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Tularemia is an infectious zoonotic disease, transmitted most often by rodents. Although it seems to us that we are safe from bacteria, because antibiotics will deal with any type – Francisella tularensis makes it necessary to rethink the issue of safety. Scientists include this bacterium in category A – biological agents of the highest risk, ie microorganisms of such virulence that they can even be used as … biological weapons.
Tularemia sticks
This small, immobile stick proves to scientists and the medical world that bacteria can be more dangerous than we think. Why? For two reasons. First of all – it has remarkable biochemical properties that allow it to perfectly trick our immune system and break its barriers. It has the ability to multiply intensively – therefore only ten bacteria are enough for infection and serious trouble. After penetrating the body so quickly and efficiently, they form an entire army that they do not need to attack with colonies. And when it is in the body, it can inhibit the so-called an oxygen explosion, with which the body tries to stun the bacteria in the first place (such an explosion effectively kills anaerobic bacteria).
It can also manipulate the body’s immunity in such a way that no inflammation occurs at the site of penetration, so the body does not react immediately to the intrusion. Even when it does react, the bacteria are resistant to some of their defense mechanisms. What’s more – it can force through cell membranes, getting inside cells, thanks to which it is easily “transported” into the body. First, they travel to the lymph nodes, where they increase their ranks to travel with the blood – to the lungs, pleura, spleen, liver and kidneys, causing acute inflammation.
The occurrence of tularemia
although Francisella tularensis it does not produce spores (it cannot survive long outside the host’s organism), is sensitive to high temperature (dies at 56 degrees Celsius and after 10 minutes), drying, UV rays and most disinfectants, although it is easy to get infected. Why? Because it is quite common, especially where there are live animals. In a cool, humid environment it stays for quite a long time – so where there is water, soil, straw or hay, it has ideal conditions for lurking.
Therefore, in natural conditions, tularemia (Latin. tularaemia) occurs almost exclusively in the countryside. In civilized countries of Europe and America, mice, rats, voles, squirrels, rabbits and hares are considered the main carriers that transmit this bacterium to man. However, this is not the end – tularemia is also transmitted by arthropods: ticks, flies and mosquitoes (the latter, fortunately, the least common).
Tick bites are especially dangerous – then erythematous papules appear at the site of the bite, which increase in size within two days, turning into pustules, and then into ulcers. These, in turn, can turn into a black scab over time, surrounded by erythema. Characteristic of tularemia is the appearance of flu-like symptoms after approximately 3-6 days. This is the most common form of the disease, fortunately, infection through contact with a tick is rarely fatal.
But tularemia can also enter the body by inhalation (by inhaling vapors containing bacteria, e.g. floating over hay), as a result of contact with an infected animal or its faeces, with contaminated soil, water or food. Fortunately, it is not transmitted from person to person, so there is no need to isolate the sick from other people or family.
Symptoms of tularemia
Tularemia takes different forms and symptoms depending on the route of infection. One thing is common: the onset of the disease is usually sudden, because after a short and asymptomatic hatching period (i.e. 3-5 days after infection, although it happens that the incubation period lasts up to 3 weeks), chills, high fever (above 38 degrees), pain head and / or throat, feeling generally weak, weakness, muscle aches. Tularemia can cause conjunctivitis, dry cough, shortness of breath, and pain behind the breastbone; all with enlarged lymph nodes, loss of appetite, weight loss and weakness.
If the infection with tularemia occurs in the gastrointestinal tract, the disease is associated with vomiting and diarrhea. If we become infected by inhaling bacteria, it becomes the most severe form of tularemia: interstitial pneumonia. This form must be treated as soon as possible, because if left untreated, it leads to death in 30-50%. sick!
If we become infected by the ingestion, in addition to gastroenteritis (even leading to ulcerative enteritis), it can also cause angina, where the bacteria cause exudative pharyngitis or stomatitis, sometimes with mucosal ulceration. It even happens to be ocular, though rare. It happens when we clog our eyes with dirty hands that have bacteria on them. Then, ulcers and nodules on the conjunctiva develop, accompanied by enlargement of the lymph nodes.
Diagnosis and treatment of tularemia
Tularemia is tricky because it gives little specific symptoms. It can often be confused with atypical pneumonia, streptococcal pneumonia, influenza, strep throat, Haemophilus influenzae and other microbes.
To be sure it’s infection through Francisella tularensis you need to collect tissue material from the infected area – sputum, skin scrapings, lymph nodes, blood samples, urine samples, throat swabs, pleural fluid, and even samples from the liver, spleen, kidneys or lungs – and examine them in a laboratory.
If the diagnosis is confirmed, the person is given antibiotics, especially a drug called streptomycin, but the bacteria also succumbs to aminoglycosides, fluoroquinolones and tertracyclines. However, it is resistant to penicillins and macrolides – so you need to choose the drug wisely to kill the bacteria, and not weaken the patient with unnecessary treatment. The therapy lasts about two weeks, but fortunately patients feel a significant improvement already 48 hours after starting it, if the antibiotic is well chosen.