Tularaemia

Tularaemia: a little-known zoonosis

Tularaemia is a rare infectious disease caused by the bacterium Francisella tularensis. It mainly affects wild animals, in particular hares, rabbits and rodents, but wild ruminants, carnivores and birds can also be infected.

The disease can also be transmitted to humans. Certain individuals may be exposed to a greater risk, such as forestry workers, workers at wild animal rescue centres, hunters, vets, butchers, gardeners, etc.

Tularaemia remains a rare disease in Europe, although cases are identified every year, in particular in France, Belgium, Germany and the Netherlands. The risk is greater in certain rural or wooded regions. In Luxembourg, only one confirmed case has been notified (in 2021).

How is it transmitted?

Tularaemia is not contagious between humans. It is possible to be infected by direct contact with blood or secretions:

• while handling an infected animal (in particular during hunting)
• via tick, fly or mosquito bites
• by inhaling contaminated dust or aerosols (during agricultural or forestry work)
• by drinking contaminated water or eating contaminated food (rare)

What are the symptoms?

• Initial non-specific symptoms, such as sudden high fever, chills and fatigue
• Skin lesion or ulcer accompanied by swollen lymph nodes (ulceroglandular form) close to the lesion in the vast majority of cases
• Sore throat, cough (if respiratory form), with pharyngitis, tonsillitis and, in some cases, gastrointestinal symptoms
• Conjunctivitis, in very rare cases
• Some cases involve more systemic forms, leading to pneumonia and septicaemia

Symptoms generally appear 3 to 5 days after exposure, but this period can often range from 1 to 14 days (some say up to 3 weeks).

Diagnosis

Diagnosis is based on a PCR test using a swab taken from the lesion or another sample, and on the level of antibodies present, which appear 2 to 3 weeks after infection. The culture test should be performed by a reference laboratory.

Prognosis

Tularaemia can be serious if left untreated, but generally responds well to an appropriate antibiotic treatment. In the majority of cases, there are no after-effects.