Hookworms + filarial nematodes Flashcards by Gethin Edwards

What is the name of hookworms in dogs + cats?

Uncinaria stenocephala

Ancylostoma spp.
* Ancylostoma caninum
* Ancylostoma tubaeforme

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What is the name of hookworms in people?

Ancylostoma duodenale
Necator americana

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What are features of Uncinaria stenocephala?

Dogs and foxes
Adult in small intestine
~1cm long
Typical hooked appearance
Large buccal capsule with 2 cutting
plates

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What are the features of Ancylostoma caninum?

Dogs and foxes
Imported dogs
Occasional transmission in UK
Adult in small intestine
~1cm long
Typical hooked appearance
Large buccal capsule with teeth

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What is the primary route of infection of Uncinaria stenocephala?

Ingestion of L3

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What is the pre patent period of Uncinaria stenocephala?

15 days

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How long are Uncinaria stenocephala eggs in the environment?

4-8 days

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How long are ancylostoma caninum eggs in the environment?

5-8 days

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What is the pre patent period of ancylostoma caninum?

15 days

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What hookworm can cause infection via percutaneous infection?

Ancylostoma caninum
-uncinaria stenocephala rarely result in infection this way

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How does percutaneous infection occur in ancylostoma?

*L3 migrate via lymphatic system & blood stream to lungs (L3+L4)
*Swallowed, small intestine L4-L5

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What can occur with Milk?

Ancylostoma L3 can be a reservoir of infection in bitch milk
*L3 remain dormant in subcutaneous tissues until pregnancy
*Swallowed = SI - L4-L5

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Which hookworm can penetrate the buccal mucosa + migrate via lymphatics+ blood to lungs

Ancylostoma caninum

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Which hookworm is highly pathogenic?

A. caninum

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What are the consequences of U. stenocephala?

Protein losing enteropathy, (anaemia)
Weight loss, lethargy
Diarrhoea
*Pedal dermatitis due to hypersensitivity following repeat exposure to L3

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What are the consequences of A. caninum?

Voracious blood suckers (0.1ml blood per worm per day)
Severe anaemia in puppies
Lassitude, under weight, poor condition
+/- diarrhoea

What dogs is A. caninum more common in?

<1y/o

How are hookworms diagnosed?

Diagnosis based on identification of typical strongyle eggs in faeces plus clinical signs
History of the dog: Imported dog/has the dog travelled

How are hookworms treated?

Benzimidazoles - fenbendazole
Macrocyclic lactones - moxidectin/ selamectin
Ivermectin is toxic in dogs – must not be prescribed

How can you reduce the risk of hookworm infection?

Dry conditions
Use concrete runs instead of earth/grass

What are examples of filarial nematodes?

*Dirofilaria spp. - Dog heartworm
*Onchocerca spp.
*Brugia spp.
*Wuchereria bancrofti (humans only)

What can be said of nematodes in the order Spirurida?

Generally large (2-50cm)
Eggs larvate in utero or L1 are born live
Use invertebrates as intermediate host
Adults may parasitize tissues other than GI tract

How is Dirofilaria immitis transmitted?

*Mosquitoes

Where is Dirofilaria immitis a problem?

*Temperate + tropical climates worldwide
*Iberian peninsula, France, Italy, Eastern Europe
*Imported dogs

How long does Dirofilaria development of L1-L3 take ina mosquito?

10-14days at 27*C

How long can the dirofilaria life cycle take?

up to 9months

How long are the L3, L5 (immature adult), and mature adult of dirofilaria?

L3 = 1.1-1.3mm L5 Immature = 2-4cm L5 Adult = F=30cm =M=20cm

What are the clinical signs of dirofilaria?

* Asymptomatic in the early stages of disease * Disease associated with adult worms * Mild persistent cough and dyspnea * Reluctance to exercise and fatigue after moderate activity * Decreased appetite and weight loss. * Right-sided congestive heart failure * ascites, abdominal swelling, anorexia, death.

How is dirofilaria diagnosed?

Knott test * detects microfilariae * ~30% of dogs and most cats are amicrofilaraemic Antigen test (serological assay) * detects adult ovarian antigens * does not detect male-only infections Knott test and antigen test * >7 months of age/7 months post-exposure * Radiography and echocardiography * Signs of cardiovascular dysfunction

What is prophylaxis for dirofilaria immitis?

* Macrocyclic lactones (selamectin, moxidectin, or milbemycin) * Once monthly for 60 days * Kill microfilariae, L3 and early L4 stages of heartworm * Typically lasts a month

How would you treat Dirofilaria immitis?

* Macrofilaricidal (adult worms) – only dogs * Doxycycline -endosymbiotic bacteria Wolbachia pipiens * Melarsomine (organoarsenical) -Only approved macrofilaricide * Exercise restriction 30-40 days after treatment -risk of pulmonary thromboembolism due to dead and dying adult worms

What is Dirofilaria repens?

*Subcutaneous / ocular skinworm

What sort of lesions does dirofilaria repens form?

* Non-inflammatory subcutaneous nodules * Ocular lesions associated with conjunctivitis

What is the eyeworm's proper name?

*Thelazia callipaeda

How is Thelazia callipaeda transmitted?

Fruit flies

How do you treat thelazia callipaeda?

Moxidectin

What does Onchocerca lupi cause?

Canine ocular onchocercosis

Where are the microfilariae + adult worms?

Microfilariae = skin Adult worms = nodules in episcleral tissues

What is the pre patent period of onchocerca lupi?

LONG - 18months +