Is it worth strengthening children's immunity in the fall?

Canadian physicians Malcolm Sears and Neil Johnston analyzed the nature of the autumn asthma exacerbation epidemics from 1990 to 2004. They found that each September, the number of hospitalizations of children due to asthma exacerbations increases sharply. This happened as a result of a very large increase in viral respiratory infections. This is shown in the figure below.

It should be emphasized that similar mass exacerbations have been reported in the USA, England, Mexico, Israel, Finland, Trinidad and Canada, where 20-25% of all asthma exacerbations in children that require hospitalization occur in September. It should be emphasized that 3 weeks after starting school in September, schoolchildren not only experience exacerbations of asthma, but also massive respiratory infections. These are viral infections, which in children without asthma, have the character of "common cold" and are usually not recorded in the statistics.

DATA SOURCES

Over the past several years, the authors have collected data from various sources related to hospitalization to investigate the nature of September asthma exacerbations in children. Data on all respiratory hospital admissions were obtained from the Canadian Institute for Health Information (1990-2004; Center for Epidemiology of the Swedish National Committee for Health and Welfare (1992-2002) and the Medical Statistics Unit of Imperial College, London, UK Britain (1990-2002).

THE ASTHMA OUTBREAK AND BACK TO SCHOOL

The peak of mass hospitalizations for asthma in children in Canada is synchronized with the return of the summer holidays. Every year between 1990 and 2004, the peak incidence occurred in week 38 (third week of September), with the exception of 1992 (week 39) and 1997 and 2003 (week 37). In 1992, school in Canada started a week later, and in 1997 and 2003 almost a week earlier.

Specific mathematical modeling* was used to assess the exact timing and magnitude of the peak, which revealed that September's peak in children's hospital admissions for asthma exacerbations occurred exactly three weeks after the start of the school year. The result is presented graphically in the figure below.

Massive cases, although to a lesser extent, were also observed in preschool children, with a peak 1.7 days later. School-age children not only show the earliest peak of the epidemic, but also its greatest amplitude, suggesting that they are the first to get sick and then transmit asthma exacerbations to older and younger family members. The peak of incidence appeared earliest in 6-year-old children and gradually decreased with a decrease and/or increase in age. Children aged 6 - 7 turned out to be most seriously affected by the epidemic, which should be associated with the fact that it is in this age group that children start school education.

THE ETIOLOGY OF THE EPIDEMIC OF ASTHMA EXTRACTIONS

Inhalant allergens, air pollution and their interaction with the climate have an impact on asthma exacerbation. However, Sears and Johnston believe that returning to school is the decisive factor in asthma exacerbations, which is supported by the exceptionally consistent timing of the peak of exacerbations relative to the start of the school year. Viral infections, especially rhinovirus infections, have been shown to be associated with about 80% of asthma exacerbations in this age group in the early fall.

Cases of children presenting to emergency departments for asthma exacerbations in major Canadian cities were reviewed during 3 weeks of September 2001. Microbiology of the nasal mucosa using PCR* was used with specific identification of human rhinoviruses, adenoviruses, influenza A and B viruses, parainfluenza 1 to 3, coronaviruses 229E and OC43, RS A and B viruses and Chlamydia pneumoniae and Mycoplasma pneumoniae. The results are shown in the figure above.

WHY DOES BACK TO SCHOOL CONTRIBUTE TO THE EPIDEMIC?

Children who return to school after the summer holidays are at risk of viral infections, most commonly rhinoviruses, after they have not been exposed to them for many weeks. Late summer is a time of high levels of environmental allergens and they are common in the school environment. Back to school is also a time of high stress, which can worsen asthma symptoms in children. Viral infection is a direct trigger of asthma exacerbations, it is probably the combination of all these factors that is the cause of the September epidemic.

The seasonality of rhinovirus infections at the end of summer and beginning of autumn must have some variability over time. One should therefore expect some volatility during the September epidemics. However, the peak in the number of hospitalizations in the 13 years of observation of the authors invariably occurred within 3 weeks of starting school, suggesting that starting school is per se a necessary condition for accelerating the transmission of rhinovirus infections to the epidemic level. This hypothesis is supported by data from those countries where school starts on a different date. For most children in Canada and England, school usually starts after the summer break on September 1. In Scotland and Sweden, school usually starts in the 3rd week of August. The greatest peak in hospital admissions for an asthma exacerbation in all these 4 countries occurs exactly 3 weeks after returning to school, regardless of the variation in the timing of summer holidays, as graphically depicted in the figure below.

