Evidence of rickettsial spotted fever and ehrlichial infections in a subtropical territory of Jujuy, Argentina

Between November 1993 and March 1994, a cluster 6 pediatric patients with a cute febrile illnesses associated with rashes was identified in Jujuy Provi nce, Argentina. Immunohistochemical staining of tissues confirmed spotted f ever group rickettsial infection in a patient with fatal diseas, and testin g of serum of a patient convalescing from the illness by using an indirect immunofluorescence assay (IFA) demonstrated antibodies reactive with spotte d fever group rickettsiae. A serosurvey was conducted among 16 households i n proximity to the index case. Of 105 healthy subjects evaluated by IFA, 19 (18%) demonstrated antibodies reactive with rickettsiae or ehrlichiae: 4 h ad antibodies reactive with Rickettsia rickettsii, 15 with Ehrlichia chaffe ensis, and 1 with R, typhi. Ambylomma cajennense, a known vector of R. rick ettsii in South America, was collected from pets and horses in the area. Th ese results are the first to document rickettsial spotted fever and ehrlich ial infections in Argentina.