clinical presentation, and outcome of infection of affected family members was obtained from heads of affected households. No human cases were conﬁrmed by laboratory diagnostic tests. Case Deﬁnitions Because of the relatively low proportion of suspected cases from which diagnostic samples were obtained, cases were classiﬁed as suspected for carcasses found that had no obvious cause of death, and probable for carcasses that showed evidence of bloody discharge from the anus, vulva, nostrils, mouth, eyes, or ears and incomplete rigor mortis. Microscopic examination of methylene blue–stained blood smears was conducted for some carcasses. Smears positive by microscopy (detection of encapsulated bacilli) were combined with probable cases (27% of probable cases were conﬁrmed by microscopy) for analyses. No samples were conﬁrmed by bacterial culture and isolation because of lack of facilities locally. Because of abundant scavengers in the ecosystem and logistical challenges of surveillance over such a large and remote area, many cases will go undetected on the basis of our deﬁnitions. Speciﬁcally, our deﬁnitions comprised only intact or partially scavenged carcasses; this second group also included carcasses obtained during major reported outbreaks. Carcasses that were too decomposed or scavenged to enable classiﬁcation were not included in either group. Serum Samples Serum samples were obtained opportunistically as part of long-term epidemiologic and ecologic studies. Samples were obtained from 3 groups. The ﬁrst group comprised wild carnivore species, including 263 Serengeti and 23 Ngorongoro Crater lions obtained during 1985–2007 and 53 Serengeti spotted hyenas (Crocuta crocuta) obtained during 1998–2007. The second group comprised Serengeti and Ngorongoro Crater ungulate species (28 and 21 buffalo [Syncerus caffer], 36 and 23 wildebeest [Connochaetes taurinus], and 74 and 11 zebra [Equus burchellii], respectively) obtained during 1998–2007. The third group comprised domestic dog (Canis familiaris) populations living adjacent to protected areas (4 villages in Loliondo Division, 13 in NCA, and 7 from areas west of SNP), which included 169 random samples obtained as part of other epidemiologic surveys and 53 samples linked to a major anthrax outbreak in pastoralist areas in 2006. Serologic Assays The QuickELISA Anthrax-PA Kit immunoassay (Immunetics Inc., Boston, MA, USA) was used to detect antibodies against protective antigen (PA) of B. anthracis in serum samples (13). The assay detects immunoglobulins in a subtype-independent and species-independent manner. Serologic Surveillance of Anthrax, Tanzania The assay was conducted according to the manufacturer’s instructions. Brieﬂy, serum (10 μL) was incubated with a mixture of 2 recombinant PA (rPA) conjugates: streptavidin-rPA and horseradish peroxidase–rPA. PA- speciﬁc, multivalent antibodies formed ternary complexes in which streptavidin-rPA and horseradish peroxidase– rPA were bound to different antigen-combining sites on 1 antibody molecule. Complexes were bound to the biotin- coated microplates by using streptavidin conjugate and detected by using horseradish peroxidase conjugate. Bound antibodies against PA were detected by using a chromogenic peroxidase substrate (tetramethylbenzidine). The color development reaction was stopped by addition of 2N sulfuric acid. Absorbance at 450 nm, corrected by a 620–650 nm background subtraction, was measured by using an ELISA microplate reader. Interpretation was based on comparison of absorbance for the sample with an assay- deﬁned cutoff value. The QuickELISA Anthrax-PA kit was conﬁgured to detect ≈300 ng/mL of PA-speciﬁc antibody at the cutoff value. The assay cutoff value was deﬁned as the mean net absorbance at 450 nm plus 0.1 of the negative control (provided in the kit); the targeted cutoff range was 0.11–0.25. Data Analysis A generalized linear modeling framework was used to investigate seroprevalence patterns in domestic dogs and wildlife with a binary outcome (seronegative or seropositive) and binomial error structure. Three models were constructed. First, we tested for overall species- speciﬁc differences in seroprevalence among lion, hyena, buffalo, wildebeest, and zebra populations in SNP and Ngorongoro Crater. Second, we tested for differences in seroprevalence in lion and hyena populations between years. Third, we analyzed seroprevalence patterns in domestic dogs in relation to their age and geographic location; village was modeled as a random effect by using a generalized linear mixed model. Results Case-Detection Patterns Wildlife Cases Potential anthrax cases, i.e., suspected and probable cases, were detected in a wide range of wildlife species, including wildebeest, buffalo, impala (Aepyceros melampus), giraffe (Giraffa camelopardalis), Thomson’s gazelle (Eudorcas thomsonii), and Grant’s gazelle (Nanger granti), hippopotamus (Hippopotamus amphibius), elephant (Loxodonta africana), and topi (Damaliscus korrigum jimela) (Table 1). The anthrax-attributed deaths of 1 cheetah (Acinonyx jubatus) and 1 serval cat (Leptailurus Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 17, No. 3, March 2011 389