Parasitic infections

• Often have migrating larvae

• can cause extensive tissue damage

• many are zoonotic and vector-borne

A. Nematodes (roundworms)

1. Pinworm (Enterobius vermicularis): children

2. Ascaris lumbricoides: ingestion, larva migrans, intestinal life; 1.3 billion cases/60,000 deaths

3. Toxocara: visceral (dogs) and neural (cats) larva migrans

4. Baylisascaris (raccoons): neural larva migrans

5. Trichiuris (whipworm): intestinal; 900,000 cases per year

6. Hookworms: skin penetration, larva migrans, intestinal life

   • > 1 billion infections/year

7. Strongyloides: skin penetration, larva migrans, intestinal life

8. Trichinella: pigs; migrating larvae; USA

9. Wuchereria bancrofti: mosquito vector; microfilariae, elephantiasis

10. Loa loa: eye infections; mango fly vector

11. Dracunculus: skin

12. Onchocerca: blackfly vector; 270,000 cases of blindness

B. Trematodes (flukes)

All flukes have a complex life cycle with snails as  an intermediate host

1. Intestinal flukes (Fasciolopsis buksi): zoonotic (pigs, dogs, rabbits); Asia;

2. Liver flukes: ingestion of contaminated plants or fish

   • Fasciola hepatica: zoonotic (sheep/cattle)

   • Clonorchis sinensis: zoonotic (fish)

3. Lung flukes: Paragonimus westermani; ingestion of contaminated crustaceans (zoonotic)

4. Blood flukes (Schistosomiasis): larvae penetrate skin; 200,000,000 infections/year, up to 1 million deaths

C. Cestodes (tapeworms)

1. Taenia solium (pig)

2. Taenia saginata (beef)

3. Diphyllobothrium (fish/snail)