II. Epidemiology
- Incidence: 906 reported cases in U.S. in 2014
- Outdoor or woods exposure
- Majority of cases occur April to September
- Highest Incidence in June and July
- U.S. regions affected
- South central and Southeast (New Jersey and south)
- Southern midwest (from Illinois to Texas)
- One third of cases are found in Oklahoma, Missouri and Arkansas
III. Pathophysiology
- Carried by Lone star tick (Amblyomma americanum)
- The less common E. muris eauclairensis is carried by the Deer Tick (Ixodes Scapularis)
- Small gram-negative organisms (Neorickettsia)
- Pleomorphic
- Obligate intracellular organisms
- Infect Monocytes
- Organisms causing Human Monocytic Ehrlichiosis
- Ehrlichia chaffeensis (primary cause)
- Ehrlichia ewingii (similar disease in Immunocompromised patients and dogs)
IV. Symptoms (Occur 7-10 days after Tick Bite)
- Common Initial Symptoms
- Other symptoms
- Malaise
- Nausea and Vomiting, Anorexia
- Abdominal Pain
- Diarrhea
- Cough
- Conjunctival Injection
- Confusion
V. Signs: Rash
- Present in 30% of patients
- Characteristics vary
- May be maculopapular or petechial or appear with diffuse erythema
- Involves trunk, and spares hands and feet
- Not associated with Tick Bite site
- Contrast with Erythema Migrans in Lyme Disease
VI. Differential Diagnosis
- See Tick Borne Illness
- Similar to Anaplasmosis presentation, and Rocky Mountain Spotted Fever Presentation (with different rash)
VII. Labs
-
Complete Blood Count
- Leukopenia
- Thrombocytopenia
- Mild Anemia (later stages)
-
Liver transaminases increased
- Aspartate Aminotransferase (AST) increased
- Alanine Aminotransferase (ALT) increased
- Cerebrospinal Fluid
- Lymphocytic Pleocytosis
- Increased CSF Protein
- Ehrlichia PCR
-
Peripheral Smear
- Morulae inclusion bodies
- Intracellular mulberry-like clusters of organisms in Monocyte vacuoles
- Contrast with the erythrocyte inclusion body of Babesiosis (tetrad or maltese)
- Morulae inclusion bodies
- Specific testing
- Other variably present laboratory findings
- Increased Erythrocyte Sedimentation Rate (ESR)
- Increased Blood Urea Nitrogen (BUN)
- Increased Serum Creatinine
VIII. Management
-
General
- Coinfection
- Concurrent transmission of Lyme Disease and Ehrlichiosis is common
- Coninfection with Babesiosis may also occur
- Antibiotics for two weeks (minimum of 10 days)
- Continue for at least 3 days after fever subsides
- Coinfection
- Agents
- Preferred regimen (regardless of age; includes use in children)
- Doxycycline
- Adult: 100 mg orally twice daily for 14 days
- Child: 2.2 mg/kg orally twice daily up to 100 mg (weight <45 kg or 100 lb)
- Precautions: Increased mortality in age <5 years old
- Do not hesitate to prescribe Doxycycline to a child with Ehrlichiosis (per AAP and CDC)
- Doxycycline
- Alternative regimens
- Tetracycline
- Rifampin
- Prior options included Chloramphenicol
- Preferred regimen (regardless of age; includes use in children)
IX. Complications: Untreated Disease
- Meningoencephalitis
- Respiratory Failure
- Uncontrolled Bleeding
- Mortality 3%
X. Prevention
XI. Resources
XII. Reference
- (2016) Sanford Guide to Antibiotics, IOS app accessed 4/14/2016
- Fritz (1998) Infect Dis Clin North Am 12:123-36 [PubMed]
- Glushko (1997) Postgrad Med 101(6):225-30 [PubMed]
- Huntington (2016) Am Fam Physician 94(7): 551-7 [PubMed]
- McQuiston (1999) Emerg Infect Dis 5:635-42 [PubMed]
- Pace (2020) Am Fam Physician 101(9): 530-40 [PubMed]
- Standaert (1995) N Engl J Med 333:420-5 [PubMed]
