title: Evidence of Rickettsia spp. infection in Sweden: a clinical, ultrastructural and serological study.
abstract: Sweden is an area potentially endemic for spotted fever rickettsioses. Rickettsia helvetica has been isolated from its tick vector Ixodes ricinus, and in a handful of cases linked to human disease. This study demonstrates for the first time in Sweden the transmission of rickettsial infection after a tick bite and the attack rate in an endemic area. We present three cases of documented rickettsial infection and a prospective serological study of Swedish recruits who were trained in the area where the patients lived and showed seroconversion to spotted fever rickettsiae. All patients showed a four-fold increase in antibody titer to the spotted fever rickettsia, R. helvetica, and immunohistochemical examination revealed rickettsia-like organisms in the walls of skin capillaries and veins. Electron microscopy showed organisms resembling R. helvetica and immunogold labeling with two anti-rickettsial antibodies demonstrated specific labeling of the rickettsial organisms in the skin biopsy specimens. Eight of the thirty-five recruits showed a four-fold increase in IgG titer reflecting a high rate of exposure. The results of this study demonstrate that spotted fever rickettsioses should be taken into consideration in the diagnosis of tick-transmitted infections in Sweden.
authors.affiliation: Unit of Infectious Diseases, Department of Medical Sciences, Uppsala University, Uppsala, Sweden. kenneth.nilsson@ltdalarna.se
authors.forename: Kenneth
authors.initials: K
authors.lastname: Nilsson
authors.forename: Agneta
authors.initials: A
authors.lastname: Lukinius
authors.forename: Carl
authors.initials: C
authors.lastname: Påhlson
authors.forename: Cecilia
authors.initials: C
authors.lastname: Moron
authors.forename: Neda'a
authors.initials: N
authors.lastname: Hajem
authors.forename: Britt
authors.initials: B
authors.lastname: Olsson
authors.forename: Olle
authors.initials: O
authors.lastname: Lindquist
mesh_terms: D000368:Aged; D000818:Animals; D015153:Blotting, Western; D002196:Capillaries / Q000382:microbiology / Q000648:ultrastructure; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007150:Immunohistochemistry; D008297:Male; D046529:Microscopy, Electron, Transmission; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D012281:Rickettsia / Q000276:immunology; D012282:Rickettsia Infections / Q000453:epidemiology* / Q000276:immunology*; D016036:Seroepidemiologic Studies; D012867:Skin / Q000294:innervation / Q000382:microbiology* / Q000648:ultrastructure; D013548:Sweden / Q000453:epidemiology; D017282:Tick-Borne Diseases / Q000175:diagnosis / Q000503:physiopathology; D014680:Veins / Q000382:microbiology / Q000648:ultrastructure
chemical_list: D007074:Immunoglobulin G