Tuberculosis exposure, infection and disease in children: a systematic diagnostic approach
Roya-Pabon and Perez-Velez Pneumonia
Tuberculosis exposure, infection and disease in children: a systematic diagnostic approach
Claudia L. Roya-Pabon 1 2
Carlos M. Perez-Velez 0 1 3 4
0 Tuberculosis Clinic, Pima County Health Department , Tucson, AZ , USA
1 Grupo Tuberculosis Valle-Colorado (GTVC) , Medellin, Antioquia , Colombia
2 Division of Pediatric Pulmonology, Department of Pediatrics, Faculty of Medicine, University of Antioquia , Medellin, Antioquia , Colombia
3 College of Medicine, University of Arizona , 1501 North Campbell Avenue, P.O. Box 24503985724 Tucson, AZ , USA
4 Division of Infectious Diseases, College of Medicine, University of Arizona , Tucson, AZ , USA
The accurate diagnosis of tuberculosis (TB) in children remains challenging. A myriad of common childhood diseases can present with similar symptoms and signs, and differentiating between exposure and infection, as well as infection and disease can be problematic. The paucibacillary nature of childhood TB complicates bacteriological confirmation and specimen collection is difficult. In most instances intrathoracic TB remains a clinical diagnosis. TB infection and disease represent a dynamic continuum from TB exposure with/without infection, to subclinical/ incipient disease, to non-severe and severe disease. The clinical spectrum of intrathoracic TB in children is broad, and the classification of clinical, radiological, endoscopic, and laboratory findings into recognized clinical syndromes allows a more refined diagnostic approach in order to minimize both under- and over-diagnosis. Bacteriological confirmation can be improved significantly by collecting multiple, high-quality specimens from the most appropriate source. Mycobacterial testing should include traditional smear microscopy and culture, as well as nucleic acid amplification testing. A systematic approach to the child with recent exposure to TB, or with clinical and radiological findings compatible with this diagnosis, should allow pragmatic classification as TB exposure, infection, or disease to facilitate timely and appropriate management. It is important to also assess risk factors for TB disease progression and to undertake follow-up evaluations to monitor treatment response and ongoing evidence supporting a TB, or alternative, diagnosis.
Latent tuberculosis; Algorithm; Diagnostic techniques and procedures; Specimen handling; Risk factors
Diagnosing tuberculosis (TB) in children is challenging
(Table 1)  and often it is only considered after the child
has failed various therapeutic trials for other disorders.
Even with intensive specimen collection and optimal
molecular and culture-based diagnostics, most children with
non-severe pulmonary TB are not confirmed
bacteriologically, despite having an exposure history,
immunebased confirmation of infection and clinical features
consistent with this diagnosis . Nonetheless, with
currently available tools, it is possible to make an accurate
clinical diagnosis of intrathoracic TB in most diseased
children. This review presents a systematic approach to
diagnosing intrathoracic TB in children.
Continuum of TB states
Although much remains unknown about its
pathophysiology, TB studies characterized a dynamic continuum of
various states that include exposure, infection,
subclinical or incipient disease, non-severe and severe disease
states (Fig. 1) [3, 4]. Generally, this continuum correlates
with bacterial burden . As the archetypical human
pathogen, Mycobacterium tuberculosis establishes a
sustained but “delicately balanced” host–pathogen
relationship . These TB states depend upon various host
(e.g. immunological competence), pathogen (e.g. strain
virulence), and environmental (e.g. intensity of exposure)
factors. The clinical outcome of infection will thus be
either self-cure, latency or disease . Understanding
that TB is a continuum of states—and not a dichotomy
of infection or disease—has important implications for
managing children in whom latent or active TB often
cannot be confirmed.
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Table 1 Challenges in diagnosing TB exposure, infection and disease in children
Current status & limitations
Detection of TB disease
and of drug resistance
Current immune-based tests (TST and IGRAs)
may not convert to positive until 2–10 weeks
after acquiring M. tb infection
Chest radiography is the first-line imaging
modality, but may not reveal abnormalities
consistent with TB disease in all cases –
especially those in early states of the
continuum of TB
Currently available immune-based tests (TST
and IGRAs) do not differentiate between
infection and disease
Currently available tests (e.g. NAATs; culture)
for bacteriological confirmation have limited
sensitivity for detecting M. tb in young children
with paucibacillary disease–especially in early
states of the continuum of TB
Specimen collection for bacteriological
confirmation currently consists of serial sampling
of three gastric aspirates/lavages or induced sputa
and requires trained personnel and facilities with
airborne infection control
Recent advances & future prospects
Mycobacteria-specific cytokine biomarkers –
alone or in combination (i.e., biosignatures) –
may distinguish between TB exposure
(without infection), and TB infection 
Chest CT, MRI, and PET  scan may
reveal findings consistent with TB disease
before symptoms develop
Mycobacteria-specific cytokine biomarkers – alone
or in combination – may distinguish between TB
infection and TB disease 
- Xpert MTB/RIF Ultra (Cepheid): next generation,
ultrasensitive NAAT for detection of both M. tb &
rifamycin resistance; in vitro study demonstrated
sensitivity comparable to culture [92, 93].
- GeneXpert Omni (Cepheid): single-cartridge
battery-operated platform that is portable/mobile;
study pending 
- Xpert XDR NAAT (Cepheid): study anticipated
in 2018 
Strategies consisting of “intensive” collection
of combinations of various specimens
(e.g., nasopharyngeal aspirates; string tests;
stool; fine needle aspirate of diseased
lymph node) that have similar or superior
bacteriological yield, require less training,
and may be carried out as an outpatient
over 1–2 days
Cytokine biomarkers and biosignatures
(possibly including IFN-γ, TNF-α, IL-2, IL-6,
IL-10 and/or IL-12) [94, 95]
18 F-FDG PET/CT is sensitive for the detection
of TB disease (in different states of the continuum)
and for monitoring response to treatment 
Mycobacterial culture is only useful in those
children who had positive cultures at time of
diagnosis (minority of cases).
CT computed tomography, IGRA interferon-gamma release assay, MRI magnetic resonance imaging, M. tb: Mycobacterium tuberculosis, NAAT nucleic acid
amplification test, PCR polymerase chain reaction, PET positron emission tomography, TB tuberculosis, TST tuberculin skin test, XDR extensively drug-resistant
Clinical spectrum of disease
Once infected with M. tuberculosis, young children
(aged <5 years) are at greater risk than adults of
progressing to disease, including its most severe forms.
