Rickettsiosis (overview) A75-79

Author: Prof. Dr. med. Peter Altmeyer

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Last updated on: 16.03.2021

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ache noire; Bush spot fever; Rock Mountain Fever American; Scrub typhus group; Spotted Fever; Tick-bite fever, Spotted fever Group; Typhus group Rickettsiosis

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Infectious diseases caused by rickettsiae (bacteria-like pleomorphic cocci), transmitted via various arthropods (e.g. ticks, lice, fleas) and occurring worldwide, see Table 1.

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Some rickettsial infections are transmitted by ticks, mites or mite larvae, others by lice or fleas (see table).

In the case of tick-borne infections (tick-borne), the pathogen is transmitted to humans via the salivary glands with the bite.

In the case of rickettsial infections caused by lice or fleas, the pathogens are found in the faeces of the animals and enter skin lesions, for example by scratching.

In the case of infections transmitted by ticks or mites, a primary lesion (eschar) and lymphadenitis occur after inoculation of the pathogen.

Clinical features
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The incubation period is 1 to 2 weeks. With appropriate exposure prophylaxis, rickettsiosis should be considered in the differential diagnosis of fever, eschar and exanthema. Clinically, rickettsialgiosis is manifested by sometimes high fever, myalgia, arthralgia, exanthema and swelling of the lymph nodes. Typical complications are thromboses and thrombophilia, which is manifested by petechiae and gastrointestinal bleeding. Other complications are encephalitis, myocarditis, nephritis, haemorrhages and gangrene. Rickettsiosis must also be ruled out in cases of fever of uncertain origin (FUO).

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Early detection by the Weil-Felix reaction. Today, more specific serological tests such as molecular biological techniques are available to identify the pathogens from blood and tissue. Detection of IgM and IgG antibodies by ELISA, immune peroxidase techniques.

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Remember! Start therapy already with clinical suspicion of rickettsialpox (serology takes 2 weeks)!

External therapy
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Control of the arthropods that have transmitted the disease, such as lice, ticks, etc.; see pediculosis below

Internal therapy
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Drug of choice is tetracycline p.o. (e.g. Tetracycline Wolff 500) 250 mg every 6 hrs. (or 25-50 mg/kg bw/day) for 8-12 days, approx. 5 days beyond the absence of fever and symptoms. Doxycycline (e.g. Doxy-Wolff) 100 mg p.o. 2 times/day for 8-10 days is also effective. Alternatively: Ciprofloxacin 2 times/day 500-750 mg p.o. or 2 times/day 100-200 mg i.v.

In the most severe cases with incipient haematogenous spread or generalisation, also glucocorticoids i.v. to counteract the toxic immune reaction triggered by the decay of the bacteria. Prednisolone (e.g. Decortin H) 100-125 mg/day for 2-3 days.

Notice. Especially in classical spotted fever and Rocky Mountains spotted fever, life-threatening situations can occur that make intensive medical care necessary.

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Healing to complete remission with antibiotic therapy appropriate to the stage of the disease. Nevertheless, the lethality rate under adequate treatment is about 1-2%.

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Classification of rickettsial diseases:





Skin symptoms and other symptoms

Epidemic spotted fever (classical spotted fever)

R. prowazekii

Lice (Pediculosis corporis)

Epidemic, ubiquitous

4th-6th day of fever Exanthema on trunk (axilla, torso), spread with ecchymoses, vasculitis to gangrene. High fever, delirium, severe course of disease.

Endemic spotted fever

(Murine spotted fever, rat typhus)

R. typhi (mooseri)

Lice, rat fleas

Endemic in subtropical and tropical regions; humans are the host failure (alternate host).

Rather discrete early rash, skin symptoms otherwise as above. Conjunctivitis, dry cough, fever.

Rickettsial pox

R. acarii

Mouse and rat mites

America, South Africa, Russia, Korea

1-1.5 cm papulovesicles at the sting site with regional lymphadenopathy, shortly followed by maculopapular and vesicular varicelliform exanthema on day 3-5 of fever.

Tick-borne fever (Mediterranean, North Asian, African, Australian).

