Hookworms + filarial nematodes Flashcards
What is the name of hookworms in dogs + cats?
- Uncinaria stenocephala
Ancylostoma spp.
* Ancylostoma caninum
* Ancylostoma tubaeforme
What is the name of hookworms in people?
- Ancylostoma duodenale
- Necator americana
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
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
What is the primary route of infection of Uncinaria stenocephala?
Ingestion of L3
What is the pre patent period of Uncinaria stenocephala?
15 days
How long are Uncinaria stenocephala eggs in the environment?
4-8 days
How long are ancylostoma caninum eggs in the environment?
5-8 days
What is the pre patent period of ancylostoma caninum?
15 days
What hookworm can cause infection via percutaneous infection?
Ancylostoma caninum
-uncinaria stenocephala rarely result in infection this way
How does percutaneous infection occur in ancylostoma?
*L3 migrate via lymphatic system & blood stream to lungs (L3+L4)
*Swallowed, small intestine L4-L5
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
Which hookworm can penetrate the buccal mucosa + migrate via lymphatics+ blood to lungs
Ancylostoma caninum
Which hookworm is highly pathogenic?
A. caninum
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
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 +
