Get documents about "TB
Shared by: t4Ri061
-
Stats
- views:
- 17
- posted:
- 11/11/2011
- language:
- English
- pages:
- 42
Document Sample
n
t
r
o
d
u
c
t
i
o
n
1
Tuberculosis Partners in Global Health Education
How to use this module Welcome to the tuberculosis (TB)
Learning outcomes
What is TB? module.
Epidemiology
Microbiology
Transmission TB is a major cause of morbidity
Section 1 quiz
and mortality all over the world but
Natural history
Section 2 quiz the greatest burden is borne by
Symptoms and signs
Section 3 quiz
developing countries. The
Diagnosis bacterium Mycobacterium
Treatment
Prevention and control tuberculosis is responsible for most
Section 4 quiz
TB cases.
Information sources
Summative assessment
For more information about the authors and
reviewers of this module, click here
IUATLD; WHO/TBP/Falise
I
n
t
r
o
d
u
c
t
i
o
n
2
How should you study this module?
Partners in Global Health Education
• We suggest that you start with the learning objectives and try to
keep these in mind as you go through the module slide by slide,
How to use this module in order.
Learning outcomes
What is TB?
• Print-out the mark sheet
Epidemiology • As you go along, write your answers to the questions on the
Microbiology mark sheet as best you can before looking at the answers.
Transmission
• Award yourself marks as detailed on the mark sheet: one mark
Section 1 quiz
for each keyword (shown in red text) in the short answer
Natural history
questions and for every correct answer in the True/False
Section 2 quiz
questions.
Symptoms and signs
Section 3 quiz • Repeat the module until you have achieved a mark of 28/35
Diagnosis (≥80%).
Treatment • Finish with the formative multiple choice questionnaire to assess
Prevention and control how well you have covered the material as a whole.
Section 4 quiz
Information sources
• You should research any issues that you are unsure about. Look
Summative assessment
in your textbooks, access the on-line resources indicated at the
end of the module and discuss with your peers and teachers.
• Finally, enjoy your learning! We hope that this module will be
enjoyable to study and complement your learning about TB from
other sources.
I
n
t
r
o
d
u
c
t
i
o
n
2
Learning Outcomes
Partners in Global Health Education
How to use this module By the end of the module, you should be able to:
Learning outcomes
What is TB? 1. Describe how TB can affect anyone, of any age, anywhere, but that
Epidemiology most cases occur in specific risk groups
Microbiology
Transmission 2. Describe how respiratory droplets are the main transmission agent
Section 1 quiz
Natural history 3. Describe how, following inhalation, M. tuberculosis causes infection in
Section 2 quiz many people and disease in some
Symptoms and signs
Section 3 quiz 4. Enumerate the general symptoms and signs of TB and the specific
Diagnosis clinical features of pulmonary TB
Treatment
Prevention and control 5. Discuss how CXR and sputum examination are used in diagnosis
Section 4 quiz
Information sources
6. Describe how TB is managed using combinations of antimicrobials
Summative assessment
7. Describe how TB is prevented at the community level by immunisation,
case finding and contact tracing
What is tuberculosis (TB)?
Partners in Global Health Education
TB is a chronic bacterial infection. The great majority of infections in
How to use this module
Learning outcomes
people are caused by Mycobacterium tuberculosis (M.
What is TB? tuberculosis). A closely related bacteria, M. bovis, causes TB in
Epidemiology animals (especially cattle) and can infect people who drink
Microbiology
unpasteurised milk from infected cows.
Transmission
Section 1 quiz Although an ancient disease, TB
Natural history
remains a world wide problem:
Section 2 quiz
Symptoms and signs
• about 1 in 3 of the world’s
Section 3 quiz population is infected with tubercle
Diagnosis
Treatment
bacilli and someone is newly
Prevention and control infected every second
Section 4 quiz
• although most infected people
Information sources
Summative assessment remain asymptomatic, there are
about 9 million new cases and
nearly 2 million TB deaths every
year.
Where does TB occur? Epidemiology 4
Partners in Global Health Education
About 95% of the world’s cases of TB occur in South East Asia, sub-
How to use this module
Saharan Africa and the Western Pacific.
Learning outcomes The largest number of cases and
What is TB? highest mortality occur in South East
Epidemiology Asia and this region accounts for 33%
Microbiology of incident cases globally.
Transmission
Section 1 quiz
The annual incidence of TB is
increasing sub-Saharan Africa mainly
Natural history
as a result of the increased
Section 2 quiz
susceptibility of people infected with
Symptoms and signs
HIV.
