Anaplasmosis and Hemolytic Anemia
Anaplasmosis typically causes mild anemia but does not directly cause hemolytic anemia. According to CDC guidelines, the characteristic laboratory findings in anaplasmosis include thrombocytopenia, leukopenia, elevated hepatic transaminase levels, increased numbers of immature neutrophils, and mild anemia 1.
Pathophysiology and Hematologic Manifestations
Anaplasma phagocytophilum is an obligate intracellular bacterium that primarily infects granulocytes, particularly neutrophils. Unlike some other tick-borne diseases:
- A. phagocytophilum induces a systemic inflammatory response, which is the primary mechanism for tissue damage 1
- The infection affects neutrophil function but does not directly target red blood cells
- Mild anemia is a common finding but is not typically hemolytic in nature 1
Clinical Presentation and Laboratory Findings
Patients with anaplasmosis typically present with:
- Fever (92-100% of cases)
- Headache (82%)
- Malaise (97%)
- Myalgia (77%)
- Shaking chills 1
Laboratory abnormalities include:
- Thrombocytopenia
- Leukopenia
- Elevated hepatic transaminases
- Increased immature neutrophils
- Mild anemia 1
Severe Manifestations and Complications
While anaplasmosis is typically self-limiting, severe cases can present with:
- ARDS (Acute Respiratory Distress Syndrome)
- Peripheral neuropathies
- DIC-like coagulopathies
- Hemorrhagic manifestations
- Rhabdomyolysis
- Pancreatitis
- Acute renal failure 1
In rare cases, severe anaplasmosis can resemble:
- Toxic shock syndrome
- Thrombotic thrombocytopenic purpura (TTP)
- Hemophagocytic syndromes 1
Differential Diagnosis Considerations
When evaluating a patient with suspected tick-borne illness and hemolytic anemia:
- Consider coinfection with Babesia microti, which is transmitted by the same tick vector (Ixodes scapularis) and is a known cause of hemolytic anemia 1
- Approximately 10% of patients with Lyme disease may have coinfection with A. phagocytophilum 1
- In patients with sickle cell disease, anaplasmosis can potentially trigger sickle cell crisis and atypical hemolytic-uremic syndrome 2
Treatment Approach
The recommended treatment for anaplasmosis is:
- Doxycycline 100 mg twice daily for 10 days 3
- Prompt institution of antibiotic therapy is critical, especially for older or immunocompromised patients 4
- Treatment typically results in rapid improvement and resolution of symptoms 4
Clinical Pearls and Pitfalls
- Delayed diagnosis in older and immunocompromised patients increases risk for adverse outcomes, including death 4
- Predictors of severe anaplasmosis include advanced age, immunosuppression, comorbid conditions like diabetes, and delayed diagnosis/treatment 1
- If hemolytic anemia is present in a patient with confirmed anaplasmosis, consider coinfection with other tick-borne pathogens, particularly Babesia 1
- Leukopenia or thrombocytopenia in a patient with Lyme disease should raise suspicion for possible coinfection with A. phagocytophilum 1