Vaccination for asthma exacerbations

Landscape biodiversity correlates with respiratory health in Australia

Megatrends of urbanisation and reducing contact with natural environments may pose a largely unappreciated risk to human health, particularly in children, through declining normal (healthy) immunomodulatory environmental exposures. On the other hand, building knowledge of connections between environments, biodiversity and human health may offer new integrated ways of addressing global challenges of rising population health costs and declining biodiversity. In this study we are motivated to build insight and provide context and priority for emerging research into potential protective (e.g. immunomodulatory) environmental exposures. We use respiratory health as a test case to explore whether some types and qualities of environment may be more beneficial than others, and how such exposures may compare to known respiratory health influences, via a cross-sectional ecological epidemiology study for the continent of Australia. Using Lasso penalized regression (to interpret key predictors from many candidate variables) and 10-fold cross-validation modelling (to indicate reproducibility and uncertainty), within different socio-geographic settings, our results show surrogate measures of landscape biodiversity correlate with respiratory health, and rank amongst known predictors. A range of possible drivers for this relationship are discussed. Perhaps most novel and interesting of these is the possibility of protective immunomodulatory influence from microbial diversity (suggested by the understudied 'biodiversity hypothesis') and other bioactive agents associated with biodiverse environments. If beneficial influences can be demonstrated from biodiverse environments on immunomodulation and human health, there may be potential to design new cost-effective nature-based health intervention programs to reduce the risk of immune-related disease at a population level. Our approach and findings are also likely to have use in the evaluation of environment and health associations elsewhere.

Vaccines: could asthma in young children be a preventable disease? ‬‬‬‬‬‬‬

‬The long battle with asthma is far from over in developed countries. Its incidence, prevalence, and severity have been increasing for decades. By reducing the risk for asthma, significant healthcare costs can be saved. The desire to create a vaccine that might prevent asthma in young children is attractive and widely considered one of the main goals in translational asthma research. Several vaccination strategies have been tested. These include allergen-specific immunotherapy, vaccination against infectious pathogens, and modification of cell and cytokine responses. The lack of success in the prevention of asthma in young children lies on the complexity of the disease, which involves many genetic, epigenetic, and environmental interactions. This review provides a summary of current literature and aims to address key questions how to develop vaccines to prevent asthma in young children. ‬‬‬‬‬‬‬‬‬‬‬‬‬‬.

Respiratory viral infections in children with asthma: do they matter and can we prevent them?

BACKGROUND

Asthma is a major public health problem with a huge social and economic burden affecting 300 million people worldwide. Viral respiratory infections are the major cause of acute asthma exacerbations and may contribute to asthma inception in high risk young children with susceptible genetic background. Acute exacerbations are associated with decreased lung growth or accelerated loss of lung function and, as such, add substantially to both the cost and morbidity associated with asthma.

DISCUSSION

While the importance of preventing viral infection is well established, preventive strategies have not been well explored. Good personal hygiene, hand-washing and avoidance of cigarette smoke are likely to reduce respiratory viral infections. Eating a healthy balanced diet, active probiotic supplements and bacterial-derived products, such as OM-85, may reduce recurrent infections in susceptible children. There are no practical anti-viral therapies currently available that are suitable for widespread use.

SUMMARY

Hand hygiene is the best measure to prevent the common cold. A healthy balanced diet, active probiotic supplements and immunostimulant OM-85 may reduce recurrent infections in asthmatic children.

Case-control study of severe life threatening asthma (SLTA) in a developing community

BACKGROUND

Distinct risk factors for asthma death have not been identified in developing communities. This study was conducted to distinguish risk factors for severe life threatening asthma (SLTA), a proxy for asthma death, in a developing country.

METHODS

A case-control study was performed at a University Hospital serving developing communities in the Western Cape Province, South Africa, over the period October 1997 to April 2000. Thirty consecutive patients with SLTA admitted to the intensive care unit (ICU) were compared with 60 chronic asthmatic patients, without a history of SLTA, who had attended the hospital outpatient respiratory clinic over the same period.

