- Approximately 2 billion people infected worldwide
- Many are WHO-designated Neglected Tropical Diseases
- At-risk populations include impoverished, children, immigrants, tourists, HIV/AIDS patients, refugees 
- Most common in subtropical and tropical areas, moist climates, poor sanitation and hygiene 
- No direct person-to-person transmission
- Fecal-oral transmission (ingestion of eggs in contaminated soil / vegetables / water)
- Ascaris and whipworm from human feces
- Toxocara from dog / cat feces
- Echinococcus from sheep / cattle feces
- Taenia eggs from human feces
- Cutaneous transmission
- Hookworm eggs hatch in the soil, mature larvae penetrate skin
- Lymphatic filariasis transmitted via bite from infected mosquito (Anopheles, Aedes, and Culex)
- Onchocerciasis transmitted via bite from blackflies (Simulium species)
- Food or waterborne transmission
- Taenia also transmitted by ingestion of larval cysts in undercooked pork or beef
- Diphyllobothrium tapeworm transmitted by contaminated freshwater fish
- Dracunculiasis transmitted by ingestion of infected Cyclops water fleas in contaminated water (adult worm erodes through skin of leg, releases larvae in water when host wades in pond / open well, infecting the water fleas)
- Parasitic infections can be in the differential diagnosis for nearly every sign/symptom (GI, dermatologic, neurologic, pulmonary, ophthalmologic, hematologic)
- Obtain a travel history in every patient
- countries of travel
- duration of stay
- activities while traveling (adventure travel, tourism, working, swimming)
- living arrangements – city / village / hotel / tent
- drinking water source
- symptom chronology
- Taenia saginata
- Taenia solium (Cysticercosis)
- Diphyllobothrium latum
- Hymenolepis nana
- Echinococcus granulosus
- Fasciola hepatica
- Fasciolopsis buski
- Opistorchis viverrini
- Schistosoma spp
- Chlonorchis sinensis
- Paragonimus spp.
- Ascaris lumbricoides
- Enterobius vermicularis (Pinworm)
- Filarial worms
- Dracunculus medinensis
- Strongyloides stercoralis
- Trichuris trichiura (Whipworm)
- Toxocara spp.
- Stool studies (ova and parasites)
- CBC to identify peripheral eosinophilia or anemia (not sensitive or specific)
- Peripheral blood smear to identify microfilariae (e.g. lymphatic filariasis)
- Pulmonary symptoms: CXR and sputum smear (e.g. Löffler’s syndrome)
- CNS symptoms
- Ultrasound or CT can localize cyst of echinococcus
- ELISA or biopsy of affected tissue to diagnosis toxocariasis, cysticercosis
- Identification of adult worm or microscopic larvae in cutaneous ulcer fluid can confirm dracunculiasis
- The 17 Neglected Tropical Diseases." World Health Organization. http://www.who.int/neglected_diseases/diseases/en/. Web. 11 Aug. 2014.
- "Parasites." Centers for Disease Control and Prevention. http://www.cdc.gov/parasites/. Web. 11 Aug. 2014.
- "Chapter 133 - Parasitic Infections." Rosen's Emergency Medicine: Concepts and Clinical Practice. Ed. John A. Marx, Robert S. Hockberger, and Ron M. Walls. Philadelphia, PA: Mosby Elsevier, 2014. 1768-784.
- Del Brutto OH, Rajshekhar V, White A, et al. “Proposed diagnostic criteria for neurocysticercosis.” Neurology, 2001; 57:177-183.
- Del Brutto OH. “Diagnostic criteria for neurocysticercosis, revisited.” Pathogens and Global Health, 2012; 106(5):299-304.