Phenotypic analysis of adults and eggs of Fasciola hepatica by computer image analysis system

Abstract

Knowledge 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 (y2 m-y2)/y2=c [(y1 m-y1)/y1](b), where y1=body area or body length, y2=one of the measurements analysed, y1 m, y2 m=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.

CIAS detection of Fasciola hepatica/F. gigantica intermediate forms in bovines from Bangladesh

“…Entry into the bile duct induces maturation and egg production. The logistic model which represents body growth and development is characterised by two phases (Valero et al 1998(Valero et al , 2005. The ''exponential'' part of logistic growth corresponds to body development during migration in the abdominal cavity and liver parenchyma, as well as to development and sexual mat- Table I.…”

“…Studies were performed using a computer image analysis system (CIAS) on the basis of standardised measurements known to be useful for the differentiation of fasciolid species (Valero et al 2005Periago et al 2006Periago et al , 2008Afshan et al 2013). Standardised measurements were taken using a microscope and images captured by a digital camera (Nikon Coolpix), which were then analysed by image analysis software (ImagePro plus version 5.0 for Windows, Media Cybernetics, Silver Spring, Maryland, USA).…”

“…A circular object will always have a roundness of 1.00, while more irregular objects will have larger values, indicating how circular an object is ). -Morphometric measurements used for fasciolid adults follow a logistic growth model with respect to time (Valero et al 2005). This implies that the morphometric development of the fasciolid adult is not limited but 'damped' and does not exceed certain characteristic maxima (Valero et al 2001a(Valero et al , b, 2006b(Valero et al , 2011.…”

“…Bovines, as the most widespread livestock species in the country, were been the hosts selected. An approach by means of a computer image analysis system (CIAS) (Valero et al 2005(Valero et al , 2012c) was applied for the morphometric characterisation of the liver flukes.…”

Impact of climate change and man-made irrigation systems on the transmission risk, long-term trend and seasonality of human and animal fascioliasis in Pakistan

“…Lastly, the presence of F. hepatica/F. gigantica intermediate forms has been confirmed in Punjab by fasciolid adult and egg phenotyping (Afshan et al, 2013) by computer image analysis system (CIAS) methodology (Valero et al, 2005).…”