Health officials on Long Island are reporting 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. Confirmation may take several weeks, according to the department.
“Confirmation of a tularemia diagnosis requires a combination of laboratory testing and fulfillment of specific clinical or epidemiologic criteria,” the department said. “The laboratory testing to confirm a tularemia diagnosis may take several weeks.”
Here is what to know about the disease, including how it spreads, the symptoms to watch for and how to prevent illness.
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.
Ticks and deer flies spread the disease after feeding on infected animals, including wild rabbits, hares, muskrats and rodents. The illness does not spread from person to person.
The CDC says humans can also become infected by handling the skin of infected animal tissue, inhaling dust or aerosols contaminated with the bacteria, or drinking contaminated water.
“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.
Tularemia is more common in males and occurs most often from May through September, according to the CDC.
Since 2019 and through 2023, fewer than 200 cases have been reported annually, CDC data shows.
What are the signs and symptoms?
Symptoms vary depending on how a person became infected, and illnesses range from mild to life-threatening, according to the CDC.
All forms include a fever that can reach 104 degrees. The period from exposure to when symptoms appear is typically three to five days but can extend up to three weeks, according to Dr. Zoe Weiss, director of clinical microbiology at Tufts Medical Center in Boston.
“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.”
Those who touch infected animal tissue and then their eyes can develop oculoglandular tularemia, which causes eye irritation and inflammation along with swelling of lymph glands in front of the ear.
Patients who eat or drink contaminated food and water can develop oropharyngeal tularemia, which may include sore throat, mouth ulcers, tonsillitis and swelling of neck lymph glands, according to the CDC.
The most serious form, pneumonic tularemia, develops after someone breathes in infected dust or aerosols. Symptoms include cough, chest pain and difficulty breathing. It can also occur when other forms go untreated and bacteria spread through the bloodstream to the lungs.
Tularemia can be difficult to diagnose because the illness is rare and symptoms resemble other common conditions.
“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 and 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.”
The CDC said a vaccine was available until recently to protect laboratory workers who interact with the bacteria. The vaccine is now under review by the Food and Drug Administration and is not generally available in the U.S.
When hiking or camping, the CDC recommends using Environmental Protection Agency-registered insect repellents containing DEET, picaridin, IR3535, Oil of Lemon Eucalyptus, para-menthane-diol, or 2-undecanone.
People should wear long pants, long sleeves and long socks to protect against ticks and deer flies. Attached ticks should be removed promptly.
When mowing or landscaping, residents should avoid mowing over sick or dead animals. Hunters, trappers and skinners should wear gloves and cook game meat thoroughly before eating, according to the CDC.