Tuberculosis

Original Editors -Lori McGarrh from Bellarmine University's Pathophysiology of Complex Patient Problems project.

Top Contributors - Lori McGarrh, Kim Jackson, Lucinda hampton, Admin, Arnold Fredrick D'Souza, Elaine Lonnemann, Nupur Smit Shah, 127.0.0.1, Laura Ritchie, Wendy Walker, Naomi O'Reilly, WikiSysop and Shaimaa Eldib  

Definition/Description

Mycobacterium Tuberculosis

Tuberculosis (TB) is an inflammatory, infectious disease that is spread by bacteria called mycobacterium tuberculosis. Pulmonary tuberculosis is a systemic disease that most commonly affects the lungs. Eventually, the TB could spread to other organ systems, which it then becomes extrapulmonary tuberculosis. TB can be placed into the following two categories:  

• Primary Tuberculosis (Dormant or Latent) – Although a person’s body can be infected with mycobacterium tuberculosis, they may not be showing clinical signs and symptoms. Most people have healthy immune systems that will never allow TB to take over their bodies.
• Secondary Tuberculosis (Active) – This will develop after the immune system of a person is lowered. Reinfection will occur and the person will start to show clinical signs and symptoms.

Prevalence

Before the 1940’s, tuberculosis was the leading cause of death in the United States. With the advancement of drug therapy, scientific and public knowledge, improvement in public health and general living standards, there was a large decline in the incidence of TB. However, immigrants started migrating from third world countries, the number of homeless people started to rise, people having prolonged lifespans, and the increase of the population with HIV resulted in an increase of TB in the mid 1980’s. Between 1985-1992, there was a 20% increase in new cases in the United States. The U.S. is just now beginning to see a decline in TB rates.

There were 11,545 tuberculosis cases in the United States that were reported to the Center for Disease Control in 2009. This is estimated to be around 3.8 cases per 100,000 people. This has been the lowest rate reported since 1953, which is when national reporting began. In 2007, the United States reported 544 deaths from Tuberculosis. 

The TB rate in foreign-born persons in the United States (18.7 cases per 100,000 persons) was approximately 11 times greater than that of U.S.-born persons (1.7 cases per 100,000 persons) in 2009. In 2009, approximately 59% of all TB cases in the United States occurred in foreign-born persons, unchanged from 2008.

Although the rates are declining in the United States, TB is still a worldwide epidemic. The highest rates of TB can be found in Southeast Asia, sub-Saharan Africa, and eastern Europe. There are about 200 to 400 cases per 100,000 each year.

Statistics

• One-third of the nation’s population is infected with TB.
• Each year, about 9 million people worldwide are infected with TB
• There are approximately 2 million worldwide deaths each year from TB.
• TB is the most prevalent killer of people who are infected with HIV.

Rates of TB for Different Racial and Ethnic Populations

• American Indians or Alaska Natives: 4.3 cases per 100,000 persons
• Asians: 23.3 cases per 100,000 persons
• African Americans: 7.6 cases per 100,000 persons
• Native Hawaiians and other Pacific Islanders: 16.7 cases per 100,000 persons
• Hispanics or Latinos: 7.0 cases per 100,000 persons
• Whites: 0.9 cases per 100,000 persons

Characteristics/Clinical Presentation

There are usually no symptoms of tuberculosis during the first year of exposure. This is when the disease would be the most curable. Symptoms suggestive of TB include: 

• Productive cough that lasts longer than 3 weeks
• Weight Loss
• Fever
• Night sweats
• Fatigue
• Malaise
• Anorexia
• Rales could be heard in the lobes of involvement in the lungs                     
• Bronchial Breath Sounds                                                                       
• Dull chest pain, tightness, or discomfort  
• Dyspnea
• Haemoptysis (late-stage symptom)

Associated Co-morbidities

• HIV/AIDS - due to comprised immunosuppressive system
• Rheumatoid Arthritis - due to immunosuppressive treatments
• Diabetes Mellitus
• End-stage Renal Disease
• Gastrointestinal Disease
• Alcoholism
• Cancer - due to chemotherapy, radiation, or steroid therapy
• Malnutrition
  

Other Risk Factors

• Healthcare workers
• Older adults
• Homeless people
• Overcrowded housing
• People who are incarcerated
• Immigrants
• Kids under the age of 5

Medications

Once tuberculosis is diagnosed, all active cases are treated and many inactive cases are treated. It is unclear if preventive treatment is helpful in people with latent TB. However, it is hoped that the disease will be less likely to become active later in life once the immune system is more likely to be compromised.