Section 3 quiz
Diagnosis Other factors which encourage TB
Treatment transmission are:
Prevention and control • the emergence of multidrug-resistant strains of M. tuberculosis
Section 4 quiz
• poor national TB control programmes and worsening socio-economic
Information sources
conditions in many countries
Summative assessment
In the UK, the annual incidence rate is increasing with >8,000 new
cases/year. Most occur in the larger cities, especially London, and
about 2/3 cases occur in people who were born abroad. TB causes
or contributes to 300-400 deaths/year in the UK.
d
e
m
i
o
l
o
g
y
2
Microbiology (1) Partners in Global Health Education
M. tuberculosis is a non-motile, rod-shaped
How to use this module
bacterium measuring 2-4 x 0.2-0.5 μm. It is
Learning outcomes
an obligate aerobe, which explains why it
tends to be found in the well-aerated, upper
What is TB?
lobes of the lungs.
Epidemiology
Microbiology
Transmission
It is a slow growing organism (dividing only
Section 1 quiz
every 16-20 hours) that lives within tissue
macrophages. Humans are the only
Natural history
reservoir of M. tuberculosis. Both animals
Section 2 quiz
and humans serve as reservoirs for M.
Symptoms and signs bovis.
Section 3 quiz The Ziehl-Nielsen stain is
Diagnosis used to demonstrate the
The organism does not have the presence of the bacilli in a
Treatment
characteristics of either Gram positive or
Prevention and control
negative bacteria. It has a peculiar cell wall smear. Note the bright red
Section 4 quiz that consists of peptidoglycan and complex rods in this sputum smear.
Information sources lipids. Once stained (e.g. with carbol
Summative assessment fuchsin), the organism will retain dyes when
treated by acidified organic compounds.
Therefore, it is classified as an “acid–fast”
bacterium.
E
p
i
d
e
m
i
o
l
o
g
y
3
Microbiology (2) Partners in Global Health Education
The cell wall is a major factor in the virulence of the organism.
How to use this module
Learning outcomes It resists destruction by many
What is TB? antibiotics, acids, alkalis, osmotic
Epidemiology lysis and oxidation and enables
Microbiology the organism to survive and
Transmission multiply within macrophages.
Section 1 quiz
Natural history
Section 2 quiz
M. tuberculosis grows in
Symptoms and signs Lowenstein Jensen medium, an
Section 3 quiz egg-based medium, which
Diagnosis contains inhibitors to keep
Treatment contaminants from outgrowing the
Prevention and control organism. Because of its slow
Section 4 quiz growth, it takes 4-6 weeks before Typical small, buff coloured colonies of
Information sources M. tuberculosis on Lowenstein Jensen
small buff-coloured colonies are
Summative assessment medium
visible on the medium.
a
n
s
m
i
s
s
i
o
n
1
How is TB transmitted? Partners in Global Health Education
How to use this module Nearly all TB infection is acquired by inhalation of respiratory
Learning outcomes
droplets from people with TB in the lungs or throat.
What is TB?
Epidemiology
Microbiology
Air droplets 3-5 μm
Transmission diameter are coughed,
Section 1 quiz
sneezed or spat-out by an
Natural history
Section 2 quiz
“open” case of TB. The
Symptoms and signs droplets are inhaled by a
Section 3 quiz
close contact. This is
Diagnosis
Treatment
more likely to occur in
Prevention and control overcrowded
Section 4 quiz
environments.
Information sources
Summative assessment
NB. Abdominal TB can also result from drinking unpasteurised
cow’s milk infected with M. bovis.
End of Section 1 Partners in Global Health Education
How to use this module
Learning outcomes Well done!
What is TB?
Epidemiology You have come to the end of the first section.
Microbiology
Transmission
Section 1 quiz
Natural history
Section 2 quiz
Symptoms and signs
Section 3 quiz
Diagnosis
Treatment
Prevention and control
Section 4 quiz
Information sources
We suggest that you answer questions 1 to assess your
Summative assessment learning so far. Please remember to write your answers on
the mark sheet before looking at the correct answers!
Question 1: Risk of exposure to TB
Write “True” or “False” on the answer sheet.
When you have completed all 5 questions, click on the boxes and mark your answers.
Partners in Global Health Education
How to use this module Now that you know how TB is transmitted, are the following
Learning outcomes people at increased risk of exposure?
What is TB? Click for the correct
answer
Epidemiology
Microbiology
a) Close contacts of people with open TB (e.g.
Transmission a
Section 1 quiz family members)
Natural history
Section 2 quiz b) People who drink unpasteurised milk b
Symptoms and signs
Section 3 quiz
c) People living in poor, overcrowded
Diagnosis
c
environments
Treatment
Prevention and control d) People who work or are residents in long- d
Section 4 quiz
Information sources term facilities
Summative assessment
e) Infants and young children e
h
o
g
e
n
e
s
i
s
1
What happens following inhalation of M. tuberculosis?
