SA Hookworms and Filarial Nematodes Flashcards Preview

PARA > SA Hookworms and Filarial Nematodes > Flashcards

Flashcards in SA Hookworms and Filarial Nematodes Deck (29):

Name two species of hookworm in dogs.

Uncernaria stenocephala, Ancylostoma caninum


Name two species of human hookworm.

A. duodenale, A. americana


Bunostomum is a hookworm of which species?

Sheep and cattle in the tropics


Describe the morphology of Uncinaria stenocephala.

  • 1 cm long
  • Hooked appearance 
  • Large buccal cavity
  • Two cutting plates

A image thumb

Foxes are an example of what type of host of Uncinaria stenocephala?

Where in the canine body would U. stenocephala?

Reservoir host

Small intestine where they feed on blood and mucosa


Outline the methods of infection of U. stenocephala.

  1. Ingestion of L3
  2. Percutaneous infection


What is the PPP of U. stenocephala?

15 days


True or False.

U. Stenocephala are capable of migrating.

True, they migrate to distant tissue such as fat or skeletal muscle.


What clinical signs are associated with Uncinaria Stenocephala?

  • Not highly pathogenic
  • Anaemia
  • Wt loss
  • Diarrhoea
  • Pedal dermatitis with repeat percutaneous infection


How can Uncinaria stenocephala infection be treated and controlled?

  • Anthelmintics - BZ, PYR, MOX
  • Dry conditions
  • Concrete rather than earth runs


Which countries can Ancytostoma caninum be found in?




Ocassionally UK


Outline the migratory routes of Ancylostoma caninum when dogs are infected:

  1. Percutaneously
  2. Ingested

  1. Percutaneously - L3 reach the blood stream and travel to the lungs where they are coughed up and swallowed
  2. Ingestion - penetrate the buccal mucosa and migrate to the lungs
    1. Migrate to the mammary glands when bitch is lactating (TMT)


How much blood is Ancylostoma caninum capable of consuming per day?

0.1mls blood per day per worm


Outline the clinical signs associated with Anocylostoma caninum.

  • Severe acute anaemia which may occur in the prepatent period
  • Chronic anaemia that results in depletion of iron reserves, especially in older puppies.
  • Poor growth and body condition.
  • Dermatitis
  • Lethargic
  • May have bloody/ mucous diarrhoea


Outline the key features of the order Spirurida.

  • Generally large (2-50cm)
  • Eggs larvate in utero or L1 are born live
  • Invertebrates are intermediate hosts
  • Adults parasitize GI tract and other tissues


Name the main filarial nematode species.

  • Dirofilaria
  • Onchocerca
  • Brugia
  • Wuchereria Bancrofti



Dirofilaria immitis


In which areas of the world is D. immitis considered endemic?

  • Iberian Peninsula
  • France
  • Italy
  • Eastern Europe
  • (3 cases have been reported in the UK)


Name the vector which transmits Dirofilaria immitis.

  • Mosquito
    • Culicine
    • Anophenline


Outline the lifecycle of Dirofilaria immitis.

  1. Adult worms in pulmonary arteries or right ventricle of the heart
  2. Microfilariae (L1) in the blood after 6-9 months
  3. Dog is bitten by mosquito which ingests L1
  4. L1 moult to L3 
  5. Infective L3 innoculate the dog when it is bitten by the mosquito
  6. 3-4 days: Moults to L4 migrates to abdomen
  7. 2 months: Moults to L5 penetrates jugular

A image thumb

How big would juvenile Dirofilaria immitis be compared to adult females and males?

  1. Juvenile - 2-4cm
  2. Adults
    1. Female - 30cm
    2. Male - 20cm


Where in the body are adults Dirofilaria immitis found?

Pulmonary arteries

Right ventricles in heavy infections


Which other species have Dirofilaria immitis been found in?

What clinical signs/ changes to the lifecycle are identified in these species?

  1. Humans
    1. Usually asymptomatic
    2. Pneumonitis - coin lesions on chest radiogram (granuloma around dead/dying worm)
    3. Usually never microfilaraemic
  2. Cats and ferrets
    1. Low worm burdens (1-3 adults)
    2. Adult worms are stunted
    3. Amicrofilaraemic/ transient microfilaraemia


Describe the clinical signs associated with Dirofilaria immitis in dogs and cats.


  1. Chronic exercise intolerence
  2. Chronic cough, dyspnoea, lipothymia
  3. Right sided CHF - ascities, anorexia, death (respiratory distress and cachexia)
  4. Acute caval syndrome - IV haemolysis and haemoglobinuria


  1. GI/ neuro signs alongside pulmonary signs
  2. Sudden death more common than in dogs


Describe the modified Knott test. What is it used for?

Haemolysis, centrifugation and staining with methylene blue before direct examination and identification of microfilariae

Used for diagnosis of Dirofilaria immitis


How is Dirofilaria immitis dignosed?

  • Knott test
  • Immunoassays for adult worm ag/ab
  • Radiography 
  • Echocardiography


Where would you find adult Dirofilaria repens?

Subcutaneous nodular swellings


How can D. immitis and D.repens be differentiated?

Repens - larger 


Staining with acid phosphatase


How can Dirofilaria infection be prevented and treated?

  1. Prophylaxis - MLs monthly prevents larval development but x adulticidal
    1. Usually given year round
    2. IVM given at low doses (selamectin/ milbemycin also)
  2. Treatment
    1. Melarsomine (only approved)
    2. Restricted exercise for 30-40days
    3. ​Doxycycline (long dose) and IVM - macrofilaricidal treatment
    4. Risk of thromboembolism