Fascinating interaction between host and pathogen.

Clinical manifestations of disease depend upon host's immune response that is induced by pathogen and modified by the host's innate and adaptive immunity. Immunocompetent children of similar age and nutrition evoke different responses to the same pathogen varying from benign to potentially fatal condition. This results in diverse clinical presentations of a disease, that is different from the standard expected pattern and thus, poses a diagnostic challenge. Even, subsequent progression of a disease is also variable. It is the balance between immune stimulation, immune suppression and immune tolerance that decides the outcome. In case of balanced response, child recovers completely without any damage. However at times, cure is at the expense of permanent sequalae while in case of unfavourable immune response, survival may not be certain inspite of successful therapy. Symptoms and physical signs of primary disease often overlap with those caused by host's immune response. In such a situation, it is difficult to decide whether therapy of primary disease has failed due to drug resistance or whether persistence or deterioration is the result of immune response. Occasionally pathogen can transform into "superantigen" that may lead to "cytokine storm". Resulting immune-mediated complications may endanger life and at best, treated symptomatically. Immune suppressive drugs such as steroids, chemotherapeutic agents, IVIG or specific antibodies may not be able to suppress undesirable immune response. It is not just the immune suppression that is required but ideally immune modulation. Immune modulation refers to enhancing protective responses while avoiding destructive ones. At present, science falls short of anticipating harmful immune responses and lacks specific immune intervention.Laboratory test results are also dependent on host response and hence need cautious interpretation based on clinical profile in consideration with multiple variables. In final analysis, fight between host and pathogen is a complex one and often unpredictable. It is hoped that most children evoke favourable response but pediatrician has to be watchful even in the most benign disease.

Reversal of severe hepato-pulmonary syndrome in congenital hepatic fibrosis after living-related liver transplantation.

We report a 5-year-old girl with congenital hepatic fibrosis who presented with clubbing and cyanosis. Partial pressure of oxygen was 40 mmHg with oxy-gen saturation of 70% on room air, which improved to 128 mmHg and 92% on inhalation of 100% oxygen. Macroaggregated albumin scan showed 58% shunting to the brain, suggestive of severe hepatopulmonary syndrome. Echocardiogram and pulmonary angiogram ruled out pulmonary hypertension. Four weeks after living-related liver transplantation, she had normal blood gases and reduction in shunting to 7% on macroaggregated albumin scan.

Tuberculosis -- persistent threat to human health.

With the increasing incidence of tuberculosis worldwide, childhood cases now constitute 40% of the total. TB control thus has global importance. Unfortunately, control of disease is not in sight. It was always thought that adult tuberculosis is the fountainhead of childhood tuberculosis but it is being increasingly realized that it is the infection acquired during childhood that promotes reactivation of adult disease, which in turn maintains the chain of transmission. Thus childhood tuberculosis needs equal or more attention for effective control. Early detection by simple tests and ensuring treatment compliance is the goal. The small number of bacilli and inaccessible sites for bacteriological confirmation makes diagnosis of childhood tuberculosis difficult. Circumstantial evidence is often the basis of diagnosis. However, as clinical manifestations depend upon host immune response and virulence of tubercle bacilli, there is no typical clinical presentation. A large number of infected children may remain asymptomatic, undiagnosed and untreated. Conventional tests such as tuberculin test and radiology are not fully dependable and newer tests have limitations. Poor patient treatment compliance contributes to failure of a tuberculosis control program and leads to drug resistance. To combat this, direct observed treatment (DOTS) has been unanimously recommended in treatment of tuberculosis. DOTS is however estimated to be used in less than 40% of new cases. Misconceptions threaten to undermine continued success in tuberculosis control. TB control is essentially a management problem. Greater accountability of governments, donors and providers is essential.

Tuberculosis - persistent threat to human health.