- Weinstein (1996) Am Fam Physician 54(6):1971-6 [PubMed]
- (1994) Ann Intern Med 120:730,6 [PubMed]
- (1995) MMWR Morb Mortal Wkly Rep 44:593-5 [PubMed]
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Definition (CSP) | febrile illness caused by infection with Ehrlichia species. |
Definition (MSH) | A tick-borne disease characterized by FEVER; HEADACHE; myalgias; ANOREXIA; and occasionally RASH. It is caused by several bacterial species and can produce disease in DOGS; CATTLE; SHEEP; GOATS; HORSES; and humans. The primary species causing human disease are EHRLICHIA CHAFFEENSIS; ANAPLASMA PHAGOCYTOPHILUM; and Ehrlichia ewingii. |
Concepts | Disease or Syndrome (T047) |
MSH | D016873 |
ICD9 | 082.40, 082.4 |
ICD10 | A77.4 , A77.40 |
SnomedCT | 77361002 |
English | Ehrlichioses, Ehrlichiosis, Erlichiosis, ehrlichiosis, ehrlichiosis (diagnosis), Ehrlichiosis NOS, Ehrlichiosis, unspecified, Ehrlichiosis [Disease/Finding], ehrlichioses, erlichiosis, Ehrlichiosis (disorder), Ehrlichiosis, NOS |
Swedish | Ehrlichios |
Czech | ehrlichióza |
Finnish | Ehrlichioosi |
Russian | ERLIKHIOZ, ЭРЛИХИОЗ |
Polish | Erlichioza, Ehrlichioza, Anaplazmoza ludzka |
Norwegian | Ehrlichiose |
Spanish | ehrliquiosis (trastorno), ehrliquiosis, Ehrlichiosis |
French | Ehrlichiose |
German | Ehrlichiose |
Italian | Ehrlichiosi |
Dutch | Ehrlichiose |
Portuguese | Ehrlichiose |
Ontology: Ehrlichia chaffeensis (C0242677)
Definition (MSH) | A species of gram-negative bacteria that is the causative agent of human EHRLICHIOSIS. This organism was first discovered at Fort Chaffee, Arkansas, when blood samples from suspected human ehrlichiosis patients were studied. |
Concepts | Bacterium (T007) |
MSH | D018469 |
SnomedCT | 59250001 |
Swedish | Ehrlichia chaffeensis |
Czech | Ehrlichia chaffeensis |
Finnish | Ehrlichia chaffeensis |
Polish | Ehrlichia chaffeensis |
Norwegian | Ehrlichia chaffeensis |
English | Ehrlichia chaffeensis Anderson et al. 1992 emend. Dumler et al. 2001, Ehrlichia chaffeensis (organism), Ehrlichia chaffeensis |
Spanish | Ehrlichia chaffeensis (organismo), Ehrlichia chaffeensis |
French | Ehrlichia chaffeensis |
German | Ehrlichia chaffeensis |
Italian | Ehrlichia chaffeensis |
Russian | EHRLICHIA CHAFFEENSIS |
Dutch | Ehrlichia chaffeensis |
Portuguese | Ehrlichia chaffeensis |
Ontology: Human ehrlichiosis (C0343771)
Concepts | Disease or Syndrome (T047) |
SnomedCT | 21885008, 240626005 |
Italian | Ehrlichiosi umana |
Japanese | ヒトのエールリッヒア症, ヒトノエールリッヒアショウ |
Czech | Lidská ehrlichióza |
Hungarian | human ehrlichiosis |
Spanish | ehrliquiosis humana, ehrliquiosis humana (trastorno), ehrliquiosis humana (concepto no activo), erliquiosis del humano (trastorno), erliquiosis del humano, Erlichiosis humana |
English | Human ehrlichiosis, Human ehrlichiosis (disorder), Human ehrlichiosis (disorder) [Ambiguous] |
Portuguese | Erliquiose humana |
Dutch | humane ehrlichiosis |
French | Ehrlichiose humaine |
German | humane Ehrlichiose |
Ontology: Ehrlichia ewingii (C0445866)
Concepts | Bacterium (T007) |
MSH | D004536 |
SnomedCT | 243360008 |
LNC | LP63456-5 |
English | Ehrlichia ewingii, Ehrlichia ewingii Anderson et al. 1992 emend. Dumler et al. 2001, Ehrlichia ewingii (organism) |
Portuguese | Ehrlichia ewingii |
French | Ehrlichia ewingii |
German | Ehrlichia ewingii |
Italian | Ehrlichia ewingii |
Norwegian | Ehrlichia ewingii |
Spanish | Ehrlichia ewingii (organismo), Ehrlichia ewingii |
Dutch | Ehrlichia ewingii |