Francisella tularensis: morphology, tradition traits, pathogenesis , prognosis and remedy

Francisella tularensis outcomes tularaemia in man and sure small mammals, resembling rabbits, hares, beavers and a number of other rodent species.
Tularaemia was initially described in Tulare county, California.
It may be transmitted by direct contact, by biting flies, mosquitoes and ticks, by contaminated water or meat or aerosols.
Francisella tularensis can also be know as Pasteurella tularensis or Brucella tulerensis)

**Morphology of Francisella tularensis:**

It’s a very small, nonmotile, nonsporing, capsulate, gram-negative coccobacillus, about 0.3 to 0.7 μm × 0.2 μm in measurement.
In tradition it tends to be pleomorphic to and bigger, even filamentous, varieties are current.
It stains poorly with methylene blue however dilute carbol fuchsin (10%) produces attribute bipolar staining.

F. tularensis is strictly cardio.
It is not going to develop on atypical nutrient media however grows properly on blood agar containing 2.5 p.c glucose and 0.1 p.c cysteine hydrochloride.
Minute droplet-like colonies develop in 72 hours.

Below appropriate circumstances acid is fashioned from glucose and maltose. Indole and urease exams are adverse.
Two biovars are acknowledged. Strains of F. tularensis have been subdivided into biotypes primarily based on their virulence and epidemiological behaviour.
Extremely virulent strains are discovered solely in N. America, whereas strains of low virulence are seen in Europe and Asia additionally.

The an infection, which is a typical zoonosis, is principally unfold by bugs or ticks amongst lagomorphs and rodents.
It’s transmitted to man by dealing with of contaminated animals, e.g. rabbits or hares tick, mosquito or fly bites, inhalation of contaminated mud, ingestion of contaminated water or meat.
Laboratory staff are at larger danger whereas dealing with contaminated laboratory animals or cultures of the organism.
Man to man transmission of an infection apparently doesn’t happen.
In human beings, tularemia could current as an area ulceration with lymphadenitis, a typhoid like fever with glandular enlargement or an influenza like respiratory an infection.
The severity of illness is way larger with sort A strains and case fatality charges could exceed 5 p.c.
Illness brought on by sort B strains is way much less extreme, with very low mortality.

F. tularensis is extraordinarily harmful to deal with within the laboratory and Class 3 containment is required for all manipulations and animal work.
Analysis could also be made by tradition or by inoculation into guinea pigs or mice. A PCR has been described, however is just not extensively obtainable.
Serology is probably to be optimistic after 3 weeks.
Rising titres of agglutinins to F. tularensis or particular person titres of 160 are diagnostic.
Serum from instances of F. tularensis could cross-react with brucellosis and vice versa, often to comparatively low titre.
An intradermal delayed hypersensitivity take a look at has been used up to now however the antigen is just not available.

Streptomycin or gentamicin are the antibiotics of alternative in tularaemia and are often healing.

Prophylaxis:

A vaccine primarily based on the live-attenuated LVS pressure confers some safety.
It may be administered by scarification to individuals who’re topic to excessive danger of an infection.
F. tularensis has been developed as a organic warfare agent and has potential software in bioterrorism.