Whether it is a long-lasting cough, fever or weight loss, people who suffer from “consumption” literally waste away, until they succumb out of weakness to the disease. Therefore, early detection of the disease, either through clinical diagnosis of the symptoms, radiography (x-rays), analysis of sputum samples, or other diagnostic methods, is of utmost importance.
The most common symptoms include increased body temperature, fatigue, chills, weight and appetite loss as well as night sweats. Another potential indicator of tuberculosis is an ongoing, productive cough with phlegm (mucus or yellowish-green sputum) for more than two weeks. If the infection spreads beyond the lungs, the symptoms will depend upon the organs involved. However, the TB infection could also be asymptomatic, where TB patients may display no symptoms at all, which could significantly complicate the diagnosis.
Tuberculosis is diagnosed most commonly through x-ray images and a bacteriologic sputum sample examination. X-ray images can display the inflammation points, i.e. the infiltrates or consolidations and/or cavities (“punctures”), in the lungs seen generally as opacification or bright spots particularly well (see images below). In a sputum sample examination, the sputum is chemically treated so that any potentially present bacteria appear visibly reddish-colored under a microscope. Since a larger amount of bacteria are necessary for this purpose, at times bacterial cultures are also bred in developed countries to determine whether TB bacteria are potentially present in a low density. However, as the breeding of cultures is both cost- and time-consuming – the process usually takes 3 to 4 weeks – it is often skipped in developing countries.
A tuberculin skin test or Mantoux test is often used to determine whether TB pathogens are present in the body as in the case of a latent infection. For this test, tuberculin is introduced into the skin. If a reddish reaction of generally about 10mm in diameter or more surfaces, it suggests that mycobacteria, which includes the TB bacteria, may be present in the body. Non-tuberculosis bacteria and an earlier BCG vaccination can also cause a reaction.
Recently, new technologies such as the GeneXpert system and the PCR assay process have enabled laboratories to detect TB infections – even drug-resistant forms – in less than two hours. However, these systems are still very new and expensive, so their use is not widespread.
For closed cases of tuberculosis, the diagnosis is extremely difficult and often only then based on clinical diagnosis by a doctor and empirical antibiotic treatment.
Read more in the next section about how the disease is treated.