What is the recommended treatment approach for a patient with a history of chronic anaplasmosis, considering potential complications and co-infections such as Lyme disease or babesiosis?

Chronic Anaplasmosis: Treatment Approach

There is no evidence supporting the existence of chronic anaplasmosis in immunocompetent patients, and treatment should only be directed at acute, laboratory-confirmed infection with doxycycline for 10 days. 1

Key Clinical Principle

The medical literature does not demonstrate convincing evidence of chronic anaplasmosis infection. 1 Anaplasmosis caused by Anaplasma phagocytophilum is an acute illness that resolves with appropriate treatment, and chronic infection has not been described in humans. 2 Any patient presenting with a history labeled as "chronic anaplasmosis" requires reassessment of their diagnosis.

Diagnostic Reassessment Required

For patients with a purported history of chronic anaplasmosis, you must first confirm whether active infection exists:

• Active infection requires: fever, headache, myalgia AND laboratory confirmation through blood smear showing morulae in granulocytes, positive PCR, or acute/convalescent serology 2
• Laboratory hallmarks of acute disease: thrombocytopenia, leukopenia, elevated hepatic transaminases, and mild anemia 2
• Seropositivity alone does not indicate active infection and should not prompt treatment 2

Treatment Algorithm for Confirmed Acute Anaplasmosis

If active infection is documented:

• Doxycycline 100 mg twice daily orally (or IV if unable to take oral) for 10 days 2
• For children weighing <100 lbs: 2.2 mg/kg twice daily, maximum 100 mg per dose 2
• Clinical improvement should occur within 24-48 hours of starting treatment 2
• Lack of response within 48 hours indicates either wrong diagnosis or coinfection 2

Critical Pitfall to Avoid

The 10-day duration (rather than the typical 5-7 days for other rickettsial diseases) is specifically recommended to provide adequate coverage for possible coinfection with Borrelia burgdorferi (Lyme disease), since the same tick vector (Ixodes scapularis) transmits both pathogens. 2

Evaluation for Coinfections

Because I. scapularis transmits multiple pathogens, assess for coinfections when anaplasmosis is confirmed:

Lyme Disease Coinfection

• Occurs in <10% of anaplasmosis cases 2
• Suspect if: patient fails to respond to doxycycline within 48 hours, or if erythema migrans rash is present 2
• Key diagnostic clue: leukopenia or thrombocytopenia in a patient with Lyme disease suggests anaplasmosis coinfection 2
• Treatment approach: the 10-day doxycycline course for anaplasmosis provides adequate coverage for early Lyme disease 2

Babesiosis Coinfection

• Simultaneous infections with Babesia microti have been documented 2
• Suspect if: persistent fever despite doxycycline, hemolytic anemia, or high-grade parasitemia on blood smear 2
• Diagnostic confirmation: identification of intraerythrocytic parasites on Giemsa-stained blood smear or positive PCR 2
• Treatment for confirmed babesiosis:
  • Atovaquone 750 mg twice daily PLUS azithromycin 500-1000 mg day 1, then 250 mg daily for 7-10 days (preferred due to better tolerability) 2
  • Alternative: clindamycin plus quinine for severe cases 2
  • Do NOT treat based on serology alone without parasitemia 2

When NOT to Treat

Do not provide antimicrobial therapy in these scenarios:

• Asymptomatic patients with positive serology but no parasitemia or clinical symptoms 2
• Patients with nonspecific chronic symptoms (fatigue, myalgias) and positive serology but no objective findings 1
• Patients previously treated for acute anaplasmosis who have persistent nonspecific symptoms without laboratory evidence of active infection 1

Severe Anaplasmosis Complications

Hospitalization and intensive monitoring required if:

• Severe thrombocytopenia, mental status changes, organ dysfunction, or need for supportive therapy 2
• Approximately 7% of hospitalized patients require ICU admission 2
• Rare but serious complications include: ARDS, DIC-like coagulopathies, rhabdomyolysis, acute renal failure, secondary hemophagocytic lymphohistiocytosis 2, 3
• Predictors of severe disease: advanced age, immunosuppression, diabetes, delayed diagnosis 2
• For hemophagocytic lymphohistiocytosis: consider adding corticosteroids and IL-1 receptor antagonist (anakinra) in addition to doxycycline 3

Bottom Line on "Chronic Anaplasmosis"

The concept of chronic anaplasmosis lacks scientific support. 1 If a patient carries this diagnosis, either they have acute infection requiring standard 10-day doxycycline treatment, or they have been misdiagnosed and require evaluation for alternative causes of their symptoms. The case-fatality rate for acute anaplasmosis is <1%, and with appropriate treatment, clinical signs and symptoms resolve in most patients within 30 days. 2