There are currently 10 drugs that are approved by the FDA to treat TB. The following medications are first-line anti TB agents that form the core medications given:

• Isoniazid
• Rifampin
• Pyrazinamid
• Ethambutol

The recommended time for taking the meds is 6-9 months. Blood work should be performed monthly to check on the liver and make sure it is handling the medicine okay.

Unfortunately, many people are not compliant with taking their medicine daily for 9 months. Many people will begin to feel better, so they will decide to stop administering the medicine. Compliance is also a problem with homeless people, alcoholics, and drug users. If treatment is not completed, multidrug-resistant TB can form which means the person will now be resistant to the medication taken previously. Multi-drug resistant TB has an even more complicated treatment than before. Some people require a pneumonectomy or chemotherapy along with two or more drugs that are used at the same time. Directly Observed Therapy (DOT) should always be used when treating multi-drug resistant TB to ensure the subject is practicing proper compliance. Treatments are the same for pulmonary and extra-pulmonary TB.

BCG Vaccine 

The Bacille Calmette-Guerin vaccine was created in 1921.  Many more strains have been developed over time. This vaccine is very controversial and its ability to protect individuals from TB has not been validated. It is used widely in foreign countries with high rates of tuberculosis. It is rarely used in the United States, and should only be given to someone after serious discussion with one's MD. This vaccine is not recommended as a way to control TB. The vaccine is problematic because:

• It has not been tested on people with immunosuppressed systems
• It has not been shown to protect adults from pulmonary tuberculosis
• It can give a false positive to the skin test, which makes it difficult to tell if someone really has TB
• It should not be used on women who are pregnant
• Many of the clinical trials have only been used on children

The following statistics have been proven by the Advisory Council for the Elimination of Tuberculosis:

• Two controlled trials that used the Tice vaccine demonstrated rates of protective efficacy ranging from zero to 75%.
• Case-control studies using different BCG strains indicated that vaccine efficacies ranged from zero to 80%.
• In young children, the estimated protective efficacy rates of the vaccine have ranged from 52% to 100% for prevention of tuberculous meningitis and miliary TB.
• The estimated protective efficacy rates of the vaccine range from 2% to 80% for prevention of pulmonary TB.

The CDC and the American Academy of Paediatrics recommend that all children adopted from high-risk countries who have received the BCG vaccine should act as if they have never received it. All children should be given a skin test and treated whether it is dormant or active.
Diagnostic Tests/Lab Tests/Lab Values

The Mantoux tuberculin skin test is performed by having 0.1ml of tuberculin purified protein derivative (PPD) injected into the inner layer of the forearm. This will determine if the body’s immune response has been activated by the presence of the bacillus. Upon injection, the skin will elevate around 6-10 mm in diameter. 48 to 72 hours later, the person should have their skin test reaction read. A positive test could reveal a palpable, swollen, hardened, or raised area that should be measured in millimetres. Redness is not measured.

                               

                                                               Mantoux Tuberculin Skin Test

How Are TST Reactions Interpreted?

Skin test interpretation depends on two factors:

• Measurement in millimetres of the induration
• Person’s risk of being infected with TB and of progression to disease if infected

Classification of the Tuberculin Skin Test Reaction

An induration of 5 or more millimeters is considered positive in:	An induration of 10 or more millimeters is considered positive in:	An induration of 15 or more millimeters is considered positive in:
HIV infected persons	Recent immigrants (< 5 years) from high-prevalence countries	any person, including persons with no known risk factors for TB. However, targeted skin testing programs should only be conducted among high-risk groups.
Recent contact of a person with TB disease	Injection drug users
Persons with fibrotic changes on chest radiograph consistent with prior TB	Residents and employees of high-risk congregate settings
Patients with organ transplants	Mycobacteriology laboratory personnel
Persons who are immunosuppressed for other reasons (e.g., taking the equivalent of >15 mg/day of prednisone for 1 month or longer, taking TNF antagonists)	Persons with clinical conditions that place them at high risk
	Children < 4 years of age
	Infants, children, and adolescents exposed to adults in high-risk categories

A positive reaction to the test is indicative of tuberculosis in the body. However, the test does not reveal if the TB if dormant or active. Other diagnostic tests (e.g. chest x-ray, sputum sample) should be used to identify active tuberculosis.