This depends on the child’s susceptibility, which is
highest during the first years of life, probably from
immunological immaturity. Without Bacille
CalmetteGuerin (BCG) vaccination, approximately 30% of
infected infants (<1 year old) will progress to
intrathoracic TB, and 10–20% will develop disseminated
disease. In children aged 1–2 years, the risk of progressing
to intrathoracic TB is 10–20 and 2–5% for disseminated
disease. These risks decline slowly until around 10 years
of age when adult-type disease starts to emerge [8, 9].
Thus, early diagnosis is important, especially in infants
and young children who are at greatest risk of rapid
disease development  and clinicians should consider
the full clinical spectrum of intrathoracic syndromes
Clinical classification of tuberculosis
Classifying intrathoracic TB by immunopathogenesis
(Table 2) assists understanding how each possible “state”
in the continuum is managed . For example, a child
with a history of TB exposure can have the features of
subclinical disease  outlined in Table 2, which in
some hierarchical diagnostic classification systems
corresponds to “possible” intrathoracic TB. A typical example
is that of a young child with isolated uncomplicated hilar
lymphadenopathy . Such a child may not meet
sufficient criteria to be clinically diagnosed with “probable”
intrathoracic TB given their lack of symptoms and
physical signs,  and consequently may not receive
treatment for tuberculosis disease or infection. Whether this
intermediate state will progress to clinically manifest
disease or be contained as latent infection is dependent
on the child’s level of immunocompetence. In those with
risk factors for progression to TB disease, treatment is
recommended. Children with disease can be further
Fig. 1 Continuum of TB states and correlations with bacterial load and with radiological and clinical manifestations. CFU: colony-forming units;
LED: light-emitting diode; LOD: limit of detection; mL: milliliter; NAAT: nucleic acid amplification test; RT-PCR: real-time polymerase chain reaction.
Adapted from C.M. Perez-Velez. Diagnosis of Intrathoracic Tuberculosis in Children. In: Handbook of Child and Adolescent Tuberculosis (p. 149),
J.R. Starke and P.R. Donald (Eds.), 2016, New York, NY: Oxford University Press. Copyright by Oxford University Press . Adapted with permission
Table 2 Clinical classification of intrathoracic TB based on immunopathogenesis
Self-cure (infection eliminated by
innate immune response; no
Quiescent infection (non-replicating
bacteria persisting with very low
metabolic activity; infection
Incipient disease (replicating bacteria
that are metabolically active;
Mild-to-moderate disease (replicating Usually
bacteria that are metabolically active; positive
infection only partially contained)
Severe disease (replicating bacteria Usually
that are metabolically active; infection positive
- Calcified non-enlarged
regional lymph nodes
- Calcified lung nodules
- Pleural thickening
Mild-to-moderate Positive cultures
(10–30% of cases)
(30–70% of cases)
Adapted from C.M. Perez-Velez. Diagnosis of Intrathoracic Tuberculosis in Children. In: Handbook of Child and Adolescent Tuberculosis (p. 149), J.R. Starke and P.R.
Donald (Eds.), 2016, New York, NY: Oxford University Press. Copyright by Oxford University Press . Adapted with permission
IGRA Interferon-gamma release assay, PCR polymerase chain reaction, TB tuberculosis, TST tuberculin skin test
classified as severe or non-severe, depending on whether
or not infection is contained and on the presence and
extent of complications.
Systematic diagnostic approach
As it is impossible to achieve bacteriological
confirmation in many childhood TB cases, systematically
identifying findings suggestive of TB can allow for its clinical
diagnosis. Excluding other differential diagnoses and
observing a positive therapeutic response increases the
probability of TB being the correct diagnosis. The
following systematic approach to diagnosing TB in
children consists of (i) identifying findings suggesting TB
disease; (ii) identifying findings supportive of TB as the
etiology; (iii) screening for risk factors for progression to
disease; and (iv) follow-up evaluations to further support
or exclude TB as the etiology (Table 3) .
Step 1: Identify findings suggestive of TB disease
Clinical evaluation: history & physical exam
Laboratory studies: composite measures (cell count and chemistry)
of body fluids (e.g., pleural fluid)
Endoscopic studies: bronchoscopy
Step 2: Identifying findings supportive of TB as the etiology
Immune-based tests: TST; IGRA
Mycobacterial detection: smear microscopy; NAAT; culture; antigen
test (in HIV-infected adolescents, lateral flow lipoarabinomannan in
urine with CD4 < 100)
Histopathological & cytopathological studies
Excluding other differential diagnoses
Step 3: Screen for risk factors for progression to TB disease
Age groups (e.g. immunological immaturity of infancy)
Immunocompromising conditions (e.g., HIV infection)
Contained TB infection-disease (e.g., noncalcified fibronodular lesions,
especially apical, on chest imaging
Environment (e.g., continued exposure)
Step 4: Follow-up evaluation to support or exclude TB as the etiology
Adapted from C.M. Perez-Velez. Diagnosis of Intrathoracic Tuberculosis in
Children. In: Handbook of Child and Adolescent Tuberculosis (p. 149), J.R.
Starke and P.R. Donald (Eds.), 2016, New York, NY: Oxford University Press.
Copyright by Oxford University Press . Adapted with permission
ADA adenosine deaminase, CD4 cluster of differentiation 4, HIV human
immunodeficiency virus, IGRA interferon gamma release assay, NAAT nucleic
acid amplification test, TB tuberculosis, TNF-α tumor necrosis factor alpha, TST
tuberculin skin test
STEP 1: Identify findings suggestive of TB disease
Each intrathoracic clinical syndrome of TB disease has
its own constellation of clinical, radiological, laboratory,
and endoscopic (if indicated) findings, although many
are shared by more than one clinical syndrome.
Furthermore, miliary lung disease may also involve potentially
any organ system (Additional file 1: Textbox 1). Most
clinical manifestations of intrathoracic TB result from
the overall balance of beneficial and harmful immune
responses to M. tuberculosis and a severe inflammatory
reaction can be triggered by a relatively low burden of
organisms. There are no clinical features pathognomonic
of intrathoracic TB, but combinations of symptoms and
physical signs with certain temporal patterns can help
differentiate it from other etiologies that might mimic
Pulmonary TB is frequently associated with intrathoracic
lymphadenopathy, and sometimes with pleural or
pericardial disease, and therefore “intrathoracic TB” is the
preferred term in children. Localized symptoms and
physical signs depend on which intrathoracic organs are
involved, while non-localized symptoms and signs are
independent of the organ-specific clinical syndrome.
