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TUBERCULOSIS Tuberculosis

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TUBERCULOSIS Tuberculosis Powered By Docstoc
					     Tuberculosis- Rob Striker,
             MD/PhD
• “Captain of all these men of death”-
  attributed to Osler
                 OBJECTIVES
The student should be able to:
 •   State the magnitude of the global tuberculosis problem in
     terms of disease morbidity and mortality (#s) &
     distribution.
 •   Define the terms MDR and XDR TB and discuss their
     impact on global health.
 •   Discuss BCG immunization as a control measure.
 •   Discuss the relationship between HIV infection &
     tuberculosis.
 •   Distinguish between exposed, infected and diseased from
     tuberculosis
 •   Explain the significance of latent TB in the elderly.
         TUBERCULOSIS
• Recognized for >3000 years
• Chronic bacterial infection causing high
  disease morbidity and mortality world-wide
• Airborne disease that is transmitted only
  after prolonged exposure to someone with
  active disease
• TB usually infects the lungs but can be
  present in any organ, can be an STD, and
  cause infertility
Mycobacterium tuberculosis
TRANSMISSION




Aerosols generated by coughing,
sneezing and talking dry to form
droplet nuclei. Those (1-5um)
containing 1-3 bacilli are inhaled
         TUBERCULOSIS
         THE PROBLEM
• DISEASE STATUS -
  – ~ 2 billion people infected world-wide
  – ~ 9 million world-wide develop active
    tuberculosis annually; ~2 million die
  – ~ 10 million new cases in 2005; 1 billion new
    cases in 2020.
  – Emergence of drug resistant Mycobacterium
    tuberculosis
  GLOBAL TUBERCULOSIS
• 98% of cases in developing countries with an
  increase of ~3% annually, 10% in African
  countries
• 80% of cases seen in 22 countries; about half in 5
  countries: India, China, Indonesia Nigeria and
  Bangladesh
• Not confined to developing countries: 70%
  increase in former USSR between 1990 and 1995
  with MDR-TB ~40% of these cases.
TUBERCULOSIS IN THE USA
• In 19th century killed more than any other disease
• Improvements in nutrition, pollution/, housing,
  sanitation in first half of 20th century cut cases to
  ~20,000
• Further decline in case rates due to effective
  antibiotic therapies in the 40s & 50s with lowest
  rates in mid-1980s
• Resurgence peaked in 1992
• Between 10-15 million have latent TB; ~10% will
  develop active disease during lifetime. Elderly
  with reactivation tuberculosis a threat to infants
  and young children.
• 18,371 active cases in 1998.
• In some sectors of US society TB rates now
  surpass those in world’s poorest countries.
• TB transmission occurs in the impoverished,
  malnourished, drug & alcohol addicted,
  overcrowded or in poor health suffering from
  chronic diseases and malignancies
• Minorities disproportionately affected.
 CONTRIBUTING FACTORS
• Societal issues
   – poverty, overcrowding, immigration (how are the poor
     overcrowded
• Political issues
   – war, resettlement, immigration
• Health issues
   – malnutrition, drug abuse, HIV infection,
     immunosuppression
• Economic issues
   – drug costs, health care
    THE PROBLEM OF DRUG
        RESISTANT TB
• Emergence of drug resistance some 50 years ago.
• Mutation frequencies range from 1 in 105 to 1 in 108
  replications.
• Primary drug resistance to single drug occurs in
  previously untreated cases ~9%.
• Secondary drug resistance occurs in patient who fails to
  complete course of treatment and relapses.
• These selected strains also have spontaneous mutations
  to other drugs-produce MDR-TB in new hosts.
• MDR-TB difficult and expensive to treat.
• XDR-TB even worse with higher mortality.
XDR-TB
   CDC & WHO SURVEY OF
   DRUG RESISTANT M.TB
         ISOLATES
• 17,690 TB isolates examined during 2000-2004
• 20% MDR
• 2% XDR
SIGNIFICANCE OF XDR TB
“ XDR TB has emerged as a threat to public
  health and TB control, raising concerns of a
  future epidemic of virtually untreatable
  TB. ”
  ( MMWR, March 24, 2006)
        CAUSES OF DRUG
          RESISTANCE
• Inadequate dosage or treatment with too
  few drugs.
• Lack of compliance
  – Patients fail to take medication consistently for
    6-12 months necessary for cure.
  – Patients feel better after 3 or 4 weeks
  – Drugs have unpleasant side effects (how many
    pills can u take a day?)
  – Addicts sell TB drugs to buy narcotics
      CONTROL MEASURES
           (Global)
• Commitment to fight TB at national and
  international levels
  –   Leadership
  –   Surveillance
  –   Control measures…immunization
  –   Research
    Diagnosis and surveillance of
            tuberculosis
•   Tuberculin test (Purified Protein Derivitive PPD)
•   Chest x ray
•   Patient history
•   Clinical signs and symptoms
•   Culture
•   PCR
•   QuantiFERON-TB Gold
•   Invasive procedures
A positive tuberculin test
         How is a PPD used?
• To identify newly infected contacts
• To identify potentially infectious spreaders
  before putting them in a shared
  housing/medical
• To identify potentially infectable people
  above
• How long do immune responses last?
   Two steps needed to rule out
   latent infection in person you
      plan on testing annually
• The first PPD/ Ag can be enough to awaken
  the immune response but not enough to get
  a positive test
• IF you test again u might accidentally think
  newly exposed
• Can NOT boost to a + test if never first saw
  tuberculosis or close relative
     CONTROL MEASURES
       (Case treatment)
• Identification of infected individuals.
• Isolation of active disease (incarceration).
• Treating infected individuals with drugs in
  combination (DOTS-directly observed therapy
  strategy).
• Identification of MDR TB & XDR TB cases
  followed by proper treatment.
• Patient education.
      BCG IMMUNIZATION
• Current vaccine, bacile Calmette Guerin (BCG), is
  a live attenuated vaccine aimed at protecting naïve
  individuals
• 100 million BCG vaccinations given to children
  each year
   – will prevent 30,000 cases of tuberculosis meningitis
     during first 5 years of life & 11,000 cases of miliary
     tuberculosis.
• BCG immunization does not protect adults against
  pulmonary tuberculosis.
      CONFOUNDING ISSUES
• WORLD WIDE
  –   HIV/AIDS epidemic
  –   Politics–the will to do something about problem
  –   Political unrest/war
  –   Economics
  –   Lack of public health infrastructure
  –   Lack of health care services
  –   Self-medication
  –   Unscrupulous drug manufactures
• USA
  –   HIV/AIDS epidemic
  –   Civil rights
  –   Politics
  –   Lack of health services
  –   Economics
  –   Lack of isolation facilities
                Resources
• MMWR, March 24, 2006
• Multidrug and extensively drug-
  resistantTB(M/XDR-TB) 2010: WHO GLOBAL
  REPORTON SURVEILANCE AND RESPONSE
• P.M. Small and M. Pai. 2010. Tuberculosis
  Diagnosis-Time for a Game Change. NEJM.
• M. C. Raviglione and I. Smith. 2007. XDR
  Tuberculosis-Implications for Global Public
  Health. NEJM. 356:7
• Mountains Beyond Mountains by Tracy Kidder–
  the story of Paul Farmer a doc who is making a
  difference.

				
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