Rickettsiae

Aka: Rickettsiae, Rickettsiaceae, Rickettsia, Rickettsioses, Ehrlichia, Coxiella, Rochalimaea, Rickettsial Disease, Weil-Felix Reaction

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II. Pathophysiology

  1. Rickettsiaceae are primarily Vector-Borne Infections
    1. Transmitted by arthropods (ticks, fleas, lice)
    2. Coxiella Burnetii (Q Fever) does not require a vector-borne transmission
      1. However, Coxiella is now classified in the Coxiellaceae family instead
  2. Rickettsiaceae target vascular endothelial cells
  3. Rickettsiaceae are more akin to viruses than Bacteria (similar to Chlamydia)
    1. Tiny Gram Negative Cocci
      1. Rickettsiaceae are only 350 nm (nearly the diameter of a large virus)
      2. Like other Bacteria, they have both DNA and RNA (while viruses have one or the other)
    2. Obligate intracellular Parasites
      1. Similar to viruses (as well as a few other Bacteria families including Chlamydia)
      2. Rickettsia uses cellular ATP, but can also generate its own energy (unlike Chlamydia)
      3. Rickettsia replicates freely in the host cytoplasm
  4. Rickettsiaceae is a family of 6 genera (3 of which are important in human disease)
    1. Rickettsia (most prominent in human disease)
      1. Spotted Fever Group
        1. Rocky Mountain Spotted Fever (Rickettsia rickettsii)
        2. Other species in the spotted fever group are found worldwide
      2. Typhus Group
        1. Rickettsia prowazekii (Louse-Borne Typhus)
        2. Rickettsia typhi (Murine Typhus)
    2. Orientia
      1. Orientia tsutsugamushi (Scrub Typhus)
    3. Ehrlichia
      1. Human Monocytic Ehrlichiosis (Ehrlichia chaffeensis, Ehrlichia ewingii)
      2. Human Granulocytic Anaplasmosis (Ehrlichia equi, Ehrlichia phagocytophila)
    4. Coxiella (previously in Rickettsiae family, now in Coxiellaceae)
      1. Coxiella Burnetii (Q Fever)

III. Types: Genus Rickettsia

  1. Spotted Fever Group (transmitted by fleas, mites and ticks)
    1. Rocky Mountain Spotted Fever (Rickettsia rickettsii)
    2. Rickettsial Pox (R. akari in North America)
    3. American Boutonneuse fever (R. parkeri in southeast U.S.)
      1. First identified in Southwestern coastal U.S. in 2002
      2. Patient presented with fever, Headache, echars and Regional Lymphadenopathy
    4. African Tick BiteFever or ATBF (R. africae in africa)
      1. Important cause of Fever in the Returning Traveler from Sub-Sahara Africa
    5. Finders Island Spotted Fever (R. honei in northwest U.S. as well as Australia and southeast Asia)
    6. Mediterranean Spotted Fever or Boutonneuse Fever (R. connori in the Mediterranean)
    7. Queensland Tick Typhus (R. australis in australia)
    8. Siberian Tick Typhus (R. sibirica in China)
  2. Typhus Group
    1. See below for Orentia tsutsugamushi (Scrub Typhus)
    2. Rickettsia prowazekii (Louse-Borne Typhus, Epidemic Typhus)
    3. Rickettsia typhi (Murine Typhus)
    4. Rickettsia mooseri

IV. Types: Other Genera

  1. Genus Orentia
    1. Orentia tsutsugamushi (Scrub Typhus)
      1. Previously categorized as Rickettsia tsutsugamushi
  2. Genus Ehrlichia
    1. Human Monocytic Ehrlichiosis (Ehrlichia chaffeensis, Ehrlichia ewingii)
    2. Human Granulocytic Anaplasmosis (Ehrlichia equi, Ehrlichia phagocytophila)
  3. Genus Coxiella
    1. Previously in Rickettsiae family (now in Coxiellaceae)
    2. Coxiella Burnetii (Q Fever)

