Special Veterinary Pathology

NASAL SCHISTOSOMIASIS

Definition

• Egyptian records and studies on mummies indicated that schistosomiasis is prevalent in egypt.
• The trematode lives in the blood vessel of their hosts and they and their ova causes pathological changes in the host

Life cycle

• Adult female lays egg in the small venules.
• S. nasale in the veins of nasal mucosa of cattle and buffalo
• S. spindale and S.indicum in mesenteric and portal veins of cattle, buffalo, sheep and goat
  S. incognitum in protal veins of pigs and dogs
• S. nairi in elephants
• S.japonicum – Hepatocellular carcinoma in human
• S.haematobium - Urinary bladder carcinoma in man
• The ova excreted through faeces develops into miracidium outside and enter suitable intermediate host, a snail.
• Within the body of snail, it releases numerous cercariae which emerge into surrounding water.
• Upon entering the suitable definitive host through skin they form metacercariae and reach vein and attain adult form at the site of predilection

Lesions

• Adult blood flukes in the vein of nasal mucosa causes nasal granuloma or snoring disease in cattle but no such symptoms are seen in buffaloes
• The adult worms may cause phlebitis and venous thrombosis
• They consume erythrocyte causing anaemia and the blood pigments discharged are engulfed by macrophages ( Bilharzial pigment)
• Dead disintegrated worm may set up toxic reaction
• Injury caused by ova are more severe
• The eggs in the venule adhere to the endothelium, rupture and reach tissues where they form pseudotubercles. This consists of schistosome eggs in the centre surrounded by pink stained area is known as “actinobody”
• Cutaneous lesions develop in humans and animals from penetration of the skin by the cercariae.
• Urticaria, itching and the formation of tiny nodules which raises the epidermis were observed.
• Cercariae even have the ability to penetrate the epidermis of hosts in which complete development of the fluke does not occur
• Cercaria dies in the dermis. This is the basis of “cercarial dermatitis” also known as “swimmer’s itch”, “collector’s itch” and “swamp itch” It is observed in agricultural workers, swimmers

Diagnosis

• Nasal washings examined for napolean cap shaped S.nasale eggs.
• Histopathological examination of biopsy specimens of rectal mucosa, liver or other affected organs