Heartworm (Dirofilaria immitis) infection in a leopard (Panthera pardus pardus) housed in a zoological park in north-eastern Italy

Abstract

Canine heartworm (cHW) disease is now recognised as potential cause of serious disease in cats and other felids, especially in endemic areas. In March 2009, a 23-years-old male African leopard (Panthera pardus pardus) housed in a zoological park located in the Province of Padova (Veneto Region), a cHW endemic area of the north-eastern Italy, died and was immediately necropsied. A cloth completely occluding the pyloric lumen was considered the presumptive cause of death. During necropsy, six nematodes (4 males and 2 females) were found within the right ventricle of the heart and the pulmonary artery. Diagnosis of HW (Dirofilaria immitis) infection was carried out by morphological features of adult worms and microfilariae, and then confirmed by detection of circulating HW antigens using a commercial SNAP kit (IDEXX Laboratories inc., USA). D. immitis infection was also confirmed by PCR amplification of the 5S ribosomal spacer region, performed on worm fragments and microfilaraemic blood samples obtained from the right ventricle of the heart. A glomerulonephritis of immuno-mediated origin and most likely associated with the HW infection is also reported. HW chemoprophylaxis and annual serological testing on wild felids housed outdoors in endemic cHW disease areas are recommended. This is the first diagnosis of D. immitis infection in an exotic felid in Italy.

Figure 1

a) Glomerulus characterized by irregular basement membrane thickening and mild proliferation of mesangial cells and minimal sclerosis (PAS, ×600); b) The small oral orifice of D. immitis, with the presence of aring and without lips; c) Rounded posterior extremity of an adultmale of D. immitis, with spicules markedly unequal, numerous caudal papillae (black arrows) and crest and striations in the ventral surface (white arrow); d) Microfilaria of D. immitis with a pointed anterior extremity and a straight tail. Many embryos of microfilariae (black square) were observed in the blood collected from the right ventricle of the heart.