Treatment of Anaplasmosis

Doxycycline is the drug of choice for the treatment of anaplasmosis in patients of all ages, including children under 8 years. 1

First-Line Treatment

Adults: Doxycycline 100 mg orally twice daily for 10 days 1, 2
Children: Doxycycline 4 mg/kg per day divided into two doses (maximum 100 mg per dose) for 10 days 2
Intravenous option: For patients unable to take oral medications, IV doxycycline at the same dosage 2

Fever typically subsides within 24-48 hours after initiating doxycycline treatment 1, 3
Lack of clinical response within 48 hours should prompt consideration of alternative diagnoses or possible coinfection 1
Severely ill patients may require >48 hours of treatment before clinical improvement is noted 1

Doxycycline is recommended by the American Academy of Pediatrics and CDC as the treatment of choice for anaplasmosis in children of all ages 1
Previous concerns about tooth staining in children <8 years have been disproven with modern doxycycline formulations 1
Studies show no evidence of tooth staining or enamel hypoplasia in children treated with short courses of doxycycline 1

Rifampin may be considered as an alternative for pregnant women with anaplasmosis 1, 2
Dosage: 300 mg orally twice daily for 7-10 days 2
Case reports document favorable maternal and pregnancy outcomes in pregnant women treated with rifampin for anaplasmosis 1

Rifampin is the only acceptable alternative for patients with:
- Documented severe allergy to tetracyclines 1, 2
- Pregnancy 1, 2
Dosage: 300 mg orally twice daily for adults or 10 mg/kg twice daily for children (maximum 300 mg per dose) 1, 2

Before using rifampin, clinicians must rule out Rocky Mountain Spotted Fever (RMSF), as rifampin is not effective against RMSF 1, 2
Rifampin does not effectively treat potential coinfection with Borrelia burgdorferi (Lyme disease) 1, 2
Chloramphenicol is not an acceptable alternative for the treatment of anaplasmosis 1, 2
Beta-lactams, macrolides, aminoglycosides, and sulfonamides are ineffective against A. phagocytophilum 2
Sulfonamides (including trimethoprim-sulfamethoxazole) are associated with increased disease severity in tickborne rickettsial diseases 1, 2

Close follow-up is essential for patients treated as outpatients 1
For patients treated with rifampin, monitor closely to ensure resolution of clinical and laboratory abnormalities 2
Complications of anaplasmosis can include shock, organ dysfunction, and rarely death (mortality <1% with appropriate treatment) 3

If coinfection with B. burgdorferi is suspected, treatment should be extended to 10 days or additional treatment with an antimicrobial effective against Lyme disease should be added 1, 2

Early treatment is critical, as delay in treatment of tickborne rickettsial diseases can lead to severe disease and death 1.