Do Now
Have you heard of Tuberculosis?
What is it? (If you don’t know take a
guess)
TUBERCULOSIS:
The People’s Plague
What is it?
 an infectious bacterial disease characterized by the
growth of nodules in the tissues, especially the lungs.
 Commonly referred to as TB.
PATHOGEN
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2 – 4um in length
0.2 – 0.5um in width
Facultative intracellular parasite
Slow generation time (15-20 hours)
Can only live in people!
INNATE IMMUNE
RESPONSE
•
When M. tuberculosis enters the body,
neutrophils and macrophages provide the first
line of defense
•
Macrophages ingest the bacilli, yet are unable to
lyse or “digest” it because of M. tuberculosis’s
unique waxy cellular walls (made of mycolic acid)
IMMUNITY
90-95% those
infected
LATENT TB
5-10% of
those infected
ACTIVE
TB
•
The host’s innate immune
response provides the bulk of
protection against TB infection
•
Only 1 in 10 individuals with TB
will develop an active infection
•
Latent infections, however, are
still a possibility
•
Likelihood of progression to an
active infection from a latent
infections increases with age,
with positive HIV status and
compromised immune systems.
Latent vs. Active TB
EPIDEMIOLOGY
•
TB disease was uncommon prior to development of major cities,
where close contact and poor circulation made it easily
transmitted
•
The CDC reports that in 2005, there were 14, 093 cases in the
United States with 62% of cases amongst African Americans,
Hispanics and Asians.
•
Globally, new cases of TB are rising in Southern and Western
Africa as well as Asia.
•
Now highly associated with regions of high HIV positive
individuals as their compromised immune systems make them
more susceptible
•
As M. tuberculosis becomes resistant to more drugs, it is reemerging as a possibly catastrophic disease
•
While active disease is uncommon in most areas, 1/3 of the
world population has been exposed to TB
•
Second most deadly infectious disease after HIV.
DIAGNOSIS
•
•
The Mantoux tuberculin skin test (TST) or the TB blood test
can be used to test for M. tuberculosis infection.
•
Small amount of fluid containing tuberculin is injected
under skin and after 48-72hrs results of indurations
are analyzed
•
Only suggests that patient had previous exposure, not
that they have an active infection
Chest X-rays
•
•
Active TB will create cavities that are visible in chest
x-rays
Culturing
•
The presence of acid-fast-bacilli on a sputum smear
often indicates TB disease
•
Cultures are initial samples are done as final
confirmation of M. tuberculosis as opposed to any
other acid fast bacteria.
•
Incredibly slow-growing, so treatment usually begins
before final confirmation from culture.
SYMPTOMS
•
Pulmonary TB
•
•
Paling of skin, fever, cough, difficulty breathing,
night sweats, and spitting up blood
Extra-pulmonary TB affects other organs such as
intestines, bones, larynx and lymph nodes
•
•
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Osteal TB - infections of the bone usually the
spine resulting in deformities
TB Meningitis - infection of the membrane
surrounding brain and spine. Common in children
Scrofula - infected lymph nodes causing visible
swelling of the neck
SYMPTOMS
VACCINES
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BCG vaccine uses attenuated bovine tuberculosis
bacteria. It cannot cause disease in humans but
would elicit immunity to human TB.
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Immunity is not permanent
Ineffective with pulmonary Tb
Useful in preventing disseminated disease in children
Current Research
•
Improving BCG by experimenting on subunits from
other bacteria.
•
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MVA85A currently in trial using VSV subunits
Using live bacteria
TREATMENTS
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Antibiotics
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•
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Streptomycin was the first antibiotic approved for
treatment of TB
1949 Streptomycin was supplemented with PAS
1952 Isoniazoid found to block mycolic acid
synthesis
1963 Rifampin to inhibit synthesis of bacterial
RNA
TREATMENT OF MULTIDRUG RESISTANT TB
o When anti-biotic treatments are not fully carried
out and not successfully completed drug resistant
TB can develop and is becoming a serious health
threat. Adherence and completion of cocktail
treatments are crucial.
o Many circulating strains of M. tuberculosis are
resistant to Isoniazoid and Rifampin
o Cocktails of second-line anti-TB drugs are often
successful in the treatment of TB. Some of these
include: ethambutol, rifabutin, PAS, interferon –y,
and thioridazine
PREVENTION
o Education and DOTS campaigns
o Vaccination of children
o Early detection and treatment
o TB drug treatment for those with
confirmed latent infections
oMaintenance of sanitary conditions and
proper ventilation
o Especially covering mouth during active
infections.
TB Prevention
Campaigns
WHO has established
“DOTS” campaigns.
Call for political activation
to support clinical
research and outreach,
better diagnostic
methods, standardized
treatments and patient
supervision and for
commitment to adequate
drug supply.
REFERENCES
•
http://emedicine.medscape.com/article/226141overview#a0101
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http://textbookofbacteriology.net/tuberculosis.html
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http://www.youtube.com/watch?feature=endscreen&NR=
1&v=JtyX694ubio
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http://www.cdc.gov/tb/publications/slidesets/selfstudymod
ules/module1/pathogenesis.htm
•
http://www.cdc.gov/tb/default.htm
•
http://www.thelancet.com/journals/lancet/article/PIIS0140
673610603935/images?imageId=gr1&sectionType=green
•
https://vimeo.com/13434164
•
Sherman, Irwin W. Twelve Diseases That Changed Our
World. Washington, DC: ASP Press, 2007
https://www.youtube.com/watch?v=I
GZLkRN76Dc
Do Now
• Double check to make sure you have all your
information for your case study.
Do not go into your groups just yet.
Once you are sure you have your information, take
out a piece of paper, write your name and one thing
you learned about TB.
Once you are done, flip the paper over and wait
silently.