What is it?
Tularemia is an infection caused by bacteria: Francisella tularensis. It is a zoonosis, a disease transmitted from the animal to the man. Nevertheless, this pathology is not contagious between humans.
Francisella tularensis is a bacterium resistant in the environment and widely found in outdoor environments. In addition, it is also resistant to freezing.
In France, the bacterial reservoir consists essentially of rodents: field mice, squirrels, rats, mice, etc. but also rabbits and hares. Domestic animals (dogs, cats) as well as sheep and cattle can be infected, but with less risk.
This disease is cosmopolitan (found on the whole planet).
It is still a rare disease with a reported number of 40 patients per year in France. However, this frequency is very variable according to the French regions.
This is a mandatory declaration disease to the ARS (Regional Health Agency).
Transmission of the bacteria is via the skin. The bacterium passes through healthy skin when in contact with infected animals, furs, organs or when the skin is damaged.
This transmission can also occur via the respiratory and conjunctival routes, during contact or when inhaling fodder dust, cereals or litter.
Finally, the contamination can also be done digestive, in the context of a consumption of water or contaminated food (meat).
Populations are more impacted than others, especially through their professional activity. They are rangers, game guards, veterinarians, and so on.
Beyond contamination from rodents, rabbits, hares, etc. The bacteria can also infect humans after they have infected ticks, flies or mosquitoes.
Symptoms of Tularemia
The characteristic symptoms of tularemia usually develop between 3 and 5 days after exposure to the pathogen (incubation period): Francisella tularensis.
Clinical manifestations usually appear suddenly. Then continues for several weeks after the onset of symptoms.
The clinical manifestations most often found in the disease include:
- chills ;
- eye irritation and conjunctivitis;
- fever ;
- joint stiffness;
- muscle pain
- redness and skin ulcers;
- shortness of breath
- A loss of weight.
Primary symptoms are, in most cases, wavy fever, chills, asthenia (severe fatigue), muscle aches, joint pain, sore throat, headache.
In addition, the presence of gastrointestinal disorders: nausea, vomiting, etc. can also be related to the disease.
Different types of the disease have been put forward.
The most common form is characteristic of cutaneous contamination and results in an ulcerative-ganglionic form.
The origins of the disease
Tularemia is an infectious disease caused by bacteria.
The origin of the disease is therefore the bacteria: Francisella tularensis.
It is a cosmopolitan bacterium, widely found in the environment and resistant to external conditions and freezing.
Transmission can be done by different routes:
– by the dermal route;
– digestive system;
– by respiratory way.
Man can be infected by these bacteria as a result of a bite by a contaminated animal. But also after a bite by a tick, a horsefly or a mosquito.
When inhaling dust from fodder or dirty litter.
Cutaneous contamination (direct contact) is effective through healthy skin when bitten by a contaminated animal or through damaged skin (scratch, cut, etc.), more fragile.
Oral infection is indirect and occurs either through the ingestion of contaminated, contaminated water or the consumption of contaminated food (including meat).
Despite the fact that the disease is found all over the world, parts of the world are more exposed than others. These are North America, parts of Europe and Asia. In the United States, the disease is most commonly found in Missouri, South Dakota, Oklahoma and Arkansas. Although some cases may occur in these areas of the United States, cases remain rare.
Risk factors for Tularemia
The risk factors for taluremia are exclusively related to exposure to the bacteria in question.
The most common reservoirs include: rodents (mice, rats, mice, squirrels, etc.), rabbits, hares.
In lesser consequences, domestic animals, sheep and cattle.
Prevention and treatment of Tularemia
The diagnosis of the disease is based first of all on a differential diagnosis when the characteristic symptoms appear.
It follows the realization of medical tests to confirm or not this first diagnosis.
These result in:
– a blood test, followed by a culture of the bacteria;
– serology: a test for measuring the immune response following a response to Francisella tularensis infection ;
– an X-ray of the rib cage;
– Performing a PCR (Polymerase Chain Reaction) from an ulcer sample.
The disease may also alter the results for febrile agglutinins and some tests for infectious mononucleosis.
The treatment of the disease aims to cure the affected subject. This essentially results in antibiotic therapy.
This antibiotic treatment includes: streptomycin and tetracycline.
Gentamicin can also be very effective in treating this condition. Nevertheless, this effectiveness only concerns certain cases of the disease.