V. Labs: Modern Testing

  1. Complete Blood Count
    1. Thrombocytopenia
  2. Comprehensive Metabolic Panel
    1. Hyponatremia
    2. Hepatic Enzyme Transaminitis (AST, ALT)
  3. Serology
    1. Indirect Immunofluorescence Test (IFA)
    2. Complement Fixation Test (CF)
    3. Enzyme Linked Immunosorbent Assay (ELISA)
  4. DNA
    1. Polymerase chain reaction (PCR)

VI. Labs: Weil-Felix Reaction (Historical)

  1. Rickettsiaceae share similar Antigens to Proteus Vulgaris
    1. Rickettsiaceae shares the Antigens OX-19, OX-2 and OX-K with Proteus Vulgaris
    2. Proteus Vulgaris is an otherwise completely unrelated organism
  2. Efficacy
    1. Weil-Felix Reaction was historically used to identify Rickettsiaceae organisms
    2. However, the test has low efficacy and has been replaced by other methods
  3. Technique
    1. Latex Agglutination test using each of the Proteus Vulgaris Antigens (OX-19, OX-2, OX-K)
    2. Serum of the test patient is mixed with these test Antigens
    3. Agglutination occurs if patient has serum Antibody to the Antigen tested
  4. Interpretation
    1. Rocky Mountain Spotted Fever is OX-19 and OX-2 positive
    2. Epidemic Typhus and Endemic Typhus are both OX-19 positive
    3. Scrub Typhus is OX-K positive

VII. Management

  1. See Rocky Mountain Spotted Fever
  2. See Typhus
  3. See Anaplasmosis
  4. See Ehrlichiosis
  5. See Q Fever
  6. Antibiotics
    1. Doxycycline
    2. Chloramphenicol

VIII. References

  1. Gladwin, Trattler and Mahan (2014) Clinical Microbiology, Medmaster, Fl, p. 115-21
  2. Abdad (2018) J Clin Microbiol 56(8):e01728-17 +PMID: 29769278 [PubMed]
  3. Blanton (2019) Infect Dis Clin North Am 33(1):213-29 +PMID: 30712763 [PubMed]

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Related Studies

Ontology: Bartonella (C0004770)

Definition (NCI_CDISC) Any bacteria that is not assigned to the species level but can be assigned to the Bartonella genus level.
Definition (NCI) A genus of aerobic, Gram-negative, rod shaped bacterium assigned to the phylum Proteobacteria and the family Bartonellaceae.
Definition (MSH) A genus of gram-negative bacteria characteristically appearing in chains of several segmenting organisms. It occurs in man and arthropod vectors and is found only in the Andes region of South America. This genus is the etiologic agent of human bartonellosis. The genus Rochalimaea, once considered a separate genus, has recently been combined with the genus Bartonella as a result of high levels of relatedness in 16S rRNA sequence data and DNA hybridization data.
Definition (CSP) genus of gram negative bacteria characteristically appearing in chains of several segmenting organisms; occurs in man and arthropod vectors; etiologic agent of human bartonellosis, bacillary angiomatosis, trench fever and cat scratch disease; the genus Rochalimaea, once considered a separate genus, has been combined with the genus Bartonella as a result of high levels of relatedness.
Concepts Bacterium (T007)
MSH D001473
SnomedCT 62496009, 112354006, 72051005, 243364004, 51988009
English Bartonella, Rochalimaea, Genus Bartonella (organism), bartonella, rochalimaea, Grahamella (organism), Bartonella (organism), Rochalimaea, NOS, Rochalimea, NOS (organism), BARTONELLA, Bartonella Strong et al. 1915 (Approved Lists 1980) emend. Birtles et al. 1995, Bartonella Strong et al. 1915 (Approved Lists 1980) emend. Brenner et al. 1993, Grahamella (ex Brumpt 1911) Ristic and Kreier 1984, Grahmia, Rocha-Limae, Rochalimaea (Macchiavello 1947) Krieg 1961, Grahamella, Rochalimea, Bartonella, NOS, Grahamella, NOS, Rochalimea, NOS -RETIRED-, Genus Bartonella
French Rochalimaea, Bartonelle, Bartonella
Swedish Bartonella
Czech Bartonella
Spanish Bartonella (organismo), Grahamella, género Bartonella (organismo), Rochalimaea, género Bartonella, Rochalimaea - RETIRADO - (concepto no activo), Grahamella (concepto no activo), Rochalimaea - RETIRADO -, Bartonella
Finnish Bartonella
Russian BARTONELLEZ, VOZBUDITELI, BARTONELLY, BARTONELLA BACILIFORMIS, BARTONELLA, ROCHALIMAEA, БАРТОНЕЛЛЕЗ, ВОЗБУДИТЕЛИ, БАРТОНЕЛЛЫ
Polish Bartonella
Japanese バルトネラ, Bartonella属, バルトネラ属, ロカリメア, ロシャメリア
Norwegian Bartonella, Rochalimaea
German Bartonella, Rochalimaea
Italian Bartonella
Dutch Bartonella, Rochalimaea
Portuguese Bartonella, Rochalimaea
Derived from the NIH UMLS (Unified Medical Language System)