Symptoms and physical signs that are well-defined have
higher specificity. However, in children who are
immunocompromised (e.g. less than three years of age with
immunological immaturity), HIV-infected, or severely
malnourished, these symptoms and signs have lower
sensitivity and specificity .
Systemic symptoms and signs may appear early or late
in the disease course . Daily fever is characteristically
>38.0 ° C, intermittent or persistent throughout the day,
and usually lasts >1 week. Night sweats are uncommon,
subjective and nonspecific, and are significant only when
they drench the child’s clothes and bedding. Chills and
rigors are rare, except in disseminated disease. Anorexia
and associated wasting or failure to thrive during the
past 3–6 months, or having lost >10% of body weight
over any interval of time, are sensitive—albeit
nonspecific—signs in most TB clinical syndromes in young
children . The immunocompromised state from severe
under-nutrition can increase the risk for a paradoxical
reaction when they receive TB treatment and nutritional
rehabilitation . Fatigue, asthenia, and malaise may
manifest in young children as listlessness (e.g. decreased
playfulness) and in infants as apathy (e.g. less interactive
with caregivers) and should be persistent and not
attributable to other causes.
Peripheral lymphadenopathy from TB typically
consists of a unilateral, enlarged, non-painful, rubbery
lymph node, sometimes becoming fluctuant, with or
without spontaneous drainage forming a sinus tract .
Respiratory symptoms and signs depend on the site, and
degree of involvement (e.g. of airway obstruction). The
cough is usually unremitting for >2 weeks and may be
“dry” or “wet”. When the airway is compressed by an
enlarged lymph node, there may be persistent cough,
wheezing or stridor that does not improve with inhaled
bronchodilators (Additional file 1: Table S1).
Characterizing the temporal pattern (including the onset, progression
and duration) of symptoms helps clinicians to identify
cases with likely intrathoracic TB.
Chest imaging—including radiography, computed
tomography (CT), and ultrasonography—is one of the most
useful diagnostic modalities for detecting intrathoracic
TB. The spectrum of radiological abnormalities in
children is very broad, and none are sufficiently specific
to confirm the diagnosis [20, 21]. Nonetheless, certain
patterns and signs are highly suggestive, especially when
accompanied by clinical features and supportive findings
(e.g. recent TB exposure, and positive T-cell-based test).
Recognizing such radiological patterns (Fig. 2) helps
narrow the differential diagnosis (Additional file 1: Table S3).
Chest radiography—including both frontal and lateral
projections—is the first-line imaging modality when
intrathoracic TB is suspected. The lateral projection helps
detect retrocarinal, subcarinal, and superimposed hilar
lymphadenopathy, especially in infants where the thymus
may obscure enlarged nodes on the frontal view [22, 23].
Additionally, CT scans may detect abnormalities
suggestive of intrathoracic TB in a child suspected of having
complicated intrathoracic lymph node or pleural disease,
endobronchial lesions, bronchiectasis, or cavities that are
not well revealed on plain radiography [24, 25]. Finally,
chest ultrasonography is useful for evaluating mediastinal
lymphadenopathy and pericardial effusions. Also, it is the
preferred imaging modality in differentiating loculated
from free-flowing pleural effusions [26, 27].
Bronchoscopy may be useful in diagnosing and
managing cases with tracheobronchial disease . However,
it is not routinely indicated for evaluating all
intrathoracic TB clinical syndromes.
While non-microbiological laboratory tests results can
suggest TB disease, they are not confirmatory of this
diagnosis. The cell count and chemistry of body fluids, such as
pleural or pericardial fluids, can raise the possibility of TB
when the composite results are consistent with the
disease. However, other diseases, including non-tuberculous
mycobacterial species and fungal infections, can also
provide similar results. The following features suggest
TB: cell count predominantly lymphocytic (may be
neutrophilic within the first few days); elevated protein
level (>30 g/L; protein/serum protein ratio >0.5);
elevated LDH (>200 IU/L; LDH/serum LDH ratio >0.6);
glucose 3.0–5.5 mmol/L (usually lower in effusions due
to pyogenic bacteria or rheumatoid arthritis); normal
lipids (elevated in chylous effusions). The most common
findings on full blood count are mild anemia, neutrophilia,
and monocytosis, but these abnormalities are found just as
frequently in other respiratory infections . Erythrocyte
sedimentation rate may be normal or elevated (e.g.
>100 mm/h), but is nonspecific, as are C-reactive protein
and procalcitonin [30, 31].
STEP 2: Identify findings supportive of TB as the
The positive predictive value of each of the following
types of findings depends on the local TB prevalence.
Children are usually infected following exposure to
someone with pulmonary TB whose sputum is positive
by microscopy or culture, who is actively coughing, and
with whom they share the same space (e.g. household,
daycare centers, schools, healthcare facilities, refugee
camps). In children aged <5 years, the source case is
most often from the same household, and the infection
usually acquired within the past year. As children
become exposed to the community outside the household,
their risk of acquiring infection from this source
increases and inquiring about confirmed or suspected TB
contacts and knowledge of the local TB epidemiology
becomes more pertinent .
Memory T-cells, detected by a tuberculin skin test (TST)
and current M. tuberculosis interferon-gamma release
assays (IGRAs) measure lasting TB immune responses
and can represent any of the following: active TB disease,
previous TB disease, latent TB infection, recent or remote
TB exposure, or exposure to environmental
nontuberculous mycobacteria (NTM; e.g. M. kansasii, M. szulgai, M.
marinum) that may have cross-reactivity. Neither IGRAs
nor TST can distinguish latent from active TB . Table 4
provides a comparison of currently approved T-cell-based
tests including TST, and IGRAs specific for M.
