Intro to Nematodes (micro) Flashcards
LO
- Nematodes
– Know the key characteristics
– Be able to determine if a life cycle is direct or
indirect
– Be able to identify the types of hosts in a life cycle – Be able to identify methods nematodes use to
ensure the survival of their species - Ancylostoma caninum
– Know the primary clinical signs
– Know the primary modes of infection
– Be able to relate morphology & behaviour to
pathology and clinical signs
PARASITES OF VET IMPORTANCE
- Phylum Nematoda (Roundworms)
- Phylum Platyhelminthes (Flatworms) – Class Cestoda (Tapeworms)
– Class Trematoda (Flukes) - Helminth=worm
- Liveextracellularly:inthegastro-intestinal tract and organs
note: roundworms can refer to all nematodes or it can refer to specific group of nematodes (we as vets have to know scientific names)
platyhelminths: also a word that can lead to confusion
- Helminth=worm
- Liveextracellularly:in the gastro-intestinal tract and organs
HELMINTHS
- Sexual reproduction
– Nematodes: Males and females
– Cestodes & trematodes: ?
– ?-laying (oviparous); some lay live ? (?)
(protozoa can divide within the host (smtms even 1000s); for nematodes they have to leave the host and then come back)
- Do not multiply within the ?
– Offspring must ? host
– Some cestode larval stages an exception - Increased infection results from increased ? exposure
- Helminth=worm
- Liveextracellularly:in the gastro-intestinal tract and organs
HELMINTHS
- Sexual reproduction
– Nematodes: Males and females
– Cestodes & trematodes: hermaphroditic
– egg-laying (oviparous); some lay live young (viviparous)
(protozoa can divide within the host (smtms even 1000s); for nematodes they have to leave the host and then come back)
- Do not multiply within the host
– Offspring must leave host
– Some cestode larval stages an exception - Increased infection results from increased environmental exposure
NEMATODES (roundworms)
?-living or ?
– Soil and plant nematodes
– ? nematodes
Elongate/?
? canal present
Sexes usually ?
– ?-laying (oviparous); some lay live ? (viviparous)
– Do not multiply within the ?
– Offspring must ? host
Increased infection results from increased ? exposure
Life cycle ? or ?
NEMATODES (roundworms)
free-living or parasitic
– Soil and plant nematodes
– animal nematodes
Elongate/cylindrical (think of meatball pasta)
alimentary canal present
Sexes usually separate
– egg-laying (oviparous); some lay live young (viviparous)
– Do not multiply within the host
– Offspring must leave host
Increased infection results from increased environmental exposure
Life cycle indirect or direct
Helminths
eggs passed in faeces
eggs embryonate in 5 days +
Then first stage larvae in faeces (L1) and second-stage larvae also in faeces
Third-stage (infective) larvae migrate onto grass in approximately 3 weeks
Ingested L3 develop through L4 and L5 to adult egg-laying worms
Helminths
eggs passed in faeces
eggs embryonate in 5 days +
Then first stage larvae in faeces (L1) and second-stage larvae also in faeces
Third-stage (infective) larvae migrate onto grass in approximately 3 weeks
(3rd stage is smaller (usually larger) as it retains the cuticle so it means it can’t eat anymore as its mouth doesn’t have access..)
Ingested L3 develop through L4 and L5 to adult egg-laying worms (cuticle helps it from desiccation )
Nematodes (roundworms)
Ancylostoma caninum
- hooks attach to host -> BLEEDS
- bc mouth hook is attached to it (hook sloppy tho) thus blood in stool occurs & also anemia as blood is being withdrawn from the host
Large Strongyles
- takes out plug of mucosa - again bleeding occurs - CLASSIC ? SIGN (anemia also occurs)
- large intestine mucosa destroyed then ? occurs as large intestine is involved in ?
** ? ? present **
Nematodes (roundworms)
Ancylostoma caninum
- hooks attach to host -> BLEEDS
- bc mouth hook is attached to it (hook sloppy tho) thus blood in stool occurs & also anemia as blood is being withdrawn from the host
Large Strongyles
- takes out plug of mucosa - again bleeding occurs - CLASSIC CLINICAL SIGN (anemia also occurs)
- large intestine mucosa destroyed then diarrhea occurs as large intestine is involved in absorption
** ALIMENTARY CANAL present **
NEMATODES (ROUNDWORMS)
Alimentary canal present
Sexes usually separate
- bursa (help in copulation (males use it to hold into females during sex))
2nd slide
- some females have vulva (females have finger-like appendages); smooth vulva then go into certain taxonomic groups and if rought then another taxonomic group; 30-40% are smooth and 60-70% are rough
Male nematodes
Nematodes (roundworms)
- Hookworm
Mammomonogamus spp. (in nematode females are usually larger than males)
- two-thirds to a quarter of size of females
- Males remain attached to females after copulation for the rest of their life; names tells us it is monogamous (same for others)
Spirocerca lupi larva in wall of thoracic aorta
(name tells us that worm is spiral in shape)
Nematodes (roundworms)
- Bursate (male) or not
- Vulva
- Mouth (shape, teeth)
- Esophagus
- Size (just like ppl they differ in shape; so big nematodes, small nematodes - big in relation to size of animals)
bigger than 2 inches is big however 2 inches could be small compared to other species
all of these characteristics aid in identification
LO
* Nematodes
– Key characteristics - alimentary canal, male and female; all are cylindrical (elongated) - (recall: think of meatball pasta - round and cylindrical/elongated)
– Life cycles – Hosts
– Means of species survival
- Ancylostoma caninum
NEMATODES - LIFE CYCLE
- E – (?) L1 - L2 - L3 - L4 - L5 - Adult
– Pre-L1 = ? (some nematodes) mff
– L5 = immature/short adult - Insert host(s)
– ? or definitive
– ?
