VPA 211: General Veterinary Parasitology and Helminthology (3+1)

DICTYOCAULUS VIVIPARUS

Host: Cattle, deer, buffalo and camel

Location: Bronchi

Morphology

• Male is 4-5.5 cm long and female is 6-8 cm long.
• The worm closely resembles the preceding species, but the medio and posterolateral rays are completely fused and the spicules are only 0.195-0.215 mm long.
• The egg measure 82-88 by 33-38 µm.

Life cycle

• Similar to that of D.filaria.
• The infective larvae exsheath in the small intestine, penetrate the bowel wall and are carried to the local mesenteric lymph nodes. Here they moult to fourth stage larve and then continue their migration to the lungs via the thoracic duct and right heart.
• In massive infections third-stage larvae may be found in the lungs as early as 24 hours after infection.

Pathogenesis and clinical signs

• The major pathogenic phases are the prepatent phase in the lungs, the patent phase and the post patent phase.
• The prepatent phase is associated with blockage of many respiratory bronchioles with an eosinophilic exudate and collapse of alveoli.
• The patent phase lasting from 25 to 55 is associated with adult parasites in the bronchi and trachea.
• Onset of tachypnoea and coughing. Emphysema may develop.
• There is severe damage to the epithelium of these organs, marked exudation into the bronchi and blockage of air passages.
• In some animals a sudden exacerbation of dysponoea is seen. This condition os often fatal and is characterized by proliferation pf the alveolar epithelialization to involve entire lung lobes.

Diagnosis

• Clinical signs of bronchitis, rapid breathing and coughing.
• Demonstration of larvae in the faeces.

Treatment

• Dietycarbamazine- 22 mg/kg/day for three days.
• Tetramisole- 15 mg/kg, Levamisole7.5 mg/kg.

Control

• Grazing management should be improved.