Reactive Airway Disorders in Children

Safety of the intranasal, trivalent, live attenuated influenza vaccine (LAIV) in children with intermittent wheezing in an open-label field trial

BACKGROUND

Safety of the intranasal, trivalent, live attenuated influenza vaccine (LAIV) in children with asthma is unknown. A previous report showed an "asthma signal" in children aged 18-35 months.

METHODS

Healthy children aged 1.5-18 years with history of intermittent wheezing received single annual LAIV doses during a 4-year trial. Rates of medically-attended acute respiratory illnesses, including acute asthma exacerbation, during 0-14 and 0-42 days post-LAIV were compared with respective reference periods (before day 0 and after 14 or 42 days). To assess the risk of new-onset asthma, LAIV recipients without history of wheezing were analyzed.

RESULTS

During each of the 4 years, 454, 656, 656, and 430 children, respectively, with intermittent wheezing who received LAIV had no increased risk for medically-attended acute respiratory illnesses, including asthma exacerbation. First-dose LAIV recipients, including those aged 1.5-4 years, and those receiving 2-4 consecutive annual doses had no increased risk. Children with parents' report of intermittent wheezing and those with administrative database codes for asthma during 2 prior years had no increased risk. During the 4 years, 2952, 3092, 2953, and 2478 children without history of wheezing had no increased risk of new-onset asthma.

CONCLUSIONS

LAIV administration in children aged 1.5-18 years with history of intermittent wheezing was safe, and was not associated with increased risk for medically-attended acute respiratory illnesses, including acute asthma exacerbation. This was true for the first and 2-4 consecutive annual doses. Parents' report of intermittent wheezing was reliable. First-dose LAIV was not associated with new-onset asthma in children without history of wheezing.

Herd protection against influenza

Mortality and hospitalization rates due to influenza have risen despite increasing vaccine coverage for the most vulnerable population; however, those most vulnerable to complications and death are the least likely to respond to the vaccine. New strategies for influenza control are needed and indirect effectiveness (herd protection) has been demonstrated for several currently used vaccines - rubella, H. influenzae type b, pneumococcus varicella and hepatitis A. The Japanese schoolchildren program provided proof of concept of indirect effectiveness of influenza vaccine. The Central Texas field trial has demonstrated significant herd protection of adults utilizing the live, attenuated influenza vaccine (LAIV) to children. Immunization of <20% of children at the intervention site resulted in an 8-18% reduction of medically attended acute respiratory illness in adults compared to rates in the comparison sites. LAIV given by nasal spray is efficacious against matched and poorly matched prevalent strains, easy to administer and readily accepted by children for annual immunization. School-based clinics could provide a platform for rapid deployment of vaccine accessible to all segments of the population. This strategy could be critical for control of pandemic influenza.

Parainfluenza virus infection in adult lung transplant recipients: an emergent clinical syndrome with implications on allograft function

Parainfluenza virus is a common cause of seasonal upper respiratory tract infections in children and adults. Studies indicate that parainfluenza virus may play an important role in the etiology of respiratory tract infections in lung transplant recipients with an estimated incidence of 5.3 per 100 patients. Parainfluenza virus type 3 is the most frequent serotype in lung transplant patients. The rate of lower respiratory tract infections with parainfluenza virus among lung transplant recipients is between 10 and 66% of cases. In addition, trans-bronchial biopsy at the time of parainfluenza infection shows signs of acute allograft rejection. Subsequently, 32% of patients have been found to have active bronchiolitis obliterans at a median time of 6 months (range 1-14) postviral infection. These findings indicate that parainfluenza virus infections may have long-term implications for lung transplant recipients. Further studies are required to identify the mechanisms of immunomodulation of parainfluenza virus among these patients. In addition, controlled studies are needed to evaluate the efficacy of aerosolized ribavarin in the treatment of parainfluenza virus infection and to determine whether vaccines may be effective in these high-risk patients.

The pathogenesis and management of influenza virus infection in organ transplant recipients

Infection with influenza viruses poses specific problems in adult and pediatric organ transplant recipients, including a higher rate of pulmonary and extra-pulmonary complications. Also, data suggest that influenza is associated with acute cellular rejection and chronic allograft dysfunction. The main strategy of influenza prevention has been influenza immunization in order to stimulate local and systemic antibodies. However, studies have shown that antibody response to inactivated influenza vaccine is decreased in all groups of organ transplant recipients. A live attenuated influenza virus vaccine is nearing approval in the United States. However, studies are needed in organ transplant recipients to determine whether the live attenuated influenza virus vaccine can enable these patients to mount a protective immune response and what degree of protection or amelioration of illness is provided by such vaccine. It is also important to verify the safety of this vaccine in organ transplant recipients because live virus may cause severe disease in these patients. Therefore, other modalities of prevention against influenza, such as chemoprophylaxis with antiviral drugs, should be considered in this patient population. The current review provides an overview of the incidence, clinical manifestations, and strategies for the prevention and management of influenza in organ transplant recipients.

