Tuberculosis (TB) is a contagious bacterial infection that primarily affects the lungs, but can spread to other parts of the body such as the brain, kidneys, liver, joints, bones and heart. It is most commonly transmitted through the air. Tuberculosis is common in areas with poor ventilation, unsanitary living conditions, and overcrowding. It strikes those with weak immune systems such children, the elderly, those with low body weight, diabetes and HIV infection. If tuberculosis is not treated, it can spread to other areas of the lungs or to other parts of the body.
More than one third of the world’s total population is infected by the tuberculosis bacteria. One in ten of those infected will have an active disease within his lifetime.
Latent tuberculosis infection
Not everyone who contracts the TB bacteria can get infected. Some individuals get exposed to the TB bacteria but do not get sick as the body fights off the bacteria. The TB bacteria remain dormant. This is called latent TB infection or silent primary infection . While there are no symptoms, one sign of infection is a positive result to a tuberculin skin test or tuberculosis blood test. Those with latent tuberculosis infection cannot spread the bacteria to others unless the bacteria becomes active and causes the carrier to get sick. Five to ten percent of those with latent TB infection develop the disease if they do not receive treatment.
People with active TB bacteria are infectious. Some people who have latent TB never manifest the disease, while others can get sick years later when resistance becomes weaker. The chances of the infection progressing to a disease are higher among those with weak immune systems, especially those affected with HIV. The dormant TB germs could be reactivated among those who experienced primary complex in childhood and whose immunity has lowered over the years. This is called secondary or reactivation tuberculosis .
Signs and Symptoms
- Chest pains
- Coughing up blood or sputum (phlegm in the lungs)
- Lack of appetite
- Night sweats
- Persistent coughing for two weeks or longer
- Significant weight loss
Patients with tuberculosis of the lymph nodes may experience enlargement of the glands resulting in spherical lumps in the neck. Those with tuberculosis of the intestines may experience diarrhea or constipation and abdominal pains. Those with tuberculosis of the brain may experience fever, nausea, seizures and possibly go into a coma.
People with latent tuberculosis infection do not experience any symptoms.
Causes and risk factors
Tuberculosis is caused by bacteria called Mycobacterium tuberculosis . When transmitted through the air via an infected person’s coughing, spitting, or sneezing in close contact, the tuberculosis germs can enter the patient’s body through the airway. People could breathe in the bacteria and get infected. Upon entrance through the airway, the tuberculosis germs can settle in the lungs and multiply. They can also move to other parts of the body via the bloodstream.
The elderly have a greater risk of getting tuberculosis because of aging or sicknesses that make their immune systems more vulnerable to the bacteria. Dormant bacteria for the elderly with the latent TB infection may reactivate and cause illness. Those with malnutrition also put an individual at greater risk of getting the disease.
Overall, those with weak immune systems may find it difficult to fight the TB bacteria. Lowered immunity can be caused by diseases like diabetes, HIV, kidney disease, and some cancers. Risk is also higher when an individual takes medication that suppresses the immune systems such as corticosteroids and chemotherapy medicine. Substance abuse can also lead to immune systems becoming more vulnerable to tuberculosis.
Close and frequent contact with someone infected with TB disease puts an individual at high risk of getting the bacteria. Health care workers who have regular contact with the sickly have a high chance of being exposed to the TB bacteria.
Individuals who live or work in places that are overcrowded, unsanitary and poorly ventilated are more prone to getting infected. Residential care facilities like prisons and nursing homes and refugee shelters are some examples.
When left untreated, tuberculosis can spread to other parts of the body and can even be fatal.
- Infection and damage of other body parts such as the kidneys, brain and bones
- Lung damage
- Meningitis - when TB infects central nervous system and the brain
- Military TB - when TB infects the whole body
- Obstruction of the intestines
- Pleural effusion – the fluid between the lungs and chest wall
- Pneumothorax - air between the lungs and the chest wall
- Severe pain and joint destruction - when TB infects the bones
Diagnosis and tests
Once an individual is suspected to have diagnosed tuberculosis, the doctor will require a complete medical evaluation and a series of tests for TB infection.
