Tularemia

What is Tularemia?

Tularemia is a disease that causes fever, and comes from an extremely infectious, negatively-charged bacteria called Francisella Tularensis. The symptoms of this disease can vary depending on how you came into contact with it, which is why it’s important for doctors to keep an eye out for possible cases of Tularemia.

Francisella Tularensis is one of the most powerful infectious bacteria that exist. In fact, only 10 to 25 of these bacteria are enough to infect people. This bacteria has several types that differ in strength and where they can be found. In the United States, Tularemia is rare, and most cases are seen in the southern and central parts. But over time, there have been a few cases reported from the northern parts of the country too.

What Causes Tularemia?

Tularemia, a disease caused by a highly infectious bacteria known as Francisella tularensis, can infect people in various ways. These include breathing it in, coming into direct contact with it through broken skin or mucous membranes, swallowing it, or being bitten by a tick or fly that carries it. There are four different types of the bacteria, but the one that causes the most severe disease, especially in North America, is F. tularensis type A. Meanwhile, F. tularensis type B, or subspecies holarctica, commonly found in parts of the northern hemisphere, like Europe, typically results in a milder disease. It’s important to note, different types of the bacteria may react differently to certain antibiotics.

You can experience Tularemia in several ways depending on how you got infected:

1. Ulceroglandular disease: causes skin ulcers and swollen lymph nodes
2. Glandular disease: causes swollen lymph nodes but no skin ulcers
3. Oculoglandular disease: leads to swollen lymph nodes near your ear and eye infection
4. Oropharyngeal disease: results in a sore throat, mouth ulcers, and swollen neck lymph nodes
5. Gastrointestinal disease: causes throwing up, stomach discomfort, and diarrhea
6. Respiratory disease: may end up as pneumonia or pleuritis, a condition where the pleura (a thin tissue covering the lungs) become inflamed.
7. Typhoid tularemia: a feverish illness with no clear early signs or symptoms

In most cases, a person gets infected by either the bacteria entering the skin or being inhaled/swallowed. Humans can’t usually spread it to each other, but it can be transmitted through an insect bite or contact with infected animal products. Properly cooking food can lower the risk of infection. The bacteria is resilient, surviving in extreme cold or heat and even in animal carcasses. Many insects and animals carry it. In Northern Europe, mosquitoes are known to carry the bacteria. In North America, ticks are common carriers.

In terms of severity, F tularensis biovar tularensis found in North American ticks and rabbits tends to cause more severe infections in humans, whereas F tularensis biovar holarctica, found in European and Asian rodents, results in a milder infection.

People at a higher risk for infection include:

* Veterinarians
* Laboratory workers
* Farmers, landscapers
* People who work with animals, particularly sheep
* People who handle meat

Risk Factors and Frequency for Tularemia

Tularemia is an infection that occurs all over the northern hemisphere and is commonly found in animals like rabbits and hares. It mainly occurs during the warm summer and early fall months. People can catch Tularemia through a tick or fly bite or by handling the tissue of an infected animal. However, the disease can also be contracted by inhaling it, consuming it, or contact with a wet surface like mucous membranes. In the United States, it is most often reported in the south-central states – Arkansas, Missouri, and Oklahoma – but it can be found all over the country. Children are most likely to catch Tularemia, and males, especially teenagers and adults, have a higher risk of infection.

• Tularemia is common in the northern hemisphere and usually found in animals like rabbits and hares.
• It’s most common in the summer and early fall.
• People can become infected through tick or fly bites, handling infected animal tissue, inhaling it, eating it, or contacting with mucous membranes.
• In the US, it’s more frequent in the south-central states, but it does occur across the country.
• Children, particularly males in adolescence and adulthood, are most commonly affected by Tularemia.

Signs and Symptoms of Tularemia

Tularemia is a disease that can cause various symptoms and physical signs, which often depend on how someone got infected. It’s essential for doctors to know about any recent travel, consumption of game or groundwater, and exposure to outdoor activities like hunting or possible tick bites. However, not having a history of tick bite or other clear exposure doesn’t rule out tularemia, as bites from ticks or insects can be brief and not noticed. Common symptoms among all forms of the disease include fever, headache, and a general feeling of being unwell.

