Serologic Sur veillance of Anthrax in the Serengeti Ecosystem, Tanzania, 1996–2009 Tiziana Lembo, Katie Hampson, Harriet Auty, Cari A. Beesley, Paul Bessell, Craig Packer, Jo Halliday, Robert Fyumagwa, Richard Hoare, Eblate Ernest, Christine Mentzel, Titus Mlengeya, Karen Stamey, Patricia P. Wilkins, and Sarah Cleaveland Bacillus anthracis, the bacterium that causes anthrax, is responsible for varying death rates among animal species. Difﬁculties in case detection, hazardous or inaccessible carcasses, and misdiagnosis hinder surveillance. Using case reports and a new serologic assay that enables multispecies comparisons, we examined exposure to and illness caused by B. anthracis in different species in the Serengeti ecosystem in Tanzania during 1996–2009 and the utility of serosurveillance. High seroprevalence among carnivores suggested regular nonfatal exposure. Seropositive wildebeest and buffalo showed that infection was not invariably fatal among herbivores, whereas absence of seropositivity in zebras and frequent detection of fatal cases indicated high susceptibility. Exposure patterns in dogs reﬂected known patterns of endemicity and provided new information about anthrax in the ecosystem, which indicated the potential of dogs as indicator species. Serosurveillance is a valuable tool for monitoring and detecting anthrax and may shed light on mechanisms responsible for species-speciﬁc variability in exposure, susceptibility, and mortality rates. Asporulating bacterium Bacillus anthracis, primarily nthrax, which is caused by the gram-positive, affects herbivorous livestock and wildlife species, but Author afﬁliations: University of Glasgow, Glasgow, Scotland (T. Lembo, K. Hampson, H. Auty, P. Bessell, S. Cleaveland); Lincoln Park Zoo, Chicago, Illinois, USA (T. Lembo); Centers for Disease Control and Prevention, Atlanta, Georgia, USA (C.A. Beesley, K. Stamey, P.P. Wilkins); University of Minnesota, St. Paul, Minnesota, USA (C. Packer); University of Edinburgh, Edinburgh, Scotland (J. Halliday); Tanzania Wildlife Research Institute, Arusha, Tanzania (R. Fyumagwa, R. Hoare, E. Ernest); Endangered Wildlife Trust, Parkview, South Africa (C. Mentzel); and Tanzania National Parks, Arusha (T. Mlengeya) DOI: 10.3201/eid1703.101290 also poses serious public health risks in many parts of the world. Carnivores may also become infected by ingesting contaminated carcasses, but disease-associated illness and death are rarer than in herbivores. Although the multihost nature of the pathogen presents epidemiologic challenges, heterogeneities in host range and infection outcome provide opportunities for disease surveillance, e.g., through the use of sentinel or indicator species to detect the pathogen and changes in its prevalence or incidence (1,2). Despite the recognized value of serologic data for disease surveillance and epidemiologic investigations, serologic analysis has only rarely been used in studies of anthrax. One reason may be the perception that case detection is relatively straightforward: a syndrome of sudden death in herbivores is useful for presumptive diagnosis, and microscopic examination of blood smears provides a relatively simple conﬁrmatory test. However, in many environments in which anthrax is endemic, carcasses deteriorate rapidly, are hazardous, and may be inaccessible for sampling for laboratory conﬁrmation. The utility of carcasses for case detection depends on the likelihood of observation and subsequent reporting (3). In many parts of Africa, anthrax is typically documented only during large, dramatic outbreaks (4–7). In remote areas or during small outbreaks, carcasses often go undetected and, even when detected, may provide only an incomplete picture of spatiotemporal patterns of infection. In humans, many anthrax cases are not reﬂected in hospital records. Underreporting is particularly likely for pulmonary and gastrointestinal anthrax, which have high case-fatality rates and pose diagnostic challenges (8,9), leading to a lack of appreciation of the true scale of the disease in anthrax- endemic regions. Another explanation for the lack of serologic studies may be the perception that because sudden death is a distinctive feature of anthrax in herbivores, most infected Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 17, No. 3, March 2011 387