Outcome 1: No infection Partners in Global Health Education
How to use this module Between 70-90% of individuals exposed to TB will not
Learning outcomes
What is TB?
develop the infection.
Epidemiology
Microbiology The reasons for this are unclear. However, in view of the
Transmission
Section 1 quiz
known risk factors for infection, people who inhale
Natural history bacilli but do not develop an infection may:
Section 2 quiz
Symptoms and signs
Section 3 quiz
• inhale too few organisms to cause infection
Diagnosis • have sufficient immunity to prevent an infection
Treatment becoming established
Prevention and control
Section 4 quiz
Information sources Any factor associated with impaired immunity, such as
Summative assessment extremes of age, malnutrition and HIV/AIDS will
increase the risk of developing infection.
t
h
o
g
e
n
e
s
i
s
2
What happens following inhalation of M. tuberculosis?
Outcome 2: Infection with formation of a primary complex Partners in Global Health Education
Following inhalation, tubercle bacilli settle in the alveoli
How to use this module and result in local inflammation in the lung
Learning outcomes parenchyma. This “primary focus” usually occurs in
What is TB? the upper lobes in adults but may occur in any of the
Epidemiology lung lobes in children. More than one focus may occur
Microbiology in the same patient.
Transmission
Section 1 quiz The organisms then spread via the local lymphatics to
Natural history
the nearest hilar lymph nodes, which may then
Section 2 quiz
enlarge.
Symptoms and signs
The primary focus and the enlarged regional lymph
Section 3 quiz
nodes form the “primary complex” or “Ghon
Diagnosis Primary focus successfully
complex”.
Treatment contained by the host immune
Prevention and control What happens next depends on the size of the system
Section 4 quiz infecting dose and the resistance of the host. Most
Information sources commonly, the primary focus is “walled-off” by the The person is infected but does not
Summative assessment immune system and lies dormant– “latent TB”. The have TB disease and cannot
infection may be reactivated years later if the immune spread TB. However, an immune
system of the host becomes weakened. response to M. tuberculosis will
have developed – and can be
demonstrated by a positive
Mantoux test (see later).
o
g
e
n
e
s
i
s
3
What happens following inhalation of M. tuberculosis?
Outcome 3: Pulmonary disease Partners in Global Health Education
If the primary focus is not contained, lung disease may
How to use this module
develop in several ways:
Learning outcomes
• The primary focus enlarges and undergoes central
What is TB?
necrosis to form a cavity
Epidemiology
Microbiology
• The infection can spread locally and result in
tuberculous bronchopneumonia
Transmission
Section 1 quiz
• Marked swelling of the mediastinal lymph nodes may
Natural history
compress large bronchi and result in lobar collapse
Section 2 quiz • The enlarged lymph node may act like a one-way
Symptoms and signs
valve causing hyperinflation of a lung or lobe
Section 3 quiz • The adjacent pleura can become infiltrated by M.
Diagnosis tuberculosis resulting in a hypersensitivity reaction
Treatment
characterised by granulomas composed mainly of
lymphocytes Infection not contained by
Prevention and control
Section 4 quiz
• Pleural infiltration may result in a pleural effusion the immune system.
Information sources
which is rich in lymphocytes – a useful pointer to the Person develops lung
diagnosis when pleural fluid is aspirated and disease and becomes an
Summative assessment
analysed open case - capable of
• Long term complications of the damage to lung tissue infecting others via
include emphysema and bronchiectasis respiratory droplets.
What happens following inhalation of M. tuberculosis?
Pathogenesis 4
Outcome 4: Systemic disease Partners in Global Health Education
Haematogenous dissemination of M.
How to use this module tuberculosis leads to granuloma formation in
Learning outcomes
many organs. Examples include:
What is TB?
Epidemiology
Microbiology • Diffuse infection of the lungs: “miliary” TB
Transmission • Brain: TB brain abscess
Section 1 quiz
Natural history
• Meninges: TB meningitis
Section 2 quiz • Bones: TB osteomyelitis – commonly affects
Symptoms and signs the spine and is then called “Potts’ disease”
Section 3 quiz
• Pericardium: TB pericarditis and pericardial
Diagnosis
Treatment
effusion
Prevention and control
Section 4 quiz As with acquiring infection after inhalation,
Information sources
disseminated disease is most likely to occur in
Summative assessment
the immunocompromised person (e.g.
HIV/AIDS, malnutrition) and at extremes of age.
h
o
g
e
n
e
s
i
s
5
Summary (1): natural history following TB
exposure
Partners in Global Health Education
How to use this module What are the likely outcomes following exposure to open TB?
Learning outcomes
What is TB?
