An outbreak of acute bartonellosis (Oroya fever) in the Urubamba region of Peru, 1998.

During May 1998, we conducted a case-control study of 357 participants from 60 households during an outbreak of acute bartonellosis in the Urubamba Valley, Peru, a region not previously considered endemic for this disease. Blood and insect specimens were collected and environmental assessments were done. Case-patients (n 5 22) were defined by fever, anemia, and intra-erythrocytic coccobacilli seen in thin smears. Most case-patients were children (median age 5 6.5 years). Case-patients more frequently reported sand fly bites than individuals of neigh- boring households (odds ratio (OR) 5 5.8, 95% confidence interval (CI) 5 1.2-39.2), or members from randomly selected households $ 5 km away (OR 5 8.5, 95% CI 5 1.7-57.9). Bartonella bacilliformis isolated from blood was confirmed by nucleotide sequencing (citrate synthase (gltA), 338 basepairs). Using bacterial isolation (n 5 141) as the standard, sensitivity, specificity, and positive predictive value of thin smears were 36%, 96%, and 44%, respec- tively. Patients with clinical syndromes compatible with bartonellosis should be treated with appropriate antibiotics regardless of thin-smear results. Bartonellosis is a diphasic illness characterized by acute bacteremia with fever and profound anemia (Oroya fever) and by a benign, chronic phase with nodular skin lesions (verruga peruana). 1 Case fatality ratios (CFRs) of untreated Oroya fever exceed 40% but may reach more than 90% when superinfection with Salmonella species occurs. 2 The geographic distribution of bartonellosis is traditionally re- stricted to remote Andean valleys in Peru, Ecuador, and Co- lombia situated at elevations of 500-3,000 meters, 1,3 al-