Eukaryotic Parasites: Helminthes

Helminths

multicellular eukaryotes with established organ systems

Parasitic Helminth

Often with reduced organ functions and complex reproductive system.

Cycle A

Worm develops in the intestines
Eggs are released with feces and into the environment
Eggs are ingested by new host

Cycle B

Larva enters through tissues and migrates
Matures in intestines and eggs are released with feces
Eggs hatch and develop in environment

Cycle C

Adult matures in human intestines
eggs are released in the environment and are eaten by grazing animals
Larval forms encyst in tissue and infected flesh is consumed

Cycle D

Eggs are released from humans
Humans Humans are infected by ingestion or direct penetration

3 types of helminths

Platyhelminthes - flat worm
nematode - round worm
Annelid - segmented worm

Ascaris Lumbricoides

intestinal nematodes
ROE: fecal oral
consumed contaminated food
Egg hatches in intestines and penetrates the mucosal layer
Goes through blood vessel into lungs and coughed out
Consumed again & reproduces

Hookworms

Intestinal Nematodes
ROE: Direct penetration
goes into lymphnode and causes iron deficient anemia and protein deficiency

Necator americanus

new world hookworm

Anclystoma deudenale

old world hookworm

Trichinella sp.

intestinal nematode
ROE: fecal-oral
human is dead end host and larve are encysted in animal muscle

Wuchereria bancrofti

causes lymphatic filariasis
ROE: mosquito bites
get into lymph nodes and reproduce which swells the nodes.

Taenia sp.

platyhelminthes and uses life cycle c
ROE: Fecal-oral

T. saginata

beef tapeworm that is largest and is stuck in the intestine

T. solium

pork tapeworm that can migrate to the eye and brain