– Vectors, ?, etc.
Insert mode of infection (per os, percutaneous, transmammary, ?)
E = egg, mff = microfilaria, L = larvae, L5 = short adult
NEMATODES - LIFE CYCLE
- E – (mff) L1 - L2 - L3 - L4 - L5 - Adult
– Pre-L1 = microfilaria (some nematodes) mff
– L5 = immature/short adult - Insert host(s)
– Final or definitive
– intermediate
– Vectors, paratenic, etc.
Insert mode of infection (per os, percutaneous, transmammary, transplacental)
E = egg, mff = microfilaria, L = larvae, L5 = short adult
Nematodes – life cycle
Life cycle
- Direct
– infective larva (usually which stage?)
– infective larva in an egg (usually NOT ?) - Indirect
– L1 infective to ? host (usually not L1 in DIRECT life cycle)
– L3 to the ? host
Nematodes – life cycle
Life cycle
- Direct
– infective larva (usually L3)
– infective larva in an egg (usually NOT L1) - Indirect
– L1 infective to intermediate host (usually not L1 in DIRECT life cycle)
– L3 to the final host
Nematodes life cycle
in feces
-> up until which stage is in the egg?
-> which stage? worm hatches from egg and migrates to ?
in the host: which stages?
(in dead cat: adult egg)
Nematodes life cycle
in feces
-> up until which stage is in the egg? L1 L2 L3 so until L3
-> which stage? L3 worm hatches from egg and migrates to grass
host: which stages? L3 -L4-L5 - Adult eggs
(in dead cat: adult egg)
OR
worms already in feces in L1
L3 moves to grass (think of tree grass - three grass)
-> Which stage? migrates to grass?
-> L3-L4-L5-Adult- eggs-L1 in egg-L1
OR
worms already in feces in L1
L3 moves to grass (think of tree grass - three grass)
-> L3 migrates to grass
-> L3-L4-L5-Adult- eggs-L1 in egg-L1
Nematodes. - life cycle
Insert means of survival
- how they ensure offspring get in a host
- Survival of ? with larva
- ? hosts
- ? (milk), transplacental
- ? rise
- Avoid ? system/crowding/“bad- weather”:
– Arrested development/Hypobiosis/Inhibited development
(notes: L3 is protected by cuticle; some eggs are viable for extended periods of time;
paratenic host can increase the chance of the host becoming infected
3rd stage larva migrates in dog usually in muscles and; once the puppy is born they can infect again)
periparturient: the time of parturition and those events within a few weeks prior to and following parturition.
Nematodes. - life cycle
Insert means of survival
- how they ensure offspring get in a host
- Survival of egg with larva
- paratenic hosts
- transmammary (milk), transplacental
- periparturient rise
- Avoid immune system/crowding/“bad- weather”:
– Arrested development/Hypobiosis/Inhibited development
Nematodes - life cycles
pic:
nematode life cycle in dog
- eggs passed in feces – (eggs embryonate) –> embryonated eggs in feces – > straight to dog or cat after it consumes it OR it can also go to rodent and then to dog/cat (note: can directly go to dog/cat without requiring a host so called direct life cycle, here rodent “can” and isn’t “required” in this life cycle)
- then it can get passed onto offspring so transplacental
- direct life cycle as rodent isn’t required as embryonated eggs can directly be transferred to dog or cat
- note: in rodents (paratenic or transport host) it remains L3 and doesn’t grow into L4
- the ones that can be transmitted through milk are common and parasitic
- which one is the infective stage? egg and transplacental (vertical) - puppy
- the diagnostic stage is the egg;
TO STOP THE LIFE CYCLE
1. remove the egg
2. sanitization
3. imp!! -> if u treat the mother at the right time (migrating
puppies with bot belies (distended) are usually this parasite
Nematodes - life cycles
- Adult worms in lungs produce eggs; larvae hatch from eggs
- Larvae move to the intestine via tracheal migration
- larvae passed in feces
- larvae ingested by intermediate hosts (snails and slugs) -> (note IH are REQUIRED!! thus an INDIRECT life cycle
- birds can eat the slug (not required so transport host / paratenic host here) and then go into the cat. (if only paratenic host then a direct life cycle)
GENERAL NEMATODE LIFE CYCLE
direct life cycle
- for a simple life cycle like this one the nematode doesn’t need a paratenic host so doesn’t need a hard shell egg as it goes directly to host.
(high adaptable parasite; now in southern parts of Canada and now has adapted to cooler parasites
but for these parasites)
- some can survive on pasture in winter
- some have to find another means of making the pasture infected - arrest and emerge in spring; periparturient rise
as more and more of lambs are consuming L3 they egg count goes up and up and so pasture becomes heaivily infected (peak of infection inside sheep here)
when do u rotate the pasture?
- sum during rise period often whole flock move whole flock into new pasture so increase in egg so all those eggs become larvae (they accumulate as they live for many months); so if u can break the egg in half (so u move halfway through lambing? season to decrease that exposure (lambing meaning?)
antibiotic resistance problem - if treating mothers
L3 when they hit abomassum; the secreting products tell it that u can’t become adult right now so those L3 go into abomassum and arrest fif grow more than that then will be killed.
l3 AND l4 - adults and then we start having eggs in the feces of cats so as eggs in calves - so looking at
put sheep on pasture early on and let them consume them and
keeping calf in barn another month or so
can’t do above 2 then try to move them to a cleaner grazer?
Ancyclostoma caninum
prepatent period: from the time of exposure to the time when worms reproduce
pre = before; patent = an established worm infection
q that can be asked for the exam:
which animals are involved in the life cycle?
can a paratenic host be involved?
whats the diagnostic stage?
alimentary canal: mouth part?
