Download TB Disease

Sarah Al-Obaydi
M.B.Ch.B, MPH(c)
Fulbright scholar
Tuberculosis
 Tuberculosis (TB) is an infection caused mostly by
Mycobacterium tuberculosis.
 TB is a multisystem disease (affects most organs)
 TB can also be caused by other Mycobacteria like:
 M. bovis
 M. africanum
 M. microti
 M. canetti
 Not all Mycobacteria cause TB
 e.g., M. avium intercellulare complex
M. tuberculosis
Tuberculosis (TB): History
 TB is an ancient disease
 Historically known by a variety of names,
including:
 Consumption
 Wasting disease
 White plague
Tuberculosis (TB): History
 Before TB drugs were
available most went to
sanatoriums:
 TB hospitals
 regimen of bed rest, open air,
and sunshine
Sanatorium patients resting outside
 TB patients who could not
afford sanatoriums often died
at home
4
Non-infected
person
Transmission by
Respiratory
droplets
Primary TB
(usually in Lungs)
Healthy
individual with
good immunity
Often Asymptomatic
Poor Immunity
TB germs are put into the air when a person
with
the Immunity
lungs or throat coughs,
Latent
TBTB disease ofPoor
Active TB
sneezes, speaks, or sings
Latent TB vs TB Disease
Latent TB Infection (LTBI)
TB Disease (in the lungs)
Inactive, contained tubercle bacilli Active, multiplying tubercle bacilli
in the body
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
Progression to TB Disease
 Risk of developing TB disease is highest in the first 2
years after infection
 Progression from Latent TB infection to TB disease can
be prevented with TB drug (usually one TB drug): TB
prophylaxis
 However, not practiced in many developing countries where
TB is endemic
 Therefore detecting TB infection, early starting TB
drugs helps to prevent new cases of TB disease
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Noninfected
person
Prevent
Transmission
Primary TB
Latent TB
Active TB
How to Prevent TB Transmission?
 Isolate infectious persons
 Those with Lung TB disease only
 Treat TB dis. as soon as possible
 They stop shedding TB bacteria with in a few weeks after
starting treatment
Noninfected
person
Primary TB
Latent TB
Active TB
Prevent progression
Testing
Treating latent
Control risk factors
Prevention of Latent TB to Active
TB progression :
 Testing high risk groups for Latent TB
 Treating Latent TB
 Control risk factors
TB in USA: High-Risk: ForeignBorn/Immigrants
 In 2011, foreign-born
people 12 times likely
to have TB
 Among US-born nonHispanic blacks are
six times more likely
to have TB
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High-Risk – decreased immunity:
 HIV infection
 Diabetes Mellitus
 Prolonged steroids treatment
 Substance abuse
 Recent TB infection:
 If exposed to TB in the last 2 yrs
Noninfected
person
Primary TB
Latent TB
Active TB
Treat TB disease
Treatment
Challenges
Treatment of TB disease
 Several drugs for 6 to 9 months. Why?
 Regimens for treating TB disease have
 initial phase of 2 months
 continuation phase of either 4 or 7 months
 Treatment must contain multiple drugs to which
organisms are susceptible
 Treatment with a single drug can lead to the development
of drug-resistant TB
Treatment: Different Phases
Initial Phase
Continuation Phase
•8 weeks with 4 drugs (INH, RIF, EMB, Pyrazinamide)
• Most bacilli killed during this phase
•They don’t spread TB
• 4- 7 months with 2 TB drugs only
• remaining Bacilli (in reservoirs) are cleared in
this phase
Challenges to TB treatment and prevention:
Relapse:
1.


when treatment is not continued for long enough
Surviving bacilli may cause TB recurrence
Multidrug resistant TB (MDR TB) is TB resistant to at
least two of the best anti-TB drugs-INH and Rifampin.
2.

Mostly because of poor adherence to treatment regimen
 How to ensure adherence to treatment?
Directly Observed Therapy (DOT)
Challenges
3. Drug interactions interfere with treatment

In TB and HIV co-infection: many ART drug interact with Rifampin
4. Lack of awareness of TB or HIV status can prevent adequate
treatment
• How to prevent this?
Anyone who is newly diagnosed with HIV or TB should be
tested for co-infection.
Resurgence of TB
Risk of TB disease
 The risk of developing TB disease
 10% each year in people with HIV infection
 10% over a lifetime if otherwise healthy
Globally: Dual Epidemic
 Globally TB is a leading cause of death in HIV patients
 What is the leading cause of death among HIV patients
in USA?
Hepatitis C
Effect of CD4 count on risk of TB among HIV-infected people
Incidence of TB (per 100 pyrs)
20
>350
200-350 <200
15
10
5
0
Italy
US
South Africa
Antonucci JAMA 1995;274:143; Markowitz Ann Int Med 1997;126:123; Badri Lancet 2002;359:2059
Treatment of TB in HIV co-infection
 Generally same as for those without HIVinfection
 But there are challenges
- Drug interaction between TB and HIV drugs
- Adherence to TB and HIV drugs
Immune Reconstitution Inflammatory
Syndrome (IRIS)
 In patients with TB & HIV infection
 If TB is not diagnosed
 ART started for HIV treatment
 Patient worsens
 This is a PARADOXICAL reaction



Immunity is improving but patient
appears worse
temporary and usually not dangerous
But important to inform patient, watch
and manage
Quiz
 The risk of developing TB disease in healthy v/s HIV
population?
 10% each year in people with HIV infection
 10% over a lifetime if otherwise healthy
 What is the leading cause of death among HIV
patients in USA?
Hepatitis C