tuberculosis, such as the ELISPOT-based T-SPOT TB (Oxford
Immunotec) and the ELISA-based QuantiFERON (QFT)
Gold In-Tube and QFT Gold Plus (Qiagen). TST and
IGRAs are complementary, so using both increases
A T-cell-based test may be positive in TB infection as
well as TB disease. When positive in a child with a
Fig. 2 Illustrations of radiological patterns caused by intrathoracic TB in children. Panel a. Primary Ghon focus with uncomplicated lymph node
disease. Hilar and mediastinal lymphadenopathy associated with an ipsilateral peripheral nodule, or “Ghon focus” (right lung); these nodules are
often subpleural with an overlying pleural reaction. Panel b. Progressive Ghon focus with uncomplicated lymph node disease. A Ghon focus with
cavitation (right lung), which is seen almost exclusively in infants and immunocompromised children; other elements of the Ghon complex are
also visible. Panel c. Complicated lymph node disease with bronchial compression. Enlarged lymph nodes compressing the airway, causing either
complete obstruction with lobar collapse (right middle and lower lobes), or partial obstruction with a ball-valve effect leading to hyperinflation (left upper
and lower lobes). Panel d. Complicated lymph node disease with bronchopneumonia. Necrotic lymph nodes erupting into bronchus intermedius, with
endobronchial spread and patchy consolidation of the middle lobe (right lung). Panel e. Complicated lymph node disease with expansile lobar
pneumonia. Necrotic lymph nodes that compress and obstruct the left upper lobe bronchus and may infiltrate a phrenic nerve, causing hemidiaphragmatic palsy
(left-sided); endobronchial spread causes dense consolidation of the entire lobe (left upper lobe), with displacement of the trachea and fissures and the
formation of focal cavities. Panel f. Miliary (disseminated) disease. Diffuse micronodules in both lungs, which may result from lymphohematogenous spread
after recent primary infection or from infiltrating a necrotic lymph node or lung lesion into a blood vessel, leading to hematogenous spread
Fig. 2 (continued) Panel g. Multiple focal pulmonary nodules. Multiple focal pulmonary nodules involving the right middle lobe with
enlargement of regional lymph nodes (right lung). Panel h. Cavitary (“adult-type”) pulmonary disease. Cavity formation in both upper lobes, with
endobronchial spread to the right middle lobe. Nodules or cavities in apical lung segments are typical of adult-type disease and are pathologically
distinct from the other cavities shown. Panel i. Bronchitis and endobronchial granulomas. Inflammation of the mucosa of main stem bronchus
with purulent secretions (left lung), and a necrotic lymph node that has eroded into the right middle lobe bronchus leading to endobronchial
spread and subsequent development of endobronchial granulomas extending proximally to the bronchus intermedius and main stem bronchus,
and distally to the lower lobe bronchus (right lung). These findings are best visualized by bronchoscopy. Panel j. Bronchiectasis and tree-in-bud-pattern.
Bronchiectasis that extensively involves the upper lobe (right lung), and shows tree-in-bud pattern observable on CT scans – reflecting dilated centrilobular
bronchioles with mucoid impaction – involving the upper lobe (left lung). Panel k. Pleural effusion. A pleural effusion that is usually
indicative of recent primary infection, with a hypersensitivity response to tuberculoprotein leaking from a subpleural Ghon focus (often
not visible) into the pleural cavity; in rare cases this effusion may also result from a chylothorax. Panel l. Pericardial effusion. A pericardial
effusion that occurs when tuberculoprotein leaks from a necrotic subcarinal lymph node (shown in “close-up” window) into the pericardial
space; it may also occur after hematogenous spread. Conceptualization and original sketches by C.L. Roya-Pabon, MD; finished artwork by
Mesa Schumacher, MA (used with permission). Adapted from C.M. Perez-Velez. Diagnosis of Intrathoracic Tuberculosis in Children. In: Handbook of
Child and Adolescent Tuberculosis (p. 154–155), J.R. Starke and P.R. Donald (Eds.), 2016, New York, NY: Oxford University Press. Copyright by Oxford
University Press . Adapted with permission
Table 4 Comparison of T cell-based tests for TB infection
Minimum number of
visits to complete testing
Booster effect with
Booster effect after prior TST
(not specific to M. tb.)
Skin induration after
in vivo stimulation
Intradermal injection of 5 units
Limited variability with
appropriate training 
Less reliable in children under
6-months of age
ELISA-based measurement of
IFN-γ production by T-cells
after in vitro stimulation
of IFN-γ-producing T-cells
(spots) after in vitro stimulation
variability [35, 36]
Possible (but likely inconsequential
if blood drawn < 3 days after TST 
Same as TST ; T-SPOT.TB slightly
less affected by immunosuppression
than QFT 
BCG bacille Calmette-Guérin, IGRA interferon-gamma release assay, M. tb Mycobacterium tuberculosis, NTM nontuberculous mycobacteria, PPD purified protein
derivative, TB tuberculosis, TST tuberculin skin test
clinical syndrome compatible with TB, a T-cell-based
test is supportive of TB as the etiology. However, these
tests—regardless of their degree of positivity—cannot
distinguish between latent infection and active disease.
Determining whether someone has active disease rather
than latent infection depends upon findings (e.g. clinical,
radiological, laboratory, or endoscopic) consistent with TB
disease being present. Furthermore, in children with
immunocompromising conditions the sensitivity of
T-cellbased tests is decreased. When negative or indeterminate
in the setting of a very recent TB exposure or of suspected
TB disease (especially one overwhelming the immune
system), it may be useful to repeat the T-cell-based test
(e.g. in 8–10 weeks) when immune conversion is complete
or effective TB treatment reduced the mycobacterial
burden. However, a negative T-cell-based (TST/IGRA) test
cannot be used to exclude TB infection or disease .
Depending on the cutoff levels used, biochemical
markers can have a sensitivity and specificity sufficiently
high enough to strongly support TB as the cause of
pleural or pericardial effusions. Although most studies
have been undertaken in adults, their results should also
apply in children. In pleural TB, using 40 U/L as the
cutoff, the sensitivity of adenosine deaminase (ADA) is
approximately 90% and its specificity is around 92% [44,
45]. In pericardial tuberculosis, the sensitivity and
specificity of ADA levels 40 U/L are approximately 88 and 83%,
In children with an intrathoracic clinical syndrome
consistent with TB, microbiological studies should always be
Fig. 3 Specimens for bacteriological confirmation of intrathoracic TB in children. Adapted from C.L. Roya-Pabon. Especímenes Respiratorios para
el Diagnóstico Microbiológico de las Infecciones Respiratorias. In: Neumología Pediátrica (p. 179), R. Posada-Saldarriaga (Ed.), 2016, Bogotá,
Colombia: Distribuna Editorial. Copyright by Distribuna Ltda. . Adapted with permission
performed as they allow for bacteriological confirmation
and for antibiotic susceptibility/resistance testing.
M. tuberculosis can be detected from various specimens
(Fig. 3). Specimen collection should be performed before
TB treatment. The specimen collection strategy should
include collecting at least two samples (preferably of
different specimen types), ensuring high -quality and
-quantity of each sample and considering pooling of
samples if necessary [47–50]. Early morning respiratory
specimens generally have the best yield. Older children
(aged ≥10 years) can usually expectorate sputum of
adequate quality and volume, without coaching or
assistance (i.e. spontaneously expectorated sputum). Younger
children (aged 5–10 years) can usually expectorate with
assistance and the very young (aged <5 years) are unable
to expectorate effectively requiring secretions in the
laryngopharynx to be suctioned following sputum
induction (i.e. induced sputum collected by laryngopharyngeal
aspiration) . The term “laryngopharyngeal aspirate”
is recommended as this specimen type is collected from
the laryngopharyngeal space, it contains less saliva, and
is less contaminated by oral microbiota than respiratory
secretions passing through the mouth. [21, 46].
