[Three Swedish cases of African tick-bite fever. Can our native Rickettsia species cause disease in humans?].

The article consists in a report of three cases of African tick-bite fever in Swedish tourists returning from brief visits to South Africa. The clinical course included eschar, regional lymphadenopathy, fever and, in two cases, maculopapular rash. Two cases were characterised by significant increases in anti-Rickettsia conorii IgG and IgM antibody titres. However, the aetiological agent was assumed to be Rickettsia africae, based on reports by others and the widespread serological cross-reactivity among spotted fever Rickettsia spp. The third case was diagnosed on clinical grounds. During the past ten years, 50 per cent (41/80) of cases diagnosed serologically as rickettsial (R. conorii antigen) spotted fever at the Swedish Institute for Infectious Disease Control were associated with travel to South Africa. Parallels are drawn to the recent finding of R. helvetica in Swedish ticks (Ixodes ricinus), and the possibility of its pathogenicity to humans is discussed, though no such clinical cases have been reported to date.