Tuberculosis (TB) is a chronic infectious disease usually caused by a bacillus called Mycobacterium tuberculososis (rarely by M. bovis). Pulmonary involvement accounts for 90% of all forms of disease presentation.
One third of the world’s population, some 1.8 billion people, are infected with TB bacilli, of which 30 million have the disease. There is a clear relationship between tuberculosis and poverty, the disease being considered as a cause of preventable death in poor countries, where only a quarter of the persones ill treated.
There are specific programs to detect and treat both internationally-carried-out by WHO and national levels, emphasizing the need to create special units to ensure the treatment, control and study of contacts of patients given that adherence to treatment is necessary for cure.
The mode of transmission of the disease is almost always by inhalation (exceptionally for digestive tract or skin).
Lack of ventilation and overcrowding favor the spread, and this increase in people living in the same room is exceptional contagion through sporadic contact.
Once produced the infection, the TB bacilli can remain dormant (asleep) or cause disease. Most clinical tuberculosis cases occur months or years after infection. Decreased immune defenses can reactivate tuberculosis that was dormant, pulmonary involvement being the most common.
For this reason, increasing the population where HIV (AIDS), constituting a diagnostic criterion of AIDS, and is also the most common opportunistic infection in people living with HIV virus.
General symptoms such as fatigue (tiredness), anorexia (loss of appetite), weight loss, fever and night sweats evening are the earliest, but given its insidious onset may go unnoticed.
Between respiratory symptoms, the most common is cough. Hemoptysis can also occur, but less frequently, and the toracalgia or dyspnea.
A 10% -20% of those infected are asymptomatic and are detected through contact tracing or by chance.
Tuberculosis infection should be ruled out in the presence of a cough that persists longer than three weeks, especially those most at risk groups, eg if immunosuppressed or crowding of people.
Sputum culture on Lowenstein-Jensen is the diagnostic certainty, but it takes between 2-8 weeks to get the result, so using other diagnostic methods such as sputum (direct microscopic examination) which is the method used for rapid diagnosis can obtain a probable diagnosis if accompanied by a clinical and / or radiological compatible.
The tuberculin skin test (Mantoux) consists of intradermal inoculation of purified protein derivative PPD called reading dermorreacción occurs between 48 and 72h later. TB infection is considered when the induration is greater than or equal to 5 mm (15 mm if there has been BCG). The tuberculin test does not distinguish between infection and disease. In both cases it requires a positive, although not coexist infection demonstrated clinical disease.
It is recommended to conduct this test in people who have not been exposed to the tuberculosis bacillus.
Other diagnostic methods include chest radiography and new techniques for nucleic acid amplification using gene probes and DNA chain reaction (PCR). The latter adopted to confirm the diagnosis before a positive smear and pending the results of cultures.
It is based on the administration of three antitubercular drugs over an extended period, typically 6 months.Use of three drug and duration of therapy due to development of resistance to individual bacillus administered drugs. HIV population in the treatment lasts until complete 9 months.
Treatment is initiated pending confirmation of sputum culture, when clinical, radiological and bacteriological suspect so.
Now, with this treatment, cure rates are achieved 96%
The most frequent cause of treatment failure is the lack of adequate compliance.
The treatment can be done at home if proper insulation is performed during the first 15 days of it.Generally, the patient can return to their jobs after 2 months.
It is important to follow monthly patient by the medical staff to assess the patient’s clinical status, potential medication side effects and compliance. It is advisable to smear and cultures become negative bimonthly and until the end of treatment, and chest radiography at two months and at the end of treatment.
There are two types of preventive treatment:
Preventive treatment of tuberculosis infection (primary prophylaxis). Treatment is based on people with PPD-, cohabiting with smear-positive patients, especially children and youth. If after 2 months of treatment, a new PPD is negative, treatment is stopped. In the case of occurrence of PPD +-injury in the absence of radiation-up treatment is maintained for 6 months.
Treatment of latent tuberculosis infection (secondary prophylaxis). It is based on the treatment of tuberculosis infection – PPD + and normal chest radiograph ante absence of disease, to prevent its occurrence. It lasts six months (12m in HIV) and is performed only once in life.
In both cases is to stop the epidemiological chain of tuberculosis.
BCG vaccination: Currently discouraged in developed countries, with an efficiency discussed. Consists of the administration of live attenuated bacteria, so it is contraindicated in immunocompromised and pregnant.
It may be useful in children and young people who are in contact with smear-positive chronic patients and among health care workers in frequent contact with TB patients or biological samples. In both cases, requires prior turberculina test negative.
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