The symptoms of lung tuberculosis include shortness of breath, chest pain, loss of appetite, fever and night sweats. Additional symptoms include a cough with cloudy, thick and bloody mucus that lasts for more than two weeks. The signs of active lung tuberculosis start and develop gradually, and some people may not know they have the disease, according to WebMD.
Lung tuberculosis occurs when a person inhales the bacteria that cause the disease, called Mycobacterium tuberculosis, into the lungs. At the initial stage of infection, called latent tuberculosis, the bacteria remain in the lung and do not spread to other body tissues or people, and the infected person has mild symptoms, notes WebMD. This is especially true for individuals with healthy immune systems. If the immune system becomes weak, the bacteria grow, causing the infection become active. About 5 to 10 percent of patients experiencing latent tuberculosis are likely to develop active tuberculosis.
Active lung tuberculosis is contagious and spreads through coughing, singing, laughing or sneezing, states WebMD. The elderly, small children, smokers and individuals whose immune systems are weak have high chances of developing this disease, says Healthline. If active lung tuberculosis remains untreated, it can cause bleeding in the lungs and block airways, leading to difficulty breathing, according to WebMD.