Model predicts cross-species contamination risk for farm animals.

 

A new mathematical model from US researchers reveals the high risk of cross-species disease spread on farms with more than one type of animal. According to the model developed by a team at North Carolina State University—and described in Veterinary Research—biosecurity efforts focused on the top three per cent of farms in a particular contact network may significantly cut back cross-species disease dissemination. 

 “Most disease-prevention programs focus control and prevention measures on one species; however, it is well known that cross-species transmissions occur,” A/Prof Gustavo Machado said. “For example, foot-and-mouth disease can be transmitted among all ungulate species. And all of these farms are connected—they sell and share animals all the time.” 

 The researchers created a stochastic mathematical model that described the ‘connectedness’ of farms in one area of Southern Brazil. 

The model included three years’ worth of data for a population of 90 million animals and traced over 1.6 million animal movements between farms, such as animal sales and grow-finishing movements. 

 The model simulated disease outbreaks that began in cattle, pigs, and small ruminants (i.e., sheep or goats), respectively, in order to determine the likelihood of cross-species contamination in each case. They ran 1000 distinct simulations 100 times each to identify,continue