Tularaemia: symptoms, causes and treatment

Tularaemia is a zoonosis, meaning an infection that passes from animals to humans. The cause is a bacterium called Francisella tularensis, which can infect many wild and domestic animals. Rabbits, rodents and ticks are the usual carriers.

ECDC describes it as a bacterial disease mainly found in the northern hemisphere. The Patient.info professional article says the bacterium is very infectious and that very few organisms are enough to start an infection, which is why laboratory staff need strict infection control when handling samples.

There are two types of the bacterium. The article says type A occurs naturally only in North America and can be fatal in people, while type B occurs throughout the northern hemisphere and causes milder illness.

ECDC lists several routes: eating or drinking something contaminated, touching infected animals, being bitten by certain insects, breathing contaminated dust, and accidental laboratory exposure. The Patient.info article adds bites from ticks and mosquitoes, entry through the skin, the eye or the mouth lining after contact with infected animals or their materials, and inhaling contaminated aerosols.

It describes the infection as spreading mainly from animal to person rather than between people. ECDC says hunters, people working with wildlife, hikers and campers should be aware of how it spreads because their risk is higher.

The first symptoms are fever, tiredness, chills and headache. After that, ECDC says the picture follows the route of entry. Swallowing bacteria in food or water causes a persistent sore throat. A tick or insect bite leads to an ulcer at the site with inflamed nearby lymph nodes. Contamination of the eye causes eye inflammation and swollen glands nearby. Breathing in the bacteria, or spread through the blood, can cause a lung infection.

The professional article names six recognised forms. Ulceroglandular tularaemia, with a skin ulcer and painful swollen glands, is the commonest. The others are glandular, oculoglandular, oropharyngeal, pneumonic and typhoidal, which is the most severe and may cause weight loss and pneumonia without an ulcer. As many as 20% of patients may have a rash, according to the same article.

• A slow-healing ulcer at a bite or scratch, with a swollen, tender lymph node nearby.

• A painful red eye with swollen glands near the ear or jaw.

• A sore throat after eating poorly cooked game or drinking untreated water.

• Cough, chest pain and breathlessness if the lungs are affected.

• High fever, chills, muscle aches and weakness without a clear local sign.

Diagnosis depends on suspecting the infection after exposure to animals, ticks or contaminated water. The professional article says blood tests often show abnormal liver tests, and that diagnosis is usually based on antibody tests, with PCR allowing earlier diagnosis. It notes that antibody tests can cross-react with other bacteria such as Brucella, so results need careful interpretation.

The bacterium can be grown from blood or tissue samples, but this needs a special culture medium and strict laboratory precautions. The article lists several illnesses doctors consider alongside tularaemia, including psittacosis, tick-borne infections and other serious bacterial infections.

Treatment is with antibiotics. ECDC says there is no effective and safe vaccine at present. The professional article states that the recommended treatment is a ten-day course of streptomycin or gentamicin, and that doxycycline and ciprofloxacin are also used. Which drug and what duration suit a person is a specialist decision and depends on the form and severity.

Supportive care is given for complications. The article lists pneumonia, lung abscess, respiratory failure, kidney injury and, rarely, meningitis and heart infection. Most patients who receive appropriate treatment recover completely, though symptoms can last several weeks.

ECDC gives a mortality rate of roughly 2% with appropriate treatment, rising to between 5% and 15% without it. It adds that infected people usually recover completely, but some need a long period of convalescence.

Prevention is practical. ECDC advises avoiding drinking untreated surface water, using insect repellent and clothing that covers arms and legs, avoiding dead animals, wearing gloves when handling wild animals, not mowing over sick or dead animals, and cooking game meat thoroughly. The professional article adds prompt careful removal of ticks.

No UK patient leaflet on tularaemia was available to read for this page, so the guidance here relies on a European agency and an archived UK-authored professional article. The article, last updated in 2016, lists Great Britain among places in Europe where the disease had not occurred. That may be out of date, and UKHSA information should be checked by clinicians.

If you develop fever and a slow-healing ulcer, swollen glands, a painful eye or a persistent sore throat after tick bites, handling wild animals or a trip to an affected area, see a GP or call NHS 111 and mention the exposure. Call 999 for severe breathlessness or collapse.