Book excerpt: From the Preface:Over a dozen years have passed since the first edition of this textbook was published. As is to be expected, tremendous progress has been made in the study of zooparasites and the nature of parasitism. This is especially true in the case of the protozoans and helminths of medical and economic importance. Continuing the original intent, this book is meant to be a teaching tool rather than a reference volume for seasoned investigators. It is meant to supplement formal lectures, but at the same time to provide students with sufficient information as to where more detailed review articles and primary research reports can be located.