Parasitic Gut diseases II

Question 1

What is toxocara spp. ?

Answer 1

• Large white round worms, 7-18 cm in length
• Adults in small intestine
• Three main species:

Question 2

What are the three main species of toxocara?

Answer 2

Toxocara canis – dog
» Toxocara cati (or mystax) – cat
» Toxascaris leonina – fox

Question 3

What are the two definitions of a paratenic host?

Answer 3

1. Host in which no development of the parasite occurs
2. Hosts which are not neccesary for the parasites life cycle but can act as a reservoir of infection

Question 4

What are the differences between T.Cati and T.leonina

Answer 4

T.Cati is-
* has paratenic hosts (rodents, earthworms, birds etc.)
* Migratory if eggs ingested, non-migratory after TM infection or paratenic host ingestion
* Eggs hatch in the stomach then migrate via the liver, lungs, trachea and back to the stomach
* no prenatal infection

T.leonina
* has no migration of larvae
* following ingestion, larvae enter the intestinal wall and remain there for two weeks

Question 5

What are the clinical consequences of Toxicara?

Answer 5

All species
* Mild to moderate infections – no clinical signs
* May be potbelly, failure to thrive, vomiting,
diarrhoea, particularly in puppies & kittens
* Due to absorption of nutrients & damage to
the intestine lining
* Obstruction of intestinal lumen or
intussusception

T.canis -> causes larval discharge

Question 6

Where can toxicara eggs be found?

Answer 6

in the faeces

Question 7

What is the difference between the eggs of T.canis and T. leonina?

Answer 7

Small finger-like process on the tail of male T. canis but not Tx. leonina

Question 8

What is the epidemiology of toxicara?

Answer 8

Very widespread due to
* female worms being fecund (producing a lot of offspring)
* larvae in the tissue of bitches is not susceptible to antithelmintics
* The eggs are resistant to climatic extremes

Question 9

What is the epidemiology of T.cati?

Answer 9

• Reservoir – larvae in tissue of dam & in paratenic hosts
• Patent infections more common in young cats
• Prevalence 10-20% in adult cats – continued shedding through life of cat

Question 10

What is the epidemiology of Tx. leonina?

Answer 10

• Infection mainly through eggs, but can occur
  » through paratenic hosts

Question 11

What are the four clinical conditions found in humans with toxocara?

mainly in children

Answer 11

1) Visceral larval migrans
2) Ocular toxocariasis – visual impairment
3) Covert toxocariasis
4) Cerebral toxocariasis

Question 12

How long are hookworms and where can they be found?

Answer 12

Up to 20 mm long and the adults are found in the small intestine

Question 13

What are the hookworm species that can infect dogs and cats?

Answer 13

Uncinaria stenocephala (temperate regions)
A. braziliense (tropical & subtopical regions)

Question 14

What are the clinical consequences of hookworms?

Answer 14

• Diarrhoea, weight loss and anaemia, may be acute or chronic signs
• Ancylostoma caninum more serious
• Disease most common in younger animals

Question 15

What are the most common hookworm species in the UK?

Answer 15

Uncinaria stenocephala & A. tubaeforme

Question 16

What kind of animal is most affected by hookworms?

Answer 16

Young animals most affected, adults pass eggs in faeces

Question 17

What is the diagnosis for hookworms?

Answer 17

clinical signs, haematology, coproantigen tests, hookworm
eggs in faeces (in pups may be severe signs before eggs in faeces)

Question 18

What are hookworms in humans associated with?

Answer 18

Poor sanitation and hygeine

Question 19

What are the symptoms of hookworms in humans?

Answer 19

Anaemia, abdominal pain, wasting & stunting in children

Question 20

What canine and feline hookworm can infect humans?

Answer 20

A. braziliense

Question 21

What hookworm species are common in asia?

Answer 21

A. ceylanicum and A.
caninum

Question 22

What is the pathogenesis of dipylidium caninum?

Answer 22

• they are adult worms and non-pathogenic
• shed segments may cause anal discomfort and itching

Question 23

What is the diagnosis for dipylidium caninum?

Answer 23

presence of segment (proglottid) on coat around peritoneum,
can break open & see egg packets under a microscope

Question 25

How would you diagnose taenia in dogs and cats?

Answer 25

The infections are generally asymptomatic
Heavy infection is a sign of gut problems
The diagnosis is- presence of tapeworm segments in perianal
area or proglottids, or eggs in faece

Question 26

What kind of parasite is echinococcus?

Answer 26

a cestode parasite

Question 27

What are the two main species of echinococcus?

Answer 27

Echinococcus granulosus
and E. multilocularis

Question 28

What is the diagnosis of eccinococus in definitive hosts?

Answer 28

• Observe adult worms on necropsy
• • Copro-antigen ELISA
• Copro-PCR

Question 29

How can you control toxocara and hookworm?

Answer 29

• You cant eliminate infection only reduce the burden and prevent transmission to people
• de-worming of pets
• pick up dog faeces

Question 30

What are three ways you can control fleas and Dipylidium caninum

Answer 30

• Adulticide
• Environmental control
• cleaning the environment

Question 31

How can you control echinococcus?

Answer 31

• Regular treatment (praziquantel) in endemic areas
• Deworming frequency dependent on hunting/feeding
  habits
• Found at meat inspection in abattoirs - risk based
  assessment
• Prevention of access to offal/carcasses

Question 32

What is the typical toxicara lifecycle for a dog under 5 weeks?

Answer 32

• eggs are ingested in the environment
• larvae are released in the intestine
• eggs are then passed on in the faeces
• the PPP= 4-5 weeks

Question 33

What is the typical toxicara lifecyle for a dog over 5 weeks? (not pregnant)

Answer 33

• When the larvae are released into the intestine they can then migrate to other tissues (formation of tissue cysts)

Question 34

What is the typical toxicara lifecyle for a dog over 5 weeks? (pregnant)

Answer 34

Tissue cysts can be reactivated
* This means that puppies can become infected (milk -> puppy)