Rationale and approach to target children with asthma for annual influenza immunization

Influenza virus infection can cause an acute exacerbation of asthma that may result in hospitalization. Annual influenza vaccination is recommended for children with asthma, but fewer than 10 percent receive it. This review summarizes the influenza-associated morbidity in children with asthma. The risk-versus-benefit of influenza vaccination in children with asthma is evaluated. Strategies to improve influenza vaccine uptake in children with asthma are investigated. Influenza virus infection causes substantial morbidity in children with asthma. Data on safety and effectiveness of the trivalent influenza vaccine in these children are limited. However, it is generally safe and effective in preventing influenza infection. The investigational live-attenuated, cold-adapted, trivalent nasal spray influenza vaccine needs evaluation for safety and efficacy in children with asthma. An annual, well-organized, computerized multicomponent strategy should be implemented for optimizing influenza immunization in the high-risk population. Children with asthma should be targeted for annual influenza immunization.

The epidemiology of parainfluenza virus infection in lung transplant recipients

Human parainfluenza virus (HPIV) is a common cause of seasonal respiratory tract infections. However, little is known about the clinical presentation and impact of HPIV infections in lung transplant recipients. We reviewed HPIV infections at the University of Pittsburgh Medical Center. From January 1990 through May 2000, 32 cases of HPIV infection were identified. HPIV infection was found in 24 lung transplant recipients (75%), all of whom were included in the study group. Diagnosis was established at a median of 2.1 years after transplantation (range, 0.6-5 years). Presenting symptoms included cough (17 patients), shortness of breath (16), and temperature elevation (4). Respiratory failure occurred in 5 patients (21%). The HPIV serotypes were HPIV-1 (7 patients), HPIV-2 (2), and HPIV-3 (15 [63%]). Twenty-two patients underwent transbronchial biopsy, and 18 (82%) showed signs of acute allograft rejection. Seven patients (32%) subsequently were found to have bronchiolitis obliterans.

A computerized reminder strategy is effective for annual influenza immunization of children with asthma or reactive airway disease

BACKGROUND

Influenza virus infection frequently triggers asthma exacerbation and hospitalization. Annual influenza immunization is recommended for children with chronic conditions, including those with asthma or reactive airway disease (RAD); however, <10% receive it each year.

METHODS

In September, 1997, we instituted a computerized staged reminder strategy for annual influenza immunization of children with asthma/RAD at the Scott and White Pediatric Clinic in Temple. A reminder letter, followed six weeks later by an autodial recall telephone message, was sent to the parent/guardian of children with asthma/RAD using the Shared Medical Systems to identify children with asthma/RAD and the Integrated Client Encounter System to record immunizations. The effect of this computerized reminder system on the influenza immunization rate of a cohort of 925 Scott and White Pediatric Clinic children with asthma/RAD was examined for the 1996 to 1997 and 1997 to 1998 influenza seasons, before and after intervention.

RESULTS

A significant increase in influenza immunization rate from 5.4% to 32.1% occurred in all age groups, regardless of the insurance status. The medically attended acute respiratory illness rate per 100 subjects was significantly higher in vaccinated than in unvaccinated children for each of the two influenza epidemics and in the period between the two epidemics.

CONCLUSION

A computerized reminder letter followed by an autodial recall telephone message is effective in increasing the influenza immunization rate of children with asthma/RAD. Children with significantly higher respiratory morbidity during and in between two influenza epidemics were more likely to be immunized after receiving written and telephone autodial reminders.

Severe pneumococcal pneumonia in previously healthy children: the role of preceding influenza infection

An outbreak of severe pneumococcal pneumonia among children occurred in Iowa from November 1995 through January 1996. An associated outbreak of influenza disease was predominantly caused by influenza A (H1N1) for the first time since 1989. We conducted a case-control study to determine whether preceding influenza infection was directly associated with pneumococcal illness. We identified 13 children with severe pneumococcal pneumonia. Patients were more likely than control subjects to report experiencing an influenza-like illness in the 7-28 days preceding admission (matched odds ratio [OR], 12.4; 95% confidence interval [CI], 1.7-306). Likewise, family members of patients were more likely than those of control subjects to report experiencing an influenza-like illness in the 28 days preceding their admission date (OR, 2.6; 95% CI, 1.0-6. 3). Patients were more likely than control subjects to have a positive influenza A (H1N1) convalescent serology (matched OR, 3.7; 95% CI, 1.0-18.1). This study provides direct and indirect evidence that influenza infection led to severe pneumococcal pneumonia among these children. Prevention of pneumococcal disease should be included among the potential benefits of influenza vaccination.

