This unique, ground-breaking book is a comprehensive clinical guide to the psychiatric disorder of Delusional Infestation (DI). DI is a psychiatric illness characterized by patients holding a monothematic fixed belief of infestations on their skin, body, or immediate environment - a belief that is not supported by objective medical evidence. Delusional beliefs may be shared among individuals, and perceived pathogens include living organisms such as parasitic worms, bacteria, fungi, and insects. Organic or non-organic infiltration by fibres, threads, or other inanimate particles or objects, known or unknown to medical science, are also described by patients. DI is severely underreported because of social stigma, limited physician awareness, and patient doctor-hopping. Written for physicians, the book offers a multidisciplinary, compassionate care model for patients burdened by this pernicious disorder. Other health professionals and administrators will find the work highly valuable, as will professionals in fields such as veterinary medicine, pest management, entomology, parasitology, and information services supported by academia. The Physicians Guide to Delusional Infestation assembles and organizes all current knowledge of DI and presents material in three parts. Part I introduces and reviews DIs historical background, showing how our understanding of the condition has developed. Its concise sections include useful tables, illustrations, algorithms, and reference lists for clinicians who work with DI patients. Part II covers differential diagnosis, treatment, and ways to work effectively with DI patients. Since these patients are often high-functioning, particular techniques of interviewing, joining with patients, sampling, and laboratory testing are explained. International travel, physician fallibilities, possible alternative diagnoses, the Internet, and veterinary and public health concerns are all addressed. PartIII is a series of chapters written by experts in their fields. This section allows each author to present personal experiences from their respective professions -- observations and opinions that show a variety of perspectives among the books authors. Part III includes a chapter on common human parasites with their biology, behaviours, and distributions. The book will serve as a comprehensive, yet concise, reference for physicians whose patients have unusual, baffling, or implausible medical histories and physical examinations. A soon to be gold-standard resource, The Physicians Guide to Delusional Infestation equips and empowers all physicians -- and many others interested in the topic -- with an expert, comprehensive understanding of this complex disorder.