Tularemia, commonly known as ‘rabbit fever,’ has seen a significant rise in cases in the U.S. in recent years, with an increase of more than 50%. This rare and potentially deadly infectious disease primarily affects children between the ages of 5-9, older men, and American Indians or Alaska Natives. The disease-causing bacterium, Francisella tularensis, has been classified as a Tier 1 Select Agent due to its potential use as a bioweapon.
Causes and Transmission of Tularemia
Tularemia is caused by the bacterium Francisella tularensis, which can infect both animals and humans. The bacteria are most commonly found in rabbits, hares, and rodents. People can contract the disease through various methods, including:
- Tick and deer fly bites
- Contact with infected animals (rabbits, rodents, hares)
- Drinking contaminated water
- Inhalation of contaminated aerosols or agricultural dust
- Laboratory exposure
Rising Incidence of Tularemia in the U.S.
According to the Centers for Disease Control and Prevention (CDC), the years 2011 and 2022 saw a 56% increase in the annual average incidence of tularemia compared to the period from 2001 to 2010. Over 2,400 cases were reported during this more recent period, with the majority of cases coming from four states: Arkansas, Kansas, Missouri, and Oklahoma. The rise in cases may be due to better detection and reporting, as well as improvements in laboratory testing.
Symptoms of Tularemia
The symptoms of tularemia vary depending on how the bacteria enter the body. Common symptoms include high-grade fever and a range of other signs depending on the form of the disease:
- Ulceroglandular Tularemia: This is the most common form, occurring after a tick or deer fly bite or handling an infected animal. It causes a skin ulcer at the site of entry and swelling of regional lymph glands (usually in the armpit or groin).
- Glandular Tularemia: Similar to ulceroglandular tularemia but without the ulcer. It involves swelling of the lymph glands.
- Oculoglandular Tularemia: This form occurs when the bacteria enter through the eye, typically from butchering an infected animal or touching the eyes after contact with the animal. Symptoms include eye irritation, inflammation, and swollen lymph glands near the ear.
- Oropharyngeal Tularemia: Caused by eating or drinking contaminated food or water, this form leads to sore throat, mouth ulcers, tonsillitis, and swollen lymph glands in the neck.
- Pneumonic Tularemia: The most severe form, this occurs when the bacteria are inhaled, causing symptoms like cough, chest pain, and difficulty breathing. It can also result from untreated forms of tularemia spreading to the lungs.
Prevention and Treatment
While there is no vaccine for tularemia in the U.S., the disease can be prevented and managed through several measures:
- Prevention:
- Use insect repellents to avoid tick and deer fly bites.
- Wear long sleeves and pants to minimize exposure.
- Remove attached ticks promptly with fine-tipped tweezers.
- Avoid drinking untreated surface water.
- Wear masks during activities like mowing to reduce the risk of inhaling contaminated dust.
- Use gloves when handling animals like rabbits and rodents.
- Cook game meat thoroughly before eating.
- Treatment:
- Tularemia is treatable with antibiotics.
- The case fatality rate is typically less than 2%, though it can rise to as high as 24% in severe cases.
Multiple-Choice Questions (MCQs):
- What is the bacterium that causes Tularemia?
- A) Francisella tularensis
- B) Salmonella enterica
- C) Escherichia coli
- D) Streptococcus pneumoniae
- Which age group is most commonly affected by Tularemia?
- A) Children aged 5-9 years
- B) Elderly adults
- C) Teenagers aged 13-19 years
- D) Adults aged 30-40 years
- Which of the following is NOT a common way to contract Tularemia?
- A) Tick and deer fly bites
- B) Drinking contaminated water
- C) Eating undercooked poultry
- D) Handling infected animals
- Which form of Tularemia is characterized by a skin ulcer at the site of entry?
- A) Glandular Tularemia
- B) Oculoglandular Tularemia
- C) Ulceroglandular Tularemia
- D) Pneumonic Tularemia
- What is the recommended action to prevent Tularemia?
- A) Wear a mask during outdoor activities
- B) Drink untreated surface water
- C) Handle animals without gloves
- D) Avoid wearing long sleeves and pants