Transcript Document

PHTHISIOLOGY
Lecture 5
CLINICAL FORMS OF TUBERCULOSIS:
Primary tuberculosis
Secondary tuberculosis
Primary TB
The development of clinical TB will
occur in 5%-10 % of primary infected
persons.
The factors involved in increased risk
of developing TB are those
interfering directly with host
immunity.
Factors that facilitate the
development of TB disease
• Diseases and conditions that weaken
immunity, such as malnutrition, alcoholism,
• advanced age, HIV/AIDS, diabetes,
gastrectomy, chronic renal insufficiency,
silicosis, paracoccidioidomycosis, leukemias,
solid tumors, immunosuppressive drug
treatments
Primary TB in children
• 3.1 million children under 15 years of age are
infected with TB worldwide.
• According to the World Health Organization
(WHO), children with TB
represent 10 % to 20 % of all TB cases.
Primary TB in children
• The majority of these cases occur in low-
income countries where the prevalence of
HIV/AIDS) is high
Primary TB in children
• children younger than five years old may
develop disseminated TB in the form of
miliary disease or tuberculous
meningoencephalitis before the TST
result becomes positive.
Primary TB in children
A very high index of suspicion must be
adopted when pediatric patients have a
contact history.
Primary TB in children
• Children with asymptomatic infection
usually have a positive TST result but do not
have any clinical or radiographic
manifestations. These children may be
identified on a routine medical examination.
Primary TB in children
• TST following standard procedures is an
important element for TB diagnosis in
children.
• Sometimes these patients are identified by a
positive TST that may be associated with
allergic manifestations such as erythema
nodosum and phlyctenular conjunctivitis.
Primary TB in children
• Erythema nodosum is a toxic allergic
erythema with nodular lesions in the skin or
under it, 2 to 3 cm large. These lesions are
spontaneously painful and very painful under
pressure, and are usually located bilaterally in
feet and legs. It is usually accompanied by
pharyngitis, fever and joint inflammation
• and is more frequent in girls over six years.
Primary TB in children
• Primary TB in children
Phlyctenular conjunctivitis is an
allergic keratoconjunctivitis characterized by the
presence of small vesicles that
usually evolve to ulcers and resolve without
scars. associated to the phlyctenular
conjunctivitis are photophobia and an
excessive lacrimation
Primary TB in children
• Progression of the primary infectious complex
may lead to enlargement of hilar and
mediastinal lymph nodes with resultant
bronchial collapse. Progressive primary TB
may develop when primary focus cavitates
and bacteria spread through contiguous
bronchi.
Primary TB in children
• Lymphohematogenous dissemination,
especially in young patients, may lead to
miliary TB when caseous material reaches the
bloodstream from a primary focus or a
caseating metastatic focus in the wall of a
pulmonary vein Tubercular
meningoencephalitis
• may also result from hematogenous
dissemination.
Primary TB in children
• Tubercular meningoencephalitis
may also result from hematogenous
dissemination
Primary TB in children
• Endobronchial tuberculosis
• This form of pulmonary TB occurs when the
infected lymph nodes erode into a bronchus.
Enlargement of lymph nodes may result in
signs suggestive of bronchial obstruction or
hemidiaphragmatic paralysis.
• Dysphagia due to esophageal compression
may be observed.
Primary TB in children
• Vocal cord paralysis may also occur as a result
of local nerve compression.
• A partial or complete bronchial obstruction
can also occur. Usually it is the result of
deposition of caseous material within the
lumen. Obstructive hyperaeration of a lobar
segment or a complete lobe is less common in
pediatric patients.
Primary TB in children
• Cavities, bronchiectasis and bullous
emphysema are occasionally seen. Many
older children are asymptomatic at he time
of diagnosis. In general, however, children are
more likely to present with wheezing, cough,
fever, and anorexia as part of the symptoms.
Primary TB in children
• Persistent cough may be indicative of
bronchial obstruction, while difficulty in
swallowing may result from esophageal
compression. Hoarseness or difficult
breathing may suggest vocal cord paralysis.
Primary TB
• Adult primary TB is paucibacillary, practically
non-contagious, difficult to diagnose.
and of variable severity in seriously
immunodepressed patients
Secondary TB
• The existence of post-primary TB, also known
as secondary TB, means that the
infection can progress after the development
of an adequate specific immune response.
TB lesions in the upper right lung
SIMON’s foci in the left lung
Secondary TB
• This TB episode can develop in two ways:
- by reactivation of the primary focus or
- by inhalation of new bacilli (super infection)
Secondary TB
• Pulmonary TB is the most common form of
post-primary disease
Secondary TB
• The response to bacillary multiplication
provokes caseous necrosis that
eventually blends and progresses to
liquefaction.
Secondary TB
• Tubercle bacilli find favorable conditions
• for population growth after liquefaction of the
caseous necrosis and subsequent cavitation,
• and may produce more than 108 bacilli per
cavity with a diameter of less than2 cm.
• The development of tuberculous cavities in
the lung characterizes the postprimary TB
Secondary TB
• infectious material can spread through
bronchi,
• resulting in the continuous production and
elimination of sputum. The natural evolution
• of post-primary lesions in immunocompetent
persons can lead to dissemination
• and death in about 50 % of cases, and to
chronicity in about 25 % to 30 %.
Secondary TB
• Natural cure can also occur in 20 % to 25 % of
cases, when the host immune response
is able to re-establish control of the disease
TB and HIV
• In HIV positive persons infected with the
tubercle bacillus, however, 7 % to 10 % will
develop active TB annually.
Parenchymal infiltrate in the upper
left lung
Parenchymal infiltrate in the upper
left lung
Lung infiltrate and cavitation in the
upper lobe of the right lung (x-ray)
Lung infiltrate and cavitation in the
upper lobe of the right lung (x-ray)
Lung infiltrate and cavitation in the
upper lobe of the right lung (CT)
infiltrate and cavitation
and in both upper lobes
Miliary TB in adults (chest X-ray)
Miliary TB in adults (CT)
Pleural involvement with no
parenchymal lesion
Pleural involvement with upper
lobe lung infiltrate
Lymph node tuberculosis
Cerebral TB:
hydrocephaly, hypodense central
areas, and atrophic lesions.
Erithema nodosum and erithema
induratum of Bazin.
Tuberculosis and HIV/AIDS
• Interactions between M. tuberculosis and HIV
infection:
• results in the worsening of both pathologies.
HIV promotes progression of M. tuberculosis
latent infection to disease and, in turn,
• M. tuberculosis enhances HIV replication,
accelerating the natural evolution of HIV
infection
X-ray of a patient with HIV coinfection and 427 CD4+ cells/μL ;
cavity images in both upper lobes
Patient with 23 CD4+ cells/μL: lower and
medial lobe opacities with hilar and
mediastinal lymph node compromise.
AIDS patient with 71 CD4+ cells/μL:
hematogenous dissemination of
TB.
Figure 17-
AIDS and disseminated MDR-TB;
CD4+ count of 23 cells/μL.
Lymphadenopathy in an AIDS
• Aspiration procedure of a cervical
lymphadenopathy in an AIDS patient
with
disseminated TB. The aspirate had a
caseous aspect and was AFB smear
microscopy + (10
AFB/field).
Lymphadenopathy in an AIDS
Kernig’s sign positive in the TB
meningitis. The spinal fluid was
positive for M. tuberculosis
culture