Childhood viral infection and the pathogenesis of asthma and chronic obstructive lung disease

Many epidemiologic studies have implicated childhood respiratory infections as an independent risk factor for the subsequent development of persistent asthma and chronic obstructive pulmonary disease (COPD). The majority of these childhood infections are viral in origin, and great strides are being made in understanding their pathogenesis at the molecular level. Some viruses, such as respiratory syncytial virus-a common cause of childhood bronchiolitis-stimulate the helper T cell type 2 (Th2) pattern of immune responses associated with allergic inflammation. Other viruses, such as adenovirus, appear to persist as latent infections in the airways of patients with COPD, and adenoviral E1A protein is capable of amplifying host genes, possibly including those involved in cigarette smoke-induced lung inflammation. Studies of the chronic, low-grade peripheral lung inflammation caused by adenoviral infection of guinea pigs will enable examination of the possibility that latent infection may induce resistance to the antiinflammatory actions of corticosteroids. Studies of the molecular mechanisms of viral infections of the airways could provide important insights into the nature of the inflammatory process involved in asthma and COPD. Hogg JC. Childhood viral infection and the pathogenesis of asthma and chronic obstructive lung disease.

Investigating severe and fatal asthma

BACKGROUND

Severe asthma continues to present a major therapeutic problem despite advances in our understanding of the disease. Innovative ideas for investigating the underlying causes and treatment of severe asthma are few, and many patients still become dependent on oral steroids. We describe two separate studies: first, a prospective investigation measuring the responses of persons with severe asthma to an allergen-free environment; second, a retrospective analysis of factors associated with eight fatalities and one near fatality caused by asthma exacerbations.

METHODS

In the prospective study 17 persons with severe asthma were admitted to a hospital clinical research unit containing an allergen-free room for steroid dose reduction. Peak flow measurements, treatment requirements, and evidence of infection were followed up. In the retrospective study, the cases of nine patients who had been evaluated for asthma and who subsequently died during an asthma attack were reviewed; where possible allergen levels in their house dust and specific IgE antibodies to common indoor allergens were measured.

RESULTS

Analysis of the patients in the prospective study revealed two categories of responses to steroid dose reduction: (1) asthmatic persons who either maintained or improved peak flow values on steroid reduction; these patients were predominantly allergic to indoor allergens; (2) asthmatic persons whose condition deteriorated; these patients were unable to tolerate reduction in steroid dose. The second group included persons with sensitization to fungal antigens who had asthmatic exacerbations in association with culture-documented fungal colonization. The retrospective study revealed that in five of the eight fatalities caused by asthma, exposure to a relevant allergen had occurred at home before death.

CONCLUSION

Some steroid-dependent persons with severe asthma are allergic to inhalant allergens and may benefit from avoiding allergens. In some cases there is no evidence that antigen exposure from diet, inhalants, fungal infections, or sinusitis is relevant to their disease. However, persons with severe asthma include individuals infected with and sensitized to fungal antigens. The results suggest that cases of severe asthma should be investigated to identify treatable causes.

Acute and persistent alterations in pulmonary inflammatory cells and airway mast cells induced by Sendai virus infection in neonatal rats

Neonatal rats inoculated with parainfluenza type 1 (Sendai) virus develop alveolar dysplasia and bronchiolar hypoplasia by 30 to 110 days after inoculation. Weanling rats do not develop these abnormalities. Because neonatal animals have hyporesponsive immune and inflammatory cell functions, and because neonatal rats support pulmonary viral replication for longer duration and are delayed in their viral antibody response compared to weanling rats, we compared inflammatory and immune responses of two age groups of rats following viral inoculation. Data from quantitative bronchoalveolar lavage 1 to 29 days following viral inoculation demonstrated that neonates had significantly fewer (P less than 0.05) lymphocytes and macrophages in their bronchoalveolar fluid per cm2 alveolar surface than weanlings. Magnitude of neutrophil responses in neonatal rats compared to weanlings were not depressed. Pulmonary interferon activity was lower in neonates than in weanlings at 2, 3, 4, and 5 days after viral inoculation. Neonates failed to make antibody following intraperitoneal inoculation of inactivated viral antigen, whereas weanling rats had detectable viral antibody by 3 to 5 days after injection of antigen. At 90 days after inoculation of neonates, viral-inoculated rats had over 100-fold greater numbers (P less than 0.05) of mast cells in enzyme-dissociated lung preparations compared to age-matched controls. Viral-inoculated rats had two- to three-fold greater densities of mast cells (#/mm) in bronchiolar walls (P less than 0.02) than did control rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Lung function and bronchial responsiveness in children who had infantile bronchiolitis

A number of studies have shown that children who had infantile bronchiolitis are at increased risk of recurrent episodes of wheezing. A genetic predisposition to atopy is mentioned in some studies and is contested by others. Lung function abnormalities and increased bronchial responsiveness (BR) have been described after infantile bronchiolitis. We investigated children who had had the clinical syndrome of bronchiolitis during infancy and compared them with asthmatic and healthy children of the same age regarding bronchial caliber, smooth muscle tone, and responsiveness to histamine. Lung function was measured by forced oscillometry. We found that most children with current symptoms had either decreased baseline bronchial caliber, increased bronchial smooth muscle tone, or increased BR. These patients are comparable to mild asthmatics. The children without current symptoms are comparable to healthy children in these respects. Recurrent respiratory symptoms after bronchiolitis should be regarded as mild asthma and treated as such.