Tuberculin skin test (TST)
The tuberculin test is the most commonly used diagnostic tool. This is a skin test where a small amount of the TB vaccine is injected into the skin. The test is read within 48 to 72 hours. Swelling at the injected site may indicate infection, whether latent or progressive. Negative tests results do not indicate the absence of TB however. Some individuals infected with the TB bacteria have a delayed or no response to the skin test.
TB blood tests
Blood tests such as the QuantiFERON®-TB Gold test (QFT-G) , QuantiFERON®-TB Gold In-Tube test (GFT-GIT) , and T-SPOT® measure how the immune system reacts to the bacteria that causes tuberculosis. These tests have higher accuracy than the skin test.
Further testing may be required if results for TB infection are positive. These tests may include a chest x-ray, which can expose nodules or cavities in the lungs caused by active tuberculosis germs. Samples of sputum or stomach secretions may also be taken for TB bacteria testing.
Tuberculosis needs effective treatment to prevent complications. Individuals with the latent TB infection are prescribed treatment to prevent the bacteria from becoming active. One medicine taken to treat latent TB infection is Isoniazid (INH), which kills TB bacteria in the body. Those with active TB disease will require more aggressive treatment. Several anti-tuberculosis drugs such as streptomycin, rifampicin, pyrazinamide, and ethambutol may be taken over a course of six to twelve months. These drugs may cause side effects. It is essential that these individuals take the prescribed course of medicine as instructed. Incorrectly taking the drugs, such as stopping medication too soon, may cause them to develop drug-resistant tuberculosis.
The Bacillus Calmette-Guérin (BCG) vaccine is the only available vaccine for tuberculosis. It is given to babies at birth. A booster dose may be given at 12 or 16 years old. While BCG does not prevent infection, it reduces the risk of tuberculosis progressing to a disease.
Tuberculosis in the Philippines
Among the 22 countries that account for 80% of tuberculosis worldwide, the Philippines is ranked number 15. Tuberculosis is the 6th greatest cause of illness and death in the Philippines. In 2007, an estimated 100 Filipinos died each day from the disease.
The Department of Health (DOH) prescribes the Directly Observed Therapy – Short Course (DOTS) , an internationally recognized strategy endorsed by the World Health Organization (WHO) and the International Union Against Tuberculosis and Lung Disease (IUATLD).
DOTS requires “political commitment with increased and sustained financing, case detection through quality-assured bacteriology, standardized treatment with supervision and patient support, effective drug supply and management system, monitoring and evaluation system and impact measurement.”
DOTS services are accessible for free in selected government hospitals, rural and urban health units, and health centers around the country.
- CDC Media Statement: Addressing the Threat of TB Drug-Resistance Worldwide. Centers for Disease Control and Prevention. (Accessed 23 November 2010)
- WHO | 10 facts about Tuberculosis. World Health Organization. (Accessed 23 November 2010)
- Screening: Primary Care for the Management of TB. EthnoMed. (Accessed 23 November 2010)
- Tuberculosis: Latency and Reactivation --- Flynn and Chan 69 (7): 4195. Infection and Immunity. (Accessed 23 November 2010)
- Tuberculosis of Lymph Nodes. Canadian Medical Association Journal. (Accessed 23 November 2010)
- http://pneumonologia.gr\articlefiles\20070307_abdominal_TBC.pdf Abdominal tuberculosis.] Pneumonologia. (Accessed 23 November 2010)
- TB meningitis. Meningitis Research Foundation. (Accessed 23 November 2010)
- Pleural Effusion. National Lung Health Education Program. (Accessed 23 November 2010)
- Spontaneous pnuemothorax and tuberculosis. Long-term follow-up. National Center for Biotechnology Information. (Accessed 23 November 2010)
- CDC Issues Guidelines on Use of QuantiFERON TB Gold Test. Medscape. (Accessed 23 November 2010)
- Recently-approved Devices T-Spot TB. U.S. Food and Drug Administration. (Accessed 23 November 2010)
- BCG Vaccine. Centers for Disease Control and Prevention. (Accessed 23 November 2010)
- Tuberculosis in Countries. Stop TB Partnership. (Accessed 23 November 2010)
- Infectious Diseases, Tuberculosis, Countries, Philippines. USAID Health. (Accessed 23 November 2010)
- Pursue high-quality DOTS expansion and enhancement. World Health Organization. (Accessed 23 November 2010)