Remarkable achievements in parasitic disease research, both basic and translational, have occurred over the last ten years, and we have incorporated the majority of these into the 6th edition of Parasitic Diseases. We have added over 1,000 new references to document these advances. Innovative work in the laboratory has provided the clinician/research scientist with a much clearer understanding of the mechanisms of pathogenesis. The number of recently discovered interleukins and their cellular networks has completely re-ordered our comprehension of how parasites and our defense system works to produce protection against infection/reinfection, or in some cases, how it becomes subverted by the offending pathogen to enable it to endure inside us for long periods of time. A plethora of molecular-based diagnostic tests have found their way into the routine of the parasitology diagnostic laboratory, improving the ease at which the offending pathogen can be rapidly identifed. Newer drugs, many with less harmful side-effects than the ones they replaced, have come on the market that make controlling parasite populations at the community level possible without the risk of harming the very ones we wish to help.