Alternatively, lower respiratory secretions that have reached the
nasopharynx can be suctioned (known as
“nasopharyngeal aspirate”) . Bronchoalveolar lavage should be
reserved for children from whom less invasive specimen
collection is not attainable, especially as its bacteriological
yield is lower than that of serial gastric aspirates [52, 53].
Since young children usually swallow their respiratory
secretions, these can be collected by gastric aspiration or
lavage (gastric aspiration is preferred). These can also be
captured in the esophagus using an intra-esophageal,
highly-absorbent nylon yarn, employing as a vehicle for its
placement either a gelatin capsule (string test) that is
swallowed or a nasogastric tube (combined
nasogastric-tubeand-string test). In cooperative children (aged >4 years)
able to swallow the gelatin capsule containing the string,
the conventional string test is associated with minimal
discomfort. In younger children unable to swallow the
capsule, the combined nasogastric-tube-and-string test
allows two specimens (one gastric aspirate and one string
test) to be collected [54, 55]. As young children swallow
their sputum, stool may also contain M. tuberculosis and a
nucleic acid amplification test (NAAT), such as Xpert
MTB/RIF (Cepheid, United States of America), on stool
can bacteriologically confirm approximately 45% of
clinically diagnosed cases of pulmonary TB [56, 57].
In children with enlarged peripheral lymph nodes
(usually cervical), a fine needle aspiration biopsy is the
specimen of choice, and should be submitted for: (i)
mycobacterial testing, i.e. NAAT (Xpert MTB/RIF has a
sensitivity of ~83% using culture as reference) and
culture; and (ii) pathological studies (cytopathology of
aspirate; histopathology of biopsied tissue) [58, 59].
Serosal fluids (e.g. pleural and pericardial) should be
collected and submitted for biochemical markers,
mycobacterial testing, and cytopathological studies. The
diagnostic yield of serosal fluids increases as more types of
tests performed. Serosal tissue generally has a higher
culture yield and so biopsy (e.g. of the pleura or pericardium)
may be justified, especially when drug-resistant TB is
suspected (allowing susceptibility testing to be undertaken).
Acid-fast staining and smear microscopy
Acid-fast staining and smear microscopy is a rapid and
relatively inexpensive test for detecting acid-fast bacilli
(AFB). Unfortunately, the sensitivity of smear
microscopy varies greatly based on AFB load. For reliable
detection, a sample must contain AFB of at least 1000–
10,000 colony-forming units (CFU)/mL . This
relatively high detection limit, together with the
paucibacillary nature of TB disease in children, contributes to the
very low sensitivity of smear microscopy.
Acid-fast stains are also not specific for M. tuberculosis
complex as they cannot differentiate between
mycobacterial species. Nonetheless, in a child with a high pre-test
probability of having pulmonary TB, a positive result has a
high predictive value, and studies using culture as a
reference standard report a very high specificity (~95%)
[61–63]. Microscopy’s low sensitivity and inability to
differentiate between AFB species (especially relevant for gastric
aspirate specimens), means it should not be used as a sole
mycobacterial test for detecting M. tuberculosis.
Nucleic acid amplification tests or antigen detection
NAATs are rapid tests that include real-time polymerase
chain reaction (RT-PCR) and line probe assays (LPAs)
(Additional file 1: Table S2). Recently developed NAATs
can also simultaneously detect genes conferring drug
resistance, allowing prompt and more appropriate treatment of
cases with drug-resistant disease. The fully automated
Xpert MTB/RIF test has high sensitivity (pooled estimate
95–96%) in sputum smear-positive samples using culture
as a reference standard, but only moderate sensitivity
(pooled estimate 55–62%) in smear-negative samples .
In 2013, the World Health Organization recommended
using Xpert MTB/RIF in samples from children, especially
those suspected of multidrug-resistant TB or HIV
coinfection . Certain LPAs detect M. tuberculosis with/
without drug resistance mutations, as well as common
NTM, such as M. avium, M. intracellulare, and M.
kansasii. GenoType MTBDRplus® (Hain Lifescience,
Holland) or Genoscholar NTM + MDRTB® (Nipro Europe,
Germany) are especially useful for simultaneously detecting
isoniazid- and rifampin-resistance in microscopy-positive
samples or culture isolates [65–67]. Regarding antigen
detection tests the urine lateral flow lipoarabinomannan
(LFLAM) assay may be useful in adolescents with advanced
HIV disease and CD4 counts <100 cells/L [68–70];
however, in young children it has poor diagnostic accuracy .
Mycobacterial cultures have the highest sensitivity and
specificity for bacteriological confirmation of
intrathoracic TB in children. The limits of detection of liquid
and solid media are approximately 10–100 CFU/mL and
50–150 CFU/mL, respectively (versus 100–150 CFU/mL
for RT-PCR or 1000–10,000 CFU/mL for fluorescent
LED microscopy) . In most prospective studies of
children with a clinical diagnosis of probable pulmonary
TB, cultures of respiratory specimens are positive in 10–
20% of cases. Studies reporting higher rates (i.e. >30%)
of culture confirmation are often retrospective and
include only children who are hospitalized (probably
have more severe disease and better specimen collection
strategies) or diagnosed following passive case finding
. For definitive species identification following
growth in mycobacterial culture, the following methods
may be utilized: (i) phenotypic analysis; (ii) antigen tests;
(iii) molecular tests such as nucleic acid hybridization
probes, matrix-assisted laser desorption/ionization
timeof-flight mass spectrometry, and DNA sequencing.
Histopathological studies should be considered in
intrathoracic clinical syndromes compatible with either TB disease
or malignancy, especially when bacteriological tests fail to
confirm an infectious etiology. Potentially useful tissues to
biopsy include lymph nodes, pleura, pericardium and lung.
