Chapter 12 Flashcards
Why are nematodes important
they are very abundant, probably more than arthropods, 1/4 of the world suffers from infection, parasitize humans, animals and plants, destroy 10% of all crops
What is the outer layer/skin of nematodes called, what is it make of is it stronger or weaker than platyhelminth outer layer
cuticle, collagen, much stronger
What happens if you put a platyhelminth in broth, and nematodes?
platyhelminth- changes size due to absorption
nematode-no absorption
What are the parts of nervous systems do nematodes have
nerve ring on small ganglia in pharynx
Are nematodes coelomates or pseudocoelomates
pseudocoelomates meaning it has no true body cavity/coelom
What kind of muscles do nematodes have, what neurotransmitter do they use for contraction
excitatory-acetylcholine-contraction
inhibitory- aminobutyric acid-release
sodium/potassium channels
What drugs are best against nematodes and why, what other creatures do they work against
ivermectim-blocks channels and causes tetani in nematodes and arthropods
What kind of sensory organs do nematodes have
amphids- chemosensory organs, on each side of the head, used to sense and release sex pheromones
phasmids-for touch and sensing light and dark, used for orientation
What kind of guts do nematodes have, name their parts
psuedocoelom
mouth, buccal cavity, pharynx, intestine, rectum, anus, males have cloaca
Explain what a cloaca is
a common urogenital opening, the rectum and the vas differens both open into this cavity
Describe the characteristics of nematode intestines
one cell thick, no muscle coating surrounding it, pseudocoelomate, food is moved by body movement
what kind of osmoregulatory abilities do nematodes have
free living forms are osmoconformers
parasitic form is more limited
excretory products stored in pseudocoelom and become isotonic with surroundings.
What does a pseudocoelomate lack that an acoelomate has
inner mesoderm-the parenchyma
How are free living nemotodes different from parasitic nematodes
free living-very small usually, no buccal cavity, no bursa
parasitic-can get up to 10m long, has a buccal cavity, might have a bursa
Explain what the buccal cavity does
attach to the villi of SI, some have teeth to rasp off mucosa
blood feeding nematodes have pharyngeal glands that produce anti-coagulants to help blood flow
Explain what the bursa is
preset in male strongyloide nematodes, is around the cloaca, wraps around female, increases efficiency of fertilization
What are the characteristics of nematode life cycles
They all have 4 larval stages and 4 molts egg Larvae 1- rhabdiform molt 1 larvae 2 molt 2 Larvae 3-filariform molt 3 Larvae 4 molt 4 adult
When is the best time to kill a nematode (what stages)
L1, L2 or L3 because you can stop the molting process by using growth regulators, very hard to kill adults
What marks the nematode’s adulthood
mating
What makes the larvae stages different
mouthparts and habitats change with each form
What makes the larvae stages different
mouthparts and habitats change with each form
What does molting mean for nematodes
shedding of the cuticle and secretion of a new one
How are nematode juveniles and adults different
juveniles are smaller and have no gonads
usually have a different diet
adults no longer molt
What is the important characteristic of the third larval stage of nematodes
often the resting or resistant stage before reaching adulthood
What kind of sexes are nematodes? what type of sperm do they have?
always separate sexes, Males are smaller and have copulatory spicules, ameboid sperm
At what life stage are nematodes usually infective?
L3 stage, non feeding resistant stage
How is nematode egg production different to digeneans
no asexual reproduction so females are egg factories- 20K to 200K eggs/day
What parasite causes pinworms, what is the household way to test for it
enterobius vermicularis, scotch tape test
What are the characteristics of order strongylida nematoes
really big, usually infect domestic animals/ sometimes humans
What parasite causes hookworms
Necator americanus and Ancylostoma duodenale
Where are hookworms found in the world? in what environments
worldwide, moist, warm climate
What clinical issues do hookworms cause
iron deficiency due to anemia, cardiac complications, gastrointestinal and nutritional issues, ground itch, respiratory complications if pulmonary migration occurs
What parasite causes ground itch, explain what causes it
hookworms, local skin infection during penetration of filariform L3
What hosts do heomonchus contortus infect
grass eating animals like cattle and sheep
How do people often get hookworms?
by being barefoot, eggs are in human feces
How are hookworms IDed in the lab
eggs in stool under microscope
What are the characteristics of order Ascaris lumbricoides
largest nematode to parasitize human intestines- up to 35cm long
Where in the human body are ascaris lumbricoides found
adult in lumen of SI
eggs in feces or swallowed
larvae in intestinal mucosa
larvae mature in lungs, alveolar walls, go up bronchial trees, to throat, swallowed again,
get to small intestine, become adult worms
What are the ideal environmental characteristics for ascaris lumbricoides eggs, how long does it take for eggs to embryonate
moist, warm, shaded soil, fertile eggs become infective after 18+ days
How long do ascaris lumbricoides adult worms live
1-2 years
What clinical symptoms does ascaris lumbricoides cause
stunted growth, abdominal pain, intestinal obstruction, pulmonary symptoms, worms might leave mouth (holy shit ew)
How are ascaris lumbricoides IDed in the lab
eggs in stool under microscope
What animals do Baylisacaris procyonis parasitize?
