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Natural history and diversity of TB in children
H S Schaaf
Question
Children with pulmonary TB are not infectious
TRUE or FALSE
Question
Extrapulmonary TB occurs in about 30% of children with TB
TRUE or FALSE
Robert Koch (1843-1910) discovered M. tuberculosis 1882
Previously uncertainty if TB was an infectious disease or
merely due to poverty, poor diet or bad air.
Microscopy diagnosis still used today! It only detects large
numbers of bacilli in sputum (>5-10 000 bacilli/ml) therefore
children are rarely detected in this way (paucibacillary disease)
Transitions in TB
Susceptible
Exposed
InfectedDiseased
Infectious
SickAccessed care
Recognized
Diagnosed
Treated
Completed
CuredDon Enarson - IUATLD
90%Info.med.yale.eduwww.info.gov.hk
10%
Active TB LTBI
Age-related risk
0
10
20
30
40
50
%
<1 1to2 2to5 5to10 10to15
Age in Years
PTB
Disseminated
Immune
compromised
Outpatient Case
• Baby-girl 14 weeks – cough >4 weeks. Was
seen at clinic several times. Amoxicillin given.
Mom told to stop smoking. Coughing bouts –
turns red says mom
• Fever for two weeks. Only had received her
6-week immunisations. No BCG given (out of
stock)
• Unbooked mom gravida 5 para 5: Baby born
at home. Breastfed since birth, but on clinic
card not thriving.
Outpatient Case
• A boarder at grandmother’s home has TB but
on effective treatment long before baby was
born – no-one else with TB at home
• Mom had TB 2009 – treated for 5 months?
Mom says she is coughing “on and off” –
describes it as a “normal cough”
• O/E (infant): Decreased air entry LUL;
hepatosplenomegaly
• Irritable baby, no neck stiffness or bulging
fontanelle, bilateral femoral hernias and low
grade fever
What next?
• FBC – HB 8.9 g/dl normocytic normochromic
• Platelets >500 x 109/L
• HIV-negative
• LP: CSF prot 0.7g/l, glucose 2.8 mmol/L,
polimorphs 10, lymphocytes 6, RBCs 2
• GAs sent for culture DST
• Boarder at grandmother’s house has TB, but
on TB Rx before baby was born
• Likely source?
• Remember to screen the caregivers!
Impact of HIV on TB in Africa
Notified cases per 100,000 pop
Percentage of global estimated HIV-positive TB cases
EMR
Cameroon
Thailand
Brazil
Democratic Republic of the Congo
China
Myanmar
EUR
Côte d'Ivoire
Malawi
United Republic of Tanzania
AMR
Zambia
WPR
Ethiopia
Mozambique
Kenya
Uganda
Zimbabwe
Nigeria
India
SEA
South Africa
AFR
1% 5% 10% 20% 50% 90%0
100
200
300
400
500
600
700
1980 1984 1988 1992 1996 2000 2004 2008
Botswana
Côte d'Ivoire
DR Congo
Gabon
Guinea
Kenya
Malawi
Mozambique
South Africa
UR Tanzania
Zimbabwe
79% of all estimated TB/HIV cases occur in Africa
South Africa
2015 Data WHO
TB 834/100,000SA 14.4 new HIV infections/1000 uninfected
Increasing TB/HIV Burden
Lawn SD et al. CID 2006; 42: 1040-7
TB - Age & Gender shift
Lawn SD et al. CID 2006; 42: 1040-7
3-4% 0-9y 25% 20-39y HIV prevalence in
general population:
Major transitions
Exposure
Infection
Disease
Understanding the
Natural History of Disease
Arvid Wallgren 1889-1973
Time-related risk
0 1 2 3 4 6 8 10 12 2 3
Infection Months Years
TimelinePhase of diseaseI Hypersensitivity
II Miliary TB and TBM
III Lymph node disease / Pleural effusion
IV Adult-type disease
HIV-infected - PERSISTENT RISK OF REACTIVATION DISEASE
I II III IV
Immune
compromised
Infection without disease
Progressive disease
Manifestations of
intra-thoracic TB
in children
DIVERSITY
OF
DISEASE
Pathophysiology
• From the primary focus bacilli may spread:
- locally and cause extension of primary focus
- lymphatically to the hilar/mediastinal lymph
nodes
- retrograde via lymphatics to abdominal
nodes or to cervical nodes
- haematogenously to any part of the body
- may break through to pleura or even chest
wall
• Rarely entry point may be the gut
(unpasteurised milk) or even the skin (injury
with local infection)
Cardiac Catheterization
Miliary or bronchopneumonic TB?
Miliary TB
Different age-related patterns
0 1 2 3 4 6 8 10 12 14
Age in years
Complicated Ghon focus
Miliary TB
Lymph node disease
Pleural effusion
Adult-type disease
Immune
compromised
Manifestations of
extra-thoracic TB
in children
DIVERSITY
OF
DISEASE
TB cervical lymphadenitis• Most common form of extra-thoracic TB
• Diagnosis - persistent mass >2x2cm
no visible local cause or response to antibiotics
• In low-incidence countries – consider non-tuberculousmycobacteria as cause
TB Meningitis (TBM)
History: Child <3yrs or immune compromised
Fever, lethargy (weight loss, recent TB contact)
LP – Cells <1000 / Lymphocyte predominance glucose low / protein high
TB Abdomen• M. tuberculosis or M. bovis (latter from
unpasteurized milk)
• Through dissemination or swallowing
• Different types of
abdominal TB
- intestinal
involvement
- lymph nodes
- solid organ TB
- peritonitis
Osteo-articular TB
TB of vertebra (gibbus) – 50% of OA-TB
TB involving other bones - infants
TB of the joint – usually weight bearing
joints
Dermatological TB manifestations
Erythema nodosum
not TB but associated with TB
Sporotrichoid lesions + old TST
Erythema induratum
Papulonecrotic TB
Other manifestations of EPTB• Ear/mastoiditis
• Pericardial
• Urogenital TB –
very rare in children
In summary
• Not all M.tuberculosis infection leads to disease
• The risk of developing disease is influenced
mainly by the age and immune status of the child
• There is a diverse spectrum of disease that
demonstrates clear age-related patterns
• Pulmonary/Intrathoracic TB most common, but
any organ/system can be affected by TB