Findings suggestive of TB are numerous granulomas in
various developmental stages, some with central caseous
necrosis . However, granulomatous inflammation is not
sufficiently specific to diagnose TB and differential
diagnoses include bacterial (e.g. NTM, nocardiosis), fungal (e.g.
histoplasmosis, coccidioidomycosis), helminthic (e.g.
schistosomiasis) and, protozoal (e.g. toxoplasmosis) infections,
autoimmune diseases (e.g. granulomatosis with
polyangiitis), idiopathic etiologies (e.g. sarcoidosis), and foreign
Excluding alternative diagnoses
In infants and children, the clinical diagnosis of
intrathoracic TB is not always certain, as other disorders can
present with similar clinical, radiological, and laboratory
abnormalities, or may be present concomitantly. Chronic
cough, failure to thrive and prolonged fever for example,
have multiple etiologies (Additional file 1: Table S1). It
may be possible to exclude some differential diagnoses
by using sensitive diagnostic tests or if the child fails a
diagnostic-therapeutic trial (i.e., no sustained
improvement with appropriate empiric therapy) . Examples
of the latter include antibiotics for possible pneumonia,
antimalarial agents for fever from presumed malaria,
and nutritional support for failure to thrive from
suspected under-nutrition. Excluding alternative
diagnoses provides further support for a clinical diagnosis of
STEP 3: Screening for risk factors for progression
to TB disease
Identifying risk factors for progression from TB infection
to disease (Additional file 1: Textbox 2) is important
when intrathoracic TB (both pulmonary and
extrapulmonary) is suspected. If these are present, this should
hasten the diagnostic evaluation; expedite TB treatment
(beginning immediately after collecting specimens for
microbiological studies) if there are sufficient findings
for a presumptive TB diagnosis; and guide preventive
therapy in children with TB exposure and infection.
STEP 4: Follow-up evaluation to further support
or exclude TB as the etiology
In very young or immunocompromised children,
intrathoracic TB can present acutely; however, in otherwise
immunocompetent children, it usually presents as a
subacute or chronic illness. In the early stages, there may be
insufficient findings to make a presumptive diagnosis,
and, even if culture confirmation is attained, this can
take weeks. It is therefore critical to perform follow-up
evaluations to reassess the patient, whether or not
treatment has been initiated, by continuing to reassess steps
1 and 2. On follow-up evaluations, failure to thrive may
become more apparent, respiratory symptoms emerge,
chest radiography may reveal new or increasing
abnormalities, immune-based tests (TST/IGRA) may become
positive, and M. tuberculosis is detected in respiratory
specimens. As most (>90%) children develop disease
within the first 12-months of their primary infection,
periodic reassessment during the first year of their
infection being diagnosed is important.
Structured diagnostic approaches
The lack of a sensitive diagnostic test for intrathoracic
TB means that many diagnostic approaches have been
developed. Some are numerical (scoring systems), some
hierarchical (case definitions for classification), and
others binary (presence or absence of disease). Few have
been validated against a gold standard . Although
some perform well in advanced disease where clinical
and radiological findings are florid, they perform less
well in patients with early or mild disease, in young
children, and in immunocompromised patients, all of whom
are challenging to diagnose . Commonly used
approaches have poor agreement with one another and
yield highly variable case frequency results from
differences in purpose (screening versus diagnosis; patient
care versus research versus epidemiological surveillance);
healthcare setting (community versus hospital); disease
severity (mild versus severe); and prevalence of
tuberculosis and/or HIV infection (low versus high) .
Clinical case definitions and management algorithms
Clinical case definitions of TB exposure, infection, and
presumptive and confirmed intrathoracic TB in children
involve findings suggestive of TB disease (clinical,
radiological); findings supportive of TB as the etiology
(exposure, immune-based testing, mycobacterial testing,
therapeutic response to TB treatment); and risk factors
for progression to disease (Table 5). Figure 4 shows an
algorithm providing recommendations for diagnosing
and managing children with recent exposure to TB
(active case finding), or with clinical and/or radiological
findings suggestive of TB disease (passive case finding).
TB exposure [ICD-10: Z20.1]
TB exposure is defined as recent close contact with an
adult or adolescent with infectious pulmonary TB
(presumptive or bacteriologically confirmed), but without
evidence of infection, and lacking clinical or radiological
findings suggestive of disease. Not all contacts become
infected with TB, but most who do will demonstrate a
positive T-cell-based test result within 2–10 weeks .
Therefore, in the initial evaluation of a child in a contact
investigation, it is not always possible to determine
whether a TB exposure has resulted in infection
demonstrable by a T-cell-based test. Consequently, until a
highly accurate test is developed for detecting an acute
TB infection soon after it occurs, it is important to
recognize “TB exposure” as a diagnosis, especially in
child contacts with risk factors for progression to disease
who will benefit from post-exposure prophylaxis. To
become infected with M. tuberculosis, a susceptible child
must inhale droplet nuclei (1–5 microns in diameter)
from someone with infectious TB disease who is
coughing. This usually involves close (i.e. shared air space in
an enclosed environment) contact with an infectious
case. Indeed, the longer the duration of exposure and
closer the proximity to the case, the higher the risk for
Table 5 Clinical case definitions and management of TB exposure, infection, and disease in children
Presumptive TB Clinical findingsd
and/or radiological findings
compatible with TB disease
Findings supportive of TB as the likely etiology?
Risk factors? (Management)
M. tb detected TB treatment response
None (consider LTBI treatment)
Yes (provide LTBI treatment)
Not applicable (TB treatment)
Not applicable (TB treatment)
Adapted from C.M. Perez-Velez. Diagnosis of Intrathoracic Tuberculosis in Children. In: Handbook of Child and Adolescent Tuberculosis (p. 168), J.R. Starke and P.R.
Donald (Eds.), 2016, New York, NY: Oxford University Press. Copyright by Oxford University Press . Adapted with permission
Dx diagnostic, IGRA interferon-gamma release assay, NAAT nucleic acid amplification test, PEP post-exposure prophylaxis, TB tuberculosis, TST tuberculin skin test,
LTBI latent TB infection
aSee “Clinical evaluation” section in text for clinical manifestations suggestive of TB ; bChest radiograph findings suggestive of TB disease (Fig. 2); cRadiological
findings suggestive of inactive TB in a healthy child without symptoms or physical signs compatible with TB include (a) non-enlarged, homogenously calcified
regional (parahilar/mediastinal or peripheral) lymph nodes; (b) calcified nodules with round borders in the lung parenchyma; (c) fibrotic scar or discrete linear
opacity in the lung parenchyma (±: calcifications within the lesion; or, volume lost, or retraction); and (d) pleural scarring (thickening or calcification). Compare
changes with previous imaging studies to ensure that they are radiologically stable; dWith TB disease up to 50% of older children with pulmonary TB may have
a normal physical exam
transmission. It is thus important to have a high index
of suspicion for possible TB infection and to screen for
risk factors (Additional file 1: Textbox 2).
