What is it about ?
Some contagious diseases are caused by bacteria mainly found in hot climates, in the tropics and subtropics. Bacteria are microorganisms that consist of a single cell. Unlike viruses, they reproduce on their own, dividing into two.
Bacteria are spread in all kinds of ways:
- Through the air (anthrax, Q fever),
- By contaminated water or food (anthrax, brucellosis, leptospirosis),
- From animals to humans (anthrax, plague, brucellosis, relapsing fever, leptospirosis, spotted fever, Q fever),
- From man to man (plague, leprosy).
In the case of transmission from animals to humans (= zoonosis), the animal is the intermediate host: the bacterium survives on or in the animal and is sometimes transmitted to humans via its coat, its meat, its milk, its mane, its wool … Sometimes, the bacteria uses a second intermediate host (a flea or a tick). In this case, this second host is infected by biting the animal, then transmits the bacteria to humans by biting it.
Where do they occur?
- We meet cases of anthrax fever worldwide, but the disease is very rare. It is better known as a potential biological weapon than as a disease.
- The plague, it too, is still present all over the world. There are about 200 cases per year.
- The leptospirosis is also found almost everywhere on the planet.
- The brucellosis is rife in parts of the Mediterranean, the Arabian Peninsula, Central America, South America and Africa. Once transmitted through goat’s milk, the disease has become rare since the invention of pasteurization.
- The relapsing fever occurs mainly in Africa and South America, but it can also appear elsewhere, in the context of larger epidemics. Mortality varies between 4 and 40%.
- The Meadow usually occurs in outbreaks in virtually all developing countries.
- The spotted fever knows many variations, spread all over the world.
- Finally, the Q fever is mainly a disease of intensive farming areas.
How to recognize them?
Anthrax (anthrax)
Infection in humans can be through the skin, respiratory tract or digestive tract. Depending on the mode of contamination, the condition presents itself in different forms: a skin condition (cutaneous anthrax), an affection of the respiratory tract (pulmonary anthrax) or an affection of the digestive system (gastrointestinal anthrax).
The cutaneous form (cutaneous anthrax) begins with a small lump (a papule), which gradually grows and turns into a small blister (vesicle). These vesicles are becoming more and more numerous. Then, after ten days, the blisters burst and give way to a painless black ulcer of a few centimeters. A crust then forms on top, before falling off on its own and leaving a scar. If left untreated, the infection can spread throughout the body.
When the bacteria have been inhaled, the condition (pulmonary anthrax) develops in two phases: first, the infected person has a flu-like illness for a few days, then they develop severe, sometimes even fatal, inflammation of the area between the lungs (mediastinitis).
Affection of the digestive tract (gastrointestinal anthrax) is rather rare. Anthrax begins with fever and vomiting, followed by stomach pain, vomiting of blood (hematemesis) and blood in the stool (melena).
Plague
The plague manifests itself in two ways:
- bubonic plague, following a bite of a flea that transmits the bacteria: after an episode of high fever, the lymph nodes in the neck, armpits and groin swell to such an extent that they are visible from the outside.
- Pulmonary plague, after inhalation of the bacteria or as a complication of bubonic plague: severe pneumonia which, without treatment, systematically leads to death.
Brucellosis
The signs and symptoms of brucellosis can be many and varied. Most infections go unnoticed and resolve on their own within three weeks. Fever, headache, back pain, inflammation of the joints, inflammation of the bones, swelling of the lymph nodes, liver and spleen may occur.
Recurrent fever
Relapsing fever begins with an episode of fever accompanied by chills, headache, muscle pain, joint pain, cough, and hypersensitivity to light (photophobia). There then follows a period of 2-3 days without fever, after which the temperature rises again. This cycle repeats up to five times or more. At the end of the fever period, swelling of the liver and spleen, rash, jaundice, meningitis, cranial nerve palsy, paralysis affecting only one side of the body (hemiplegia) and seizures may occur. epilepsy.
Leptospirosis
Leptospirosis can be accompanied by a wide range of complaints and symptoms. Most often, the disease starts like the flu or looks like meningitis or an inflammation of the liver (hepatitis). Fever, headache, vomiting, muscle pain, sensitivity to light, bleeding from the conjunctiva of the eye, swelling of the glands and spleen, inflammation of the heart (carditis) and kidney failure can occur.
Meadow
On the leprosy side, a tuberculoid type and a lepromatous type are distinguished:
- in the tuberculoid leprosy, there are only small amounts of bacteria present in the skin. These cause lighter colored skin patches, which are also less sensitive and no longer sweat.
- in the lepromatous leprosy, large amounts of bacteria are present, as well as large areas of thickened skin dotted with small bumps (nodules). The sensations disappear in the fingers and toes, often resulting in injuries and lesions. Eventually, serious deformities can develop.
Spotted fever
Spotted fever (rickettsiosis) presents with a wide variety of symptoms. The disease begins with a sudden high fever, muscle pain, nausea, and headache. It is characterized by abnormalities of the skin with spots and pimples that look like eczema lesions, sometimes small blisters filled with fluid, and extensive bruising (purpura). Sometimes a black crust appears where a tick or louse has bitten. Swelling of the glands, cough, tonsillitis, pneumonia, conjunctivitis, swelling of the liver and spleen, inflammation of the muscle of the heart with arrhythmias, nervous system disorders and heart failure may also occur. renal failure.
Q fever
Q fever usually doesn’t cause many symptoms. A slight transient flu is possible. A small minority of those affected develop pneumonia, inflammation of the liver, inflammation of the heart muscle, meningitis, and kidney failure. In 5-7% of cases, the disease becomes chronic and results in inflammation of the valves of the heart.
How is the diagnosis made?
These conditions can cause symptoms that are so different that it is very difficult to make a diagnosis. The doctor cannot make the diagnosis just on the basis of your symptoms. This is why blood is taken from all people who return from infected areas and have an unexplained fever. The aim is to detect the presence of antibodies against the agents responsible for the disease (pathogens). Sometimes the blood is cultured, which often allows the bacteria to be observed directly under a microscope. Any sign of meningitis requires a lumbar puncture. This examination is performed in the hospital.
What can you do ?
Prevention is better than cure. Prevention is therefore the key word. In the case of well-organized trips under normal hygienic conditions, the risk of coming into contact with these diseases is very low.
The risk is higher when traveling in more adventurous conditions or staying for a long time in an infected area. If so, avoid contact with sick people and animals, especially disease spreaders such as rats. Watch out for tick and lice bites. Do not drink unpasteurized raw goat milk and do not eat raw meat. Wash the vegetables in potable water. Or better yet, cook them. Drink only bottled water and refuse bottles that are already opened.
What can the doctor do?
Bacterial infections are treated with antibiotics. But the doctor must first be sure of the diagnosis. It is not necessary to isolate the sick.
Some countries have a vaccine against anthrax, leptospirosis and leprosy. In areas where leptospirosis is prevalent, 200 mg of doxycycline is sometimes given once a week as a preventative measure. However, there is no evidence that this treatment prevents contamination.
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