Ontology: Coxiella (C0010239)

Definition (NCI) A genus of Gram-negative, acidophilic, rod-shaped, obligate intracellular bacteria in the phylum Proteobacteria.
Definition (NCI_CDISC) Any bacteria that is not assigned to the species level but can be assigned to the Coxiella genus level.
Definition (MSH) A genus of gram-negative, rod-shaped bacteria that is widely distributed in TICKS and various mammals throughout the world. Infection with this genus is particularly prevalent in CATTLE; SHEEP; and GOATS.
Concepts Bacterium (T007)
MSH D003381
SnomedCT 12220009
English Coxiella (organism), Genus Coxiella (organism), Genus Coxiella, Coxiella, coxiella, Coxiella (Philip 1943) Philip 1948, Burnetia, Coxiella Smith, 1894, COXIELLA, Coxiella, NOS
Swedish Coxiella
Spanish género Coxiella (organismo), género Coxiella, Coxiella (organismo), Coxiella
Czech Coxiella
Finnish Coxiella
Russian KOKSIELLY, КОКСИЕЛЛЫ
French Coxielles, Coxiella
Polish Coxiella
Norwegian Coxiella
German Coxiella
Italian Coxiella
Dutch Coxiella
Portuguese Coxiella
Derived from the NIH UMLS (Unified Medical Language System)

Ontology: Ehrlichia (C0013722)

Definition (CSP) genus in the order Rickettsiales, family Anaplasmataceae which produces disease in dogs, cattle, sheep, and humans.
Definition (MSH) Small, often pleomorphic, coccoid to ellipsoidal organisms occurring intracytoplasmically in circulating LYMPHOCYTES. They are the etiologic agents of tick-borne diseases of humans; DOGS; CATTLE; SHEEP; GOATS; and HORSES.
Concepts Bacterium (T007)
MSH D004536
SnomedCT 42684003, 27334000
English Cowdria, Ehrlichia, ehrlichia, cowdria, Rickettsia (subgen. Ehrlichia), Cowdria (organism), Cytoecetes, Ehrlichia (subgen. Cowdria), Kurlovia, Nicollea, Cowdria Moshkovski 1947, Ehrlichia Moshkovski 1945 (Approved Lists 1980) emend. Dumler et al. 2001, Cowdria, NOS, Ehrlichia, NOS, Genus Ehrlichia (organism), Genus Ehrlichia, Ehrlichia (organism)
Spanish género Ehrlichia, Ehrlichia (organismo), Cowdria (organismo), Cowdria, Ehrlichia, género Ehrlichia (organismo)
French Cowdria, Ehrlichia
Swedish Ehrlichia
Czech Ehrlichia
Finnish Ehrlichia
Italian Cowdria, Ehrlichia
Russian ERLIKHII, EHRLICHIA, ЭРЛИХИИ
Japanese エールリッヒア, エールリッヒ属, エールリキア属, エールリッヒア属, エールリキア, エールリヒア, Cowdria属
Polish Ehrlichia, Cowdria, Cowdria ruminantium
Norwegian Ehrlichia, Cowdria
German Cowdria, Ehrlichia
Dutch Cowdria, Ehrlichia
Portuguese Cowdria, Ehrlichia
Derived from the NIH UMLS (Unified Medical Language System)

