Plant and Animal Pathogens

With respect to farm animals, only a small number of viral diseases are capable of inflicting major economic damage. Examples include foot-and-mouth disease (FMD) in cattle and pigs, classical swine fever and African swine fever in pigs, and avian influenza and Newcastle disease in poultry. Some livestock diseases are “zoonotic,” meaning that they cause illness in humans as well as animals; examples include anthrax, tularemia, brucellosis, avian influenza, and Rift Valley fever, caused by a mosquito-borne virus.2

What are the greatest threats to agricultural biosecurity? And what is being done to combat these risks? - Jacqueline Fletcher

The World Organization for Animal Health classifies five non-endemic livestock pathogens as “List A” agents because of the severity of the illnesses they produce, their ease of dissemination, and their high level of transmissibility: FMD, bluetongue, Rift Valley fever, bovine spongiform encephalitis (“mad cow disease”), and avian influenza. A second group of pathogens on “List B” are moderately easy to disseminate and cause moderate diseases with low fatality rates; they include brucellosis, salmonella, glanders, typhus fever, viral encephalitis, and two non-living toxins (ricin and Staphylococcus enterotoxin B). In 2011, a major pathogen of cattle, rinderpest, was eradicated worldwide, a major achievement of international animal health.3

What (infectious disease?) threats currently pose the greatest (public health) risk and which do you foresee in the future? - James A. Roth

Terrorist attacks against crops or livestock could be carried out with a variety of harmful agents, including viruses, bacteria, fungi, nematodes, and insect pests. Most serious plant diseases are caused by fungal pathogens, such as wheat smut, rice blast, brown stripe mildew of corn, and karnal bunt of wheat. Fungal spores can be grown in large quantities, are stable under different weather conditions, and are naturally transmitted through the air. These agents dramatically reduce the yields of corn, rice, and wheat. Small amounts of fungal pathogens could spread to large areas of cropland, and their long incubation period makes them hard to detect at an early stage2.

How significant is the risk of intentional or accidental contamination of the food supply? (How skilled are we at mitigating this risk? - Jacqueline Fletcher