Parasites & Protozoa

GI (Giardia, Crypto, Entamoeba) + tissue (Toxo, Trypanosoma, Trichinella) + helminths.

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◆GI protozoa & parasites

•Giardia lamblia: hiker/camper + fatty foul diarrhea + bloating; stool ELISA antigen; tinidazole or metronidazole
•Cryptosporidium: HIV CD4<100 + chronic watery diarrhea; oocysts on acid-fast smear; nitazoxanide + ART
•Entamoeba histolytica: bloody diarrhea (amebic colitis) + flask-shaped ulcers; LIVER ABSCESS (anchovy paste); metronidazole + paromomycin
•Ascaris: most common helminth worldwide; pulmonary symptoms (Loeffler) → migratory eosinophilic infiltrates → GI; albendazole
•Enterobius (pinworm): perianal itching at night; Scotch tape test; albendazole or pyrantel pamoate (whole household)
•Strongyloides: chronic eosinophilia in immigrants; ivermectin; CAUTION pre-steroids — hyperinfection
•Schistosoma: freshwater swimming abroad; eggs in stool/urine (haematobium = bladder cancer); praziquantel
•Taenia (tapeworm) solium: pork → cysticercosis (CNS calcified cysts → seizures in Latin American immigrants); praziquantel + steroids
•Diphyllobothrium latum: fish → B12 deficiency (megaloblastic anemia); praziquantel

•Toxoplasma gondii: cat litter / undercooked meat. Congenital: chorioretinitis + hydrocephalus + intracranial calcifications. AIDS: multiple ring-enhancing basal ganglia. Pyrimethamine + sulfadiazine + leucovorin
•Trypanosoma cruzi (Chagas): kissing bug, S/Central America; acute Romaña sign; chronic megacolon/megaesophagus + cardiomyopathy; benznidazole
•T. brucei (African sleeping sickness): tsetse fly; encephalopathy; suramin/eflornithine
•Leishmania: sandfly. Cutaneous: ulcer that heals slowly. Visceral (kala-azar): hepatosplenomegaly + pancytopenia. Liposomal amphotericin
•Trichinella spiralis: undercooked pork/wild boar → periorbital edema + myositis + eosinophilia; albendazole
•Babesia: see Tick-borne notes
•Plasmodium: see Malaria

◆Giardia + IgA deficient = chronic infection
◆Liver abscess + anchovy paste = Entamoeba (not Echinococcus which is hydatid cyst)
◆Schistosoma haematobium → squamous cell bladder cancer in endemic areas
◆Diphyllobothrium → B12 deficiency
◆Strongyloides hyperinfection if given steroids — treat with ivermectin FIRST
◆Toxo seroconversion in pregnancy → spiramycin (1st trim) or pyrimethamine + sulfadiazine (later)

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