Acute Gastroenteritis Caused by GI/2 Sapovirus, Taiwan, 2007

Antibodies to B. melitensis were detected by agglutination by using the Rose Bengal and Brucella Wright tests (both from BioRad, Hercules, CA, USA). Of the 63 patients, 9 had a positive antibody response against a tested antigen (Table): 1 to phase I C. burnetii and 8 to Bartonella spp. (IgG >200). Of these, 7 had a 1-fold dilution higher titer to B. quintana than to B. henselae, including 1 with a lowlevel cross-reaction with C. burnetii, and 1 with identical titers to both. For all 8 patients, Western blot results were consistent with Bartonella endocarditis. For 7, cross-adsorption identifi ed B. quintana as the causative species; for the other, the infecting Bartonella species remained undetermined because adsorption with B. quintana and B. henselae antigens removed all antibodies. Serologic results for B. melitensis were negative for all patients. B. quintana is mostly associated with human body lice but has also been found in fl eas (9). The predisposing factors for B. quintana endocarditis are homelessness, alcoholism, and exposure to body lice (10). For our patients, the common predisposing factors were poor hygiene and low socioeconomic status, which may expose them to ectoparasites including lice and fl eas. In contrast with previous study fi ndings, B. quintana infectious endocarditis developed on preexisting valvular lesions in all patients (10). This fi nding may refl ect a different clinical evolution than in Europe, where studies have suggested that B. quintana infectious endocarditis followed chronic bacteremia in patients who did not have previous valvular defects (10). In summary, prevalence of negative blood culture among patients with infectious endocarditis was high (72%). The most commonly associated risk factor was rheumatic heart disease (Table). C. burnetii and Bartonella spp. were responsible for 8% of all infectious endocarditis cases and 14% of blood culture–negative cases. No case of infectious endocarditis caused by B. melitensis was identifi ed. Our preliminary study suggests that zoonotic agents, especially Bartonella spp., are prevalent causative organisms of blood culture–negative endocarditis in India. We recommend serologic screening for antibodies to zoonotic microorganisms as diagnostic tools for this disease in India.