As TomCat says, fleas and ticks primarily. because this is a bacteria it is more easily controlled and treated than a viral infection. Fairly rare.
Tularemia, or rabbit fever, is caused by a bacterium (Franciscella tularensis). The common mode of transmission is the tick, especially the wood tick, dog tick, and pacific coast tick. However, mosquitoes and fleas can also tramsit the bacteria. There have been cases of ingesting the bacteria, inhaling the aerosolized bacteria and bacterial fomites contaminating mucous membranes. It is possible to get tularemia from handling contaminated animal carcasses, especially rabbits and rodents. Fortunately, tularemia is not spread directly from person to person.
Cats appear to be at a higher risk than dogs for tularemia.
The Centers for Disease Control has some great information about tularemia on its website, www.cdc.gov
Tomcat