Rickettsia helvetica

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Rickettsia helvetica
Scientific classification edit
Domain: Bacteria
Phylum: Pseudomonadota
Class: Alphaproteobacteria
Order: Rickettsiales
Family: Rickettsiaceae
Genus: Rickettsia
Species group: Spotted fever group
R. helvetica
Binomial name
Rickettsia helvetica
Beati, Peter, Burgdorfer, Aeschlirnami & Raoult, 1993[1]

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]


Morphology of R. helvetica in partly decomposed host cells

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]


As with other rickettsioses, the treatment of choice is doxycycline[15]


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]

See also


  1. Xue-Jie Yu & David H. Walker (2005). "Genus I. Rickettsia da Rocha Lima 1916, 567". In Don J. Brenner; Noel R. Krieg; George M. Garrity & James T. Staley (eds.). The proteobacteria, Part 3. Bergey's Manual of Systematic Bacteriology. Vol. 2 (2 ed.). Springer. pp. 96–114. ISBN 978-0-387-24145-6.
  2. "Rickettsia helvetica". Archived from the original on 2015-09-06. Retrieved 2023-01-17.
  3. Piller, Charles (October 12, 2016). "The 'Swiss Agent': Long-forgotten research unearths new mystery about Lyme disease". Archived from the original on November 21, 2016. Retrieved December 19, 2016.
  4. 4.0 4.1 Parola, P.; Davoust, B.; Raoult, D. (2005). "Tick- and flea-borne rickettsial emerging zoonoses" (PDF). Veterinary Research. 36 (3): 469–492. doi:10.1051/vetres:2005004. PMID 15845235. Archived (PDF) from the original on 2019-05-04. Retrieved 2023-01-17.
  5. 5.0 5.1 Walker, D. H. (2007). "Rickettsiae and Rickettsial Infections: The Current State of Knowledge". Clinical Infectious Diseases. 45: S39–S44. doi:10.1086/518145. PMID 17582568.
  6. Beati, L.; Péter, O.; Burgdorfer, W.; Aeschlimann, A.; Raoult, D. (1993). "Confirmation that Rickettsia helvetica sp. nov. Is a distinct species of the spotted fever group of rickettsiae". International Journal of Systematic Bacteriology. 43 (3): 521–526. doi:10.1099/00207713-43-3-521. PMID 8102245.
  7. Dobler, G.; Wölfel, R. (2009). "Typhus and other rickettsioses: Emerging infections in Germany". Deutsches Ärzteblatt International. 106 (20): 348–354. doi:10.3238/arztebl.2009.0348. PMC 2689634. PMID 19547738.
  8. Fournier, P. E.; Grunnenberger, F.; Jaulhac, B.; Gastinger, G.; Raoult, D. (2000). "Evidence of Rickettsia helvetica infection in humans, eastern France". Emerging Infectious Diseases. 6 (4): 389–392. doi:10.3201/eid0604.000412. PMC 2640907. PMID 10905974.
  9. Nilsson, K.; Elfving, K.; Pahlson, C. (2010). "Rickettsia helvetica in Patient with Meningitis, Sweden, 2006". Emerging Infectious Diseases. 16 (3): 490–492. doi:10.3201/eid1603.090184. PMC 3322002. PMID 20202426.
  10. Dobec, M.; Golubic, D.; Punda-Polic, V.; Kaeppeli, F.; Sievers, M. (2009). "Rickettsia helvetica in Dermacentor reticulatus ticks". Emerging Infectious Diseases. 15 (1): 98–100. doi:10.3201/eid1501.080815. PMC 2660705. PMID 19116063.
  11. "Rickettsia slovaca". Archived from the original on 2021-12-05. Retrieved 2023-01-17.
  12. "Rickettsia helvetica in Ticks | CDC EID". Cdc.gov. 2008-12-23. Archived from the original on 2009-11-05. Retrieved 2011-08-13.
  13. 13.0 13.1 Lindblom, A.; Wallménius, K.; Nordberg, M.; Forsberg, P.; Eliasson, I.; Påhlson, C.; Nilsson, K. (2012). "Seroreactivity for spotted fever rickettsiae and co-infections with other tick-borne agents among habitants (sic) in central and southern Sweden". European Journal of Clinical Microbiology & Infectious Diseases. 32 (3): 317–323. doi:10.1007/s10096-012-1742-3. PMC 3569577. PMID 22961007.
  14. "Fästingar sprider fläcktyfus". Archived from the original on 2016-03-04. Retrieved 2023-01-17.
  15. Botelho-Nevers E, Socolovschi C, Raoult D, Parola P. Treatment of Rickettsia spp. infections: a review. Archived 2013-02-21 at the Wayback Machine Expert Rev Anti Infect Ther 2012; 10:1425–1437