Epidemiology
Exposure to TB
Microbiology
Transmission
Section 1 quiz
Natural history
No infection Infection
Section 2 quiz
Symptoms and signs (70-90%) (10-30%)
Section 3 quiz
Diagnosis
Treatment
Dormant TB (90%) Active TB (10%)
Prevention and control
• well • ill and likely to die if
Section 4 quiz
• no TB disease untreated
Information sources
• not infectious to • infectious
Summative assessment
others
Activation of infection
results in disease
h
o
g
e
n
e
s
i
s
1
Summary (2): natural history following TB exposure
Partners in Global Health Education
How to use this module
Learning outcomes
What is TB? There are 4 possible outcomes following inhalation of TB bacilli:
Epidemiology
Microbiology
Transmission Outcome Person Person Person develops
Section 1 quiz unwell? transmits an immune
Natural history disease? response to TB?
Section 2 quiz
Symptoms and signs
1: No infection No No No
Section 3 quiz
2. 1o lung complex No No Yes
Diagnosis
Treatment
3. Pulmonary disease Yes Yes Yes
Prevention and control
Section 4 quiz
4: Systemic disease Yes Yes Yes
Information sources
Summative assessment
Note: outcomes 3 and 4 can develop many years after formation of the 1o lung
complex
End of Section 2 Partners in Global Health Education
How to use this module
Learning outcomes Well done!
What is TB?
Epidemiology You have come to the end of the second section.
Microbiology
Transmission
Section 1 quiz
Natural history
Section 2 quiz
Symptoms and signs
Section 3 quiz
Diagnosis
Treatment
Prevention and control
Section 4 quiz
Information sources
Answer questions 2 through 4 to assess your learning so
Summative assessment far. Challenge yourself: complete the mark sheet before
looking at the correct answers!
Question 2: Groups of people at increased risk of TB disease
and disseminated infection following exposure are:
Write “True” or “False” on the answer sheet.
Partners in Global Health Education
Click for the
correct answer
How to use this module
Learning outcomes
What is TB? a) Infants and children <5 years a
Epidemiology
Microbiology
Transmission
b) People with HIV/AIDS b
Section 1 quiz
Natural history
Section 2 quiz
c) People with diabetes mellitus, measles,
Symptoms and signs
c
Section 3 quiz
pertussis or on prolonged corticosteroid therapy
Diagnosis
Treatment
d) Young adults
d
Prevention and control
Section 4 quiz
Information sources e) Alcoholics and IV drug users e
Summative assessment
Question 3: Factors underlying the resurgence of TB in
the last 2 decades are:
Write “True” or “False” on the answer sheet. Partners in Global Health Education
Click for the
correct answer
How to use this module
Learning outcomes
What is TB? a) HIV pandemic a
Epidemiology
Microbiology
Transmission
b) Poverty/worsening socioeconomic conditions b
Section 1 quiz
Natural history
Section 2 quiz
c) Poor hygiene c
Symptoms and signs
Section 3 quiz
Diagnosis
d) Emergence of drug resistance strains d
Treatment
Prevention and control
e) Poor national TB control programmes
Section 4 quiz e
Information sources
Summative assessment
Question 4: Following exposure to M. tuberculosis
Write “True” or “False” on the answer sheet.
Partners in Global Health Education
Click for the
correct answer
How to use this module
Learning outcomes
a) The usual outcome is a primary
What is TB?
infection a
Epidemiology
Microbiology
Transmission b) The primary complex consists of a
Section 1 quiz cavity in the lung parenchyma and b
Natural history hilar lymphadenopathy
Section 2 quiz
Symptoms and signs
Section 3 quiz
c) A pleural aspirate rich in neutrophils c
Diagnosis
suggests TB as a cause
Treatment
Prevention and control d) Miliary TB refers to disseminated d
Section 4 quiz infection spread via the bloodstream
Information sources
Summative assessment
i
n
i
c
a
l
f
e
a
t
u
r
e
s
1
What are the symptoms and signs of TB?
1. Primary infection with no spread of the disease Partners in Global Health Education
Individuals with primary infection do not
How to use this module
Learning outcomes usually have any symptoms or signs of ill
What is TB?
health although some people develop a
Epidemiology Erythema nodosum:
Microbiology minor flu-like illness. ecchymotic papules found
Transmission along the shin or on the
Section 1 quiz
Infection triggers an immune response flexural surfaces of the limbs
Natural history and, in a minority of people, this may
Section 2 quiz Phlyctenular
Symptoms and signs
result in clinical signs of hypersensitivity keratoconjunctivitis: raised,
Section 3 quiz to M. tuberculosis for example: yellowish nodule at the
Diagnosis
corneoscleral junction. Small
Treatment • erythema nodosum blood vessels may be seen
radiating from the nodule.
Prevention and control
Section 4 quiz • phlyctenular keratoconjunctivitis
Information sources
Summative assessment They will also have a positive Mantoux
test (see below).
c
a
l
f
e
a
t
u
r
e
s
What are the symptoms and signs of TB?
