What Is Tularemia? US Sees Surge In Rare Rabit Fever Cases

Tularemia, commonly referred to as “rabbit fever,” has seen a significant rise in the United States over the past decade. According to a recent report, the incidence of this rare infectious disease increased by over 50% between 2011 and 2022 compared to the previous decade. Often affecting children aged 5 to 9, older men, and American Indians or Alaska Natives, tularemia can sometimes be fatal. The disease-causing bacterium, Francisella tularensis, is categorized as a Tier 1 Select Agent due to its potential use as a bioweapon.

What is Tularemia?

Tularemia is an infectious disease that can affect both animals and humans. Rabbits, hares, and rodents are especially susceptible, but humans can contract the disease through various means:

• Insect Bites: Tick and deer fly bites are common transmission methods.
• Animal Contact: Handling infected rabbits, rodents, or hares can lead to infection.
• Contaminated Water or Air: Drinking contaminated water, inhaling agricultural dust, or coming into contact with aerosols can also spread the bacteria.
• Laboratory Exposure: Workers handling the bacterium are at risk without proper safety protocols.

Surge in Tularemia Cases: A Concerning Trend

The Centers for Disease Control and Prevention (CDC) reports a 56% rise in tularemia cases between 2011 and 2022. During this period, over 2,400 cases were documented, with most originating from four states: Arkansas, Kansas, Missouri, and Oklahoma. These states accounted for nearly half of the reported cases.

Experts attribute this increase to better case detection and advancements in laboratory testing. The authors of the report noted:
“These findings might reflect an actual increase in human infection or improved case detection amid changes in commercially available laboratory tests during this period.”

Symptoms of Tularemia

The severity of tularemia symptoms can vary depending on how the bacteria enter the body. Common signs include high fever, but other symptoms depend on the route of infection:

1. Skin Ulcers and Swollen Lymph Nodes

   • Most common after a tick or insect bite or handling infected animals.
   • A painful skin ulcer forms at the entry site, often accompanied by swollen lymph nodes in the armpit or groin (ulceroglandular tularemia).
   • Glandular tularemia features swollen lymph nodes without skin ulcers.

2. Eye Irritation and Inflammation

   • Occurs when bacteria enter the eyes (oculoglandular tularemia).
   • Symptoms include eye redness, irritation, and swollen lymph nodes near the ear.

3. Sore Throat and Mouth Ulcers

   • Results from consuming contaminated food or water (oropharyngeal tularemia).
   • Symptoms include throat pain, mouth sores, tonsillitis, and swollen lymph nodes in the neck.

4. Respiratory Issues

   • The most severe form, caused by inhaling contaminated aerosols or untreated infections spreading to the lungs.
   • Symptoms include cough, chest pain, and difficulty breathing.

How to Prevent Tularemia

Preventing tularemia requires vigilance and protective measures:

• Avoid Tick Bites: Use insect repellents and wear long-sleeved clothing in tick-prone areas.
• Safe Handling of Animals: Wear gloves when handling rabbits, rodents, or other susceptible animals.
• Avoid Contaminated Water: Refrain from drinking untreated surface water.
• Minimize Dust Exposure: Wear masks during activities like mowing to avoid inhaling bacteria.
• Cook Meat Thoroughly: Game meat should be fully cooked before consumption.
• Prompt Tick Removal: Use fine-tipped tweezers to remove ticks quickly and effectively.

Treatment and Outlook

Although there is no vaccine for tularemia in the U.S., the disease is treatable with antibiotics. The case fatality rate is generally less than 2% but can rise to 24% in severe, untreated cases. Early diagnosis and treatment are crucial to prevent complications.