The purpose of purifying a spore suspension is to remove unwanted host tissues and microbial contaminants that may confound experimental data. A high purity of spores can facilitate accurate microscopic counting and is an important quality assurance parameter in pathological studies. A number of purification methods describe below give high purity preparations, and the choice of purification method depends upon the specific requirements and applications of spore suspension. For in vivo feeding assays, it is sufficient to purify spores using filtration and centrifugation techniques. Alternatively, methods of triangulation or density gradient purification, in addition to initial filtration, are recommended for experiments that require a very high level of spore purity. Note that amount of water added to resuspend the pellet will affect the spore concentration and the final concentration of the inoculum must therefore be checked using a haemocytometer (see section and the BEEBOOK paper on miscellaneous methods (Human et al., 2013).