Infestation with filarial worms of the genus Dirofilaria and especially with the heartworm. Dirofilaria is a genus of roundworm (nematodes). These worms cause Dirofilariasis in humans defined as infection by filarial nematodes of the genus Dirofilaria. there are two forms of the disease (a) pulmonary dirofilariasis caused primarily by Dirofilaria immitis and (b) subcutaneous dirofilariasis caused primarily by D. tenuis and D. repens.
Symptoms: It have symtoms such as cough,chest pain fever and pleural effusion. Diagnosis: Complete blood count (CBC) - Using a CBC, eosinophilia may be detected in up to 20% of cases of HPD. Sputum cytology, Using ELISA, serologic studies may yield positive results in 75% of patients with HPD. Biopsy and histology.
Treament: No treatment is recommended as the infection is self-contained,but if invasive sugery is performed,removal of the pulmonary nodule will end the infection.
Pathogenesis: Heartworm disease primarily affects the cardiopulmonary system and the severity and extent of lesions depends on several factors. Parasites in the pulmonary arteries cause mechanical irritation, leading to endothelial damage, proliferation of the intima and perivascular cuffing with inflammatory cells. This results in narrowing and occlusion of the vessels which in turn causes pulmonary hypertension. A combination of pulmonary hypertension and inflammatory mediators can lead to an increase in the permeability of pulmonary vessels, giving periarterial oedema and intersitial and alveolar infiltrates. Eventually, irreversible interstitial fibrosis arises.