Health officials on Long Island are investigating at least three probable cases of a rare bacterial illness known as tularemia, or “rabbit fever.”
The Suffolk County Department of Health said laboratory testing is needed to confirm the cases, a process that could take several weeks.
“Confirmation of a tularemia diagnosis requires a combination of laboratory testing and fulfillment of specific clinical or epidemiologic criteria,” the department told a regional news outlet. “The laboratory testing to confirm a tularemia diagnosis may take several weeks.”
Here’s what residents should know about the disease, including how it spreads, what symptoms to watch for and how to reduce the risk of infection.
What is tularemia?
Tularemia is a rare, potentially serious illness caused by the bacterium Francisella tularensis, according to the Centers for Disease Control and Prevention.
The disease most often spreads through tick bites and deer flies that have fed on infected animals, including wild rabbits, hares, muskrats and rodents. It does not transmit from person to person.
People can also become infected by handling the skin or tissue of an infected animal, inhaling dust or aerosols contaminated with the bacteria, or drinking contaminated water, the CDC said.
“It’s often called rabbit fever because hunters who shoot rabbits and then skin and eviscerate them can become contaminated by that close contact with their tissues,” said Dr. William Schaffner, a professor of preventive medicine at Vanderbilt University Medical Center in Nashville.
Cases are more common in males and typically occur between May and September, according to the CDC. Fewer than 200 cases have been reported annually nationwide since 2019 through 2023, federal data shows.
What are the signs and symptoms?
Symptoms vary depending on how a person was infected, and illnesses range from mild to life-threatening, the CDC said.
All forms of tularemia include a fever that can reach 104 degrees. Dr. Zoe Weiss, director of clinical microbiology at Tufts Medical Center in Boston, said the incubation period is typically three to five days but can extend to three weeks.
“Tularemia presents the way a bad flu starts — sudden fever, chills, headache, body aches, feeling wiped out,” Weiss said. “What sets it apart is what shows up alongside that: a sore or ulcer where you were bitten and a swollen, painful lymph node near it.”
People who touch infected animal tissue and then their eyes can develop oculoglandular tularemia, marked by eye irritation, inflammation and swollen lymph glands in front of the ear.
Those who consume contaminated food or water can develop oropharyngeal tularemia, which may cause sore throat, mouth ulcers, tonsillitis and swelling of neck lymph glands, the CDC said.
Pneumonic tularemia, the most serious form, develops when someone inhales infected dust or aerosols. Symptoms include cough, chest pain and difficulty breathing. It can also occur when other forms of the illness go untreated and bacteria spreads through the bloodstream to the lungs, according to the CDC.
Diagnosing tularemia can be difficult because cases are rare and symptoms resemble other, more common illnesses.
“Most kinds of pneumonia are very, very similar in their presentation because they all cause inflammation of the same organ, the lungs, and so distinguishing the causes depends upon two things: one, getting a good specimen and sending it to the laboratory, and the other is … having the physician inquire about what sources,” Schaffner said.
How to prevent, treat tularemia
“Tularemia is highly treatable with commonly used antibiotics,” Weiss said. “It used to be deadly, but now it is much more treatable with antibiotics.”
Until recently, a vaccine was available to protect laboratory workers who handle the bacteria, the CDC said. The vaccine is currently under review by the Food and Drug Administration and is not generally available in the United States.
When hiking or camping, the CDC recommends using Environmental Protection Agency-registered insect repellents containing DEET, picaridin, IR3535, Oil of Lemon Eucalyptus (OLE), para-menthane-diol (PMD) or 2-undecanone.
People should wear long pants, long sleeves and long socks to guard against ticks and deer flies and remove any attached ticks promptly, the agency advised.
When mowing or landscaping, residents should avoid running equipment over sick or dead animals, according to the CDC. Hunters, trappers and anyone skinning animals should wear gloves and cook game meat thoroughly before eating.