AbstractKnowledge of the morphological phenotypes of the liver fluke Fasciola
hepatica (Trematoda: Digenea) is analysed. The influence of
parasite age on its dimensions, the adult fluke growth model, variation in a
biometric variable versus time, and variation in a biometric variable versus
another biometric variable (allometric model) are revised. The most useful
allometric model appears to be
(y2m]#x2212;y2)/y2=c
[(y1m−y1)/y1]b, where
y1=body area or body length, y2=one of the
measurements analysed, y1m, y2m=maximum values towards
which y1 and y2, respectively, tend, and c, b=constants. A
method based on material standardization, the measurement proposal and
allometric analysis is detailed. A computer image analysis system (CIAS), which
includes a colour video-camera connected to a stereomicroscope (for adult
studies) and a microscope (for egg studies), facilitates the processing of
digital imaging. Examples of its application for the analysis of the influence
of different factors on the liver fluke phenotype are shown using material from
the Northern Bolivian Altiplano, where human and domestic animal fascioliasis is
caused by F. hepatica only. Comparisons between the development
of livestock fluke populations from highlands and lowlands are discussed and the
relationships between host species and liver fluke morphometric patterns is
analysed.