Diseases are often characterized according to their biology, such as:
*. Virus, Bacteria, Parasites, Fungi, and their causes, e.g. nutritional disorders.
However, in the following the most important diseases in poultry are divided into three categories according to their severity and importance in village-based small-scale production systems. Distinct features, such as their characteristics during outbreaks (symptoms), and possible treatments (prevention or control), as well as the time of occurrence, will be presented.
*. The importance of a disease is judged by mortality rates and effect on production, and will vary greatly from area to area and from season to season.
Combination of diseases
Some less important diseases mayinteract with other diseases to create a more severe effect on thebirds. This is the case for: E. coli infections, nutritional deficiencies and internal parasites. Such diseases rarely kill the individual bird, but have a remarkable effect on the immune system of the birds, thus creating the basis for easy infection by other diseases.