''Rickettsia helvetica'', previously known as the Swiss agent, is a
bacterium
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were amon ...
found in ''
Dermacentor reticulatus
''Dermacentor reticulatus'', also known as the ornate cow tick, ornate dog tick, meadow tick, and marsh tick, is a species of tick from the family Ixodidae. It is the type species for the genus ''Dermacentor''.
''D. reticulatus'' is an ornate ti ...
'' and other
tick
Ticks (order Ixodida) are parasitic arachnids that are part of the mite superorder Parasitiformes. Adult ticks are approximately 3 to 5 mm in length depending on age, sex, species, and "fullness". Ticks are external parasites, living by ...
s, which has been implicated as a suspected but unconfirmed human pathogen.
First recognized in 1979 in ''
Ixodes ricinus
''Ixodes ricinus'', the castor bean tick, is a chiefly European species of hard-bodied tick. It may reach a length of when engorged with a blood meal, and can transmit both bacterial and viral pathogens such as the causative agents of Lyme disea ...
'' ticks in Switzerland (hence the designation ''helvetica'') as a new member of the spotted fever group of ''
Rickettsia
''Rickettsia'' is a genus of nonmotile, gram-negative, nonspore-forming, highly pleomorphic bacteria that may occur in the forms of cocci (0.1 μm in diameter), bacilli (1–4 μm long), or threads (up to about 10 μm long). The term "ricke ...
'', the ''R. helvetica'' bacterium was eventually isolated in 1993.
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.
Croatia
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, capit ...
, as many as 10% of ''D. reticulatus'' ticks are infected with ''R. helvetica''.
Signs and symptoms
Erythema migrans or rash was observed at all combinations of seroreactivity, with symptoms including fever, muscle pain, headache, and respiratory problems.erythema migrans
Erythema migrans or erythema chronicum migrans is an expanding rash often seen in the early stage of Lyme disease, and can also (but less commonly) be caused by southern tick-associated rash illness (STARI). Page last reviewed: October 22, 2015 ...
) are described as red spots, much lesser in size than those seen in Lyme disease
Lyme disease, also known as Lyme borreliosis, is a vector-borne disease caused by the ''Borrelia'' bacterium, which is spread by ticks in the genus ''Ixodes''. The most common sign of infection is an expanding red rash, known as erythema migran ...
, but sometimes no spots occur at all.
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
Treatment
As with other rickettsioses, the treatment of choice is doxycycline[Botelho-Nevers E, Socolovschi C, Raoult D, Parola P]
Treatment of Rickettsia spp. infections: a review.
Expert Rev Anti Infect Ther 2012; 10:1425–1437
See also
* Ticks of domestic animals
Ticks of domestic animals directly cause poor health and loss of production to their hosts. Ticks also transmit numerous kinds of viruses, bacteria, and protozoa between domestic animals. These microbes cause diseases which can be severely debilita ...
References
{{Taxonbar, from=Q7331933
Zoonoses
Rickettsiaceae
Bacteria described in 1993