Ontology: Rickettsia Infections (C0035585)

Definition (CSP) gram negative bacterial infection with the bacteria in the Rickettsiales order.
Definition (MSH) Infections by the genus RICKETTSIA.
Concepts Disease or Syndrome (T047)
MSH D012282
ICD9 083.9
ICD10 A75-A79.9 , A79.9, A75-A79
SnomedCT 37246009, 266205000, 187387005, 187382004, 154375001, 186790005, 409904000, 416829003
English Infection, Rickettsia, Infections, Rickettsia, Rickettsia Infection, Rickettsia Infections, rickettsial disease, Rickettsioses, Rickettsioses NOS, Rickettsiosis, unspecified, [X]Rickettsioses, [X]Rickettsiosis, unspecified, RICKETTSIA INFECT, INFECT RICKETTSIA, Rickettsiales disease, Disease caused by Rickettsia, Rickettsial disease (diagnosis), Rickettsiosis NOS, Rickettsial infection NOS, Rickettsia Infections [Disease/Finding], rickettsial infection, rickettsiosis, rickettsial diseases, Rickettsioses (A75-A79), Rickettsial infectious disorders, Rickettsioses etc, Rickettsioses etc., [X]Rickettsiosis, unspecified (disorder), [X]Rickettsioses (disorder), Rickettsioses NOS (disorder), Rickettsial diseases, Rickettsial infectious disease, Rickettsial infection, Rickettsial disease, Rickettsia; rickettsiosis, rickettsiosis; Rickettsia, Disease caused by Rickettsia, NOS, Rickettsial infection, NOS, Rickettsial infectious disease, NOS, Disease due to Rickettsiales (disorder), Disease due to Rickettsiales, Rickettsial Infectious Disease, Rickettsial Infectious Disorder, Rickettsiosis, Disease due to Genus Rickettsia (disorder), Disease due to Genus Rickettsia, Disease due to Rickettsia, Disease caused by rickettsiae, Disease caused by Rickettsia (disorder), Disease caused by rickettsiae (disorder)
Spanish enfermedad causada por ricketsias (trastorno), enfermedad causada por ricketsias, Rickettsiosis NEOM, Rickettsiosis no especificada, enfermedad causada por Rickettsia, enfermedad causada por Rickettsia (trastorno), Infecciones por Rickettsia, [X]rickettsiosis, no especificada, rickettsiosis, SAI (trastorno), [X]rickettsiosis, [X]rickettsiosis, no especificada (trastorno), rickettsiosis, SAI, [X]rickettsiosis (trastorno), enfermedad causada por Rickettsias (trastorno), enfermedad causada por Rickettsias, enfermedad infecciosa rickettsial, infección rickettsial, rickettsiosis, Enfermedades por rickettsias, Rickettsiosis, enfermedad por Rickettsiales (trastorno), enfermedad por Rickettsiales, enfermedad causada por organismos del género Rickettsia (trastorno), enfermedad causada por organismos del género Rickettsia
Italian Patologie infettive da Rickettsia, Rickettsiosi, Rickettsiosi, non specificate, Rickettsiosi NAS, Infezioni da Rickettsia
Dutch rickettsiose NAO, rickettsiose, niet-gespecificeerd, Rickettsia; rickettsiose, rickettsiose; Rickettsia, Rickettsiose, niet gespecificeerd, Rickettsia-infectieziekten, rickettsiose, Rickettsiose
French Rickettsiose SAI, Rickettsiose, non précisée, Rickettsiose, Troubles infectieux à Rickettsiaceae, Infections à Rickettsia, Infections à rickettsies, Rickettsioses
German Rickettsiose NNB, Rickettsiose, unspezifisch, Rickettsiose, nicht naeher bezeichnet, Infektionserkrankungen durch Rickettsien, Rickettsiose, Rickettsieninfektionen
Portuguese Riquetsioses NE, Riquetsiose NE, Infecções por Rickettsia, Riquetsiose infecciosa, Riquetsioses
Japanese リケッチア症、詳細不明, リケッチア症ＮＯＳ, ﾘｹｯﾁｱｼｮｳNOS, ﾘｹｯﾁｱｼｮｳｼｮｳｻｲﾌﾒｲ, ﾘｹｯﾁｱｼｮｳ, ﾘｹｯﾁｱｶﾝｾﾝｼｮｳ, リケッチア感染症, リケッチア症
Swedish Rickettsiainfektioner
Czech Rickettsia - infekce, Ricketsióza, blíže neurčená, Ricketsióza NOS, Ricketsióza, Rickettsiová infekční onemocnění
Finnish Riketsiainfektiot
Russian RIKKETSIOZY, РИККЕТСИОЗЫ
Korean 상세불명의 리켓치아병
Croatian RIKECIOZE
Polish Riketsjozy, Infekcje riketsjowe, Zakażenia riketsjowe
Hungarian rickettsiosis, Rickettsiosis, nem meghatározott, Rickettsia fertőzéses betegségek, rickettsiosis k.m.n.
Norwegian Rickettsioser, Rickettsiainfeksjoner
Derived from the NIH UMLS (Unified Medical Language System)

