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CHAPTER 18

Tuberculosis

Shilpa Sharma
Devendra K. Gupta

Introduction • children with certain human leukocyte antigen (HLA) types that
Tuberculosis (TB) is a dreadful disease that is still rampant in the devel- have a predisposition to TB.
1–4
oping world. It can involve almost any organ or tissue in the body
from the brain to the bones. The problem is more significant in children Tubercular Bacilli
in developing countries, as they are the neglected lot who are often Mycobacterium tuberculosis is the most common cause of TB. Other
entrapped with infection, be it pneumonia or gastroenteritis. This delays rare causes are M. bovis and M. avium. M. bovis infection has been
the diagnosis of the disease and increases the tendency of the disease to traced to the use of cheese made from unpasteurised milk. M. tubercu-
spread into miliary infection in the sick undernourished child. losis is an aerobic, non–spore-forming, nonmotile, slow-growing bacil-
Tuberculosis was declared a global public health emergency in 1993 lus with a curved and beaded rod-shaped morphology. It can survive
by the World Health Organization (WHO). According to the WHO, under adverse environmental conditions. The acid-fast characteristic
5
developing countries, including India, China, Pakistan, Philippines, of the mycobacteria is its unique feature. Humans are the only known
Thailand, Indonesia, Bangladesh, and the Democratic Republic of reservoirs for M. tuberculosis.
Congo, account for nearly 75% of all cases of TB. There are about 0.5 Epidemiology
million deaths worldwide every year from this disease. 6 The overall incidence of tuberculosis is as high as 0.7–2 per 1,000
Tuberculosis is still a major cause of morbidity in developing children in the developing countries, with chest, meninges, and lymph
countries. Today, 19–43.5% of the world’s population is infected with nodes being commonly involved. The disease is predominant in
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Mycobacterium tuberculosis, with more than 8 million new cases of females. Infants are more susceptible to tuberculous bacilli and may
TB occurring each year. The incidence and severity of pulmonary develop severe extrapulmonary and miliary forms of the disease.
7
13
infections such as TB are expected to increase with the increasing Tubercular infection of the abdominal cavity accounts for 15% of all
incidence of human immunodeficiency virus (HIV) infection. The intestinal obstructions. It is more common in children, affecting those
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1,2
highest TB incidences and HIV infection prevalence are recorded in >5 years of age and particularly those residing in rural areas.
3
sub-Saharan Africa (with about 35% of mothers known to be infected Tuberculosis in infants and children <4 years of age is much more
with HIV), and as a consequence, children in this region bear the likely to spread throughout the body through the bloodstream. Thus,
9
greatest burden of TB/HIV infection. The incidence is rising in children are at much greater risk of developing miliary tuberculosis.
Western countries due to immigration from Third World countries and Hence, prompt diagnosis and treatment of tuberculosis is essential.
the rising trend of HIV infection. There has been a decrease in mortality
in cases of pulmonary tuberculosis without HIV due to recent improved Routes of Infection
health care and prompt initiation of therapy. The route of infection for pulmonary tuberculosis is inhalation of
Diagnosis of tuberculosis in children is difficult because children airborne bacteria. After inhalation, the bacilli are usually deposited in
are less likely to have obvious symptoms of TB. Tubercular infection the mid-lung zone, into the subpleural distal respiratory bronchiole or
has been identified in all organs in children. Genitourinary tuberculosis, alveoli. The alveolar macrophages then phagocytose the inhaled bacilli
although rare in children, has vague symptoms and presentation with but are unable to kill them, thus the bacilli continue to multiply unim-
the delayed diagnosis due to the late presentation leading to cicatrisation peded. The infected macrophages are then transported to the regional
sequelae. Children and young adults comprised 70% of the study lymph nodes. The initial pulmonary site of infection and its adjacent
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population in a large series of craniovertebral junction tuberculosis. lymph nodes are known as the primary complex or Ghon focus.
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This chapter focusses only on chest and abdominal tuberculosis. Progression of the primary complex may lead to enlargement
The children most at high risk for tuberculosis include: of hilar and mediastinal nodes with resultant bronchial collapse.
• children living in a household with an adult who has active tuberculosis; Progressive primary TB may develop when the primary focus cavitates
and the organisms spread through the contiguous bronchi.
• children of poor socioeconomic status; Lympho-hematogenous dissemination of the mycobacteria may occur
• children residing in rural areas; to other lymph nodes, and regions in the body (e.g., kidney, epiphyses
of long bones, vertebral bodies, meninges, and, occasionally, the apical
• undernourished children;
posterior areas of the lungs) or may spread widely as miliary TB. This may
• children living in small enclosed areas and in areas with poor ventilation; occur when caseous material reaches the bloodstream from a primary focus
or a caseating metastatic focus in the wall of a pulmonary vein (Weigert
• children living in a high endemic region;
focus). Bacilli may remain dormant in the apical posterior areas of the lung
• children infected with HIV or in an immunocompromised state fol- for several months, or even years, with later progression of disease.
lowing chemotherapy or prolonged steroid use; The gastrointestinal tract is involved in more than 60% of cases
of abdominal tuberculosis. The postulated routes of infection into the
• children with infections such as measles, varicella, and pertussis,
which may activate quiescent TB; and gastrointestinal tract include: