Tropical Medicine 13: Antiparasitic Primer
Antimalarials
| Agent | Prophylaxis | Treatment | Notes |
| Chloroquine | 500 mg weekly beginning 1 to 2 weeks prior to travel through 4 weeks after return; PEDS: weekly doses: 5 mg/kg base weekly up to 500 mg maximum. (Chloroquine dihydrochloride is not indicated for pediatric prophylactic use.) | 1000 mg, followed by 500 mg 6 hours later; then, 500 mg daily for 2 days to a total dose of 2500 mg; PEDS: 10 mg/kg base initially, then 5 mg/kg base at 6, 24, and 48 hours. (Chloroquine dihydrochloride pediatric treatment dose is 3.5 mg base every 6 hours to a total of 25 mg/kg). | The old standard for treatment and prophylaxis. Chloroquine is inexpensive, but resistance is widespread in Africa and Asia. |
| Mefloquine | 250
mg weekly beginning one week prior
to travel through 4 weeks after return; PEDS: weekly doses: < 1-year-old = 31mg, 1-to 4-years-old = 62 mg, 5-to 12-years-old = 125 mg |
1250 mg once; PEDS: 15 mg/kg once | Received negative press in the British tabloids a decade ago. Contraindicated in patients with psychoses or taking antiarrhythmics. |
| Malarone | 250/100
mg daily beginning 1 to 2 days prior to travel through 7 days
after return. PEDS
daily
doses: 11 to 20 kg = 62.5 mg/25 mg, 21 to 30 kg = 125 mg/50 mg, 31 to 40 kg = 187.5 mg/75 mg, >40 kg = adult dose. |
Note:
not for severe or complicated cases. 1000/400 mg
daily for 3 days. PEDS
daily dose
for 3 days: 5 to 8 kg = 125 mg/50 mg,
9 to 10 kg = 187.5 mg/75 mg, 11 to 20 kg = 250 mg/100 mg, 21 to 30 kg = 500 mg/200 mg, 31 to 40 kg = 750 mg/300 mg, > 40 kg = same as adult dose |
Less convenient than mefloquine, but good for psychiatric and cardiac patients (including those with arrhythmias, coronary artery disease, hypertension treated with certain other agents) |
| Doxycycline | 100 mg daily beginning 1 to 2 days prior to travel through 4 weeks after return | 100 mg PO twice daily for 7 days; PEDS: (>8 years 2 mg/kg twice daily for 7 days) | Alternative for resistant malaria; (PEDS) not for children; watch for photosensitivity |
| Fancidar | 2 tablets every 2 weeks beginning 1 week prior to travel through 4 to 6 weeks after return | 3 tablets once | Formerly used in resistant P falciparum; less commonly used now |
| Quinine | N/A | 650 mg every 8 hours for 3 to 7 days; used with other agents; PEDS: 10 mg/kg every 8 hours for 3 to 7 days up to adult dose | Used for resistant malaria; quinidine has similar actions and might be more readily available. |
| Primaquine | N/A | 30 mg daily for 2 weeks; alternately 45 mg weekly for 8 weeks if G6PD deficient; PEDS: 0.25 mg/kg base daily for 14 days or 0.75 mg/kg base weekly for 8 weeks. | Use after chloroquine to prevent relapse of P vivax and P ovale (kills the hypnozoites). |
In addition to these agents, artemisins are agents derived from Chinese herbs, which are useful for treatment of resistant malaria and are not available in the United States.
Anthelminthics
| Organisms | Dose | Notes | |
| Albendazole | Larval
migrans Neurocysticercosis Hydatid disease |
400 mg twice daly; 28 days on, 14 days off for 3 cycles for hydatid disease; PEDS (> 1 year) 15 mg/kg/day divided twice daily | Monitor LFTs every 2 weeks during therapy |
| Ivermectin | GI and tissue roundworms, including the filariae | 0.2 mg/kg once | One of the most important anthelmintic drugs |
| Mebendazole | GI
roundworms Some biliary flukes |
100 mg once for pinworm, for 3 to 5 days for other roundworms. 200 mg twice daily for capillariasis; PEDS: > 2-years-old, use adult dose; data for patients < 2-years-old is lacking | |
| Praziquantel | Schistosomiasis
Tapeworms Liver flukes |
20 mg/kg every 4 to 6 hours for 1 day for schistosomiasis; 25 mg/kg once for tapeworms and other flukes; PEDS (> 4 years) 20 mg/kg 2 to 3 times daily for 1 day | Like ivermectin, this agent has revolutionized treatment for parasites since its introduction. |
| Thiabendazole | GI
roundworms Larval migrans Trichinosis |
1.5 g every 12 hours for 2 days for GI worms, 25 mg/kg every 12 hours for 5 to 7 days tissue roundworms (maximum of 3 g/day); PEDS: 25 mg/kg every 12 hours for the durations above |
Many additional agents such as pyrantel, piperazine, diethylcarbamazepine (DEC), quinacrine, and others are available inexpensively overseas but not in the United States.
Antiprotozoan Agents
| Organisms | Dose | Notes | |
| Amphotericin B (liposomal) | Leishmania
Amoeba |
3 mg/kg/day IV on days 1 to 5, 14, 21; PEDS: same as adult, unless immunocompromised, then give 4 mg/kg/day on days 1 to 5, 10, 17, 24, 31, 38 | |
| Metronidazole | Amoeba
Balantidium Giardia Trichomona |
For amebiasis, 750 mg 3 times daily for 5 to 10 days. For trichomoniasis, 2000 mg once. (Alternately, 375 mg twice daily or 500 mg twice daily for 7 days, 1000 mg twice daily for 1 day.) For Giardia, 250 mg 3 times daily for 7 days. (Alternately, 2000 mg once.) PEDS: 35 to 50 mg/kg/day PO divided every 6 hours | Avoid alcohol due to disulfrim reaction |
| Nitrazoxanide | Cryptosporidium Giardia | 500 mg every 12 hours for 3 days; PEDS every 12 hours for 3 days: (1-to 3-years-old) 100 mg; (4-to 11-years-old) 200 mg; (> 11 years) same as adult. | |
| Paromomycin | Amoeba Cryptopsoridium Leishmania | For amoebae, 30 mg/kg/day divided 3 times daily for 5 to 10 days. For cryptosporidium, 1500 to 3000 mg/day divided 3 times daily (alternately, 1000 mg twice daily) for 12 weeks in combination with azithromycin 600 mg 4 times daily for 4 weeks. For leishmania, 20 mg/kg/day for 21 days. PEDS: cryptosporidium dose: 25 to 35 mg/kg/day PO divided 2 to 4 times per day; other indications, same as adult | |
| Pentamidine | Leishmania
African trypanosoma |
For leishmania, 5 mg/kg IM every other day for 5 to 25 weeks. PEDS: 4 mg/kg alternating days for 10 to 15 doses. For trypanosome, 4 mg/kg/day for 10 days. PEDS: 4 mg/kg/day IM or slow IV for 10 to 25 days. | |
| Pyrimethamine | Isospora Toxoplasmosis Malaria | For toxoplasmosis and isospora, 50 mg 4 times daily for 4 to 5 weeks (administered with folinic acid, and sulfadoxine for toxo). PEDS: Congenital toxoplasmosis: < 2 months of age = 1 mg/kg PO daily for 6 months; >2 months = 1 mg/kg PO twice daily for 3 days then 0.5 mg/kg PO twice daily for 4 weeks, maximum 100 mg/day for load, 25 mg/day for maintenance. For malaria prophylaxis, 25 mg weekly through 10 weeks after exposure. For malaria treatment, 50 mg 4 times daily for 2 days with sulfadiazine and quinine. PEDS: Malaria prohylaxis: 0.25 mg/kg PO weekly, maximum of 25 mg/dose. Malaria treatment: < 10 kg = 6.25 mg PO daily for 3 days; 10 to 20 kg = 12.5 mg daily for 3 days; 20 to 40 kg = 25 mg daily for 3 days. | For chloroquine-resistant areas only |
As with the other categories of agents, other drugs such as pentamidine, melarsoprol, eflornithine, suramin, nifurtimox, and benznidazole are not available in the United States. (Although, occasionally special use drugs may be obtained directly through CDC.)