Newcastle disease is a devastating malady in unvaccinated chickens of any age. This often results in high mortality (up to 95%) specifically in young birds all over the village and in the worst case when infected birds are brought to the market to all the surrounding area.
General information on disease
Newcastle disease is a devastating malady in unvaccinated chickens of any age. This paramyxo virus is infecting most birds by contact or faeces. The severity of symptoms may vary greatly in different species but dependents as well on the virus strain. So infection can be spread by migrating wild birds and affect unprotected chicken.
This often results in high mortality (up to 95%) specifically in young birds all over the village and in the worst case when infected birds are brought to the market to all the surrounding area. So the assets of families can be wiped out in a few days. (FAO)
In Kenya mortality rates are usually high in January (80-100%) in non-vaccinated flocks (Njue, et al., 2001). Outbreaks are usually associated with the introduction of local chickens from elsewhere especially during Christmas festivities (Kasiiti, 2000) when they are sold in open-air markets. The owners of the local chicken are aware of the clinical signs of the disease and as soon as some birds start to die of the disease, the rest are sold off or given out as gifts. Most of them would be in the incubation period, which is a further reason to spread the disease.
Many species of birds, both domestic and wild. The mortality and morbidity rates vary among species, and with the strain of virus. Chickens are the most susceptible poultry, ducks and geese are the least susceptible poultry. (OIE)
Transmission is by direct contact with secretions, especially faeces, from infected birds or by contaminated feed, water, implements, premises, human clothing, etc.
The first sign in laying chickens is usually a marked drop in egg production followed within 24 to 43 hours by high death losses. At the onset, 10-15 percent of a flock may be lost in 24 hours. After 7 to 10 days, deaths usually subside, and birds surviving 12 to 14 days generally do not die but may display permanent paralysis and other neurologic signs. The reproductive system may be permanently impaired, and thus egg production does not return to previous levels. In vaccinated chickens, the clinical signs are less severe and are proportional to the level of protective antibodies. The most noteworthy clinical sign in unvaccinated flocks is sudden death without prior indications of illness. This often causes the owner to suspect poisoning. (Foreign Animal Diseases)
Prevention - Control - Treatment
There is no treatment for the disease once it occurs. Diseased birds have to be killed in a humane way and disposed off properly.
Disease can be prevented by sanitary methods such as:
- Isolation of outbreaks
- Avoid contact with birds of which you do not know their health status
- One age group per farm breeding is recommended ('all in all out')
- Dispose properly of dead birds
- Vaccination with live and/or oil emulsion vaccines can markedly reduce the losses in poultry flocks
- Live B1 and La Sota strains are administrated in drinking water or as a coarse spray. Sometimes administered in nose or eyes. Healthy chickens may be vaccinated as early as day 14 of life, but delaying vaccination until the second or third week increases its efficiency
- Some other infections (e.g. Mycoplasma) may aggravate the vaccine reaction. Killed virus vaccine should then be used.
Signs of New Castle disease
- Respiratory and/or nervous signs:
- gasping and coughing
- drooping wings, dragging legs, twisting of the head and neck, circling, depression, inappetence, complete paralysis
- Partial or complete cessation of egg production
- Eggs are misshapen, rough-shelled, thin-shelled and contain watery albumen
- Greenish watery diarrhoea
- Swelling of the tissues around the eyes and in the neck
Information Source Links
- Foreign Animal Diseases. "The Gray Book" Online-version
- Joint FAO/IAEA Programme: Newcastle Disease control of chicken improves the welfare of rural households in Africa. www-naweb.iaea.org
- Kasiiti, J.L. (2000): Isolation of Avian paramyxoviruses from village chickens and wild bids in Kenya, Msc thesis, University of Nairobi.
- Njue, S.W., et al. (2001): A Survey of the disease status of Village chicken in Kenya. In: Proceedings of Association of the Institutes of Tropical Veterinary Medicine (AIMVT) conference proceedings, 20-23 August 2001, Copenhagen, Denmark. pp 36
- S.W. Njue, J.L.Kasiiti, J.M.Macharia, S.G.Gacheru and H.C.W.Mbugua: Evaluating the Effect of Newcastle Disease Control and Improved Feeding on Productivity of Village Chickens in Kenya.
- World Organization for Animal Health (OIE) - Technical disease card on Newcastle disease, www.oie.int