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[[Image:dirofilariasis 2.jpg|right|thumb|125px|<small><center>'''Dirofilariasis'''. Courtesy of T. Scase</center></small>]]
[[Image:dirofilariasis 2.jpg|right|thumb|125px|<small><center>'''Dirofilariasis'''. Courtesy of T. Scase</center></small>]]
[[Image:Dirofilaria immitus.jpg|thumb|right|150px|''Dirofilaria immitus'' - Courtesy of the Laboratory of Parasitology, University of Pennsylvania School of Veterinary Medicine]]
[[Image:Dirofilaria immitus.jpg|thumb|right|150px|''Dirofilaria immitus'' - Courtesy of the Laboratory of Parasitology, University of Pennsylvania School of Veterinary Medicine]]
'''''Dirofilaria immitis''''':
'''''Dirofilaria immitis''''':
*up to 250 worms may establish in the heart and pulmonary arteries
*up to 250 worms may establish in the heart and pulmonary arteries
*produce microfilariae, not eggs.
*produce microfilariae, not eggs.
*May cause [[Muscles Degenerative - Pathology#Ischaemia|muscle ischaemia]] in dogs due to arteritis and thrombosis of external iliac arteries and their branches
*''Dirofilaria immitis'' live in heart and [[Respiratory Parasitic Infections - Pathology#Dirofilaria immitis|pulmonary arteries]] of dogs and cats
'''Microfilariae''':
'''Microfilariae''':
**up to 12 L3 deposited on skin
**up to 12 L3 deposited on skin
**enter body via puncture wound.
**enter body via puncture wound.
'''Zoonotic hazard''':
'''Zoonotic hazard''':
*As in dogs above
*As in dogs above
*Not very infective in cats but one dead adult causes acute pulmonary crisis - [[Lungs Circulatory - Pathology#Embolism, thrombosis and infarction|thromboembolism]]
*Not very infective in cats but one dead adult causes acute pulmonary crisis - [[Lungs Circulatory - Pathology#Embolism, thrombosis and infarction|thromboembolism]]
== Nematodes of Dogs - CANINE HEARTWORM ==
*''Dirofilaria immitis'' is one of the most important causes of morbidity and mortality in dogs in many regions of the world that have a warm, humid climate, including parts of southern Europe, USA and Australia.
*The presenting signs are usually those of heart failure, but sudden collapse may occur in heavily infected dogs.
*The endemic zone for canine heartworm disease is spreading as people increasingly travel with their pets.
*Strains of ''D. immitis'' are adapting to cooler climates.
*It is not endemic in the UK, but more infected dogs are likely to be imported now that the quarantine regulations have been relaxed.
*It has a very long prepatent period, so clinical signs may not appear for many months after importation.
*Although primarily a canine parasite, cats and ferrets can become infected.
*Owners taking their pets into endemic regions require advice on how the disease can be prevented.
'''In dog''':
*larvae migrate through connective tissues and moult twice
*immature adults (L5) are 1-5cm long → caudal distal pulmonary arteries in 4months → diffuse eosinophilic reaction in lung parenchyma, then migrate back towards right ventricle
*start producing microfilariae 6-7months post-infection.