Ontology: Rickettsiaceae (C0035591)

Definition (NCI) A taxonomic family of Gram negative, non acid fast bacterium in the phylum Proteobacteria that includes the genera Rickettsia and Wolbachia, among others.
Definition (MSH) A family of small, gram-negative organisms, often parasitic in humans and other animals, causing diseases that may be transmitted by invertebrate vectors.
Concepts Bacterium (T007)
MSH D012287
SnomedCT 115081009
English Rickettsiaceae, Family rickettsiaceae, Rickettsiaceae Pinkerton 1936 (Approved Lists 1980) emend. Brenner et al. 1993, Rickettsiaceae Pinkerton 1936 (Approved Lists 1980) emend. Dumler et al. 2001, Family Rickettsiaceae (organism), Family rickettsiaceae (organism), Family Rickettsiaceae
Swedish Rickettsiaceae
Czech Rickettsiaceae, Symbiotes
Spanish Rickettsiaceae, familia Rickettsiaceae (organismo), familia Rickettsiaceae
Finnish Rickettsiaceae
Russian SIMBIOTY, RICKETTSIACEAE, СИМБИОТЫ
Croatian Not Translated[Rickettsiaceae]
Polish Rickettsiaceae, Symbiotes
Norwegian Rickettsiaceae
French Rickettsiaceae
German Rickettsiaceae
Italian Rickettsiaceae
Dutch Rickettsiaceae, Symbionten, Rickettsiaceeën
Portuguese Rickettsiaceae
Derived from the NIH UMLS (Unified Medical Language System)

Ontology: Order Rickettsiales (C0035596)

Definition (CSP) order of gram negative proteobacteria; obligate intracellular parasites that cause a variety of diseases including typhus and Rocky Mountain spotted fever; organisms multiply in endothelial cells of small blood vessels, the resulting damage is the cause of the spotted appearance.
Concepts Bacterium (T007)
SnomedCT 115178001, 312331000
English rickettsias, Rickettsias, Order Rickettsiales, Rickettsiales (organism), Rickettsiales Gieszczykiewicz 1939 (Approved Lists 1980) emend. Brenner et al. 1993, Rickettsiales Gieszczykiewicz 1939 (Approved Lists 1980) emend. Dumler et al. 2001, Order Rickettsiales (organism), Rickettsiales
Spanish Rickettsiales, rickettsias (organismo), rickettsias, orden Rickettsiales (organismo), orden Rickettsiales
Derived from the NIH UMLS (Unified Medical Language System)

Ontology: serum Weil-Felix antibody test (C2229902)

Concepts Laboratory Procedure (T059)
English serum Weil-Felix antibody test, serum Weil-Felix antibody test (lab test)
Derived from the NIH UMLS (Unified Medical Language System)

Related Topics in Bacterial Infections

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