Tuberculosis Infection


The tuberculosis is a transmittable infectious disease and not immunizing provoked by a mycobactérie of the complex tuberculosis corresponding to different germs and principally Mycobacterium tuberculosis or Bacillus of Koch (BK).

Formerly cared for in the sanatoriums, by courses of treatment of sun and full air, she was reduced by the antibiotics in the years 1950, but she kills again close to two millions of persons each year in the world.

The lung tuberculosis (phtisie) is by far the most frequented and the most shed one, but there exist the attained bony (poorly of Pott, white tumor of the knee. ..), more kidney, more intestinal, more genital, méningées, skin (tuberculomes), etc.

The tuberculosis was isolated other diseases lung by Laennec in 1819. In 1839, the German doctor Schönlein gives his final name to the disease, meeting in a unified description its demonstrations clinics varied.

In 1865, the doctor John Antoine Villemin proves by the experimental method the transmission of the tuberculosis and asserts consequently that this disease, of nature even then unknown, is had to an invisible microbe with the technical means of the era. One can therefore itself to protect about it by measures aiming to avoid the contagion.

At last, following the works of Minister, this is a German doctor, Robert Koch, that discovers the bacillus, in 1882: at this point in time, the tuberculosis was in Europe causes it of a death on seven.

According to a study of the Institute Minister, based on the African stumps, the tuberculosis bacilli existed there is three millions of years, while the preceding estimations banked on an apparition dating only of 35 000 years. The original stump would have appeared in Africa of the East, considered also as the humanity cradle. The disease would be therefore as old as humanity and his expansion through the world intimately would be linked to the one of the man.

The annual number again case in the world, including the cases of relapses, is of about 5.4 million (2006), causing about a million deaths. According to the World Health Organization (WHO):

* Of 5 to 10% of the infected subjects develop the disease or become contagious during their existence.

Most of the new cases (49%) are situated in the areas populated Asia: Bangladesh, Pakistan, India, China and Indonesia. It exists an increase in the countries of eastern Europe (including Russia). The growth remains very strong in Africa, with near of 13% against less than 1% in the Asian countries.

She is with the frequent drug users by intravenous injection and carriers of the HIV, his impact being able to attain then close to 10%.

It is a matter essentially of an infection touching the young adult, and the men are close to two attained more time than the women.

The malnutrition and the medicinal poisoning are recognized causes of the increase of the number of case.

The resistance to the classical tuberculosis medicines remainder rare (about 4% of the new cases) but attains 10% in certain countries of Europe of the East. This rate increases very noticeably in case of antecedent of previously treated tuberculosis. The resistance to the tuberculosis medicines of second line remains rare but has a very strong mortality in a short delay. The number of this last form stretches nevertheless to increase (notably in Russia strongly enough) and to spread itself geographically. It stretches, on the contrary, to stabilize itself in the Baltic countries and to diminish to the USA.

The tuberculosis triply deserves his call of "social disease":

* His frequency in a community is a good index of the degree of social evolution of this one. The main factors of the decrease of tuberculosis are the nutrition conditions of habitat, of hygiene and of sanitary education. * The tuberculosis prevention necessitates, to be effective, a medical equipment and a well developed social organization. * The main victims are young adults undergoing a long disability, seen the slow evolution and the necessity of an effective treatment.

In 2003, the number of patients of the tuberculosis diminished of 30% in China (China is again the second country the more touched on the world after India) thanks to the treatment of brief length under direct supervision (DOWRIES) of the WHO, only actually effective to this day, but that had to impose breads in the world. At the end of 2006, the number of case in the whole Congo was estimated to 80 000, against 60 000 in 2002. Despite the support of the international organizations, the position had to itself worsens poverty, but also to insecurity and to the fight, that push the people to move itself, from which more of contamination. The treatment rests on measures of individual and collective prevention, as well as on a severe and complete treatment of the sick subjects:

* Authorities warn the commitment to tuberculosis while improving the availability of the basic conveniences: water, food, hygiene, housing, * tuberculosis screening by microscopic examination of the smears with the subjects
that present symptoms * supplying uniform in tuberculosis medicines * antibiotic treatment under supervision for a sufficient length (several months) * notification systems to verify the action of the treatment and the program

Discovery fortuitous
Achieving a intradermoréaction can detect persons whose body hosts the bacillus Koch before clinical manifestations of the disease in the absence of BCG vaccination. Indeed the latter positivise the test, making non interprêtable in this direction.

The interpretation of a intradermoréaction is purely based on the size of the induration and not viewing a rash.

The intradermoréaction for tuberculosis is also called Mantoux test.

A chest x-ray search for signs radiological.

A search of contamination in the family and professional is essential.

Clinical signs
The symptoms are a low-grade fever (38-38,5 ° C) during the course, a cough sometimes accompanied by hemoptysis, a weight loss of 5 to 10 kg occurring in a few months and night sweats. A intradermoréaction (IDR) positive tuberculin. The risk factors are malnutrition, immunosuppression, intravenous drug abuse, lack of fixed abode, direct contact with infected persons and certain health professionals.

Signs radiological

* Radio chest: classically, reaching the apex (upper end of the lungs) with tuberculosis in advanced cave (cavities in the lung tissue, containing air and many BK, this bacterium is in effect aerobic). These caves do not disappear the healing they calcifient and produce radiological consequences once called "the lung blemishes."

