Filariasis Filarial Dermatitis, Cutaneous stephanofilariasis, onchocercosis, dirofilariasis

Definition: chronic parasitic arthropod born disease of domestic animal caused by filarial nematode and characterized by intramuscular, cutaneous and subcutaneous lesion

Etiology Filarial dermatitis caused by parafilaria bovicola and P. multipapillosa Cutaneous stephanofilariosis caused by stephnofilaria Onchocercosis Dirofilariosis Dipetalonema or filaria evansi

Life cycle Adult worm in skin nodule Pierce skin and lay egg on surface Blood sucking fly (intermediate host) Ingest egg or larvae during blood meal Larvae developed to infective form (microfilariae) Infect animal during blood meal

Epidemiology Distribution: wide spread in tropical and subtropical countries including Egypt Animal susceptibility: domestic, wild animal and human Transmission: biting arthropod

Pathogenesis and clinical signs Filarial dermatitis: P. Bovicola and P multipapillosa cause haemorrhagic dermatitis in cattle, buffaloes and equine, Characterised by nodule in head, neck, wither, shoulder and side

2. Cutaneous stephanofilariosis Cause: stephanofilaria Characterized by skin lesion (3-5 cm), exudative, haemorrahgic dermatitis

3. Onchocercosis: Caused by onchocerca spp. Microfilaria in skin or subcutaneous lnn transmit by midges, sand or black fly Nodules in subcutaneous tissue of brisket and lateral surface of thigh, free movable under skin Misdiagnosed with bovine tuberculosis

In horse: O. cervecalis cause alopecia, pruritus especially ventral of abdomen, extend to forelegs, hind legs, face ,neck and thorax and inflammation in ligamentum nauchae through infection with adult worm O. Reticulata caused swelling and inflammation in suspensory ligament of posterior part of canon (lameness)

4. Dirofilariosis Cause: dirofilaria immitis infect dog and cat Adult worm present in right vertical, pulmonary artery and vena cava Worm obstruct posterior vena cava and cause acute hepatic syndrome and sudden death

5. Dipetalonema or filaria evansi Infect camel and inhabit in mesenteric, pulmonary, spermatic and genital blood vessels or present as cyst in internal organs Characterized by emaciation, orchitis, swollen of scrotum and cardiac insufficiency

Diagnosis Field diagnosis History Clinical signs Epidemiology Laboratory diagnosis Sample: skin biopsy, skin scraping, tissue lesion, blood samples Detection of microfilaria in blood film after staining with leishman or geimsa stain

2. Knott or fullborne technique: 1 ml of blood + 9 ml 2% formalin, centrifugation, sediment stained with MB 3. Histopathological examination 4. Serological test as ELISA 5. Allergic cutaneous test

Treatment Surgical treatment Two dose of Invermectin with one week interval

Control Isolation of infected animal Treatment of infected animal Control of insect through using of insecticides