Ehrlichiosis: causes, symptoms, diagnosis, treatment, prognosis, and prevention

Ehrlichiosis is caused by Ehrlichia transmitted by ticks. The pathogen invades monocytes or neutrophils and forms mulberry-shaped inclusions in the cytoplasm. Sudden onset is present and rash is less common. Symptoms resemble those of rocky mountain spotted fever. Leukopenia and thrombocytopenia are present. Hepatocellular injury and liver dysfunction can occur. Serious complications may cause death.


Causes

Ehrlichiosis is caused by Ehrlichia chaffeensis, Ehrlichia ewingii, or Ehrlichia muris, transmitted by ticks, and the pathogens are clustered in the cytoplasm but close to the cytomembrane, with a diameter of about 0.2 - 1.5 μm, and inclusions are like mulberries.


Signs and Symptoms

The incubation period is about 12 to 14 days.

The clinical manifestations are very difficult to differentiate from rocky mountain spotted fever. Sudden onset, chills, high fever, often accompanied by slow pulse (<90 beats / min), headache, myalgia, nausea, vomiting, fatigue, and discomfort may be present. No obvious signs can be seen in physical examinations. About 20% of patients infected with Ehrlichia chaffeensis have rash, but patients with human granulocytic ehrlichiosis (HGE) have no rash. The rash can be maculopapular rash, papules, macules, petechiae, or erythema, more common on the chest, legs, and arms. The rash occurs about 5 days after onset. The natural duration of the disease is 3 to 19 days, averagely 7 days.

Severe patients may develop renal failure, meningitis, coma, disseminated intravascular coagulation, pancytopenia, hematopoietic disorders, and hemophagocytic syndrome. Patients may die if without prompt treatment.


Diagnosis

On the basis of epidemiology such as exposure in the epidemic area and a history of tick bites, clinical manifestations, mulberry-shaped inclusions on the white blood cell smears, indirect immunofluorescence, and PCR, the disease can be diagnosed.


Treatment

Macrolides, such as erythromycin, roxithromycin, azithromycin, clarithromycin, have a good effect against typhus.

Tetracyclines, such as tetracycline, doxycycline, and minocycline, are effective to treat typhus, but are contraindicated in children aged under 8 years, pregnant women, and lactating women.

Chloramphenicol has a good effect for the treatment of typhus. Because chloramphenicol can induce aplastic anemia, it should not be preferred. Chloramphenicol are contraindicated in young children, pregnant women, and lactating women.

Quinolones, such as ofloxacin, ciprofloxacin, pefloxacin, fleroxacin, lomefloxacin, and enoxacin, can be administered, but contraindicated in children aged under 8 years, pregnant women, and lactating women.


Prognosis

After early diagnosis and prompt treatment, good prognosis is present in most patients. Patients with prolonged fever, renal failure, disseminated intravascular coagulation, meningitis, respiratory distress syndrome, seizures, and coma have poor prognosis. Patients with impaired immune system have poor prognosis.


Prevention

Tick bites should be avoided, and ticks should be eliminated.