Rickettsia helvetica,[2] previously known as the Swiss agent, is a bacterium found in Dermacentor reticulatus and other ticks, which has been implicated as a suspected but unconfirmed human pathogen.[3][4][5] First recognized in 1979 in Ixodes ricinus ticks in Switzerland (hence the designation helvetica) as a new member of the spotted fever group of Rickettsia, the R. helvetica bacterium was eventually isolated in 1993.[6] Although R. helvetica was initially thought to be harmless in humans and many animal species, some individual case reports suggest that it may be capable of causing a nonspecific fever in humans.[4][5][7] In 1997, a man living in eastern France seroconverted to Rickettsia 4 weeks after onset of an unexplained febrile illness.[8] In 2010, a case report indicated that tick-borne R. helvetica can also cause meningitis in humans.[9]
Molecular evidence suggests that in Croatia, as many as 10% of D. reticulatus ticks are infected with R. helvetica.[10]
In addition to this, R. slovaca[11] is found in another 2%, and 1% are infected with both species.[12]
Signs and symptoms
Erythema migrans or rash was observed at all combinations of seroreactivity, with symptoms including fever, muscle pain, headache, and respiratory problems.[13]
The spots (erythema migrans) are described as red spots, much lesser in size than those seen in Lyme disease, but sometimes no spots occur at all.[14]
Epidemiology
In 80 healthy Swedish blood donors, about 1% were seroreactive for Rickettsia spp., interpreted as past infection. In a prospective study of Swedish recruits who trained in the coastal areas, 8.9% showed seroconversion[13]
Treatment
As with other rickettsioses, the treatment of choice is doxycycline[15]