TB infection [ICD-10: R76.11 (by TST); R76.12 (by IGRA)]
TB infection is defined clinically as an infection with any
species of the M. tuberculosis complex, demonstrated by
a positive T-cell-based test (TST and/or IGRA) result,
without clinical manifestations or radiological
abnormalities consistent with active TB. In a healthy child without
symptoms or physical signs compatible with active TB,
the following chest imaging findings—when shown to be
radiologically stable (i.e., without changes compared to a
previous imaging study within the past 4–6
months)—are generally considered indicative of previous TB
disease that is currently inactive: (i) non-enlarged,
homogeneously calcified regional (parahilar/mediastinal
or peripheral) lymph nodes; (ii) calcified nodules with
round borders in the lung parenchyma; (iii) fibrotic scar
or discrete linear opacity in the lung parenchyma (with
or without calcifications within the lesion; or, with or
without volume loss, or retraction); and (iv) pleural
scarring (thickening or calcification).
TB disease: clinical syndromes of intrathoracic TB [ICD-10:
Intrathoracic TB can affect lung parenchyma, the
airways, regional lymph nodes, pleura, and pericardium,
while more than one organ may be involved
concomitantly. The differential diagnosis of intrathoracic
TB is broad, and making a syndromic diagnosis based
on clinical, radiological, laboratory, and endoscopic
(when indicated) findings helps narrow the list.
Intrathoracic lymph node disease
Infection and subsequent inflammation of intrathoracic
lymph nodes is the pathophysiologic mechanism that
determines most of the clinical and radiological findings
of intrathoracic TB in children. Many of the radiological
patterns in pediatric intrathoracic TB are characterized
by intrathoracic lymph node involvement out of
proportion to that of the lung parenchyma. Because
radiographic density of lymph nodes is similar to that of the
heart and consolidated lung, the exact extent of lymph
node involvement may be difficult to discriminate on
plain radiographs. Their presence is sometimes
suggested when the airways are narrowed or displaced.
However, chest CT scans can clearly reveal lymph node
abnormalities not evident on plain radiography.
Children with isolated, uncomplicated non-calcified,
intrathoracic lymphadenopathy are frequently
asymptomatic. They are most often found during contact
investigations or screening of children with high-risk factors for TB
exposure. This radiological pattern may exist in a relatively
early state (e.g. subclinical disease) of intrathoracic TB.
Chest radiography may reveal one or more enlarged lymph
nodes, most often in the right hilum. Subcarinal
involvement leads to a splaying of the origins of the two main
bronchi. While chest CT scans in these children may find
Fig. 4 Proposed diagnostic and management algorithm for a child with recent exposure to, or with clinical or radiological findings compatible
with TB. AFB: acid-fast bacilli testing; Cont.: continue; c/w: compatible with; CXR: chest radiography; eval.: evaluation H/o: history of; IBT:
immune-based test IGRA: interferon-gamma release assay; mycobact.: mycobacterial; NAAT: nucleic acid amplification test; PEP: post-exposure
prophylaxis; PTD: progression to TB disease; TB: tuberculosis; TST: tuberculin skin test; Tx: treatment; wks: weeks
lung parenchymal abnormalities undetectable by plain
chest radiography, this investigation is not indicated if they
are completely asymptomatic.
Lymph node enlargement, occurring mostly in
children aged <5 years, may progress to tracheal or
bronchial compression. If complete, this leads to lobar
collapse, or if partial to a ball-valve effect causing
airtrapping and hyperinflation. Enlarged paratracheal nodes
can cause partial tracheal obstruction and stridor.
Symptoms vary with the degree of airway compression, from
asymptomatic to persistent cough, wheeze or stridor;
dyspnea and respiratory distress from extensive
atelectasis; or hyperinflation created by pressure from the
enlarged lymph nodes on adjacent structures. Chest
radiography (especially high-kilovoltage radiography)
and CT scans may demonstrate severe narrowing of a
bronchus leading to either collapse or hyperinflation,
most commonly of the right upper or middle lobes, or
the left upper lobe.
Endotracheal and endobronchial disease most often results
from bronchogenic spread of TB after a diseased lymph
node erodes into the airway, most commonly the left or
right main bronchus and bronchus intermedius [24, 28].
Disease may be diffuse or localized with visible granulation
tissue . Damaged bronchi may dilate (bronchiectasis) or
develop bronchostenosis . Tracheobronchial disease can
have an acute, insidious, or delayed onset, with symptoms
or physical signs of airway obstruction that depend on the
location and severity, including persistent cough, rhonchi,
wheeze, stridor, and/or dyspnea. Chest radiography is not
sensitive in detecting tracheobronchial disease, unless it is
severe or has an associated fibronodular appearance in the
lung parenchyma. Bronchiolar disease is revealed on CT
scans and may appear as a tree-in-bud pattern or as
centrilobular nodules consisting of dilated bronchioles that are
thick-walled and filled with mucus. Bronchiectasis is also
more easily noted on CT scans, which may show bronchial
dilatation and wall-thickening. Bronchoscopy may
demonstrate abnormalities suggestive of tracheobronchial disease,
including hyperemia, edema, ulcers, masses, stenosis,
granulation tissue or caseous lesions [80, 81].
If inhaled M. tuberculosis bacilli are not destroyed
immediately by the innate immune response, a small
parenchymal focus of infection (primary/Ghon focus) may
develop and drain via local lymphatic vessels to regional
lymph nodes. Most nodular TB lung disease in children
resolves spontaneously and is identified only by radiographic
screening during contact investigations. Multiple, focal
pulmonary nodules may be seen on chest imaging in the early
stages of a TB bronchopneumonia. A child with a solitary
pulmonary nodule, with or without associated
lymphadenopathy, is most often asymptomatic. Chest radiography
may reveal isolated lung opacity with enlarged ipsilateral
thoracic lymph nodes, known as a primary/Ghon complex.
When lymph node lesions are calcified, it is a Ranke
complex. Chest CT scans are more sensitive at detecting small
ill-defined airspace nodules that tend to coalesce in some
parts, but are different from the discrete, sharply defined
micronodules seen in miliary disease.
