October 9, 2013
Tuberculosis Transmission - Only respiratory forms (pulmonary, bronchial, laryngeal) are contagious: Mycobacterium tuberculosis is transmitted by air through secretions emitted by a person with infectious tuberculosis (see & 1.3), coughing, spitting or sneezing.Extra-pulmonary forms are not contagious.
TB is less contagious diseases like flu transmission usually requires prolonged contact in confined spaces, such as living in the same dwelling as the infectious person, depends on the degree of infectiousness and the duration of contact and the thereof.
These conditions explain that all people in contact with a case of tuberculosis are not systematically infected: about 30% of highly exposed to infectious TB infected people. Furthermore not all develop TB disease (see & 1.3).
Disease and latent TB infection (LTBI)
Once in the body, in 90% of cases, the tubercle bacillus remains quiescent and does not cause disease is latent TB infection (LTBI).
TB disease develops in about 10% of cases.
Latent TB infection (LTBI)
in 90% of cases of TB disease does not develop: The latent TB infection is the result of a balance between the immune system of the infected person and bacteria. The infected person is not sick, has no symptoms and is not contagious.
Approximately 10% of infected persons will develop TB disease during their lifetime. This risk decreases with time: it is most important during the two years following infection. (5% of infected people develop TB disease in the two years following infection, the remaining 5% will develop beyond two years later). This risk is especially important in children and people with weakened immunity.
Occurring several months to several years (in more than half the cases in 2 years) after infection, TB disease most frequently affects the lungs (pulmonary form) but it can also more rarely reach of other organs spread of bacilli: it is called extra-pulmonary tuberculosis (lymph node, bone / joint or subarachnoid example).
Only pulmonary tuberculosis is contagious.
The general symptoms of tuberculosis are not specific: it may be a fever, weight loss, night sweats. Symptoms of pulmonary tuberculosis typically include cough, chest pain, occasionally coughing up blood. Symptoms of TB depend on other locations of the affected organs.
Untreated tuberculosis disease progresses, can cause death. It heals when effective treatment is properly followed to completion. Non-treatment or poorly followed induce the development of resistance to antituberculosis drugs.
TB disease in all cases and latent tuberculosis infection in children under 15 years are among the notifiable diseases in France report