What is the fine-grained topic of the following text: Salmonella is one of the biggest food safety concerns in the U.S., with more than one million people contracting the infection every year, according to estimates from the Centers for Disease Control and Prevention, and an average of 20,000 hospitalizations and almost 400 deaths according to a 2011 report. Only return the topic.
The prevalence and impact of Salmonella infections in the U.S.