Direct causes of disease are: (1) bacteria, (2) viruses, (3) parasites, (4) fungi, (5) nutritional deficiencies, (6) chemical poisons, and (7) unknown causes. Infectious diseases are the greatest threat to livestock health. They are caused by bacteria, viruses, rickettsia and fungi.

Direct causes of disease are: (1) bacteria, (2) viruses, (3) parasites, (4) fungi, (5) nutritional deficiencies, (6) chemical poisons, and (7) unknown causes. Infectious diseases are the greatest threat to livestock health. They are caused by bacteria, viruses, rickettsia and fungi.

Direct causes of disease are: (1) bacteria, (2) viruses, (3) parasites, (4) fungi, (5) nutritional deficiencies, (6) chemical poisons, and (7) unknown causes. Infectious diseases are the greatest threat to livestock health. They are caused by bacteria, viruses, rickettsia and fungi.

Direct causes of disease are: (1) bacteria, (2) viruses, (3) parasites, (4) fungi, (5) nutritional deficiencies, (6) chemical poisons, and (7) unknown causes. Infectious diseases are the greatest threat to livestock health. They are caused by bacteria, viruses, rickettsia and fungi.

Direct causes of disease are: (1) bacteria, (2) viruses, (3) parasites, (4) fungi, (5) nutritional deficiencies, (6) chemical poisons, and (7) unknown causes. Infectious diseases are the greatest threat to livestock health. They are caused by bacteria, viruses, rickettsia and fungi.