PH8.7 | PH8.7 | Protozoal and Vector-Borne Disease Pharmacotherapy — SDL Guide — Summary & Reflection

KEY TAKEAWAYS

Amoebiasis: Tissue amoebicide (metronidazole 750mg TDS × 7–10 days OR tinidazole 2g/day × 3–5 days) for invasive disease → luminal amoebicide (diloxanide furoate 500mg TDS × 10 days) to clear cysts. Metronidazole alone leaves cyst-passers. Metronidazole-alcohol disulfiram reaction — strict warning.

Kala-azar: L-AmB 10mg/kg single IV dose (India first-line, RES-targeted delivery); miltefosine oral 28 days (teratogenic — contraindicated in pregnancy, contraception required 3 months post-treatment); sodium stibogluconate — high resistance in Bihar, not used. Combination L-AmB + miltefosine for HIV-VL and resistance prevention.

Malaria: P. falciparum uncomplicated → ACT (artemether-lumefantrine); severe → IV artesunate. P. vivax → chloroquine (blood stage) + primaquine (radical cure, hypnozoites — G6PD screen mandatory). Chloroquine: FP polymerisation inhibitor; resistance via PfCRT. Primaquine: G6PD deficiency → weekly low-dose schedule. Second trimester: ACT for P. falciparum; chloroquine for P. vivax; no primaquine in pregnancy.

Filariasis: DEC (microfilaricidal); ivermectin (glutamate-Cl channel, microfilaricidal); albendazole (β-tubulin, synergistic MDA partner); doxycycline × 4–6 weeks (Wolbachia depletion → macrofilaricidal). MDA: DEC+albendazole (standard); ivermectin+albendazole (onchocerciasis co-endemic); triple-drug MDA (ivermectin+DEC+albendazole) for faster transmission interruption. DEC contraindicated in onchocerciasis (severe ocular Mazzotti) and Loa loa (encephalopathy).

REFLECT

You are posted at a primary health centre in a malaria-endemic tribal district. You see 20 patients per day; most are malnourished workers and children. A 35-year-old tribal woman with P. vivax presents — her third relapse in 2 years. She has never received primaquine. You don't have a G6PD testing kit. What do you do? How does this clinical scenario illustrate the gap between pharmacological knowledge (primaquine is essential for radical cure) and health systems reality (G6PD testing unavailable)? What systemic change would you advocate for — and what can you do immediately for this patient?