racoon roundworms, eggs can get eaten by mice, squirrels, beavers and humans
How does Baylisascaris procyonis cause pathology in animals/humans, what name do these hosts have
paratenic hosts (small mammals and birds) larvae penetrate gut and migrate to tissues where they encyst, infect visceral organs, CNS and or eyes causing ocular larval migrans, can be asymptomatic or lethal
Describe the life cycle of Trichinella spiralis / Trichina worm infection
transmitted when pigs/ other farm animals are fed meat scraps that are infected, can also be transmitted by rats, larva encyst in striated muscle of host and are released in SI
What parasite is also called a whipworm
Trichuris trichiura
Where in the human body are Trichuris trichiura
larvae in SI
adults in cecum
unembryonated eggs passed in feces
embryonated eggs ingested
What other name does Loa loa have
African eye worm
What vectors Loa loa
deer flies-day biters, Chrysops
Describe the life cycle of Loa loa in humans
Deer fly bites human introduces L3 onto skin
larvae in subcutaneous tissue,
adults produce diurnal microfilariae
Explain the how Loa loa migrate during the day and night
day-in peripheral blood
noncirculation phase-in lungs
Describe the Loa loa life cycle in its vector
deer fly
ingests microfilariae, looses sheath and migrate from midgut to hemocoel to throacic muscle
third stage larva migrate to probiscis to get into human skin during blood meal
What clinical symptoms does Loa loa cause
can be asymptomatic, might cause lymphatic dysfunction, elephantiasis
night cough and wheezing with fever
could cause ocular lesions that lead to blindness
How are Loa loa IDed in the lab
microfilaria are found in a blood smear
What vectors onchocerca volvulus
blackflies simulium
What disease does onchocera volvulus cause
onchocerciasis, riverblindness
Describe the Onchocerca life cycle in humans
L3 introduced to human skin by blackfly
larva develops in subcutaneous tissue into adult filariae, in nodules produces microfilariae
How long de Onchocerca live
adults-15 years
produce microfilariae-9 years
microfilariae-2 years
Where in the human body are Onchocerca usually found
skin. lymphatics of connective tissue
Describe the Onchocerca life cycle in its vestor
blackfly-ingests during blood meal
microfilariae go to midgut, develop into L1-L3
Migrate to proboscis to reach human skin
What pathology does onchocerca cause
loss of elasticity and pigment in skin
plugged up lymph vessels
blindness caused by migrating larva in cornea
What disease does wuchereria bancrofti cause
brancroftian filariasis, elephantiasis
What parasite causes filariasis/elephantiasis
Brugia malayi and Wuchereria bancrofti
What disease does Brugia malayi cause
brugian filarisis, elephantiasis
What vectors filariasis
culex, anopheles, aedes, mansonia and coquillettidia all mosquitoes
Describe the life cycle of filariasis in humans
mosquito introduces L3 onto human skin
adults in lymphatics
produce nocturnal microfilariae
migrate to lymph and blood chanels
What physical characteristic do filarial worms that help distinguish them
double uterus
Describe the life cycle of filariasis in its vector
mosquito ingests microfilariae from blood meal, goes to midgut
L1-L3 in thoracic muscles
L3 migrates through hemocoel to probiscis to reach human skin
What is the pathology of Filariasis
enlargement of lymph nodes, elephantiasis
Describe the Dirofilaria life cycle
adult worms in RV and Pulmonary artery of dogs
microfilariae circulate blood
larvae develop in mosquito
mosquito can transmit to dogs and humans
What vectors dirofilaria
mosquito Culex
How long does it take for Dirofilaria to develop
180 days in dogs
never mature in humans
What disease does dirofilaria immitis cause
canine heartworm
What symptoms does Dirofilaria cause in humans and dogs
humans-asymptomatic, lesions in lungs seen in radiological exams, nodules caused by dead or dying worms that can become necrotic or calcified
what disease does dracunculus medinensis cause
guinea worm, fiery serpent
How is Drancunculus medinensis transmitted to humans
by drinking water contaminated with L3 copepods
Explain the Drancunculus medinensis life cycle
human drinks contaminated water with copepods
larva released when copepods die
larva penetrate stomach and intestinal wall where they mature or reproduce
F migrate to skin and discharge larvae into water
copepod consumes larvae
What symptoms does Drancunculus medinensis cause
blisters on skin, lesions on feet or legs.
worm emerging from legion
