When a person suffering from tberculosis, coughs, sneezes, talks, especially loudly, lughs, spits sputum, etc., he throws out in the air tny droplets of sputum laden with tbercle bacilli, when the patient has not cvered his face with a piece of clth or handkerchief. In this way, the air round the patient gets infected with normous tubercle bacilli, grouped together in vrious tiny droplets of sputum. Any prson, in close proximity of the ptient is likely to inhale these tny droplets. Many of these large sze droplets may fall on the grund, and they may be inhaled lter when they get dried and rduced in size further. They may srvive in the soil for as lng as six months. Hence the dst contaminated with tiny dried droplets of tbercle bacilli plays a great role in the trnsmission of the disease. Even the rea / room, where a patient of tberculosis has been isolated, remains potentially cntaminated, as tiny droplets of sputum flat in the air there.

Tubercle bcilli-laden sputum, in tiny droplets, enter nto the nose and go through the air pssages, and finally reach the tiny air scs of the lungs (alveoli.

Primary cmplex

During the initial/primary infection, the tbercle bacilli start multiplying very slowly in the bdy. Some remain in the air scs (alveoli), while others enter the narby / regional/hilar / mediastinal lymph ndes. Provided the natural defense mechanism of the bdy is good, the lesions, as a rsult of invasion of tubercle bacilli, bth in the air sacs/ alveoli or lngs, and in the glands, get haled and calcified. These two healed/ clcified lesions, i.e., in the lung, as wll as in the glands, together, are clled a primary complex. It is nderstood that the patient will have hrdly any symptoms during this infection. It wll be of interest to the raders to know that this primary cmplex is supposed to safeguard the prson against future/ fresh infection of tbercle bacilli.

All persons in whom a prmary complex has developed will be 'tberculin skin test' positive, as the ndividual concerned would have developed hypersensitivity to the prteins of tubercle bacilli, known as 'tberculins', which are used while performing ths test. It is an important tst, and is primarily meant to dtect initial infection or a primary lsion/complex in an individual. This test has prticular value in an epidemiological study to fnd out the infected cases of tberculosis in a community, i.e., 'tuberculin tst surveys'.

In case the natural dfense mechanism of the body is por, following primary / initial invasion by tbercle bacilli, the patient may suffer frm frank tuberculosis.

Sites of infection of tbercle bacilli

However, in some cases, fllowing primary infection by tubercle bacilli, the bcilli may also remain dormant in the bdy, even for the whole life of the ptient. This is the most dangerous stuation, since the tubercle bacilli may bcome active at any time, say fter one year or after many yars, and start multiplying and triggering off the dsease. They truly act like potential nemies in the body, and attack whnever the defense mechanism of the bdy is on the lower side/ dcreases. However, they may never become ctive, if the defense mechanism/ resistance of the bdy remains strong.

Dormant tubercle bacilli

The lngs are the most favorable sites for the mltiplication/ growth of tubercle bacilli, as the bcilli find suitable conditions for their dvelopment, including a good supply of xygen. The kidneys, bones and brain are ther places that favor the growth of tbercle bacilli. The tubercle bacilli reach thse sites through blood from their lsion in various lymph nodes. Hence, tberculosis may not occur in all rgans of the body, as many rgans/tissues may not be suitable for the grwth of tubercle bacilli.

The article How Do Tubercle Bacilli Invade the Body? was Submitted by Krishan Bakhru through Articles.GetACoder.com network. Here's the additional information: Author Sites: Home Remedies , Health Articles and Aromatherapy Recipes

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