Tularemia - Missouri, 2000-2007

Abstract

Tularemia is an uncommon but potentially fatal zoonotic disease caused by the gram-negative coccobacillus Francisella tularensis. Approximately 40% of all tularemia cases reported to CDC each year occur in Arkansas, Oklahoma, and Missouri. To define the epidemiologic and clinical features of tularemia in Missouri, the Missouri Department of Health and Senior Services (MDHSS) analyzed surveillance data and conducted a retrospective clinical chart review of cases that occurred during 2000--2007. This report describes the results of that analysis, which identified 190 cases (87 confirmed and 103 probable), for an average annual incidence of 0.4 cases per 100,000 population statewide. Most cases occurred during the summer months (78%) and among males (66%). Analysis of 121 clinical charts revealed that children were more likely than adults to be diagnosed with glandular tularemia, whereas adults were more likely to be diagnosed with pneumonic tularemia. Sixty-three (52%) patients were hospitalized; one patient died. Among 78 cases with a documented exposure source, 72% were associated with tick bite. In 33 (85%) of 39 culture-confirmed cases, the laboratory received specimens without any indication of suspicion of a tularemia diagnosis. Clinicians should 1) be aware of the range of tularemia symptoms, 2) consider the diagnosis in patients reporting fever and tick or animal exposure, and 3) initiate empiric antimicrobial therapy while awaiting laboratory confirmation. Laboratory staff should take appropriate precautions when processing culture specimens from tularemia-endemic regions, even if suspicion of tularemia is not noted when the specimen is submitted.