Tularemia (rabbit fever)

Tularemia is caused by a germ that infects rabbits, hares, and rodents in nature. People can catch it in several ways, so symptoms depend on how the germ enters the body. Tick and deer fly bites most often cause a skin sore (ulcer) with swollen, tender lymph nodes, or swollen lymph nodes alone. The germ infects people easily and spreads in many ways. So public health agencies track it across the country (it is a nationally notifiable disease).

• Sudden fever, chills, headache, muscle aches, and tiredness
• Skin form (ulceroglandular): a skin sore (ulcer) where the bite or contact happened, with swollen, painful lymph nodes. This is the most common form after a tick or deer fly bite
• Gland form (glandular): swollen, painful lymph nodes without a visible skin sore
• Eye form (oculoglandular): red, irritated, watery eyes that are sensitive to light. Lymph nodes near the ear and neck swell
• Throat form (oropharyngeal): sore throat, mouth or throat sores, and swollen neck lymph nodes. It comes from contaminated food or water
• Lung form (pneumonic): cough, chest tightness, and trouble breathing. This is the most serious form

Symptoms usually begin 3–5 days after exposure, CDC clinical guidance says. The reported range is about 1–21 days.

A licensed doctor makes the diagnosis. They look at your symptoms, how you may have been exposed, and lab tests. Exposures include tick or deer fly bites, handling wild animals, and outdoor work. Lab tests include blood cultures or antibody tests. The germ is highly infectious. So tell the lab when tularemia is suspected, so that samples are handled safely. You cannot diagnose it yourself.

It is treated with antibiotics. Most people recover fully when treatment starts quickly. CDC lists options including gentamicin, ciprofloxacin, levofloxacin, and doxycycline. A doctor chooses the drug, dose, and length of treatment based on the form of illness and how severe it is. Several of these drugs are used off-label for this illness. Do not try to treat yourself. See a doctor if you think you may have been exposed.

The most practical protection is to avoid bites and other ways of catching it. Use EPA-registered insect repellent, wear long sleeves and pants, and check for and remove attached ticks right away. Wear gloves when you handle wild animals, above all rabbits and rodents. Cook game meat all the way through. Avoid drinking untreated surface water, such as from streams or ponds. Do not mow over sick or dead animals. When you can, check the area for dead animals before mowing.

Natural cases of tularemia have been reported in every U.S. state except Hawaii, though it is still uncommon. CDC recorded an average of about 205 cases a year across the US during 2011–2022 (roughly 150–315 per year). Counts varied and have risen in recent years. Cases cluster in south-central states such as Arkansas, Missouri, Oklahoma, and Kansas. The ticks that spread it (the American dog tick, Rocky Mountain wood tick, and Lone Star tick) together cover much of the eastern, central, and western US. Deer flies spread it more often in western states.