Doc likes to work with livestock and companion animals. His son, prefers birds to horses and goats. During the summer of 1971, the community is jolted by a national emergency as an epidemic of horse sleeping sickness sweeps into the United States. All horses on the border with Mexico are required to vaccinated developed to protect troops in case of biological warfare. Doc is handed a copy of the with bold headlines HORSE PLAGUE SPREADS PERILS HUMANS. Scores in Texas Hospitals Harlingen, Tex - A mosquito-carried disease that acts like sleeping sickness in horses and produces flu-type symptoms in people spread through Texas on Wednesday, including the state's first confirmed cases in humans. The number of affected animals was increasing so fast officials could not keep up with all the new cases. Dr. John Copenhaver, director of the joint Hidalgo-Cameron County Health Department said the disease has been confirmed in three persons at Mercy Hospital in Brownsville and that a total of 34 persons in the lower Rio Grande Valley are hospitalized with "clinically observed" symptoms of it .