week 11- TB Flashcards
Prevalence
WHO reports there were 9.2 million new cases of TB in 2006
1600 new cases reported in Canada each year
Kills more people worldwide than any other infectious disease
Between 19% and 43% of world’s population estimated to be infected
TB did not disappear by 2000 as anticipated
Multidrug-resistant strains of M. tuberculosis
Who is at Risk?
• Immunocompromised Patients
HIV
o Organ transplants
o Lung disease
o Chronic kidney failure requiring dialysis
o Cancer of the head and neck
o Taking glucocorticoids or TNF-alpha inhibitors (eg: for RA)
o Diabetes
• Previous infection with TB bacteria within the past two years
• CXR showing signs of old TB
• Being underweight (BMI equal to or less than 20)
• Being under five years of age when first infected
• Cigarette smoking (one ppd or more)
• ETOH intake greater than 3 drinks/day
Spread via airborne droplets when infected person
Coughs
Speaks
Sneezes
Sings
Tuberculosis involves
usually lungs lymph nodes kidneys brain and spinal cord bones and joints intestines
Bacteria can stay in the air for hours *brief exposure rarely causes infection
Infectiousness directly related to the number of infected droplet nuclei in the air
Body’s immune system may kill the TB bacteria
If not, they can remain alive but inactive in your body= Latent TB Infection
If TB becomes active = Active TB Disease
Symptoms present with active disease and it is transmissible
TB Transmission
- TB is not easily transmitted. Household and non-household contacts sought. Highest priority: household contacts, children under 5 and immunocompromised
- People have a higher risk of developing active TB disease within the first two years of getting latent TB infection.
- Contacts who have been infected will be offered treatment of latent TB infection to help their immune system fight the infection and reduce their risk of developing active TB disease
- Infectiousness usually rapidly declines with effective treatment but may vary person to person*
Higher Risk of infection with:
Overcrowding
Poor ventilation
Longer exposure
Closer proximity
Etiology and Pathophysiology
• Spread
o Inhaled bacilli pass down bronchial system and implant themselves on bronchioles or alveoli
o Multiply with no initial resistance
o Replicates slowly and spreads via the lymphatic system
Clinical Manifestations
Early stages are usually free of symptoms
Fatigue Malaise Anorexia Cough longer than 2 weeks Weight loss Low-grade fevers Night sweats Sputum Hemoptysis
clinical manis- Cough becomes frequent
o Produces mucoid or mucopurulent sputum
o May have dull or tight chest pain
o Hemoptysis is not common and is usually associated with advanced disease
Acute symptoms
o High fever * not typical-usually low grade fever o Chills o Generalized flu-like symptoms o Pleuritic pain o Productive cough
Steps in Diagnosing Active TB
• Complete hx and physical exam
o S &S?
o Exposure to active TB?
o History of latent or active TB?
o Risk factors? (includes travel to endemic areas)
• CXR
• Sputum AFB and C&S (ID strain and determine abx resistance)
Diagnosing Latent TB
- Mantoux or TB skin test
- Reaction measured by HCP 48 to 72 hours after test
- If no reaction or not positive at 48 hrs, check at 72 hrs
- Measured in mm and interpreted as ‘positive’ or ‘negative’
- > 10mm is positive
- > 5mm may be considered positive in patients with HIV