Ascarids And Other Nematodes

Question 1

Ascarids

Answer 1

Large white opaque
Lumen of small intestine
Adult feed on intestinal digesta
Direct
Migratory
Dis due to presence of adults and migration of larvae
Strong host acquired and age related imm
Zoonotic

Question 2

Ascaroid lifecycle

Answer 2

Adult f b prplific
Eggs are thick shelled and unembryonated when passed
Dev to L2 in enviro
Host ingests egg cont L2
L2 released pass to intestine and penetrate mucosa
Migrate to liver then alveoli via portal circ
Moult to L3 in lungs
Enter bronchi and trachea
Swallowed
2 more moults
Adukts in lumen of s intest

Question 3

Toxocara canis

Answer 3

Ill throft and poor growth in puppies
Parasitic pneumonia
Pot belly
Sometimes occlusion and perforation of small intestine

Question 4

T canis ingestion pathway

Answer 4

Notmal ascaroid lifecycle

Question 5

T canis prenatal infrvt via placenta pathway

Answer 5

In older dogs hepatic tracheal migration less common instead L2 travel to many tissues and organs
If preg migrate to lungs of foetus 3 wk preparturition
L2 moult to L3 just before birth
Lifecycle completes in newborn pups
Some L2 complete in preg bitch giving incr of fec and source of infect for puppies

Question 6

T canis lactogenic infection pathway

Answer 6

Sucking puppies may be infect by ingest L3 in milk during first 3 wk of lact
No migration in pup following infection of this route

Question 7

T canis infection by paratenic hist

Answer 7

Rodents and burds may ingest eggs
L2 travel to tissues or paratenic hist
Remain dormant
Predated by a dog and L2 complete dev only in host intestinal tract

Question 8

T canis clin and epidem

Answer 8

Most dont cause clin dis
Heavy infect may cause resp dis or enteritis and gut occlusion
Infection conmon
Thick walled eggs are highly res and can survive for yrs
Dormant L2 in bitches are constant infection reservoir
Not killed by most anthelmithics

Question 9

T canis management

Answer 9

Red enviro contam
Clean accomodation
Pick up faeces
Strategic anthelmintic use on sucking pups dam newly purchased pups routine dog administration

Question 10

T canis bisceral larval migrans

Answer 10

Rare
Children
Contam dog faeces
Control by ascarid control in dogs
Most ltd to liver other organs involved in some cases rg can cause visual impairment

Question 11

T cati

Answer 11

Cause of pot belly kittens diarrhoea dull coat failure to throve
Similar to t canis
Occur in mixed infect with toxacaris leonina
No pre natal infection

Question 12

Toxacaris leonina

Answer 12

Similar to t canis
Infect by L2 ingest
Subseq dev in wall and lumen of s intestine
No migration

Question 13

Parascaris equorum

Answer 13

Ill thrift in young horses
V large!
Basic migratory lifecycle
Resp and hepatic dis caused by L2 migration
Ill thrift as compete for nutrients
Occassional obstruction or perforation of intest

Question 14

Ascaris suum

Answer 14

Pigs
Basic ascaroid lifecycle
Invert paratenic hosts
Moult L2-3 in livet
Partial age imm in older pigs
Migratory L2 can cause resp dis
Inflam reaction to migration in liver of prev sensitised pigs cause fibrosis
Ill thrift due to competition
Can cause intest obstruct
Rarely migrate to bile duct causing blockage
Infection reported in cattle grazed on land used to keep pigs, reported in sheep and lambs

Question 15

T vitulorum

Answer 15

Key dis of cmtropical cattle and buffalo calves
Temp alter rate of L2 dev
IDed in UK
Transmammary infect most important
No kigration in calves after transmamm trans
Can cause ill thrift

Question 16

Poultry ascarids

Ascaridia spp

Answer 16

Non migratory
Earthworm transport hist
Enteritis in prepatent phase when larvae in intest mucosa
Not highly pathigenic

Question 17

Poultry ascarids heterakis spp

Answer 17

Migratory
Earthworms
Rel nonpathogenic
H gallinarum is vector of protozoa causing blackhead in turkeys: flagellate monoexenous EC protozoa released forom L2 when egg hatches and enter caecal mucosa

Question 18

Fish ascarids

Answer 18

Def: marine manmal cetacean fish eating bird
Paratenic: fish crustacean mollusc
Zoonotic by sushi ingestion raw undercooked fish

Question 19

Oxyuris equi

Pin worms

Answer 19

Perianal pruritus
Adult in lumen and colon
F migrate to anus and protrude posterior and deposit clumps of eggs on the perianal skin
L3 dev in egg
Infection by ingestion of eggs cont L3
L3 released into intestine and move to large intestine to dev into L4 and adults
Cam cause erosion and inflam in l intest mucosa
Adult f cause irritation during egg laying
Control by washing sticky eggs off use broad spec anthelmintics

Question 20

Trichinella spiralis

Answer 20

Pigs
Wide hist range
Zoonotic
Indirect
Dev adults in villi of s intest
After repro m die and f burrow into intest muc and prod L1
L1 enter lymphatics and travel to skel m where penetrate m and are encapsulated
Paralysed m is now nurse cell and L1 survive for life of host and dev resumed when m cont L1 ingested
L1 freed in stonach moult and mature
Mass infection only in predators eg man

Question 21

Angiostrongylus vasorum

Answer 21

Right ventric and pulmon art of dogs and foxes
Adults in pul vessels lay eggs cont L1
Eggs carried to capillaries to hatch
L1 break into alveoli migrate to trachea then swallowed into alimentary tract and shed
Penetrate mollusc foot and dev ti L3
L3 freed by mollusc digestion hy dog
Moult to adults in intestinal lymph nodes
Effects due to adults in blood vessels and eggs and larvae in pul arterioles and capillaries

Question 22

Dirifilaria immitis

Answer 22

CV syst of dog
Mosquito intermediate
Key prob in warmer country
Only seen in imported dogs in Uk
Adult in heart and adjacent blood vessels
Microfilariae released directly into blood stream ingested by f mosquitoes
Dev into L3
L3 move to mouthparts and spread to new host
Migrate to subcutaneous or subserosal tissue and moult twice
After final moult adults pass to heart via venous circ
Min ppp 6mnth