Murine typhus as a common cause of fever of intermediate duration: a 17-year study in the south of Spain.

BACKGROUND Fever of intermediate duration (FID), characterized by a febrile syndrome lasting from 7 to 28 days, is a frequent condition in clinical practice, but its epidemiological and etiologic features are not well described. Murine typhus (MT) is a worldwide illness; nevertheless, to our knowledge, no studies describing its epidemiological and clinical characteristics have been performed in the south of Spain. Also, its significance as a cause of FID is unknown. OBJECTIVE To determine the epidemiological features, clinical characteristics, and prognosis of MT and, prospectively, its incidence as a cause of FID. DESIGN Prospective study of cases of MT over 17 years (1979-1995) and of all cases of FID treated in a tertiary teaching hospital in Seville, Spain. RESULTS One hundred and four cases of MT were included, and MT was the cause in 6.7% of 926 cases of FID. Insect bites were reported in only 3.8% of the cases of MT previous to the onset of illness. Most cases (62.5%) occurred in the summer and fall. A high frequency of rash (62.5%) was noted. Arthromyalgia (77%), headache (71%), and respiratory (25%) and gastrointestinal (23%) symptoms were also frequent. Laboratory findings were unspecific. Organ complications were uncommon (8.6%), but they were severe in 4 cases. The mean duration of fever was 12.5 days. Cure was achieved in all cases, although only 44 patients received specific treatment. CONCLUSIONS Murine typhus is prevalent in the south of Spain and is a significant cause of FID. Clinical signs are benign, but some patients may develop severe complications. A high degree of clinical suspicion is required for diagnosis.