This bacterial organism causes unpredictable outbreaks,
especially in multi-site production systems. Today, young
growing pigs become exposed to disease-causing bacteria, but
their immune systems ward off the spread of the organisms in the
body. These bacteria are harbored in the tonsil or lungs,
without causing clinical disease. When naive pigs encounter
other pigs shedding the organisms, they may become infected and
develop clinical disease, depending on bacterial load and
various stress factors. One such bacterial organism causing
unpredictable outbreaks is Actinobacillus suis (A. suis). This
bacteria is more common in pigs reared in multi-site production
systems, where a few carrier animals pose a risk of exposure to
the rest of the population. These carrier pigs can shed the A.
suis organism from the tonsil, where it resides in these
clinically normal animals. Susceptible animals develop a
bacterial septicemia causing acute respiratory disease or sudden
death. A. suis is sensitive to many antibiotics, an