[Newcastle disease in southern Chad: peak epidemic periods and the impact of vaccination].

In spite of its universally acknowledged importance, backyard chicken production is still being hampered by Newcastle disease in some parts of the world. In Chad, the disease has been reported almost everywhere in the country and confirmed in several regions, but there are no control measures in place. A survey was conducted at three sites in south-eastern Chad in July and August 2001, based on face-to-face interviews with 20% of the peasant farmers keeping chickens at these sites. The aim was to collect information on peak epidemic periods and on ways in which the infection spreads. The survey revealed that the peak epidemic periods for Newcastle disease are April, during the mango harvesting and selling period, and December, when trade increases for the seasonal festivities. The survey also showed that peasant farmers attach great importance to chicken farming. The survey was followed by a vaccination trial in November 2001 and February 2002, using the La Sota strain administered ocularly. All of the birds vaccinated during the trial were successfully protected from the disease and both chicken production and the income of the villagers increased. The authors conclude that in order to sustain poultry farming and maximise production in the southern zone, vaccination programmes must be urgently introduced, campaigns to raise awareness of Newcastle disease should be carried out and financial support to pay for vaccines should be provided. Efforts to combat other causes of poultry mortality must also be undertaken.