RESEARCH animals will not survive to produce an antibody response. However, susceptibility varies widely among species, and even within a susceptible species, seropositive animals have been detected, e.g., in cattle in the United Kingdom (10) and bison (Bison bison) species in North America (11). Turnbull et al. documented serologic evidence of infection in Etosha lions (Panthera leo) and suggested that lions can serve as an indicator species of anthrax in disease-endemic areas because of their territorial behavior (10,12). The potential of using serologic analysis for comparative studies has also been limited because, up until now, serologic assays for detecting antibodies to anthrax in a variety of species have not been widely available, even in research settings. The constraints of anthrax surveillance, particularly in tropical areas, highlight the need to identify alternative approaches to overcome these difﬁculties. We present results of analyses of data obtained opportunistically in the Serengeti ecosystem in Tanzania to explore the value of serologic analysis for providing information about anthrax infection and exposure patterns in large, remote, and complex ecosystems. Using seroprevalence data obtained with 1 assay for a range of species, we also investigate within-species and between-species variations in exposure and survival to evaluate which species may be useful as indicators of anthrax for surveillance purposes, speciﬁcally to identify high-risk areas for human and livestock populations. Materials and Methods Study Area The study area in the Serengeti ecologic region in northwestern Tanzania comprised wildlife-protected areas, including the Serengeti National Park (SNP) and adjacent game reserves (Maswa, Ikorongo, and Grumeti). Study sites also included multiethnic, agropastoralist communities west of SNP and Ngorongoro District east of SNP, a multiple land use game controlled area inhabited by low-density Maasai and Sonjo communities that had production systems based on traditional pastoralism and limited cultivation. Ngorongoro district is divided into the Loliondo Game Control Area in the north and the Ngorongoro Conservation Area (NCA) in the south (Figure 1). Disease Monitoring Operations Disease detection in wildlife was based upon passive surveillance operations in the study area during 1996–2009. Sightings of carcasses were reported through a network of veterinarians from Tanzania National Parks (TANAPA) and Tanzania Wildlife Research Institute (TAWIRI), rangers, scientists, and tour operators. Passive surveillance data from outside SNP were available through veterinary ofﬁce records (government ofﬁces, TAWIRI, TANAPA, and NCA Authority). Human anthrax cases were compiled from records of government and mission hospitals in the study area for 1995–2008. Further information about human anthrax cases was obtained through key informants in villages affected by a major anthrax outbreak in 2006, and data on the age, sex, Figure 1. Anthrax cases and exposure to anthrax in the study area, Tanzania. Blue areas indicate lakes. A) Location of wildlife carcasses during anthrax outbreaks. Shaded areas indicate regions where human anthrax cases were reported during 1995– 2008. Exact locations of carcasses obtained during the Sopa 1998 outbreak were not available; open circles indicate area where 549 probable cases and 67 suspected cases were detected. For the Seronera 2003 outbreak, locations of cases were randomized within a 10-km radius of the outbreak area because exact locations of carcasses were not available. B) Seroprevalence in domestic dog populations from sampled villages. Sample size is indicated by the radii of the pie charts. Green border indicates Serengeti ecosystem. LGCA, Loliondo Game Control Area; SNP, Serengeti National Park; NCA, Ngorongoro Conservation Area. 388 Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 17, No. 3, March 2011