Antiprotozoal Drugs

Introduction & scope

• Antiprotozoal (non-malarial) drugs — agents against pathogenic human protozoa other than Plasmodium — Entamoeba histolytica (amoebiasis), Giardia lamblia (giardiasis), Trichomonas vaginalis (trichomoniasis), Leishmania spp. (kala-azar), Trypanosoma spp. (sleeping sickness, Chagas) and Toxoplasma gondii.
• Why they matter — no effective vaccines exist, so chemotherapy is the only means to treat and to reduce transmission; many protozoa cause severe/opportunistic disease in the immunosuppressed (HIV/AIDS, transplant) — leishmaniasis, cryptosporidiosis and toxoplasmosis are recognised AIDS-associated infections.
• Indian burden — amoebiasis is endemic across most of India (~15% infected); India, with Bihar as the epicentre, carries a large share of the world's visceral leishmaniasis — Bihar alone ~50% of global VL — driving distinctive Indian treatment policy.
• Central problem — many antiprotozoals are toxic at therapeutic doses and drug resistance is rising (antimony-resistant kala-azar, metronidazole-resistant Trichomonas, melarsoprol resistance).