What are the treatments for toxoplasmosis and cat scratch disease?

Treatment for Toxoplasmosis and Cat Scratch Disease

For toxoplasmosis, the first-line treatment is pyrimethamine plus sulfadiazine with folinic acid supplementation, while cat scratch disease is primarily treated with azithromycin. 1

Toxoplasmosis Treatment

First-Line Treatment

• Pyrimethamine plus sulfadiazine with folinic acid (leucovorin) is the recommended regimen 2, 1
  • Pyrimethamine dosing: 2 mg/kg/day orally divided twice daily for first 2 days, then 1 mg/kg/day daily for 2-6 months, followed by 1 mg/kg/day three times weekly 2
  • Sulfadiazine dosing: 100 mg/kg/day orally divided twice daily 2
  • Folinic acid (leucovorin): 10 mg three times weekly 2
  • Treatment duration: 12 months for congenital toxoplasmosis 2

Special Considerations for Toxoplasmosis

• For severe chorioretinitis or elevated CSF protein (≥1 g/dL), corticosteroids may be added after 72 hours of anti-Toxoplasma therapy 2
• Regular monitoring is essential:
  • Complete blood count weekly during daily pyrimethamine treatment due to risk of bone marrow suppression 1, 3
  • Ophthalmologic evaluations every 2-3 weeks for active chorioretinitis 1

Alternative Regimens for Toxoplasmosis

• Trimethoprim-sulfamethoxazole (TMP-SMX) is an alternative, especially for HIV patients with CD4+ count <100/μL 1
• Pyrimethamine plus clindamycin can be used for patients who cannot tolerate sulfadiazine 4
• Atovaquone with or without pyrimethamine may be considered in cases of intolerance to first-line agents 1, 4

Cat Scratch Disease Treatment

First-Line Treatment

• Azithromycin has been shown to speed recovery in cat scratch disease 5
• Most cases of cat scratch disease are self-limited and do not require antibiotic treatment 5

Special Considerations for Cat Scratch Disease

• More disseminated forms with hepatosplenomegaly, meningoencephalitis, or bacillary angiomatosis (especially in immunocompromised patients) require more aggressive treatment 5

Prevention Strategies

Toxoplasmosis Prevention

• Pregnant women should avoid changing cat litter or wear gloves and wash hands thoroughly if unavoidable 1
• Cook all meat thoroughly until no longer pink (internal temperature of 165°F/73.8°C) 1
• Keep cats indoors and feed only commercial cat food or well-cooked food 1
• Wear gloves when gardening or handling soil 1

Cat Scratch Disease Prevention

• Avoid rough play with cats that could lead to scratches or bites
• Promptly clean any scratches or bites with soap and water
• Control fleas on pets, as they are responsible for horizontal transmission of Bartonella henselae 5

Monitoring and Follow-up

For Toxoplasmosis

• Clinical evaluation and neurologic assessment regularly during treatment
• Ophthalmologic examination to monitor for chorioretinitis
• Serologic testing every 3-4 months during the first year, then every 6 months in the second year, and yearly thereafter 2

For Cat Scratch Disease

• Most cases resolve spontaneously within 2-4 months
• Monitor for resolution of lymphadenopathy
• Watch for rare complications such as neuroretinitis or encephalopathy

Treatment Pitfalls to Avoid

• Do not substitute folic acid for folinic acid (leucovorin) when administering pyrimethamine, as this will not prevent hematologic toxicity 3
• Do not delay treatment in congenital toxoplasmosis, as earlier treatment is associated with better outcomes 6
• Do not overlook potential drug interactions with pyrimethamine, particularly other antifolic drugs which may increase bone marrow suppression 3
• Do not discontinue monitoring after treatment completion, as reactivation can occur, particularly in immunocompromised patients 1