Ehrlichiosis and anaplasmosis

Overview 
Theory 
Diagnosis 
Management 
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Key diagnostic factors

common

history of tick bite/exposure

Ehrlichiosis has a seasonal distribution that coincides with higher tick activity in warmer months (e.g., April through September in the US), when people tend to spend more time outdoors.

Tick attachment has to last for 24 to 48 hours for disease to occur. Incubation time is 1 to 2 weeks after tick bite.[21] Lack of a tick bite history cannot exclude diagnosis in patients with signs, symptoms, and investigation results consistent with tick-borne illness, as many people will not recall being bitten.

Tick bite does not always result in disease.

history of immunosuppression

Associated with more severe disease in human monocytotropic/monocytic ehrlichiosis (HME) and human granulocytotropic/granulocytic anaplasmosis (HGA).[57] Most cases of human ewingii ehrlichiosis (HEE) occur in immunosuppressed patients.[4][58][59]

fever

One of the most common constitutional symptoms and generally has an abrupt onset.

May or may not be associated with rigors.

Lasts for 10 to 14 days without antibiotic treatment.[16][61][62][63][69][80][99][100]

Present in 99% of human monocytotropic/monocytic ehrlichiosis (HME) cases and 93% of human granulocytotropic/granulocytic anaplasmosis (HGA) cases. Unknown occurrence in human ewingii ehrlichiosis (HEE).[16][61][62][63][66][69][70][72][80][100][101]

headache

One of the most common constitutional symptoms and may be severe.

Present in 64% of human monocytotropic/monocytic ehrlichiosis (HME) cases and 76% of human granulocytotropic/granulocytic anaplasmosis (HGA) cases. Unknown occurrence in human ewingii ehrlichiosis (HEE).[16][61][62][63][66][69][70][72][80][101]

malaise

One of the most common constitutional symptoms.

Persists for months after acute disease.

Present in 53% of human monocytotropic/monocytic ehrlichiosis (HME) cases and 94% of human granulocytotropic/granulocytic anaplasmosis (HGA) cases. Unknown occurrence in human ewingii ehrlichiosis (HEE).[16][61][62][63][66][69][70][72][80][100][101]

myalgia

One of the most common constitutional symptoms.

Present in 53% of human monocytotropic/monocytic ehrlichiosis (HME) cases and 77% of human granulocytotropic/granulocytic anaplasmosis (HGA) cases. Unknown occurrence in human ewingii ehrlichiosis (HEE).[16][61][62][63][66][69][70][72][80][100][101]

arthralgia

One of the most common constitutional symptoms.

Present in 43% of human monocytotropic/monocytic ehrlichiosis (HME) cases and 46% of human granulocytotropic/granulocytic anaplasmosis (HGA) cases. Unknown occurrence in human ewingii ehrlichiosis (HEE).[16][61][62][63][66][69][70][72][80][100][101]

nausea

One of the most common constitutional symptoms.

Present in 48% of human monocytotropic/monocytic ehrlichiosis (HME) cases and 38% of human granulocytotropic/granulocytic anaplasmosis (HGA) cases. Unknown occurrence in human ewingii ehrlichiosis (HEE).[16][61][62][63][66][69][70][72][80][100][101]

uncommon

small erythematous lesion with or without necrotic center

On examination of the skin, a small round erythematous lesion with or without a small necrotic dark center (eschar) may be seen (tick bite).

[Figure caption and citation for the preceding image starts]: Tick bite at later stage with central necrosis (dark area around tick bite) surrounded by a markedly erythematous areaCourtesy of Lucas Blanton, MD [Citation ends]. com.bmj.content.model.Caption@2f44166f

nonspecific rash

One of the more infrequent constitutional symptoms in adults, but more common in children.

Can be macular, maculopapular, or petechial, and occur anywhere on the body. [Figure caption and citation for the preceding image starts]: Erythematous macular rash involving the lower extremity in a pediatric case of human monocytotropic/monocytic ehrlichiosisCourtesy of Edwin Masters, MD [Citation ends]. com.bmj.content.model.Caption@37819d00

Present in 28% (adults) and 67% (children) of human monocytotropic/monocytic ehrlichiosis (HME) cases and 6% of human granulocytotropic/granulocytic anaplasmosis (HGA) cases. Unknown occurrence in human ewingii ehrlichiosis (HEE).[16][61][62][63][66][69][70][72][80][100][101]