2
2. Active infection: symptoms Partners in Global Health Education
Symptoms of TB can be divided General symptoms
How to use this module
into general symptoms and those • Fever
Learning outcomes
specific to the organ infected. • Loss of weight in adults or growth
What is TB?
Epidemiology
faltering in children
TB can result in a myriad of • Night sweats
Microbiology
Transmission
symptoms depending on which • Malaise, tiredness and anorexia
Section 1 quiz organs are involved and how their
Organ specific - examples include:
Natural history function is affected.
Section 2 quiz
The lung is the predominant Lungs
Symptoms and signs
• Cough – usually chronic (lasting >6
Section 3 quiz organ affected, being involved in weeks)
Diagnosis over 75% of cases. • Productive of whitish or mucoid sputum
Treatment in adults but usually unproductive in
children
Prevention and control Commonly affected organs
• Haemoptysis (coughing-up blood)
Section 4 quiz following haematogenous spread
Information sources
from the lung are the abdomen, Central Nervous System
Summative assessment
lymph nodes, spine, meninges, • TB meningitis
• Tuberculoma, with the classical features
kidneys, bone and reproductive of a space-occupying lesion simulating a
organs. brain tumour
c
a
l
f
e
a
t
u
r
e
s
What are the symptoms and signs of TB?
3
2. Active infection: signs
Partners in Global Health Education
How to use this module General examination - look for:
Learning outcomes
What is TB? • fever
Epidemiology • signs of malnutrition signifying a chronic illness
Microbiology
• enlargement of the peripheral lymph nodes
• digital clubbing as a consequence of chronic
Transmission
infection/inflammation in the chest or abdomen
Section 1 quiz
Natural history
Section 2 quiz TB lymphadenitis presents as painless
Symptoms and signs enlargement of the superficial lymph nodes. The
Section 3 quiz neck is the commonest site involving the cervical,
Diagnosis submandibular, pre and post-auricular lymph
Treatment nodes. The lymph nodes are non-tender, matted
Prevention and control together and rubbery in consistency. It is common
Section 4 quiz
for enlarged lymph nodes to ulcerate and
discharge.
Information sources
Summative assessment
Look at this picture of a 4 year old boy from West
Africa. Note that he is generally wasted and has
marked enlargement of the cervical lymph nodes
– especially on the right side.
c
a
l
f
e
a
t
u
r
e
s
3
What are the symptoms and signs of TB?
3. Pulmonary and abdominal TB Partners in Global Health Education
Pulmonary TB (PTB)
How to use this module The apical region is the most
Learning outcomes commonly affected in adults.
What is TB? Pulmonary lesions may involve any
Epidemiology part of the lung in infancy and
Microbiology childhood.
Transmission
Section 1 quiz Abnormalities detected clinically
Natural history include consolidation, collapse,
Section 2 quiz
pleural effusion and fibrosis. But
Symptoms and signs
beware: examination of the
respiratory system may be
Section 3 quiz
completely normal even in active
Diagnosis
disease! Upper lobe changes on CXR
Treatment
Source: WHO/TBP/Pierre Virot
Prevention and control Abdominal TB
Section 4 quiz
Information sources Pathology affects the mesenteric and the retroperitoneal glands, the omentum and
Summative assessment the gastrointestinal tract. Patients may present with weight loss, diarrhoea or
constipation, abdominal distension (from ascites) or chronic intestinal obstruction.
Enlarged mesenteric lymph nodes may be palpable as multiple intra-abdominal
masses.
Tuberculosis of the spine – “Pott’s disease”
Partners in Global Health Education
How to use this module
TB commonly affects the spine,
Learning outcomes
especially in young children, and
What is TB? usually presents as a swelling on the
Epidemiology back.
Microbiology
Transmission
The lower thoracic and the upper
lumbar vertebrae are the usual sites,
Section 1 quiz
however any vertebra can be
Natural history affected.
Section 2 quiz
Symptoms and signs The patient may also present with
Section 3 quiz kyphosis, scoliosis, kyphoscoliosis,
Diagnosis
or features of spastic paraparesis.
There may be a sharp angulation of
Treatment
the spine caused by collapse of a
Prevention and control vertebra – referred to as a “gibbus”
Section 4 quiz
Information sources
Summative assessment A young child from West
Africa. Note the swelling over
the lower thoracic vertebrae.
End of Section 3 Partners in Global Health Education
Well done!
How to use this module
Learning outcomes
What is TB?
Epidemiology
This is the end of the second section.
