Health officials in New York's Suffolk County have confirmed a fourth case of tularemia, commonly known as rabbit fever, prompting renewed public health advisories on preventing tick-borne infections. The latest case follows several infections reported earlier this summer, including a nine-year-old child who became ill after a tick bite, the NYP reported. What Is Rabbit Fever? Rabbit fever, or tularemia, is a bacterial infection caused by Francisella tularensis. Nationwide, the CDC reports approximately 200 to 300 tularemia cases each year, with infections occurring most frequently between May and September.