HOW CAN WE PROTECT OUR CHILDREN?

Phytomedica offers a proven preparation that strengthens the immunity of both children and adolescents as well as adults. It is Immulina in the form of a tasty syrup for small children or people who have trouble swallowing capsules and in the form of capsules for adolescents and adults.

IMMUNOGLOBULIN A (IgA)

The vast surfaces of the gastrointestinal, respiratory, and genitourinary tracts represent major sites of potential attack by invading micro-organisms. Immunoglobulin A (IgA), as the principal antibody class in the secretions that bathe these mucosal surfaces, acts as an important first line of defence.

IgA, also an important serum immunoglobulin, mediates a variety of protective functions through interaction with specific receptors and immune mediators. The importance of such protection is underlined by the fact that certain pathogens have evolved mechanisms to compromise IgA-mediated defence, providing an opportunity for more effective invasion.

Our animal study showed that after 5 days of a diet containing spirulina extract, IgA levels increased almost 4-fold from 230 pg/ml to 815 pg/ml.

INTERLEUKIN 6 (IL-6)

Interleukin 6 (IL-6) is produced rapidly and transiently in response to infection and tissue damage. It contributes to host defense by stimulating the acute phase response, hematopoiesis and immune reactions. IL-6 expression is tightly controlled by transcriptional and post-transcriptional mechanisms

IL-6 is secreted by macrophages in response to specific microbial molecules, referred to as pathogen-associated molecular patterns (PAMPs). These PAMPs bind to an important group of detection molecules of the innate immune system, called pattern recognition receptors (PRRs), including Toll-like receptors (TLRs). These are present on the cell surface and intracellular compartments and induce intracellular signaling cascades that give rise to inflammatory cytokine production. IL-6 is an important mediator of fever and of the acute phase response.

IL-6 is responsible for stimulating acute phase protein synthesis, as well as the production of neutrophils in the bone marrow. It supports the growth of B cells and is antagonistic to regulatory T cells.

The same animal study as referred above showed that after 5 days of a diet containing spirulina extract, the level of IL-6 increased 4-fold from 35 pg/ml to 140 pg/ml.

INTERFERON GAMMA (INF-γ)

IFN-γ is a cytokine that is critical for innate and adaptive immunity against viral, bacterial and some protozoan infections. IFN-γ is an important activator of macrophages and inducer of major histocompatibility complex class II molecule expression.

Studies have confirmed that the active ingredient of both preparations - a special extract of Spirulina platensis (LECPEEN) activates the mechanisms of innate immunity. Immunity that does not threaten to trigger chronic immune processes. The improvement of immunity occurs quickly, because within a few days (4 - 5 days) from the start of the treatment. This is manifested by an increase in the production of protective antibodies for the mucous membranes (IgA), an increase in the production of proteins (cytokines, especially IL-6) involved in the immune processes and stimulates a number of other substances (lymphokines, IFN-γ) and stimulates the cells of the immune system (among others NK lymphocytes).

The animal study mentioned above showed that after 5 days of a diet containing spirulina extract compared to the AIN diet*, the level of INF-gamma increased more than 3 times from 2100 pg/ml to 7500 pg/ml.

REFERENCES

• Sears MR, Johnston NW, Understanding the September asthma epidemic. J.Allergy Clin.Immunol. 2007; 120: 526-9.
• Johnston NW, Johnston SL et al. The September epidemic of asthma exacerbation in children, search for etiology. J.Allergy Clin.Immunol. 2005; 112: 132-8.
• Johnston NW and Sears MR, The epidemiology of asthma exacerbations. Thorax 2006; 61: 722-8.
• Johnston NW, Johnston SL, et al The September epidemic of asthma hospitalization: School children as disease vectors. J Allergy Clin.Immunol.2006;117:557-62.