SPOTTED-FEVER GROUP RICKETTSIAL INFECTION IN SOUTH-EASTERN AUSTRALIA - ISOLATION OF RICKETTSIAE

Flinders Island spotted fever (FISF), a spotted fever group (SFG) rick ettsial disease first described in 1991, occurs in south-eastern Austr alia. The isolation of the aetiological agent is described for the fir st time having been obtained from the blood of two patients. An additi onal 22 cases are also reported. Of these patients four had positive i nitial serology, and 20 showed seroconversion (using Rickettsia austra lis as antigen). Acute phase blood specimens taken from seven patients caused neonatal mice to seroconvert to R. australis and a blood speci men from one of these patients (and one other) yielded rickettsiae. A field survey for possible reservoir and vector animals on Flinders Isl and, Tasmania and in Gippsland, Victoria (both in south-eastern Austra lia) yielded 217 vertebrates and 1445 invertebrate ectoparasites, most ly ticks. Ixodes cornuatus from humans and dogs in Gippsland produced seroconversion to SFG rickettsia when inoculated into mice but no inve rtebrate pools from Flinders Island produced seroconversion in mice. H aemolymph from an individual I. cornuatus removed from a human in Gipp sland, yielded a SFG rickettsia on tissue culture. Sera from several s pecies of native vertebrates, especially the bush rat, Rattus fuscipes , were positive for antibodies to SFG rickettsia.