There are several types of tularemia, each with its own specific symptoms:

• Ulceroglandular tularemia: A sore forms at the infection site, along with swollen and tender lymph nodes nearby.
• Glandular tularemia: Lymph nodes in the infection area become swollen and tender, but no sore is present.
• Oculoglandular disease: This includes a tearful and pus-filled eye infection, along with swollen lymph nodes.
• Oropharyngeal tularemia: Symptoms for this type include a pus-filled sore throat and swollen lymph nodes.
• Gastrointestinal tularemia: This includes stomach pain, diarrhea, and vomiting.
• Pneumonic tularemia: This is a severe lung infection that can be lethal in 30% to 60% of cases.

Regardless of the type of tularemia, the associated lymph nodes may become fluctuant (wavy or shifting) as the disease progresses, even after general symptoms have subsided. Systemic or typhoidal tularemia, which results in fever, septic shock, and enlargement of the spleen and liver, can occur regardless of the infection route. While these types are the most reported, tularemia can also lead to meningitis, bone infection, and other infectious diseases.

Testing for Tularemia

Diagnosing tularemia, a type of bacterial infection, can be a bit tricky and needs you to be highly alert to its signs and symptoms as it may be hard to confirm through lab tests. One common method to confirm tularemia is a blood test that checks for the presence of antibodies against the bacteria causing the disease. Initially, the antibody level may be high (a reading more than 1:160) or it may show a four-fold increase between two tests. However, this may not be the case if the test is done too early, because it takes some time for your body to produce these antibodies. Therefore, a negative result on this test doesn’t rule out tularemia.

Another method to diagnose tularemia is to culture, or grow, the F. tularensis bacteria from samples of your blood, spinal fluid, lymphatic tissue, or swabs of any ulcer tissue you might have. But, this approach comes with some risk because if the bacteria become airborne in the lab, people working there could accidentally inhale it and develop a version of tularemia that affects the lungs. That’s why this testing should be done under strict conditions and the lab needs to be informed if tularemia is suspected so that they can handle the sample right. Finally, growing this bacterium in the lab can take longer than usual and might need special media, or growth materials.

Some other lab tests like one that checks for elevated inflammation markers (C-reactive protein, erythrocyte sedimentation rate) or increased white blood cell count may also be done. Even these tests, however, are not definitive for tularemia. If the results are normal, it still doesn’t mean you don’t have tularemia.

Treatment Options for Tularemia

As of now, we don’t have any specific research-based guidelines on the best way to use antibiotics to treat tularemia, an infectious disease. Doctors usually recommend a treatment of an antibiotic called gentamicin that is given through an IV for seven to fourteen days, depending on how severe the sickness is. Fluoroquinolones, another type of antibiotic which includes drugs like ciprofloxacin, can also be used to treat mild cases of tularemia. However, the effectiveness of this treatment for severe or type A tularemia in the United States is not well-established. In Europe, where a less severe type of tularemia is common, ciprofloxacin is used more often.

The use of antibiotics called tetracyclines in the treatment of tularemia is not highly recommended because they’re bacteriostatic, meaning they only stop the bacteria from growing but don’t kill them. As a result, there is a high chance of the disease coming back after the end of the treatment.

In some cases, it might be necessary to make a small cut and drain the infected lymph nodes, which are small glands that make up part of the body’s immune system.

What else can Tularemia be?

These are examples of diseases that can be confusing to diagnose due to their similar symptoms:

• Chlamydial infections
• Diphtheria
• Bacterial endocarditis (infection of the heart’s inner lining)
• Fungal endocarditis (also an infection of the heart’s inner lining, but caused by fungi)
• Legionella infection (also known as Legionnaires’ disease, causing severe pneumonia)
• Lyme disease (transmitted by ticks, affecting joints, heart and nervous system)
• Malaria (a parasitic disease transmitted by mosquitos)
• Psittacosis (an unusual bacterial infection transmitted by birds)
• Q-fever (a bacterial infection that can affect the lungs, liver, heart and other parts of the body)

What to expect with Tularemia

Tularemia, if left untreated, can be quite serious, with a death rate of 10-50%. The most fatal form of this disease is typhoid tularemia. Even if a patient survives tularemia, they may still experience lingering effects such as scars, damage to the lungs and kidneys, and loss of muscle.

Possible Complications When Diagnosed with Tularemia

Common Complications:

• Lung abscess or pneumonia
• Acute Respiratory Distress Syndrome (ARDS)
• Rhabdomyolysis (Damage to muscles from injury)
• Renal failure (Kidney failure)
• Meningitis (Inflammation of the brain and spinal cord membranes)
• Peritonitis (Inflammation of the tissue lining inside of the abdomen)