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Lung worms
Order/Family:
Dictyocaulus species
Description:
Nematode infection of cattle, sheep and horses
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Introduction
Dictyocaulus species
There are three species of economic importance in livestock keeping:Dictyocaulus filaria, Dictyocaulus viviparous and Dictyocalus arnfieldii The species are host specific since D. filaria affects sheep; D. viviparous affects cattle while D. arnfieldii affects horses.
Dictyocaulus viviparous
It occurs in the bronchi of cattle, mainly in cold temperate climates but may be found in tropical countries. The male measures 4.5 - 5.0 cm while the female is 6 - 8 cm long. The life cycle is direct and the eggs contain larvae when laid and may hatch in the air passage or may be coughed up and expelled. The eggs may as well be swallowed and hatch in the alimentary canal where they may also develop. Outside the host, the larvae become infective in 6 - 7 days and infection occurs by ingestion. Larvae penetrate the intestinal wall and pass through lymphatic vessels, mesenteric lymph glands, then via the blood vessels to the lungs where they break from the capillaries into the alveoli then they mature in the air passages. The development from infection to adult worm takes about a month.
Infection of calves with D. viviparous larvae confers immunity to subsequent infection. Immunity can also be induced by injection from preparations made from adult worms or larvae.
Signs of Lung worms
- Affected animals have distressed breathing and cough
- There is stunted growth in calves
Diagnosis
Post mortem examination reveals worms and froth in the lungs accompanied by edema and damaged bronchi. Air would be present in the alveoli tissues of the lungs and the interseptal lymphatics would be enlarged and have a marbled appearance.
Prevention - Control - Treatment
Prevention and control
- Remove the host from infected surroundings to clean dry areas.
- Separate young animals from mature animals
- Vaccination of calves and mature cattle with X-irradiated vaccine is also effective.
Recommended treatment
Early treatment of the larval lung worms with 10% solution of diethylcarbamazine at 55 mg per kilogram live weight administered intramuscularly for 5 days.
Oral administration of tetramisole given at 15 mg per kilogram or subcutaneous injection with levamisole at 7.5 mg per kilogram is effective.
Oral administration of tetramisole given at 15 mg per kilogram or subcutaneous injection with levamisole at 7.5 mg per kilogram is effective.
Information Source Links
- Barber, J., Wood, D.J. (1976) Livestock management for East Africa: Edwar Arnold (Publishers) Ltd 25 Hill Street London WIX 8LL. ISBN: 071310063X
- Blood, D.C., Radostits, O.M. and Henderson, J.A. (1983) Veterinary Medicine - A textbook of the Diseases of Cattle, Sheep, Goats and Horses. Sixth Edition - Bailliere Tindall London. ISBN: 0702012866
- Blowey, R.W. (1986). A Veterinary book for dairy farmers: Farming press limited Wharfedale road, Ipswich, Suffolk IPI 4LG
- Force, B. (1999). Where there is no Vet. CTA, Wageningen, The Netherlands. ISBN 978-0333-58899-4.
- Hall, H.T.B. (1985). Diseases and parasites of Livestock in the tropics. Second Edition. Longman Group UK. ISBN 0582775140
- Hunter, A. (1996). Animal health: General principles. Volume 1 (Tropical Agriculturalist) - Macmillan Education Press. ISBN: 0333612027
- Hunter, A. (1996). Animal health: Specific Diseases. Volume 2 (Tropical Agriculturalist) - Macmillan Education Press. ISBN:0-333-57360-9
- ITDG and IIRR (1996). Ethnoveterinary medicine in Kenya: A field manual of traditional animal health care practices. Intermediate Technology Development Group and International Institute of Rural Reconstruction, Nairobi, Kenya. ISBN 9966-9606-2-7.
- Pagot, J. (1992). Animal Production in the Tropics and Subtropics. MacMillan Education Limited London. ISBN 0-333-53818-8
- The Organic Farmer magazine No. 50 July 2009