Hookworms and filarial Nematodes Flashcards
What hookworms are found in dogs and cats?
Uticaria stenocephala
Ancylostoma spp-
Ancylostoma caninum
Ancylostoma tubaeforme
What hookworms are found specifically in dogs?
Uncicaria stenocephala
Anclylostoma caninum
What hookworm is this?
Where is it found?
Describe its appearance
Unicinaria stenocephala- northern hookworm
Adult in small intestine
1cm long, typical hooked appearance- large buccal cavity with 2 cutting plates
What hookworm is this?
Where is it found in the body?
Where is it found in the world?
Ancylostoma caninum
Adult in small intestine- typical hooked appearance- 1cm long, large buccal capsule with teeth
Found in tropics, subtropics- Europe, USA- occasional transmission in the UK and imported dogs
Describe the life cycle of unicaria stenocephala
Egg to infective L3 after 4-8 days in environment
Primary route of infection is ingestion of L3
no migration, within gut L3-L5
Eggs from L5 pass through faeces into environment
Percutaneous infection- rarely results in mature infection
PPP- 15 days
Describe the life cycle of the ancylostoma caninum
Egg to infective L3 5-8 days- temp over 15 degrees
Routes:
Ingestion of L3- no migration within gut L3-L5
Percutaneous infection- L3 migrate via lymphatic and blood stream to lungs (L3-L4), swallowed (L4-L5)
Ingestion of L3- penetrate buccal mucosa and migrates as above
L3 in milk- bitch reservoir, L3 remain dormant in subcutaneous tissues until pregnancy
Eggs passed through faeces
PPP 15 days
Describe the disease of U. stenocehpala
Not highly pathogenic- protein losing enteropathy (anaemia), weight loss, lethargy, diarrhoea
Typically in dogs kept on earth rubs
Pedal dermatitis due to hypersensitivity following repeat exposure to L3
Describe the disease from A. caninum
Highly pathogenic- voracious blood suckers, severe anaemia in puppies, lasstitude, underweight, poor condition, with or without diarrhoea
Typically in dogs less than 1 years old
How are hookworms diagnosed, treated and controled?
Diagnosis based on identification of typical stronglye eggs in faeces plus clinical signs- history (imported/travelled)
Treatment- susceptible to most anthelmintics- benzimidazoles, macrocylic lactones, not ivermectin
Control- dry conditoins, concrete runs
Name all filarial (spirurida) nematodes
Dirofilaria- dog heart worm
Onchocerca spp
Brugia spp
Wuchereria bancrofti (humans)
Thelazia sp
Habronema sp
Parafilaria sp
Describe the general appearence of parasites 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
What are the species of these two eggs?
How is dirofilaria immitis transmitted?
Where is the disease most found?
Transmitted by mosquitoes- broad vector specificity, both culcine and anopheline species
Major disease of dogs and cats in temperate and tropical regions- USA major problem
UK- imported dogs
Describe the dirofilaria immitis life cycle
- Infected mosquito L3 deposited on surface of dog skin, enter through mosquito puncutre wound
- L3-L4 in the dermis
- L4 migrate through tissues and migrate L5 to venous blood stream
- Blood stream to pulmonary blood vessels and matures
- Grow in the pulmonary blood vessels to pulmonary artery
- Induces inflammation causing pulmonary hypertension leading to rightheart hypertrophy then failure
- 7-9 months- produce ofspring and circulate in blood
- Ingested in blood meal of mosquito
- L1 to L3 in 14 days in mosquito
What size are dirofilaria immitis L1 (microfilariae) and L3, L5 and adult?
L1- 270-365 um
L3- 1.1-1.3mm
L5- 2-4cm
Adult- females 30cm, males 20cm
PPP- 7-9 months total- remember for diagnosis of dogs
What usually happens with a cat with an infection dirofilaria immitis?
Relatively resistant to infection
Often does not result in patent infection- no microfilariae
If patency does occur- low numbers over a short period of time
What are the clinical signs of a significant infection of heart worm?
Asymptomatic in early stages of disease
Disease asssociated with adult worms
Mild persistent cough and dyspnoea
Reluctanct to excervise and fatigue after moderate activitiy
Decreased appetite and weight loss
Right-sided congestive heart failure-
ascites, abdominal swelling, anorexia, death
How is dirofilaria immits diagnosed?
Knott test
detect microfilariae in blood
insensitive
Antigen test
detects adult ovarian antigens
does not detect male-only infections
Knott and antigen test
only useful >7 months of age/7 months post exposure
Radiography and echocardiography
Signs of cardiovascular dysfunction
How is dirofilaria immitis prophylactically controlled?
Prophylaxis
- Macrocyclic lactones- selamectin, moxidectin or milbemycin
- Kill microfilariae, L3 and early L4 stages of heart worm
- Typically lasts a month
How is heart worm treated?
Macrofilaricidal- only dogs- adult worms
Doxycycline
endosymbiotic bacteria- wolbachia pipens
Melarsomine- only approved macrofilaricide
Excercise restriction- 30-40 days ater treatment- risk of pulmonary thromboembolism due to dead and dying worms
Start with doxycline, then melarsomine (3 dose regiment)
What is the proper name of the ‘oriental’ eyeworm?
Thelazia callipaeda
How is thelazia callipaeda transmitted?
What species does it affect?
Where are adult parasites found and what do they cause?
What is used to treat it?
Vector borne- transmitted by fruit flies (phortica spp)
Affects dogs and zoonotic
Adult parasites found in the eye and associated tissues- causes ulceration and conjunctivitis
Treat with moxidectin
