Common Parasites & First-Line Treatments

🦠 Common Parasites & First-Line Treatments

Disease	Causative Agent	Drug of Choice	Dose & Notes
Strongyloidiasis	Strongyloides stercoralis	Ivermectin	200 mcg/kg PO daily × 1–2 days; repeat in 2 wks if chronic
Enterobiasis (Pinworm)	Enterobius vermicularis	Albendazole	400 mg PO single dose; repeat in 2 wks
Ascariasis (Roundworm)	Ascaris lumbricoides	Albendazole or Mebendazole	400 mg PO single dose
Hookworm	Ancylostoma duodenale, Necator americanus	Albendazole	400 mg PO daily × 3 days
Trichuriasis (Whipworm)	Trichuris trichiura	Albendazole	400 mg PO daily × 3 days
Taeniasis (Tapeworm)	Taenia saginata, T. solium	Praziquantel	5–10 mg/kg PO single dose
Neurocysticercosis	T. solium (larvae)	Albendazole + Dexamethasone + Anticonvulsant	Albendazole 15 mg/kg/day × 28 days
Schistosomiasis	Schistosoma spp.	Praziquantel	40–60 mg/kg PO divided doses × 1 day
Opisthorchiasis/Clonorchiasis	Opisthorchis viverrini, Clonorchis sinensis	Praziquantel	25 mg/kg PO TID × 1 day
Fascioliasis	Fasciola hepatica	Triclabendazole	10 mg/kg PO; repeat in 12–24 hrs
Giardiasis	Giardia lamblia	Metronidazole or Tinidazole	Metronidazole 250 mg PO TID × 5–7 days; or Tinidazole 2 g single dose
Amebiasis (Intestinal)	Entamoeba histolytica	Metronidazole then Paromomycin	Metronidazole 500–750 mg TID × 7–10 days, then luminal agent
Malaria (P. vivax/ovale)	Plasmodium spp.	Chloroquine + Primaquine	Region-specific chloroquine + Primaquine 15 mg/day × 14 days (G6PD test first)
Malaria (P. falciparum)	P. falciparum	ACT (Artemisinin-based)	E.g., Artemether-lumefantrine BID × 3 days
Toxoplasmosis	Toxoplasma gondii	Pyrimethamine + Sulfadiazine + Leucovorin	For CNS/systemic infections

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💊 Common Antiparasitic Drugs Summary (Adult Doses)

Drug	Indications	Dose	Route	Duration
Albendazole	Nematodes (Ascaris, Hookworm, Strongyloides, Trichuris)	400 mg daily	PO	1–3 days
Mebendazole	Same as Albendazole	100 mg BID × 3 days or 500 mg single dose	PO	As indicated
Ivermectin	Strongyloides, Scabies	200 mcg/kg/day	PO	1–2 days (repeat PRN)
Praziquantel	Tapeworms, Schisto, Clonorchis	25–60 mg/kg/day	PO	1 day (divided doses)
Triclabendazole	Fasciola	10 mg/kg PO twice	PO	1 day
Metronidazole	Giardia, Amoeba, Trichomonas	500–750 mg TID	PO	5–10 days
Tinidazole	Giardia, Amoeba	2 g single dose	PO	Single
Paromomycin	Luminal amoebicide	25–35 mg/kg/day ÷ TID	PO	7 days
Pyrimethamine	Toxoplasmosis	200 mg loading, then 50–75 mg/day	PO	Weeks
Sulfadiazine	Toxoplasmosis	1–1.5 g q6h	PO	Weeks
Nitazoxanide	Cryptosporidium, Giardia	500 mg BID	PO	3 days
Chloroquine	P. vivax, P. ovale	600 mg base, then 300 mg base at 6, 24, 48 hrs	PO	3 days
Primaquine	Liver stage of vivax/ovale	15 mg base daily	PO	14 days (test for G6PD first)

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🔔 Critical Clinical Notes

• G6PD test required before Primaquine.

• Avoid Albendazole in the 1st trimester of pregnancy.

• Praziquantel tablets are usually 600 mg → calculate mg/kg!

• CNS Toxoplasmosis needs triple therapy: pyrimethamine + sulfadiazine + leucovorin.

• Neurocysticercosis requires anti-helminth + steroids + seizure prophylaxis.

• Chronic Strongyloidiasis → Ivermectin may require longer or repeated doses.