How to treat anaplasmosis with doxycycline (Doxycycline)?

Treatment of Anaplasmosis

Doxycycline 100 mg twice daily for 10 days is the recommended first-line treatment for anaplasmosis in all patients, regardless of age, including children and pregnant women, due to the risk of complications and potential fatality if left untreated. 1

Treatment Regimen

• Adults: Doxycycline 100 mg twice daily orally (or intravenously for patients unable to take oral medications) for 10 days 1
• Children: Doxycycline 4 mg/kg per day in 2 divided doses (maximum 100 mg per dose) orally or intravenously for 10 days 1

Rationale for Doxycycline Use

Doxycycline is the treatment of choice for anaplasmosis because:

1. It is highly effective against Anaplasma phagocytophilum
2. The mortality rate is less than 1% with appropriate treatment 2
3. Alternative antibiotics have shown limited efficacy or treatment failure

Special Populations

Children

• Despite traditional concerns about tooth discoloration, doxycycline should be used in children of all ages with anaplasmosis due to the potentially life-threatening nature of the infection 1
• The risk of dental staining with short courses of doxycycline is minimal compared to the risk of untreated anaplasmosis 3

Pregnant Women

• Doxycycline should be used even during pregnancy due to the potentially severe complications of untreated anaplasmosis 1
• There is documented successful treatment of a pregnant woman who developed symptomatic anaplasmosis during childbirth 1

Alternative Treatment

For patients with documented severe allergy to tetracyclines:

• Rifampin 300 mg twice daily orally for adults and 10 mg/kg twice daily for children (maximum 300 mg per dose) for 7-10 days 1
• Important caveat: Patients treated with rifampin should be closely monitored to ensure resolution of clinical and laboratory abnormalities 1

Treatment Failures and Pitfalls

• Avoid fluoroquinolones: Despite in vitro activity against A. phagocytophilum, levofloxacin has been associated with clinical and microbiological relapse after treatment completion 4
• Do not delay treatment: Empiric therapy should be started based on clinical suspicion without waiting for laboratory confirmation 2
• Monitor for response: Clinical improvement typically occurs within 24-48 hours; lack of improvement should prompt reevaluation of diagnosis
• Complete the full course: Even if symptoms resolve quickly, the full 10-day course is necessary to prevent relapse

Diagnostic Confirmation

While treatment should not be delayed pending results, diagnostic confirmation can be obtained through:

• PCR testing (preferred method during acute illness) 2
• Serology (IgG titers ≥1:64 indicate recent or current infection)
• Examination of peripheral blood smears for characteristic morulae in neutrophils

Follow-up

• Clinical improvement is typically seen within 24-48 hours of starting doxycycline
• Follow-up testing is not routinely required if symptoms resolve
• Monitor for resolution of laboratory abnormalities (thrombocytopenia, leukopenia, elevated liver enzymes)

Prophylaxis Considerations

Prophylactic doxycycline after tick bites is not routinely recommended for anaplasmosis alone, as evidence for its efficacy is limited 5. The focus should be on prompt recognition and treatment of symptoms if they develop.