How are nematodes typically transmitted?
Typically direct lifecycle
vertebrate gut->pooped out (goes through several larvae stages-> ingested by vertebrate
What allows the nematodes to have good mobility?
Hydrostatic skeleton due to cuticle
What are geohelminths?
parasites known as soil-transmitted helminths that infect humans through contaminated soil, typically from eggs or larvae passed in feces
What is the unholy trinity?
whipworm (Trichuris), giant intestinal worm (Ascaris), hookworm (Ancylostoma duodenale and
Necator americanus)
Ascaris lumbricoides
Giant intestinal worm
egg ingested->small intestine->liver->heart->lung->migrates up trachea and are swallowed->live in small intestine->pass in feces
Trichuris trichiura
Whipworm
occupies a portion of the large intestine
tissue parasite
Whip portion is in tissue
direct lifecycle
Ancylostoma duodenale
Necator americanus
hookworms (only in humans)
enter host through hair shaft through skin
enters blood->migrates up trachea and is swallowed
Eat tissue and sucks blood
Larvae “quest” on grass
Prevents blood from clotting through 2 methods
passed through feces
Anasakis
Marine mammal round worms that infect cetaceans
eggs->krill->cephalopods->fish->cetaceans
Cannot survive humans
Increasing over time
Pseudoterranove
Marine mammal round worms that infect pinniped
Eggs->copepods-2nd->3rd->mammal
Cannot survive humans
Trichinella spiralis
Trichinellosis disease
Infect almost all mammals usually humans get it from pigs
infected muscle tissue->small intestine->eggs go into bloodstream->imbeds in muscle tissue
Wuchereia bancrofti
Lymphatic Filariasis
Elephant limbs
Mosquito deposit larave on skin->larvae enter skin->adults mature in lymphatic->microfilariae enter blood stream->mosquito take blood and get microfilariae.
In the lymphatics they block inflammation. When the worms die, there is a large amount of inflammation causing enlargement of limbs
dracunculus metinensis
Dracunculosis
Guinea worm disease
Copepod intermediate host
larvae freed in small intestine
adult live in subcutaneous tissues
create blisters which pop in freshwater
Very common in Africa and stepwells
Onchocerca volvulus
Onchocercaiasis
River blindness
Blackfly deposit larvae on skin
Microfilariae migrate through subcutaneous tissue
immunological response occur to microfilariae dying
blackfly eat larvae with blood meal
Nodules of adults seen through skin
Loa Loa
Loiasis
Deer fly larvae transmits worm
Adult stays in sub cutaneous tissues
eats host material and creates microfilaria
swelling occurs behind worms due to secretions
trichostrongylus
humans infected through feces
live in the small intestine, usually asymptomatic
Infect the grouse and show sexual selections
Heligmosomoides polygyrus
Intestinal round worm of rodents
example of how rodents compensate for pathology
mice have larger litter size to maximize fitness before infection gets worse
Hererodera glycines
Parasite of soybean plants