Microbiology
Transmission
Section 1 quiz
Natural history
Section 2 quiz
Symptoms and signs
Section 3 quiz
Diagnosis
Treatment
Prevention and control We suggest that you proceed to answer question 5 to
Section 4 quiz
assess your learning further. Do remember to write your
Information sources
Summative assessment
answers on the mark sheet before looking at the right
answer!
a
l
f
e
a
t
u
r
e
s
Q
u
i
z
1
Question 5: What 2 features are consistent with
pulmonary TB in this man? Partners in Global Health Education
How to use this module
Learning outcomes
What is TB?
Epidemiology
Microbiology
Transmission
Section 1 quiz
Natural history
Write Down Your
Section 2 quiz Answers on your
Symptoms and signs mark sheet, then
Section 3 quiz click below to reveal
Diagnosis
the answers
Treatment
Prevention and control
Section 4 quiz
Information sources
Summative assessment
Man with advanced TB in Bangladesh
source: WHO/TBP/England
Click to Reveal Answers
e
s
t
i
g
a
t
i
o
n
1
Diagnosis Partners in Global Health Education
In developing countries, the diagnosis
How to use this module of TB is based on the combination of
Learning outcomes clinical assessment and simple
What is TB? laboratory methods:
Epidemiology
Microbiology 1. History of chronic cough with the
Transmission general symptoms of fever, malaise
Section 1 quiz
and weight loss
Natural history
2. Presence of general and specific
clinical signs
Section 2 quiz
Symptoms and signs
3. Positive findings on relevant
investigations – usually CXR and
Section 3 quiz
sputum smear stained for acid-fast
Diagnosis bacilli
Treatment
Prevention and control Examining a CXR in China
It is important to note that specific Source: WHO/TBP/Pierre Virot
Section 4 quiz symptoms and signs may be absent.
Information sources
Summative assessment
TB should be suspected in any chronically ill person!
v
e
s
t
i
g
a
t
i
o
n
4
Bacteriological diagnosis
Partners in Global Health Education
• Sputum microscopy is most useful in
How to use this module
adults with a productive cough. A sputum
smear is stained with the Ziehl-Nielsen
Learning outcomes stain to demonstrate the presence of the
What is TB? acid and alcohol fast bacilli (AFB). When
Epidemiology positive, the patient is “smear-positive” or
Microbiology
“open TB” and the risk of transmission of
infection to others is very high. However,
Transmission the test is often falsely negative in patients
Section 1 quiz with TB. The yield of the test is higher in
Natural history patients with lung cavities.
Section 2 quiz
Symptoms and signs • Gastric washings examined for AFB:
Section 3 quiz
Carried out in children as they swallow
rather than cough-up sputum. The test
Diagnosis aims to recover the swallowed AFB from
Treatment the stomach using a naso-gastric tube. The
Prevention and control test is positive in only about one third of
Section 4 quiz
children with TB. Sputum samples collected in a
Information sources health facility in Ethiopia
Summative assessment
• Bacterial culture: This takes about 6-8 source: WHO/TBP/Jan Van den
weeks and so is of limited use in clinical Hombergh
diagnosis. M. tuberculosis grows on a
special medium called the Lowenstein
Jensen medium.
n
v
e
s
t
i
g
a
t
i
o
n
5
Mantoux or tuberculin skin test
Partners in Global Health Education
This test detects a delayed hypersensitivity, cutaneous reaction to a purified
How to use this module
protein derivative (PPD) of M. tuberculosis – also called “tuberculoprotein”:
Learning outcomes
What is TB?
1. PPD is injected intradermally
Epidemiology 2. the injection site is inspected 48-72 hours later
Microbiology 3. erythema and induration at the site signify an immune response and,
Transmission
therefore, previous exposure to mycobacteria
Section 1 quiz
Natural history The limitations of this test are well-known:
Section 2 quiz False positive: a skin reaction in people who do not have TB because of
Symptoms and signs exposure to non-pathogenic mycobacteria and also due to the immune
Section 3 quiz
response following BCG immunisation (see later).
Diagnosis
False negative: a negative result in a person with TB in early primary
infection or because they are immunocompromised – for example, due to
Treatment
HIV/AIDS, malnutrition or people who develop disseminated TB.
Prevention and control
Section 4 quiz
In general, the greater the degree of erythema and induration, the more likely
Information sources
the patient has TB disease. Several detailed criteria are available to guide
Summative assessment the interpretation of Mantoux results, e.g. from the American Thoracic
Society and Centers for Disease Control & Prevention
v
e
s
t
i
g
a
t
i
o
n
7
Diagnosis: Other investigations
Partners in Global Health Education
Other investigations are indicated depending on the organs/ systems
How to use this module
affected by the disease
Learning outcomes
What is TB? Spinal radiographs in Pott’s disease
Epidemiology Lymph node aspirate (microscopy, culture and cytology) or biopsy
Microbiology (histology and culture) in TB lymphadenitis
Transmission
Section 1 quiz
Lumbar puncture for cerebrospinal fluid analysis in TB meningitis
Natural history
(microscopy, biochemical analysis and culture)
Section 2 quiz
Symptoms and signs
Section 3 quiz
A recent development is the detection of the growth of TB in liquid
culture by microscopy. Diagnosis can be made within 10 days and
Diagnosis
addition of drugs to the cultures allows the detection of drug
Treatment
resistance.*
Prevention and control
Section 4 quiz Also, a number of new diagnostic tests have been developed based
Information sources on molecular methods such as the amplification of nucleic-acid.
