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Tuberculosis
Tuberculosis
 TB is a common
infectious disease caused
by the bacterium
Mycobacterium
tuberculosis.
 The bacteria usually
affects the lungs but it
can attack any part of the
body.
 If not treated properly,
TB can be fatal
History of TB
TB has affected humans for
millennia
Historically known by a
variety of names, including:
Consumption
Wasting disease
White plague
TB was a death sentence for
many
History of B
 Before TB antibiotics, many patients were sent to
sanatoriums
 Drugs that could kill TB bacteria were discovered in
1940s and 1950s
 TB death rates in U.S. began to drop dramatically
 Most TB sanatoriums in U.S. had closed by the mid
1970s
History of TB
 Increase in TB in mid
1980s
 Contributing factors:





Inadequate funding for TB
control programs
HIV epidemic
Increased immigration from
countries where TB is
common
Spread in homeless shelters
and correctional facilities
Increase and spread of
multidrug-resistant TB
Symptoms
 A bad cough that lasts 3 weeks or longer
 Pain in the chest
 Coughing up blood or sputum
 Weakness or fatigue
 Weight loss
 No appetite
 Chills
 Fever
 Sweating at night
Transmission
 TB is spread person to
person through the air
via droplet nuclei
 M. tuberculosis may
be expelled when an
infectious person:




Coughs
Sneezes
Speaks
Sings
 Transmission occurs
when another person
inhales droplet nuclei
Transmission
 Probability that TB will be transmitted depends on:

Infectiousness of person with TB disease

Environment in which exposure occurred

Length of exposure

Virulence (strength) of the tubercle bacilli
 The best way to stop transmission is to:
 Isolate infectious persons
 Provide effective treatment to infectious persons as soon
as possible
Treatment
 A person with active TB




disease has a large amount of
TB bacteria in the body.
TB disease can be treated by
taking several drugs for 6 to
12 months.
It is very important that
people who have TB disease
finish the medicine
If the drugs are not taken
correctly, the germs that are
still alive may become
resistant to those drugs.
TB that is resistant to drugs is
harder and more expensive to
treat.
Directly Observed Therapy, Short course
 DOTS is the internationally recommended strategy for
TB control that has been recognized as a highly efficient
and cost-effective strategy. DOTS comprises five
components:





Sustained political and financial commitment
Diagnosis by quality ensured sputum-smear microscopy
Standardized short-course anti-TB treatment (SCC) given under
direct and supportive observation (DOT).
A regular, uninterrupted supply of high quality anti-TB drugs.
Standardized recording and reporting
 DOTS costs only US $3 - $7 for every healthy year of life
gained.
LTBI vs. TB Disease
Latent TB Infection (LTBI)
TB Disease (in the lungs)
Inactive, contained tubercle bacilli in
the body
Active, multiplying tubercle bacilli in
the body
TST or blood test results usually
positive
TST or blood test results usually
positive
Chest x-ray usually normal
Chest x-ray usually abnormal
Sputum smears and cultures negative
Sputum smears and cultures may be
positive
No symptoms
Symptoms such as cough, fever,
weight loss
Not infectious
Often infectious before treatment
Not a case of TB
A case of TB
Multidrug Resistance Tuberculosis (MDR TB)
 Caused by M. tuberculosis
organisms resistant to at
least one TB treatment
drug
Isoniazid (INH)
 Rifampin (RIF)
 Pyrazinamide (PZA)
 Ethambutol (EMB)

 Resistant means drugs can
no longer kill the bacteria
Resistance
Resistance
Description
Mono-resistant
Resistant to any one TB treatment drug
Poly-resistant
Resistant to at least any 2 TB drugs (but
not both isoniazid and rifampin)
Multidrug resistant
(MDR TB)
Resistant to at least isoniazid and
rifampin, the 2 best first-line TB
treatment drugs
Extensively drug resistant
(XDR TB)
Resistant to isoniazid and rifampin,
PLUS resistant to any fluoroquinolone
AND at least 1 of the 3 injectable
second-line drugs (e.g., amikacin,
kanamycin, or capreomycin)
How does drug resistance happen?
 Resistance to anti-TB drugs can occur when these




drugs are misused or mismanaged.
When patients do not complete their full course of
treatment
When health-care providers prescribe the wrong
treatment, the wrong dose, or length of time for
taking the drugs
When the supply of drugs is not always available
When the drugs are of poor quality.
TB and HIV
 Worldwide, TB is a leading cause of death among
persons infected with HIV
 The epidemics drive and reinforce one another: HIV
activates dormant TB in a person, who then becomes
infectious and able to spread the TB bacillus to
others
Epidemiology
 TB is one of the leading causes of death due to infectious
disease in the world
 Almost 2 billion people are infected with M. tuberculosis
 Each year about:

9 million people develop TB disease

2 million people die of TB
People at risk for tuberculosis infection
 Close contacts of people
 Health care workers who
 Foreign-born persons
 Racial and ethnic
infected with TB
 Low-income groups and
homeless persons
serve high-risk groups
minorities
 Infants, children, and
adolescents
 Individuals who live
and/or work in special
settings
 People who inject drugs
Worldwide TB incidence rates, 2000