Pulmonary tuberculosis is a bacterial infection that primarily affects the lungs, but may spread to other organs. It is a contagious disease as the bacteria gets transmitted through air. Inside the body it spreads to other organs from lungs through blood and lymph nodes.
TB develops in previously infected person when his immune system weakens, such as in people with HIV or elderly adults. Those with strong immune power do not develop symptoms, even though exposed to TB bacteria.
TB can remain in an inactive (dormant) state for years without causing symptoms or spreading to other people.
When the immune system of a patient with dormant (inactive) TB is weakened, the TB can become active and cause infection in the lungs or other parts of the body.
The risk factors for acquiring TB include close-contact situations, alcohol and IV drug abuse, and certain diseases (for example, diabetes, cancer, and HIV) and occupations (for example, health-care workers).
Inactive tuberculosis may be treated with an antibiotic, isoniazid (INH), to prevent the TB infection from becoming active.
Active TB is treated, usually successfully, with INH in combination with one or more of several drugs, including Rifampin , ethambutol, pyrazinamide, and streptomycin.
Drug-resistant TB is a serious, public-health problem, especially in Southeast Asia, and African countries.
In 15-20% of active cases, the infection spreads outside the respiratory organs, causing other kinds of TB. These are called as "extrapulmonary tuberculosis". It occurs more commonly in immunosuppressed persons and young children. In those with HIV, this occurs in more than 50% of cases.
Common extrapulmonary infection sites include the pleura (in tuberculous pleurisy), the central nervous system (in tuberculous meningitis), the lymphatic system (in scrofula of the neck), the genitourinary system (in urogenital tuberculosis), and the bones & joints (in Pott's disease of the spine), among others. When it spreads to the bones, it is also known as "osseous tuberculosis" a form of osteomyelitis.
A potentially more serious, widespread form of TB is called "disseminated" TB, commonly known as miliary tuberculosis. Miliary TB makes up about 10% of extrapulmonary cases.
Causes and risk factors:
Pulmonary tuberculosis (TB) is caused by the bacteria Mycobacterium tuberculosis (M. tuberculosis). It is transmitted by breathing in air droplets from a cough or sneeze of an infected person. This is called primary TB.
Most people, who develop symptoms of a TB infection, had got infected in the past. However, in some cases, the disease may become active within weeks after the primary infection.
The following people are at higher risk for active TB:
Elderly
Infants
People with weakened immune systems, for example due to AIDS, chemotherapy, diabetes, or certain medications
Frequent contact with people who have TB
Poor nutrition
Living in crowded or unhygienic conditions
Symptoms:
The symptoms of TB usually range from without symptoms (latent tuberculosis) to symptoms of active disease. Usually the patient remains unaware of a latent TB infection until it's revealed through a skin test.
Following are the symptoms of active disease:
Cough, at first with yellow or green mucus
Cough with bloody mucus later in the disease
Fatigue
Weight loss
Difficulty in breathing or wheezing
Fever
Sweating at night
Pain in the chest, back, or kidneys
Symptoms often improve in 2 - 3 weeks. The prognosis is excellent if pulmonary TB is diagnosed early and prompt treatment is available.
Complications:
Multi drug resistant tuberculosis
Pneumonia and other lung complications
Meningitis
Bone and joints affection can lead to pain, swelling and even arthritis
Painful urination
Weight loss
Retina in eyes can get affected and lead to defective vision
Investigations:
The complete clinical examination of Tb patient reveals:
Clubbing of the fingers or toes (in people with advanced disease)
Swollen or tender lymph nodes in the neck or other areas
Fluid around a lung (pleural effusion)
Unusual breath sounds (crackles)
Tests may include:
Tuberculin skin test (also called a PPD test)
Sputum examination and cultures
Interferon-gamma blood test such as the QFT-Gold test to test for TB infection
Chest x-ray
Chest CT scan
Bronchoscopy
Thoracocentesis
Biopsy of the affected tissue (rare)
Treatment:
The goal of treatment is to cure the infection with drugs that fight the TB bacteria. Treatment of active pulmonary TB consists of a combination of drugs such as:
Isoniazid
Rifampin
Pyrazinamide
Ethambutol
Streptomycin
Patient requires taking prescribed medicines as per instructions for 6 months or longer. It is very important to take the medicines regularly. This will prevent the TB bacteria to become resistant to medicines.
Necessary hygiene and sanitization measures should be taken to prevent others n near ones getting affected with TB.
Prompt treatment is extremely important in controlling the spread of TB from those who have active TB disease to those who have never been infected with TB.
Prevention:
TB is a preventable disease, even in those who have been exposed to an infected person. Skin testing (PPD) for TB is used in high risk populations or in people who may have been exposed to TB, such as health care workers.
Active tuberculosis (TB) is very contagious. The World Health Organization (WHO) estimates that one-third of the world's population is infected with the bacteria that cause TB.
Measures of prevention from an active TB infection include:
Do not spend long periods of time in crowded, enclosed rooms with anyone who has active TB until that person has been treated for at least 2 weeks.
Use protective measures, such as face masks, if someone works in a facility that cares for people who have untreated TB.
Those living with someone who has active TB, should always take precautionary measures like above and encourage the person to follow treatment instructions.
Some countries with a high incidence of TB give people a BCG vaccination to prevent TB. However, the effectiveness of this vaccine is limited.