When the primary infection is poorly contained,
mycobacteria replicate and the initial lesion may enlarge (lobar
pneumonia). Hilar lymph nodes may also enlarge and
sometimes compress or infiltrate contiguous bronchi, most
commonly the right or left main bronchus, or bronchus
intermedius . If a necrotic hilar lymph node
erupts into a bronchus, endobronchial spread leads to
patchy or multifocal consolidation of the respective
lobe (bronchopneumonia). When enlarged hilar lymph
nodes are also compressing the bronchus, the
endobronchial spread may cause distal expansion and
dense consolidation of the entire lobe (expansile
pneumonia) displacing the trachea, bowing the
fissures and forming focal cavities. Cavities are
uncommon in children, occurring predominantly in infants
with extensive, uncontained disease or in adolescents
with “adult-type” disease. Chest radiography and CT
scans may reveal an oval-shaped lucency that is either
isolated or within a consolidation or nodule, with walls
that may be either thin or thick. In older children
and adolescents there may be multiple cavities,
located typically in the apical segments of the upper
or lower lobes .
TB pleural effusions typically occur 3–6 months after a
primary infection and are usually unilateral, mostly
resulting from a delayed-type hypersensitivity reaction to M.
tuberculosis antigens that leaked into the pleural space from
a subpleural primary focus. Pleural thickening is a
common component of the primary complex, but it rarely
leads to a significant effusion. Large effusions are seen
more often in older children (age >5 years) and
adolescents. The child most often presents with pleuritic chest
pain (58%), cough (80%) and fever (67%) . Chest
radiography will reveal a homogeneously opacified fluid
level, with pulmonary parenchymal abnormalities (usually
consolidation) and intrathoracic lymphadenopathy often
becoming visible post-drainage . Chest ultrasonography
is useful in determining the nature and quantity of the
effusion and detecting early loculations and septations. Chest
CT scans are useful in cases with complicated pleural
effusion, detecting associated parenchymal lesions and
intrathoracic lymphadenopathy, and differentiating between
pleural thickening and a chronic loculated effusion or
empyema. TB pleural fluids are most often exudative with
lymphocytic pleocytosis. Because of its protein-rich nature,
care must be taken to not remove too much pleural fluid in
a severely malnourished child because this can acutely
worsen the child's oncotic pressure. TB empyema has
also been described , where pleural fluid is purulent
. Chylothorax is a rare type of pleural effusion
resulting from disruption or obstruction of the thoracic
duct (or its tributaries), leading to lymphatic fluid
(chyle) leakage into the pleural space. The pleural
fluid typically has a milky white appearance, and is
predominantly lymphocytic with elevated levels of
triglycerides (>1.2 mmol/L) .
TB is one of the most common causes of pericardial
effusion in children in TB-endemic countries, and
approximately 1–4% of children with TB develop pericarditis .
It has three main presentations: pericardial effusion (the
most common), constrictive pericarditis, and a
combination known as effusive-constrictive disease. It
most frequently occurs after an infected contiguous
subcarinal lymph node infiltrates the pericardium. It
can also arise from lymphohematogenous
dissemination of M. tuberculosis. HIV infection predisposes a
patient to such disseminated disease, and is associated
with greater severity of pericardial TB . Children
with TB pericarditis usually present with symptoms
and signs of heart failure, including persistent cough
(70%), dyspnea (77%), chest pain (30%), hepatomegaly
(77%), elevated jugular venous pressure (7%), soft
heart sounds, and a pericardial friction rub (18%), in
addition to fever (52%), night sweats, failure to thrive
(36%), fatigue, and malaise . Chest radiography
typically reveals cardiomegaly with a globular heart
silhouette (91%). Echocardiography is the most
sensitive study to confirm a pericardial effusion, and may
reveal associated mediastinal lymphadenopathy or
Miliary lung disease results from a TB lesion infiltrating
into a blood vessel, leading to hematogenous
dissemination . The temporal pattern of miliary disease is
usually acute, but it can also present with a delayed
onset. Pulmonary involvement and respiratory symptoms
occur relatively late in the disease. Given the
multisystem involvement, presenting symptoms may include
cough (72%), dyspnea, diarrhea and vomiting (33%),
irritability, headache, convulsions, hepatomegaly (82%),
splenomegaly (54%), lymphadenopathy (46%), fever
(39%), chills, loss of appetite and failure to thrive (40%),
fatigue, generalized weakness, decreased activity, and
malaise. The main complication is TB meningitis .
Chest radiography may reveal innumerable rounded
micronodules (≤3 mm in diameter) scattered diffusely
throughout both lungs, but in the initial stages of
disseminated disease the radiological abnormalities may
not be apparent (9%) [79, 89]. Often these nodules are
best seen on the lateral projection of the chest
radiograph in the retrocardiac area.
Using currently available tools, a systematic diagnostic
approach to the child with recent exposure to, or with
clinical or radiological findings compatible with, TB can
allow the clinician to classify most patients into one of
the major diagnostic categories of TB exposure,
infection, or disease. In cases of TB exposure and infection,
identifying risk factors for progression to disease helps
hasten diagnostic evaluation and initiating appropriate
prophylaxis or treatment when indicated.
Additional file 1: Textbox 1. Spectrum of possible organ involvement in
TB disease. Table S1. Differential diagnosis of chronic cough in children.
Table S3. Differential diagnosis of clinical-radiological syndromes associated
with intrathoracic TB in children. Table S2. Nucleic acid amplification tests
for detecting Mycobacterium tuberculosis complex and genes encoding
targets of mutations conferring drug resistance. Textbox 2. Risk factors for
TB infection in children. (DOCX 21 kb)
ADA: Adenosine deaminase; AFB: Acid-fast bacilli; BCG: Bacille Calmette-Guerin;
CFU: Colony-forming unit; CT: Computed tomography; DNA: Deoxyribonucleic
acid; HIV: Human immunodeficiency virus; ICD-10: International statistical
classification of diseases and Related health problems, 10th revision;
IGRA: Interferon-gamma release assay; LDH: Lactate dehydrogenase;
LED: Light-emitting diode; LF-LAM: Lateral flow lipoarabinomannan;
LPA: Line probe assay; M.: Mycobacterium; MDR: Multi-drug-resistant;
NAAT: Nucleic acid amplification test; NTM: Nontuberculous mycobacteria;
PPD: Purified protein derivative; RT-PCR: Real-time polymerase chain reaction;
TB: Tuberculosis; TST: Tuberculin skin test
Sonia L. Villegas, MD, MPH, Charite - Medical University Berlin, Germany for
her contributions to previous versions of the diagnostic and management
algorithm for tuberculosis in children.
Both authors defined the scope of the review, searched the literature,
assessed the evidence base, synthesized included studies, analyzed the
findings, designed and drafted the manuscript and tables and figures,
critically revised the manuscript, and approved the final version of the
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