Parasite load is a measure of the number and virulence

Virulence

Virulence is by MeSH definition the degree of pathogenicity within a group or species of parasites as indicated by case fatality rates and/or the ability of the organism to invade the tissues of the host. The pathogenicity of an organism - its ability to cause disease - is determined by its...

 of the parasites that a host organism harbours. Quantitative parasitology

Quantitative parasitology

-Counting parasites:Quantifying parasites in a sample of hosts or comparing measures of infection across two or more samples can be challenging.The parasitic infection of a sample of hosts inherently exhibits a complex pattern that cannot be adequately quantified by a single statistical measure...

 deals with measures to quantify parasite loads in samples of hosts and to make statistical comparisons of parasitism across host samples.

In evolutionary biology, parasite load has important implications for sexual selection

Sexual selection

Sexual selection, a concept introduced by Charles Darwin in his 1859 book On the Origin of Species, is a significant element of his theory of natural selection...

 and the evolution of sex

Evolution of sex

The evolution of sexual reproduction is currently described by several competing scientific hypotheses. All sexually reproducing organisms derive from a common ancestor which was a single celled eukaryotic species. Many protists reproduce sexually, as do the multicellular plants, animals, and fungi...

, as well as Openness to experience

Openness to experience

Openness to experience is one of the domains which are used to describe human personality in the Five Factor Model Openness involves active imagination, aesthetic sensitivity, attentiveness to inner feelings, preference for variety, and intellectual curiosity. A great deal of psychometric research...

External links

• notes on parasite-driven sexual selection from a parasite ecology/evolution course