Parasites/parasitism individual variation

Initial proteomic studies in parasitic flat-worms have been undertaken using pooled samples. However, proteomic maps can be derived from individual F. hepatica worms (Fig. 17.2), although individual variation... 

Investigating phenotypic diversity is not easy. A basic requirement is to have different lines of parasite available and in natural host species. However, being aware of the possibility of variation between individual worms would be a start. The few studies that have molecularly considered individual worms (Bianco et al., 1990 Fraser and Kennedy, 1990 Currie et al., 1998) have found variation between individual worms. Such variation may be the basis of some experimental noise . Perhaps efforts should be focused on this noise The phenotypic diversity that exists in natural, and even laboratory, populations of nematodes is maintained there by natural selection. This tells us, anthropomorphically, that such diversity matters to parasitic nematodes. It is hoped that this chapter has shown that it should also matter to us. 

Data on the chemical analysis of cestodes are of limited value unless the nutritional status of the host is known, as significant fluctuations in individual parasite components can occur. Furthermore, the chemical composition may vary with the strain of both parasite and host, the host species, the age of the cestode and its degree of maturation. This is partly illustrated in Table 4.1, which shows the variation in biochemical composition of Echinococcus granulosus obtained from different hosts. Some of the available data must also be accepted with caution on technical grounds, because a number of the older analytical methods have been shown, by more modern workers, to be unreliable. 

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