Tularemia – Rising Cases of Rabbit Fever

January 4, 2025

Recent reports indicate a concerning rise in tularemia cases, also known as rabbit fever, in the United States. The disease, caused by the bacterium *Francisella tularensis*, has seen over a 50 per cent increase in reported cases. This rise is particularly notable among children aged 5-9, older men, and American Indians or Alaska Natives. The Centers for Disease Control and Prevention (CDC) categorises this bacterium as a Tier 1 Select Agent due to its potential as a bioweapon.

About Tularemia

Tularemia is an infectious disease that can affect both animals and humans. Rabbits, hares, and rodents are the primary carriers of the bacterium. Human infection can occur through various routes, including bites from ticks and deer flies, direct contact with infected animals, consumption of contaminated water, and inhalation of contaminated dust or aerosols.

Recent Statistics

The CDC reported increase in tularemia cases between 2011 and 2022, with a 56 per cent rise in annual average incidence compared to the previous decade. More than 2,400 cases were documented, primarily in four states – Arkansas, Kansas, Missouri, and Oklahoma. The increase may reflect better case detection methods and increased reporting rather than a true rise in infections.

Symptoms of Tularemia

Symptoms of tularemia vary based on the infection route. Common symptoms include:

Skin Ulcer: A skin ulcer appears at the site of entry, often accompanied by swollen lymph glands.
Ocular Symptoms: Irritation and inflammation of the eyes occur if the bacteria enter through the eye, leading to oculoglandular tularemia.
Sore Throat and Mouth Ulcers: These symptoms arise from consuming contaminated food or water, leading to oropharyngeal tularemia.
Respiratory Issues: Severe cases may present with cough, chest pain, and breathing difficulties, particularly if left untreated.

Preventive Measures

Preventing tularemia involves several key practices:

Use insect repellents to deter ticks and deer flies.
Wear long sleeves and trousers to minimise skin exposure.
Promptly remove ticks using fine-tipped tweezers.
Avoid drinking untreated surface water.
Wear masks during activities like mowing to reduce inhalation risk.
Use gloves when handling potentially infected animals.
Ensure game meat is thoroughly cooked before consumption.

Treatment Options

While no vaccine for tularemia is currently available in the U.S., the illness is treatable with antibiotics. The case fatality rate generally remains below 2 per cent, but it can rise to as high as 24 per cent in severe cases.

Francisella tularensis is the causative agent of tularemia.
Tularemia is classified as a Tier 1 Select Agent.
Arkansas, Kansas, Missouri, and Oklahoma report the highest cases.
Oculoglandular tularemia occurs due to eye exposure.
No vaccine for tularemia is currently available in the U.S.

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