Rural poultry flocks in developing countries make little use of conventional vaccines or therapies. Appropriate vaccines must be robust, cheap and suited for local production in relatively unsophisticated laboratories. Only diseases producing high mortalities warrant attention. Appropriate therapies depend on local ethnoveterinary knowledge.
Newcastle disease is the most important constraint to the productivity of village chicken flocks. The Australian Centre for International Agricultural Research (ACIAR) initiated projects on vaccines to control this disease in rural flocks in 1984. Thermostable variants of the avirulent strains V4 and I-2 were developed and shown to be safe and effective in laboratory and village trials. Master seed of I-2 vaccine is made available without cost to developing countries. Vaccine is produced by a seed-lot system and involves allantoic sac inoculation of non-SPFeggs. Harvested allantoic fluid is the basis of the vaccine. Sustainable vaccination campaigns require components other than an appropriate vaccine. Appropriate extension messages must be developed to target the neglected village flocks, and the women who usually control them. Systems of cost recovery must be developed. Appropriate training must be available at all levels – to administrators, laboratory staff and village vaccinators. With the control of Newcastle disease, villagers can be convinced of the full potential of their flocks to produce food and income. Other interventions including housing, nutrition and control of otherdiseases can be introduced.
The thermostable vaccines have been tested in at least 30 developing countries and produced on a large scale in at least 9. International agencies otherthan ACIAR and various NGOs have supported the projects. The next village vaccine could be fowlpox, with virus adapted to production in the allantoic cavity.
The major killing disease of duck flocks in Asia is duck plague. An ACIAR project has seen the development of an improved vaccine in Vietnam The vaccine, adapted to grow in cultured chick embryo fibroblasts, is registered foe use throughout Vietnam. Various remedies, mainly herbal, are used on village flocks to improve performance. These probably do not assist in treating established disease.
The commercial industry could ask, are our vaccines too sophisticated and expensive, is there a place for food vaccines, should we investigate herbal remedies and how can we help the rural poor?