Tuberculosis bone

* Spondylodiscite tuberculosis or sickness Pott
* Tumour white knee
* Spina ventosa

Tuberculosis lymph node

* Ganglion lymphatic Body ovalaire surrounded by a fibrous capsule in which it identifies as capsular lymphatic sinuses. Two separate zones are present:
o the cortical where differ lymphoid follicles,
o the bone marrow, little visible here, containing the vascular network.
* Injury In terms of cut, this node contains multiple nodular lesions corresponding to the follicles tuberculosis (Fig. a). Within a single node, several tuberculous lesions can be observed:
o Injury follicular (Fig. a): Focus rounded formed giant cells and cells épithélioïdes, surrounded by a crown of lymphocytes. The giant cells are cells plurinucléées, low abundant eosinophilic cytoplasm (Fig. b) (h). The cells are cells épithélioïdes elongated, the limits cytoplasmic poorly visible and the nucleus elongated shoe soles (Fig. b) (t).
o Injury caséofibreuse (Fig. c): Central eosinophilic necrosis anhiste: caseous necrosis (h) surrounded by a fibrous hull.
o Injury caséofolliculaire: Focus centered on a beach caseous necrosis, surrounded by cells épithélioïdes, giant cells and a crown of lymphocytes. The presence of bacilli Koch may be revealed on the coloration of Ziehl Neelsen (Fig. d)
* Dignostic Tuberculosis lymph node.

It is based on identification of the germ, either direct examination of a sample (sputum) under the microscope, after placing a culture of the same sample. The latter procedure is, however long (several weeks), thus delaying both the diagnosis. It allows a antibiogram (test of the sensitivity of seeds to different antibiotics).

The detection of certain genes of the mycobacterium after PCR amplification seems to be promising with a cost, however, more important.

TB can be caused by various germs:

* Mycobacterium tuberculosis (TB Koch), the most common
* Mycobacterium bovis
* Mycobacterium africanum
* Mycobacterium canetti (mainly in Djibouti)

The test tuberculin (intra-skin reaction) is injected under the skin a dose of the latter and view the presence or absence of allergic reaction (size of the papule) after 48 to 72 h. This test, however, is insensitive, especially in patients immuno-depressed, and few specific (patient vaccinated or been in contact with other mycobacteria).

The determination of strains resistant to the usual anti-tuberculosis is important to adapt the treatment. The planting of seeds identified in different environments rich in antibiotics (antibiotic) remains the reference method but may take several weeks for a response. The genetic probes to identify resistant strains directly in a very short time have been developed with a good sensitivity and specificity.

Treatment for TB
The treatment is for a period of six months for pulmonary tuberculosis sensitive to BK in a patient immunocompetent, including 2 months of quadri-antibiotic therapy (isoniazid pirilène rifampicin + + + ethambutol) and 4 months of dual therapy (isoniazid and rifampicin ).

* In 2006, WHO recommendations are to continue quadrithérapie for 6 months.

The long-term treatment is essential in order to cure disease and prevent the emergence of resistant strains whose development is often much more serious.

Isoniazid is generally used at a dose of 5 mg, in association with three other antibiotics. Isoniazid inhibits the multiplication of bacteria responsible for tuberculosis.

Rifampicin is used usually at a dose of 10mg/kg/jour, for a period of 6 months for treatment of tuberculosis. This antibiotic is a strong inducing enzyme: it accelerates the degradation of other drugs, including oral contraceptives. The women in contraceptives are invited to review their treatment up (after consulting gynecologist), or even to move a mechanical contraception (condoms ,...) for the duration of treatment. Rifampicin causes an orange colour of urine. It is a good way to objectify treatment adherence.

Streptomycin (discovered by Waksman to 1946) was the first antibiotic active against the bacillus Koch. It is against-indicated during pregnancy and must be combined with other anti-tuberculosis (INH and PAS).

* Dosage:
o For intramuscular adult: 15 to 25 mg per kg per day.
o By intrathecal: For adults, twenty-five hundred milligrams per day for a child, twenty to forty milligrams per kilogram per day to 2 or 4 injections.

* Monitoring of treatment: The hearing and kidney function should be monitored regularly.

The ethambutol be used in pregnant women.

* Dosage for adults: the morning on an empty stomach in a single dose, fifteen to twenty milligrams per kilogram. Do not exceed twenty-five milligrams per kilogram per 24 hours without exceeding 60 days, then reduce to fifteen milligrams per kilogram per day.
* Monitoring

Detection of cows with TB
To prevent transmission of the bacillus to humans either by air directly by contact or through the digestive tract after eating meat or milk inadequately cooked or pasteurized, most developed countries have undertaken to clean up their cattle population.

The detection carrier animals is through clinical research and allergic lesions suggestive on carcasses at the slaughterhouse. In France, this prophylaxis is mandatory since 1963 throughout the national territory for all cattle older than 6 weeks. For that animals can move without constraint, the herd must obtain the status of "officially free of tuberculosis. For this, all animals are tested regularly by intradermal. The frequency is annual but can be alleviated when the prevalence of the disease in the department is low.

The animals may be reacting tested compared with an avian tuberculin (to detect false positives), is sent to the slaughterhouse (culling is then subsidized) where lesions suggestive will be sought by a veterinary inspector, and eventually confirmed by diagnosis laboratory. The herds where the infection is confirmed can be a total slaughter, also subsidized.

Meanwhile, France, a network of 5 000 veterinary health monitors the appearance of clinical signs suggestive. Visits biennial health of all herds of cattle are required.

The BCG vaccination positivant the intradermal test, it is prohibited on the french territory.

This policy has resulted in a lower prevalence of bovine tuberculosis. In 2000, the European Commission acknowledged the France country status officially free. In 2006 the incidence rate was 0032% of infected herds when he was nearly 25% in 1955.

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