Three types of Helminths

• Nematode - roundworm
• Cestode - tapeworm
• Trematode - flatworm

33% of the world's population has helminth infection

Ascariasis

Helminth

H: Ascaris lumbricoides (nematode)

• Eating fecally-contaminated food or soil (STH: soil transmitted helminth, geohelminth)
• Intestinal
• 1 billion people infected worldwide

Trichuriasis

Helminth

H: Trichuris trichiura (Nematode: whipworm)

• Eating fecally-contaminated food or soil (STH: soil transmitted helminth)
• Intestinal
• 795 million people infected worldwide

Hookworm

Helminth

H: Necator americanus, Ancyclostoma duodenale (Nematode: hookworm)

• Intestinal but enters through bare feet (STH)
• Compromises health and nutrition (bleeding -> iron loss); impairs child growth
• Tropical and subtropical: ~740 million infected
• STHs usually treated with a single dose of albendazole

Clonorchiasis

Helminth

H: Clonorchis sinensis (Trematode: flatworm, platyhelminth / liver fluke)

• Undercooked or raw freshwater fish
• Asia, especially China

Cysticercosis

Helminth

H: Cysticerca spp. (Cestode: tapeworm)

• Undercooked pork
• Worms embed in muscles, brain, eyes, and elsewhere

Echinococcosis

Helminth

H: Echinococcus spp. (Nematode: roundworm)

• Hydatid cyst disease
• Mostly a zoonosis, dogs, sheep, and goats
• Humans are accidental hosts, cysts in liver and lungs

Enterobiasis

Helminth

Paragonimiasis

Helminth

H: Paragonimus westermani (Trematode: flatworm, platyhelminth/lung fluke)

• Undercooked or raw freshwater crabs or crawfish
• Asia, esp China, Middle East, S. America, also Carribean

Strongyloidiasis

Helminth

H: Strongyloides stercoralis (Nematode: threadworm)

• Enters body through the skin
• Tropical and temperate areas

Taeniasis

Helminth

H: Taenia solium, T. saginata (Cestode: tapeworm)

• Undercooked pork, beef, or other meat
• Worldwide

Trichinosis/Trichinellosis

Helminth

H: Trichinella spiralis (Nematode)

• Undercooked pork, beef, or other meat
• Infects body tissue
• Worldwide

Ringworm

Helminth

F: Tinea spp.

• Not a worm infection
• The same types of fungi cause several dermatomycoses (fungal skin infections)
• Diaper rash, thrush, and vaginal yeast infections are caused by a different fungus, Candida albicans