International Journal of Primatology, Vol. 27, No. 4, August 2006 ( C  2006) DOI: 10.1007/s10764-006-9064-x Noninvasive Assessment of Gastrointestinal Parasite Infections in Free-Ranging Primates Thomas R. Gillespie 1 Received December 10, 2004; revision March 24, 2005; accepted June 24, 2005; Published Online August 11, 2006 Recent evidence of emerging human diseases with origins or likely transmis- sion to humans, or both, that involve primates and a greater recognition of the risk of human pathogen transmission to free-ranging primates have raised awareness of the potential impact of zoonotic pathogen transmission on pri- mate conservation and nonhuman primate and human health. As human population density continues to increase exponentially, speeding the reduc- tion and fragmentation of primate habitats, greater human-primate contact is inevitable and even higher rates of pathogen transmission are likely. Thus interest has grown in collecting baseline data on patterns of parasitic infec- tions in wild primate populations to provide an index of population health and to begin to assess and, to manage disease risks. Primatologists tradition- ally have been involved with such surveys through noninvasive assessment of gastrointestinal parasites. Unfortunately, previous studies have tended to- ward divergent methodologies, compromising the potential for longitudinal and comparative work. Here, I provide practical guidelines and standardized methodologies for the noninvasive assessment of gastrointestinal parasites of primates. KEY WORDS: field protocols; intensity; parasitology guidelines; sample size; standardized methodologies. INTRODUCTION Parasites play a central role in ecosystems, affecting the ecology and evolution of specific interactions (Esch and Fernandez, 1993), host 1 To whom correspondence should be addressed at Program in Ecology and Evolutionary Bi- ology and Departments of Anthropology and Veterinary Pathobiology, University of Illinois, Urbana, IL 61802; e-mail: trg@uiuc.edu. 1129 0164-0291/06/0800-1129/0 C  2006 Springer Science+Business Media, Inc.