cruziIIa (Clark and Pung1994, Barnabe et al.2001, Roellig et al.2008), including the strains isolated in the current study (Roellig et al.2008). Arizona. Culture-based prevalence rates for raccoons were significantly greater than those for opossums; however, seroprevalences of raccoons and opossums from several geographic locations in Georgia and Florida were not different, EsculentosideA indicating that exposure rates of these two species are comparable within these areas. For both raccoons and opossums, seroprevalence was significantly higher in females than in males. No difference was detected in seroprevalence between adults and juveniles and between animals caught in urban and rural locations. Our results indicate thatT. cruziprevalence varies by host species, host characteristics, and geographic region and provides data to guide future studies around EsculentosideA the natural history ofT. cruziin the United States. Key Words:Anaplasma, Ehrlichi, Trypanosome, Zoonosis == Introduction == Trypanosoma cruzi, a hemoflagellate protozoan parasite, is the causative agent of American trypanosomiasis (Chagas’ disease) in domestic animals and humans.T. cruziis an important public health concern in Latin America, where 1012 million people are estimated to be infected (Morel and Lazdins2003). In North America,T. cruziis commonly detected in several species of mammalian wildlife, and is increasingly diagnosed in domestic dogs and amazing animals (Kasa et al.1977, Jaime-Andrade et al.1997, Meurs et al.1998, Kjos et al.2008). Autochthonous cases in humans are rare, with only six cases previously reported (Herwaldt et al.2000, Dorn et al.2007); however, serologic studies indicate that many autochthonous cases may be undiagnosed (Woody et al.1965, Burkholder et al.1980, Stramer et al.2007, Bern et al.2008). The two most commonly reported reservoirs in North America are the raccoon (Procyon lotor) and the Virginia opossum (Didelphis virginiana). In raccoons, published prevalence rates range from 1.5% in southwestern Georgia and northwestern Florida (McKeever et al.1958) to 63% in Oklahoma (John and Hoppe1986), with rates varying widely depending on the assay used (e.g., serology, culture, or both) and the geographic location. Reported prevalence rates for opossums have generally been lower, and range from 8% in North Carolina (Karsten Comp et al.1992) to 33% in southern Louisiana (Barr et al.1991). Other wildlife species in the United States that are naturally infected with the parasite based on either serology or culture include the armadillo (Dasypus novemcinctus) (Yaeger1988, Barr et al.1991), badger (Taxidea taxus) (Burkholder et al.1980), coyote (Canis latrans) and gray fox (Urocyon cinereoargenteus) (McKeever et al.1958), striped skunk (Mephitis mephitis) (McKeever et al.1958, Ryan et al.1985), and various rodent species (Burkholder et al.1980). The majority of previous studies ofT. cruziin wildlife have focused on blood culture as the primary method for determining infection status, but this method has been shown to have a lower sensitivity than serologic testing (Jansen et al.1985, Yabsley et al.2001, Hall et al.2007). Since culture of the parasite depends on high numbers of circulating parasites, animals in the chronic stage of contamination, which are seropositive, are less likely to be culture positive. For example, Hall et al. (2007) tested 50 lemurs from St. Catherine’s Island, GA, forT. cruziusing culture and serology, and found a 5% prevalence rate with culture and a 50% seroprevalence rate, and EsculentosideA Yabsley et al. (2001) tested raccoons from Georgia using both serologic and culture techniques, and found a 30% prevalence rate using culture, but a 51% prevalence rate using serologic testing. The aim of the current study was to determine the prevalence ofT. cruziin several species of mammals throughout the United States using serologic testing, and to further assess exposure rates of raccoons and opossums from several individual geographic locations in Georgia and Florida using both culture and serologic methods. Several demographic parameters of raccoons and opossums were also investigated in a subset of samples to assess any correlation withT. cruziseroprevalence to determine if any broad-scale hostparasite associations exist with this parasite. == Materials and Methods == == Sample collection == In Georgia, Florida, and Missouri, animals were captured in box traps (Tomahawk Live Trap, Tomahawk, WI) baited with sardines or mackerel. Raccoons were anesthetized by intramuscular injection of either ketamine hydrochloride (25 mg/kg body weight; Aveco, Fort Dodge, IA) plus xylazine (0.25 mg/kg body weight; Mobay, Animal Health Division, Shawnee, KS), or tiletamine plus zolazepam (Telazol, 0.6 mg/kg body weight; Aveco). Opossums were anesthetized by intramuscular injection of tiletamine plus zolazepam. Approximately EsculentosideA 10 mL of blood was collected via cardiac puncture from anesthetized animals (Georgia and Florida) or from the femoral vein (Missouri). Whole blood in ethylenediaminetetraacetic acid was collected for culture, and plasma.