                               

                                                         [Photo Courtesy of Sao Paulo Medical Journal]

Aetiology

Tuberculosis is spread by airborne particles known as droplet nuclei. Droplet nuclei are spread when infected people sneeze, laugh, speak, sing, or cough. In order to contract this disease, a person has to have prolonged exposure with an infected person in an enclosed space. It is suspected that there could be a genetic component to susceptibility and resistance, but that has yet to be proven. In other countries, it is common for bovine TB to be spread through unpasteurised milk and other dairy products due to cattle with tuberculosis.

The reason the bacteria is able to be dormant in someone for years is it is capable of surviving for months in sputum that is not exposed to sunlight. It becomes trapped within the body (primary TB). Once the person’s resistance is lowered, the TB can become active (secondary TB). This could be due to advancing age, alcoholism, cancer, or immunosuppression.

Systemic Involvement

10%-15% of tuberculosis is extra-pulmonary. It can spread through the blood vessels from organ to organ and/or the lymphatic system. Extra-pulmonary TB can involve the: 

• Kidneys
• Bone Growth Plates
• Lymph Nodes
• Meninges
• Hip Joints - can cause avascular necrosis of the hip
• Elbows
• Vertebrae (Pott's Disease)
  

Pott's Disease

In Pott's Disease, the infection usually begins in the body of the vertebrae. It can then spread to the intervertebral discs and to the adjacent vertebrae. As the infection continues to spread throughout the spine, the following problems can occur:

• Irritation of the nerve roots
• Pressure from the abscess - can produce hip pain if the abscess goes to the psoas muscle
• Collapse of the vertebral body - can cause cord compression and possible paraplegia
  

Miliary Tuberculosis

This occurs when TB spreads throughout the body. It is more common for this to present in adults over the age of 50 and children with weakened or unstable immune systems.

Medical Management

Treatment does not differ for pulmonary and extra-pulmonary tuberculosis.  The same medications are used in both cases (see medications).  Sometimes decompressive surgery is needed if someone has Pott's Disease.

Physical Therapy Management

All physical therapists should be aware of the proper personal protective equipment (PPE) that should be worn.  There is a specialised mask that is worn that has been sized to specifically fit your face.

Pulmonary Tuberculosis

People with pulmonary TB are typically not treated in physical therapy because medications are vital for curing TB.  However, therapists are able to provide percussion and postural drainage to clear secretions out of the lung.

Extrapulmonary Tuberculosis

Clients with extra-pulmonary TB are usually not seen in the physical therapy setting.  However, patients may present in clinic with musculoskeletal problems with unknown causes or arthritic pain.  PT's should be prepared to take a thorough history and a proper examination in order to better identify TB.  A patient could also be seen in physical therapy if they have had surgery on their back, in which case the normal rehabilitation protocols would be followed.

It is very important to take a thorough history when TB is suspected.  It is important to ask if the person has travelled outside the country recently, their occupation, or if there is any way they have possibly been exposed to someone who could have TB.  Recognize your patient's signs and symptoms.  Palpation of the lymph nodes could also be informational during an examination. 

Differential Diagnosis

• Chronic Bronchitis
• Bronchiectasis
• Atelectasis
• Pneumonia
• Influenza
• Arthritis (Extrapulmonary)

Case Studies

• Jha A, Shojania K, Saint S. Forgotton but not gone. The New England Journal of Medicine. June 3, 2004; 350(23):2399 - 2405.
• Flynn, J. Immunology of tuberculosis and implications in vaccine development.  Tuberculosis. 2004;84(1):93-101.
• Brudney K, Dobkin J. Resurgent tuberculosis in New York City. Human immunodeficiency virus, homelessness, and the decline of tuberculosis control programs.  The American Review of Respiratory Disease. 1991;144(4):745-749. 
• Corbett, EL, Watt, CJ, Walker, N, Maher, D; Williams, BG, Raviglione, MC, Dye, C. The Growing Burden of Tuberculosis:
  Global Trends and Interactions With the HIV Epidemic. Archives of Internal Medicine. 2003;163:1009-1021.
• Colditz, GA, Brewer, TF, Berkey, CS, Wilson, ME, Burdick, E, Fineberg, HV, Mosteller, F. Efficacy of BCG Vaccine in the Prevention of Tuberculosis. The Journal of the American Medical Association.1994;271(9):698-702.