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BACKGROUND: Tularemia is caused by Francisella tularensis, a Tier 1 select agent. Arkansas has the second highest number of tularemia cases reported annually in the United States. Tularemia can manifest as 7 major forms, depending on exposure. The ulceroglandular/glandular forms, which feature regional lymphadenopathy, have historically been reported most commonly and typically result from tick exposure or handling sick or dead animals. The typhoidal form (fever without early localizing symptoms) has been less commonly reported. We describe initial clinical presentation and exposure history associated with Arkansas tularemia cases to guide diagnostic recommendations.
METHODS: We reviewed clinical records for positive Francisella tularensis laboratory reports from Arkansas for 2009–2012, and applied the standard case definition. A probable case was compatible symptoms with 1 elevated antibody titer or positive fluorescent assay; a confirmed case was compatible symptoms plus a ≥4-fold change in titer on a second sample or isolation of F. tularensis from a clinical specimen. Frequencies of disease manifestations on initial presentation and reported exposures were computed.
RESULTS: We identified 99 cases: 67 (67.7%) probable and 32 (32.3%) confirmed. Among 92 cases with initial presentation data, 48 (52.2%) presented as typhoidal and 34 (37.0%) as ulceroglandular/glandular. If limited to the 26 confirmed cases with presentation data, 13 (50.0%) presented as typhoidal and 9 (34.6%) as ulceroglandular/glandular. Tick exposure was reported in 72/99 (72.7%) cases; 39/72 (54.2%) initially presented as typhoidal and 26/72 (36.1%) as ulceroglandular/glandular.
CONCLUSIONS: The predominant initial presentation of tularemia reported recently in Arkansas was typhoidal, even among patients reporting tick exposure. Using lymphadenopathy as a primary feature to initiate tularemia testing can delay recognition of individual cases or an outbreak. Recommendations regarding diagnostic practices in endemic areas should incorporate up-to-date surveillance data.