Evidence of Rickettsia spp. infection in Sweden: a clinical, ultrastructural and serological study

• Published in: APMIS : acta pathologica, microbiologica et immunologica Scandinavica microbiologica et immunologica Scandinavica, 2005-02, Vol.113 (2), p.126-134
• Main Authors: NILSSON, KENNETH, LUKINIUS, AGNETA, PÅHLSON, CARL, MORON, CECILIA, HAJEM, NEDA'A, OLSSON, BRITT, LINDQUIST, OLLE
• Format: Article
• Language: English
• Subjects: Aged; Animals; Bacteriology; Biological and medical sciences; Blotting, Western; Capillaries - microbiology; Capillaries - ultrastructure; Dermatologi och venerologi, klinisk genetik, invärtesmedicin; Dermatology and venerology,clinical genetics, internal medicine; Diagnosis, Differential; Female; Fundamental and applied biological sciences. Psychology; fästingar; Humans; Immunoglobulin G - blood; Immunohistochemistry; Infectious diseases; Male; Medical sciences; MEDICIN; MEDICINE; Microbiology; Microscopy, Electron, Transmission; Middle Aged; Miscellaneous; Polymerase Chain Reaction; Rickettsia - immunology; Rickettsia Infections - epidemiology; Rickettsia Infections - immunology; Rickettsios; Rickettsiosis; Seroepidemiologic Studies; serologi; serology; Skin - innervation; Skin - microbiology; Skin - ultrastructure; Sweden - epidemiology; tick; Tick-Borne Diseases - diagnosis; Tick-Borne Diseases - physiopathology; ultrastructure; ultrastruktur; Veins - microbiology; Veins - ultrastructure
• ISSN: 0903-4641; 1600-0463; 1600-0463
• DOI: 10.1111/j.1600-0463.2005.apm1130206.x

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.