Human monocytotropic ehrlichiosis
Medical condition
From Wikipedia, the free encyclopedia
Human monocytotropic ehrlichiosis[1] is a form of ehrlichiosis associated with Ehrlichia chaffeensis.[2] This bacterium is an obligate intracellular pathogen affecting monocytes and macrophages.[3]
| Human monocytic ehrlichiosis | |
|---|---|
| |
| Ehrlichia chaffeensis | |
| Specialty | Infectious diseases  |
Signs and symptoms
The most common symptoms are fever, headache, malaise, and muscle aches (myalgia). Compared to human granulocytic anaplasmosis, rash is more common.[4] Laboratory abnormalities include thrombocytopenia, leukopenia, and elevated liver tests.[citation needed]
The severity of the illness can range from minor or asymptomatic to life-threatening. CNS involvement may occur. A serious septic or toxic shock-like picture can also develop, especially in patients with impaired immunity.[5]
Cause
Human monocytotropic ehrlichiosis is caused by infection with Ehrlichia chaffeensis, an obligate intracellular bacterium that primarily infects monocytes and macrophages.[6] Humans usually acquire the infection through the bite of infected ticks, particularly the lone star tick (Amblyomma americanum) in the United States.[7]
Diagnosis
Tick exposure is often overlooked. For patients living in high-prevalence areas who spend time outdoors, a high degree of clinical suspicion should be employed.[citation needed] Ehrlichia serologies can be negative in the acute period. Polymerase chain reaction is therefore the laboratory diagnostic tool of choice.[8]
Treatment
If ehrlichiosis is suspected, treatment should not be delayed while waiting for a definitive laboratory confirmation, as prompt doxycycline therapy has been associated with improved outcomes.[9] Doxycycline is the treatment of choice.[citation needed]
Presentation during early pregnancy can complicate treatment.[10] Rifampin has been used in pregnancy and in patients allergic to doxycycline.[11]
Epidemiology
In the US, human monocytotropic ehrlichiosis occurs across the south-central, southeastern, and mid-Atlantic states, regions where both the white-tailed deer (Odocoileus virginianus) and its ectoparasite, Lone Star ticks (Amblyomma americanum), thrive.[12][13][14]
Human monocytotropic ehrlichiosis occurs in California in Ixodes pacificus ticks and in Dermacentor variabilis ticks.[15] Nearly 600 cases were reported to the CDC in 2006. In 2001–2002, the incidence was highest in Missouri, Tennessee, and Oklahoma, as well as in people older than 60.[16]