On the interpretation of age-intensity profiles and dispersion patterns in parasitological surveys.
The present paper describes how age-intensity profiles of macroparasite burdens are affected by processes underlying the distribution of the parasite numbers in host populations. In a comparative way, we consider the following 6 processes: (i) age-dependent exposure, (ii) parasite-induced host mortality, (iii) heterogeneity within, the host population, (iv) clumped infection, (v) density-dependent parasite mortality and (vi) density-dependent parasite establishment. For each of these processes, we show typical patterns in the age-intensity profile and provide, if possible, explicit and simple solutions for the age-dependent mean parasite burden and the corresponding dispersion patterns. Emphasis is given to density-dependent parasite establishment and to age-intensity profiles resulting from the superposition of different processes. By means of 2 examples we show that the interpretation of observed patterns can be ambiguous if more than 1 process takes place. These findings underline that age-intensity profiles should be interpreted on the basis of available a priori knowledge about the processes assumed to be involved. For purposes of testing different hypotheses, a simulation program is provided with which discrepancies between model prediction and data can be explored.
Duerr
H P
HP
Department of Medical Biometry, University of Tübingen, Germany. hans-peter.duerr@uni-tuebingen.de
Dietz
K
K
Eichner
M
M
D000375:Aging / Q000502:physiology*; D000818:Animals; D003625:Data Collection; D006790:Host-Parasite Interactions; D008017:Life Expectancy; D008954:Models, Biological; D010271:Parasites / Q000302:isolation & purification* / Q000502:physiology*; D010272:Parasitic Diseases / Q000469:parasitology* / Q000503:physiopathology*; D011157:Population Dynamics