Angiostrongylus Vasorum Flashcards
What is this worm sometimes surprisingly called?
French Heartworm
How does epidemiology differ to the other spp. of Angiostrongylus?
It does not appear to infect humans.
What is its distribution?
Worldwide, prevalent in western Europe and absent from N americal except in canada where its range is expanding. It is an emerging disease.
How are dogs infected?
Ingestion of molluscs or paratenic hosts (e.g. frogs) containing L3 larvae. Or eating food contaminated with mollusc slime
Describe the LC.
L3 migrate to mesenteric lymph nodes where they moult from L3-L5. These enter the portal circulation, migrating through the liver to get to the right ventricle and pulmonary artery. Here they mature to adults which multiply and produce eggs which hatch into alveolar capillaries. The L1 can then be coughed up and swallowed. The PPP is 6-10 weeks.
What are the main epidemiology points of this worm?
Geographical location - mainly confined to foci with sporadic cases outside of these
Final host (domestic) - 5% infected dogs are aysmptomatic so are shedding larvae without being noticed.
Final Host (Wild) - Dogs can be infected from fox parasites and infected foxes are often seen in area with infected dogs so likely these contribute to epidemiology. Other wild animals can act as final hosts but epidemiological role is unknown.
Intermediate hosts - can infect a very wide range of mollusc spp.
Paratenic hosts - e.g. frog
What are the clinical signs dogs can present with?
Cardio respiratory signs
Coagulopathies
Neurological dysfunction
Why do you see cardio-respiratory signs?
Blood vessels become blocked by adult worms, eggs and larvae
What are the different types of coagulopathies that might be seen?
Consumption coagulopathy - clotting factors overused so there is a reduction in their number
Subcutaneous haematomas - platlets are attracted to AG-AB complexes which leads to thrombocytopenia so not enough platlets to clot. Also reduction in other clotting factors
Hypochromic aneamia - parasite interferes with haemoglobin synthesis.
What causes neurological dysfunction in infected dogs?
Haemorrhages in the cerebellum
How can the disease be diagnosed?
Clinical signs
Faecal exam
Serology
PME
Why is faecal diagnosis challenging?
larval numbers are often low and there is a long PPP so might get false negative results
Adult worms produce eggs intermittently.
How can the clinical syndromes be used to the advantage of serological testing?
Can test from circulating clotting ability and hypochromic aneamia.
What might be seen at PM?
Mottled lungs
Subcut haematomas
Larger BVS due to endarditis and fibrosis
endocarditis of the RV and tricuspid valve.
How is the worm treated in the UK?
Moxidectin single dose and milbemycin weekly for 4 weeks.
Fenbendazole off label daily for 1-3 weeks