R. conorii, R. australis


Europe, Africa, India, South and East Asia, Australia

Possibly a small ulcer at the site of the bite, possibly with blackish crusts (tache noir) and regional lymphadenopathy. On the 4th day of fever generalized maculopapular exanthema. Sudden fever.

Q fever

R. burneti

Ticks (in wild animals); human to human: aerogenic


At the site of the bite, possibly a small ulcer, possibly with blackish crusts (tache noir) and regional lymphadenopathy. Sudden fever, severe malaise, conjunctivitis, cough, atypical pneumonia.

Tsutsugamushi Fever (Scrub Typhus)

R. tsutsugamushi

Running mites (rats, field mice, forest and field rodents)

South- and East Asia, North Australia, Islands in the Indian and Pacific Ocean

1-1.5 cm papulovesicles or ulcer at the sting site with regional lymphadenopathy. Generalized maculopapular exanthema on the 5th-8th day of fever. Conjunctivitis, sudden fever, generalized lymph node swelling.

Rocky Mountain spotted fever (tick fever)

R. rickettsii

Ticks (Ixodes dammini)


There may be a small ulcer at the site of the bite, possibly with blackish crusts (tache noir) and regional lymphadenopathy. On the 4th-5th day of fever, petechial or haemorrhagic exanthema (more rarely ulceration) on the periphery (hands, feet, ankles, neck, face). Sudden fever, chills, headache, muscle, joint pain. Possibly delirium, coma, severe course of the disease.

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The pathogens were named after the pathologist Howard Taylor Ricketts (1871-1910), who, among other things, researched the Rocky Mountain spotted fever, whose pathogen he was able to detect in the blood of infected people (vector = tick species). In 1909 he travelled to Mexico City with the aim of researching typhoid fever. In the process he became infected with Rickettsia and died in 1910.

Case report(s)
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Infection by Reckiettsia conori:

3 days after a holiday stay in South Africa a 46 years old patient fell ill with flu-like symptoms with fatigue, medium fever and catarrhal symptoms. At the same time a rather discreet, not itchy, bright red, truncated, maculo-papular (0.1-0.2 cm large efflorescences) exanthema developed.

Findings: A 0.5 cm large ulcer with blackish crusts (tache noir) was found on the extensor lower leg. A slightly painful regional lymphadenopathy was striking. The blood count showed clear leukopenia (2,200/ul) and monocytosis (15.5%). On admission no positive rickettsial serology. Only 5 weeks later clearer IgG-titer (1:320) on R. conori.

Therapy: Doxycycline 2 times/day 100 mg p.o. for 10 days. Immediate clinical improvement. Ulcer healed under usual wound treatment after 6 weeks.

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  1. Baumann D et al (2003) Fever after a tick bite: clinical manifestations and diagnosis of acute tick bite-associated infections in northeastern Switzerland. Dtsch Med Weekly 128: 1042-1047
  2. Diaz IA et al (2003) Rickettsiosis caused by Rickettsia conorii in Uruguay. Ann N Y Acad Sci 990: 264-266
  3. Lee HC et al (2002) Clinical manifestations and complications of rickettsiosis in southern Taiwan. J Formos Med Assoc 101: 385-392
  4. Murray KO et al (2017) Typhoid Group Rickettsiosis, Texas, USA, 2003-2013 Emerg Infect Dis 23:645-648 .
  5. Orfanos CE et Garbe C: Rare infections of the skin. In: Therapy of skin diseases. Orfanos CE (Ed.). Springer-Verlag Berlin Heidelberg New York. S. 173–176
  6. Oteo JA et al (2003) Epidemiological and clinical differences among Rickettsia slovaca rickettsiosis and other tick-borne diseases in Spain. Ann N Y Acad Sci 990: 355-356
  7. Raoult D et al (2002) Spotless rickettsiosis caused by Rickettsia slovaca and associated with Dermacentor ticks. Clin Infect Dis 34: 1331-1336
  8. Toutous-Trellu L et al (2003) African tick bite fever: not a spotless rickettsiosis! J Am Acad Dermatol 48: S18-19


Please ask your physician for a reliable diagnosis. This website is only meant as a reference.


Last updated on: 16.03.2021