With the increasing incidence of tuberculosis worldwide, childhood cases now constitute 40% of the total. TB control thus has global importance. Unfortunately, control of disease is not in sight. It was always thought that adult tuberculosis is the fountainhead of childhood tuberculosis but it is being increasingly realized that it is the infection acquired during childhood that promotes reactivation of adult disease, which in turn maintains the chain of transmission.Thus childhood tuberculosis needs equal or more attention for effective control. Early detection by simple tests and ensuring treatment compliance is the goal. The small number of bacilli and inaccessible sites for bacteriological confirmation makes diagnosis of childhood tuberculosis difficult. Circumstantial evidence is often the basis of diagnosis. However, as clinical manifestations depend upon host immune response and virulence of tubercle bacilli, there is no typical clinical presentation. A large number of infected children may remain asymptomatic, undiagnosed and untreated. Conventional tests such as tuberculin test and radiology are not fully dependable and newer tests have limitations. Poor patient treatment compliance contributes to failure of a tuberculosis control program and leads to drug resistance. To combat this, direct observed treatment (DOTS) has been unanimously recommended in treatment of tuberculosis. DOTS is however estimated to be used in less than 40% of new cases. Misconceptions threaten to undermine continued success in tuberculosis control. TB control is essentially a management problem. Greater accountability of governments, donors and providers is essential.

Cough and asthma.

Cough is a common symptom in office practice. Though troublesome, it serves to maintain normal function of respiratory tract. Chronic or recurrent cough may be caused by variety of diseases, asthma being the most common amongst them. Cough, wheeze and breathlessness are classical features of asthma syndrome. Many diseases may lead to this syndrome. Asthmatic children present with cough of variable intensities and patterns. At times, wheeze and breathlessness may not be clinically apparent. It was well known that all that wheezes is not asthma but now it is well understood that every asthmatic child does not wheeze. In an acute attack of asthma, cough often starts at the end of wheezing episode. It leads to expulsion of thick, stringy mucus often in the form of casts. Though cough is a minor symptom during acute attack, it ensures removal of secretions and avoid complications. Cough is a prominent symptom in persistent asthma especially between acute exacerbations. Episodic nocturnal cough may be the only symptom of chronic asthma. Children with cough variant asthma do not wheeze. It is postulated that they have milder degree of airway hyperresponsiveness and higher wheezing threshold. However, they show all the characteristics of asthma on laboratory tests. Cough represents bronchial hyperresponsiveness and is not a measure of asthma. Hence it may be caused by many diverse etiologies such as gastroesophageal reflux, enlarged adenoids, sinusitis or tropical eosinophilia. Cough in such conditions mimicks asthma and relevant tests may be necessary for proper diagnosis.

Natural history of asthma in children.

Asthma is a syndrome of reversible bronchial obstruction in hyperresponsive airways mediated by allergy or other trigger factors. Allergic disease represents true asthma while transient wheezing may be caused by factors such as viral infection, aspiration, prematurity and neonatal lung damage and is likely to outgrow within few years. Personal or family history of atopy, increased serum IgE and positive skin tests may suggest allergic asthma, which persists throughout life irrespective of presence or absence of symptoms. Onset of age beyond 2 years, severity, persistence or recurrence of symptoms beyond 6 years of age, airway hyperresponsiveness and abnormal lung function even in absence of symptoms, strong family history especially in the mother, exposure to allergens, parental smoking and delay in starting appropriate therapy are some of high risk factors in persistence of asthma in adult life. As outcome of asthma depend upon multiple variable factors, it is difficult to predict natural history of asthma in an individual child.

Emerging issues in pediatric pulmonology in India.

With the advent of ventilatory care for newborn in India, the practicing pediatrician is likely to see the "intensive care nursery survivors" who are likely to manifest an abnormal pulmonary outcome during infancy. These include: sudden death, bronchopulmonary dysplasia (with chronic lung disease and even core pulmonale), reactive airway disease, an increased propensity for respiratory infections and anatomical complications as subglottic stenosis, tracheobronchomalacia or palatal grooves. These not only have effects on respiratory compromise but also impact on feeding, growth and development.