Summative assessment However, these assays have not been fully evaluated and are
expensive.
* Moore DA et al. Microscopic-observation drug-susceptibility assay for the diagnosis of
TB. N Engl J Med 2006; 355:1539-50
Treatment Partners in Global Health Education
Resistance of M. tuberculosis to antimicrobials is a major
How to use this module
Learning outcomes
problem in TB treatment. Because it is a slow growing
What is TB? organism, treatment courses are long - at least 6 months.
Epidemiology
Microbiology
Transmission
• Treatment requires a
Section 1 quiz
combination of drugs to which
Natural history the organisms are sensitive.
Section 2 quiz
Symptoms and signs • Treatment courses must be
Section 3 quiz completed for effective cure
Diagnosis and to prevent the emergence
Treatment of drug-resistant strains.
Prevention and control
Section 4 quiz • Longer treatment courses are
Information sources
needed for TB meningitis or if Combination antibiotic therapy
Summative assessment
the bacteria are resistant and in India
additional drugs are required. Source: IUTBLD WHO/TBP/Gary
Hampton
M
a
n
a
g
e
m
e
n
t
Treatment: DOTS
Partners in Global Health Education
How to use this module
DOTS is the acronym for Directly Observed Treatment Short Course.
Learning outcomes
It involves the daily administration of a combination of antituberculous drugs to
What is TB? a TB patient under the supervision of a healthcare personnel. DOTS helps to
Epidemiology ensure compliance, reduce transmission by shortening the period of infectivity,
Microbiology improve the cure rate and reduce the risk of drug resistance.
Transmission
Section 1 quiz There are many regimens for treating TB. The most frequently recommended
Natural history regimen that is also effective in people with HIV infection is:
Section 2 quiz
Symptoms and signs
Drug 0-2 months 3-6 months
Section 3 quiz
Diagnosis Isoniazid + +
Treatment Rifampicin + +
Prevention and control
Section 4 quiz Pyrazinamide + -
Information sources Ethambutol* + -
Summative assessment
*IM streptomycin is often substituted for oral ethambutol for children < 6 years
Drug-resistant TB
Partners in Global Health Education
There are 2 classes of drug resistant TB:
How to use this module
Learning outcomes
What is TB?
1. Multidrug-resistant (MDR)
Epidemiology • defined as resistance to rifampicin and isoniazid, +/- other
Microbiology drug resistance
Transmission • worldwide, >4% of TB patients are MDR, with the highest
Section 1 quiz prevalence in Eastern Europe
Natural history • treatment requires longer drug regimens, is less effective,
Section 2 quiz more costly and poorly tolerated
Symptoms and signs
Section 3 quiz
Diagnosis
2. Extensively drug-resistant (XDR)
Treatment • defined as resistance to rifampicin and isoniazid and, in
Prevention and control
addition, resistance to any quinolone and at least on
Section 4 quiz
injectable second-line drug
Information sources • XDR TB is essentially untreatable and has a very high
Summative assessment mortality
e
v
e
n
o
n
Prevention and Control
Partners in Global Health Education
TB control strategies include –
How to use this module • Case finding: aims to identify TB cases promptly, treat them
Learning outcomes with an effective combination of drugs and ensure that the
What is TB? course is completed.
Epidemiology
Microbiology
• Contact tracing: Close contacts of TB cases are screened for
Transmission
evidence of infection. Mantoux positive cases are treated with
Section 1 quiz oral isoniazid for 6-12 months to prevent them from developing
Natural history the disease. This regimen is also used in HIV-positive people.
Section 2 quiz
Symptoms and signs
Section 3 quiz
• Bacillus Calmette-Guérin (BCG) vaccine
Diagnosis • contains an attenuated strain of M. bovis
Treatment • is administered as a single intradermal injection
Prevention and control • Has limited efficacy against pulmonary TB (and, therefore,
Section 4 quiz TB transmission) but does appear to prevent disseminated
Information sources disease and death – especially in children
Summative assessment
• is given routinely to infants in developing countries and to
people at increased risk of TB infection in developed
countries
TB: the future Partners in Global Health Education
WHO declared TB a global health emergency in 1993 and aims to
How to use this module eliminate TB as a public health problem by 2050.
Learning outcomes
• Other organisations involved in TB
What is TB?
control include the International Union
Epidemiology
Against TB and Lung Disease, the
Microbiology
Center for Disease Control (USA) and
Transmission the Global Plan to Stop TB.
Section 1 quiz
• TB remains a worldwide challenge.
Natural history
There is a need to improve DOTS
Section 2 quiz
coverage and meet the emerging
Symptoms and signs
challenges of TB in people with
Section 3 quiz
HIV/AIDS and multidrug resistant TB.
Diagnosis
Treatment
• Improved techniques for diagnosis are
required especially in people with
Prevention and control
compromised immunity where diagnosis
Section 4 quiz
is difficult such as HIV/AIDS and
Information sources
malnourished children.
Summative assessment
• A more effective vaccine and improved
treatment strategies that would decrease
the duration of treatment are also high IUATLD; WHO/TBP/Falise
priorities.
End of Section 4 Partners in Global Health Education
You have come a long way!
How to use this module
Learning outcomes
What is TB?
Epidemiology
This is the last of the sections.
Microbiology
Transmission
Section 1 quiz
Natural history
Section 2 quiz
Symptoms and signs
Section 3 quiz
Diagnosis
Treatment
Prevention and control
Section 4 quiz For the section just ended, you should be able to answer
Information sources Questions 6 - 8 to assess what you have learnt. It is still
Summative assessment required that you put down your answers on the mark
sheet before looking at the right answer!
Question 6: A person with latent TB
Write “True” or “False” on the answer sheet.
Partners in Global Health Education
Click for the
correct answer
How to use this module
Learning outcomes
What is TB? a) Is infectious to other people a
Epidemiology
Microbiology
Transmission
b) Feels well b
Section 1 quiz
Natural history
Section 2 quiz
c) Tuberculin skin test is positive c
Symptoms and signs
Section 3 quiz
Diagnosis
d) Can not develop TB later in life d
Treatment
Prevention and control
Section 4 quiz
Information sources
Summative assessment
Question 7: The following are recognised
manifestations of TB Partners in Global Health Education
Click for the
correct answer
How to use this module
Learning outcomes
What is TB? a) Pericarditis a
Epidemiology
Microbiology
Transmission
Section 1 quiz b) Meningitis b
Natural history
Section 2 quiz
Symptoms and signs
c
Section 3 quiz
Diagnosis
c) Erythema nodosum
Treatment
Prevention and control
d
Section 4 quiz
Information sources
d) Osteomyelitis
Summative assessment
e) Phlyctenular conjunctivitis e
Question 8: The following are indicated in the
management of miliary TB Partners in Global Health Education
Click for the
correct answer
How to use this module
Learning outcomes
What is TB? a) High protein diet a
Epidemiology
Microbiology
Transmission
Section 1 quiz
b) BCG Vaccination b
Natural history
Section 2 quiz
Symptoms and signs c) Contact tracing c
Section 3 quiz
Diagnosis
Treatment
Prevention and control
Section 4 quiz
d) Isoniazid prophylaxis for 6-12 d
Information sources months
Summative assessment
e) Lumbar puncture e
Sources of information / bibliography
Partners in Global Health Education
You can copy and paste the links below into your browser to access
How to use this module the resources:
Learning outcomes
What is TB?
• Maartens G, Wilkinson RJ. Tuberculosis. The Lancet 2007; 370:2030-
Epidemiology 43
Microbiology
• Diagnostic atlas of intra-thoracic tuberculosis in children; A guide for
Transmission
Low Income Countries. Dr. Robert Gie, International Union against
Section 1 quiz Tuberculosis and Lung Disease (IUATLD) 2003. Available at:
Natural history http://www.iuatld.org
Section 2 quiz
• The Division for Tuberculosis Elimination, Centre for Disease Control
Symptoms and signs (CDC), Atlanta, USA http://www.cdc.gov/nchstp/tb/faqs/qa.htm
Section 3 quiz
• Stop TB Partnership; http://www.stoptb.org/
Diagnosis
Treatment • WHO – several information resources available at
Prevention and control
http://www.who.int/tb/en/
Section 4 quiz • Treatment guidelines: http://www.Nice.ac.uk
Information sources • TB in the UK: http://www.Hpa.org.uk
Summative assessment
Partners in Global Health Education
How to use this module Summative assessment
Learning outcomes
What is TB?
Epidemiology
Microbiology
Transmission
• Well done! We hope that you enjoyed
Section 1 quiz
Natural history
completing this module.
Section 2 quiz
Symptoms and signs • Now try the summative assessment
Section 3 quiz
Diagnosis (available from
Treatment
Prevention and control
http://www.medicine.swansea.ac.uk/inthealth.html)
Section 4 quiz
Information sources • … and good luck!
Summative assessment
