Study Provides New Insights on Flea-Borne Bacteria With Implications for Cats and People 


  • Fleas are a bother. All pet owners, particularly cat owners, know the annoyance they present. But fleas pose more of a risk than just an itchy pet. 
  • “Fleas aren’t just a nuisance; they actually carry disease,” says Erin Lashnits, assistant professor of small animal internal medicine at the University of Wisconsin School of Veterinary Medicine. 
  • Lashnits and colleagues at North Carolina State University recently published research in the journal Parasites & Vectors, revealing exactly what disease-causing bacteria cat fleas carry. The study’s goal was to understand better what flea-borne pathogens are present in individual fleas and their implications on cats and people. 
  • The researchers explored these questions by collecting and examining the fleas on free-roaming cats brought in for spaying or neutering at community Trap-Neuter-Release programs. The cats were then returned to their original location. 
  • They came up with this project to understand more about flea-borne bacterial pathogens. It’s a really understudied type of vector-borne disease in the U.S.  
  • The idea was to test individual fleas and see not just what bacterial pathogens that cause disease were in fleas, but also what other bacteria were throughout the flea.  
  • We know that ticks’ and mosquitoes’ microbiomes have a lot of influence on whether they can transmit different diseases.  
  • Nobody has looked at that for fleas. So, we wanted to do that with individual fleas. Because as you might imagine, if you pour a bunch of fleas together in a vial and look at their bacteria, you don’t know what any one flea contains. 
  • They found three different bacterial genera were common in all the fleas: Bartonella, Rickettsia and Wolbachia. Many species of Bartonella and Rickettsia cause disease in people but also can cause disease in cats. 
  • The big takeaway is that fleas can carry pathogens and are not just a nuisance or something to overlook. 
  • Fortunately, there are good and easy ways to prevent fleas 
  • Flea preventatives are effective and not very expensive 
  • Flea prevention helps prevent flea infestation in the first place 
  • The next step is looking at the cats. For this study, we only looked at the fleas, but we’re now working with cats too. We will compare the pathogens we’re finding in the fleas to what pathogens we’re finding in the free-roaming cats. 
  • The big picture step is to add people to the mix. Because ultimately, of course, we want cats to be healthy. We don’t want them to get these diseases. But in a lot of ways, it matters for people. Because if people are exposed to diseases from the fleas on free-roaming cats, that is a big impact on human health. 
  • We want to know the risk factors for people getting these infections from fleas. 
  • What can we do to break that transmission cycle before people get infected and, ideally, before cats get infected? 
  • Would standard flea prevention methods break that transmission? 
  • Or is there something else? 

These are the questions we want to answer.