By Maribel Alonso, Public Affairs Specialist • ARS, Office of Communications

Dr. Dayna M. Harhay is a Research Microbiologist at the U.S. Meat Animal Research Center (USMARC) in Clay Center, NE. For two decades with ARS, Harhay’s knowledge and expertise in microbiology, molecular biology, bacterial metabolism, serotyping, and genomic sequencing has been instrumental in the study, identification, and prevention of Salmonella bacteria and other foodborne pathogens that can be associated with beef products. 

Isn’t Salmonella a Chicken Problem? 
Harhay smiles as she looks back at the beginning of her career with ARS when she was tasked to find the answer to this question. She didn’t know then that she would become a pioneer in creating novel methods to define the amounts of Salmonella in beef samples and characterize these pathogen serotypes, particularly Salmonella enterica, a major source of foodborne disease in the United States. 

20 Years of Research with ARS
Harhay started her career with ARS in 2004 as a post-doctoral research associate at the USMARC Meat Safety and Quality Research Unit, where she then accepted a Research Microbiologist position in 2005. Before joining ARS, Harhay attended the University of North Texas in Denton, where she earned her doctorate in microbiology and molecular biology in 2003.

“Prior to beginning my work at ARS, my research focused on pseudomonas bacteria, with no formal training in food safety. Still, my former research leader Dr. Mohammad Koohmaraie and my mentors in the Meat Safety and Quality Research Unit recognized and supported my ability to identify research gaps and to develop unique solutions to address those gaps, adding a fresh and valuable perspective to our investigations in the unit,” Harhay stated.

With her new role at USMARC, Harhay focused on learning more about foodborne pathogens associated with beef, leading an extensive survey on cull dairy cattle at harvest, to find the existence of Salmonella on carcasses and identify the possible presence of drug-resistance phenotypes in the population. The survey allowed Harhay to develop rapid tools and techniques for determining the number of pathogens in cattle samples.

After building an extensive collection of Salmonella in-house, Harhay proceeded to use sequencing technology at USMARC to construct first-ever complete (“closed”) genomes (gene sequences) of this pathogen, knowing that it would help facilitate the identification of Salmonella during foodborne outbreak investigations. Harhay believes that more research in this field is necessary to improve the ability to identify illness outbreaks and protect public health promptly, and these novel genome sequences are a great place to start.

Harhay and her colleagues at USMARC have contributed a substantial number of closed genome sequences (~20 percent of 330 closed genomes corresponding to 11 different types of Salmonella) that are currently available in public databases. 

By 2010, Harhay was asked to join a team of scientists in a project that aimed to better understand how Salmonella gets into the food chain through meat products. Harhay’s methods were critical in confirming that bovine peripheral lymph nodes can be, and often are, a primary source of Salmonella contaminationin ground beef. Findings from this study prompted changes in food inspection procedures and guidelines for ground beef products going to the USDA National School Lunch Program.  

Contributions and Recognitions
As a result of her experience with Salmonella enterica linked to production agriculture, Harhay received invitations from the beef industry to join the National Cattlemen’s Beef Association Salmonella Working Group, the North American Meat Institute Salmonella Research Group, and the global animal health company Zoetis’ Salmonella Research Cluster. 

Harhay was invited to help lead the ARS-wide Salmonella Grand Challenge project because of her cutting-edge research on Salmonella detection and characterization and innovative problem-solving skills. The project aims to provide effective and affordable solutions to the beef, pork, turkey, and chicken industries.

In addition, the food safety community has taken a keen interest in Harhay’s most recent work on identifying virulence genes to target for rapid detection of more pathogenic versions of Salmonella. The targets identified are being developed into a test kit that will help testing laboratories identify these highly pathogenic Salmonella at the speed of commerce. The ultimate goal is to provide tools for a risk-based strategy to manage Salmonella contamination in food and reduce the risk of foodborne illness associated with consuming red meat.

Outside of ARS
When not working with Salmonella research, Harhay enjoys traveling with her husband, learning new languages, and exploring different cultures. She and her husband Greg have hiked through the Cinque Terre in Italy, and most recently hiked the last 115km of the Camino de Santiago in   Spain. 

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