Aquest Link no existeix en el seu idioma, Veure en: English (en),
O utilitzar Google Translate:  

extension.msstate.edu/sites/defaul...P3505_web.pdf

Chickens are the most common species of poultry raised around the world, with the total chicken population estimated at over 23 billion head (FAO, 2019). Roughly 80 percent of all chickens raised in Africa are local indigenous chickens. These chickens are well-adapted to harsh and stressful environments and are excellent scavengers (Msoffe et al., 2002). Unfortunately, viral infections are a serious threat to smallholder chicken production among poor, rural households in many developing countries across sub-Saharan Africa (Mpenda et al., 2019). However, improved biosecurity and better Extension programming can address many challenges and help protect indigenous chickens against viral diseases, such as Newcastle disease (ND), Marek’s disease (MD), and infectious bursal disease (IBD), that cause enormous losses each year. Extension programming must emphasize isolation, sanitation, and traffic control.