Atlas of livestock parasites
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Dirofilaria immitis (cats)



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  Portugal, Spain, South of France, Italy, Greece, Croatia, Bosnia, Czech Republic and Turkey.

Host: Rarely occurs with cats, and usually short 3rd stage larvae transmitted by mosquito vector (intermediate host).  Pre-patent period about 8 months.

Diagnosis:  Microfilaria and/or antibody detection. 

Detection of microfilaria: from 8 month p.i. may be negative as levels can be very low in cats and may be improved by concentration of microfilaria with Defil - Test or Knott’s Test.  Microfilariae can be speciated using morphological, biochemical or molecular species identification in specialist laboratories.  Antibody tests: are sensitive, but can be positive in pre-patent infections which will not develop into a patent infection. Diagnosis of heartworm infection can only be obtained by a combination of haematological and serological tests in conjunction with thoracic radiography and echocardiography.

Clinical features:  Often worm burdens asymptomatic.  Initial signs as the worms reach the heart.  Later disease acute symptoms associated with worm death including cough, tachycardia, tachypnoea.

Zoonosis: human infection is rare.


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