite in host population Increases potential for regulatory processes (density dependent immunity, density dependent worm growth,.Probability of acquiring new parasites may be increased by a previous infection Consequences of Parasite aggregation Parasite-induced mortality in few hosts (20%) Ecology = host behaviour, host size, previous infection Immunity factors, host size, gender, behaviour Genes = Genetic predisposition, genetically-based Infective stages not random (waves of clumped exposures).behaviour, ecology, no resistance mechanisms *look at formula Causes of Parasite Aggregation Requires knowledge of parasite transmission, life cycle, used to determine the effects of virulence in individuals and a population Transmission Threshold Ro=1 A high k value means there are few to no parasites in most hosts but a few hosts have lots of parasites. u: death rate due to not finding a host Index of Aggregation How parasites are distributed in a population. Seal-Intensity about 100, tightly regulated and consistentĭucks- not consistent, no regulation, 0-1000'sĮnvironment decides variation Theoretical Considerations Quantitative science, with rate-limiting steps What factors regulate parasite population size?.What factors determine parasite population sizes?.biomass, reproductive maturity Patterns in parasite population dynamics What determines virulence and transmission? eggs per gram feces (e.p.g.), eggs per day Parasite quantity prevalence, mean abundance, mean intensity (kill and Suprapopulation A population that includes all of the developmental phases of a parasite species at a particular time and place. All of the infrapopulations of a single host species within a ecosystem. Component Population All of the individuals of a specified life history phase at a particular place and time. Infrapopualtion The number of parasites (one species) within one individual.
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