RESULTS

The risk of SLTA in comparison with controls increased with female sex (odds ratio (OR) 3.3, 95% CI 1.2 to 9.6, p = 0.02), rural residence (OR 8.1, 95% CI 2.6 to 25.3, p = 0.0005), and absence of a formal income (OR 5.7, 95% CI 2 to 16.6, p = 0.002). Cases were more likely to have had more than one hospital admission in the previous year (OR 8, 95% CI 2.5 to 25.2, p = 0.0009) and more than one emergency room visit in the previous year (OR 4.4, 95% CI 1.19 to 16.4, p = 0.04). Patients with SLTA were less likely to use inhaled corticosteroids (OR 5.6, 95% CI 1.9 to 16.5, p = 0.003) and more likely to use inhaled fenoterol (OR 6, 95% CI 2.2 to 16.2, p = 0.0004). Patients with SLTA also had lower mean (SE) forced expiratory volume in 1 second (FEV(1)) measurements (66.9 (9.5)% predicted v 82.5 (4.0)% predicted; p = 0.03) and lower FEV1/FVC ratios (60.7 (4.1)% predicted v 69.6 (1.9)% predicted; p = 0.05) documented before the episode of SLTA.

CONCLUSIONS

Risk factors for SLTA that are mainly analogous to those distinguished in other environments have been identified in a geographical area characterised by a third world socioeconomic context. Rural residence and poverty may increase the risk of SLTA.

Risk factors for intensive care in children with acute asthma

OBJECTIVE

A retrospective case-control study at Monash Medical Centre (MMC), a tertiary referral hospital in Melbourne, Australia, was conducted to identify risk factors associated with very severe asthma in paediatric patients.

METHODOLOGY

Asthmatics admitted to an intensive care unit (ICU; n=52) were identified and considered to represent cases of very severe/near fatal asthma (NFA group). This group was compared to asthmatics who had been admitted on one occasion only to the emergency department at MMC (non-NFA controls, n=53). Patient files were examined and factors that may be linked to NFA were recorded. Information not on file was obtained from patients/parents during a structured telephone interview. Data for the two groups were compared, univariate and multivariate logistic regression analyses were performed, and odds ratios (OR) were calculated.

RESULTS

Univariate analysis indicated that asthmatics with NFA were more likely to be older (P=0.01) and have a longer duration of asthma (P=0.02). They were also more likely to have hay fever (P=0.002; OR, 7.6), use inhaled corticosteroids (P=0.001), long acting beta(2) agonists (P=0.02), have an asthma management plan (P=0.006), and see a respiratory specialist (P=0.001). Parental smoking habits were not different between the groups. Multivariate logistic regression analysis identified male gender (P=0.05; OR, 5.7) and use of inhaled corticosteroids (P=0.07; OR, 7.2) as factors that may be predictive of NFA.

CONCLUSIONS

This study identifies a number of factors associated with NFA; many are similar to those reported in adult patients. Asthma severity explains some findings, but the data also suggest that additional independent risk factors such as gender and duration of asthma may operate in children.

Persistence of rhinovirus RNA after asthma exacerbation in children

BACKGROUND

Rhinoviruses (RVs) are believed to cause most asthma exacerbations but their role in the severity of acute asthma and subsequent recovery of airway function is not defined. The importance of atopy in virus-host interactions is also not clear.

OBJECTIVE

We postulated that RV infection and atopic skin prick responses influence the severity of asthma exacerbations as measured by peak expiratory flow (PEF).

METHODS

Patients aged 4-12 years admitted with acute severe asthma to a hospital emergency room (ER) were recruited. PEF measurements were obtained and nasal aspirates (NA) were taken. Atopy was diagnosed by skin prick responses to allergen and the presence of RV RNA and respiratory syncytial virus (RSV) RNA in NAs was detected using validated PCR assays. Patients were restudied after 6 weeks and after 6 months.

RESULTS

Fifty children with acute asthma (mean age+/-SD, 7.4+/-2.7) were enrolled; atopy was present in 37 (74%). RV RNA was detected in 41 (82%) and RSV RNA in six (12%) subjects. After 6 weeks 41 patients were restudied and RV RNA was again detected in 18 (44%). RV RNA was detected after 6 months in four of 16 patients restudied (25%; P=0.008 vs. ER) and in two of nine children from a control group with stable asthma (22%; P=0.009 vs. ER). Overall PEF measurements were reduced in asthmatics admitted to ER (% predicted, 63.4+/-16.4%) but did not differ between patients with RV RNA, RSV RNA or neither virus present. In subjects with RV RNA detectable in ER and after 6 weeks, measurements of PEF in ER were significantly lower than in patients in whom RV RNA was present in ER but absent after 6 weeks (P=0.009). Regression analysis linked persistence of RV RNA, but not skin prick responses to allergen, to severity of PEF reductions in ER.

CONCLUSION

RV RNA was detectable in >40% of asthmatic children 6 weeks after an acute exacerbation. Asthma exacerbations were more severe in patients with persistence of RV RNA suggesting that the severity of acute asthma may be linked to prolonged and possibly more severe RV infections.