DISCUSSION
The data obtained in this investigation indicate that there is a direct
statistically and clinically significant relationship between the levels
of specific immunoglobulin A against Respiratory Syncytial Virus in
respiratory samples (nasopharyngeal exudate) and the level of severity
of the clinical picture presented by pediatric patients infected with
this agent, the presence of serious clinical variables such as
thoraco-abdominal dissociation and dry cough which are more common in
those whose antibody levels are lower. The afore mentioned agrees with
what was published by Walsh et al (2018), who measured IgG antibodies
against RSV F protein in infected patients, finding in a multivariate
analysis adjusted for age, a significant correlation between the
decrease in clinical severity and the increase in titers of the
antibodies, with greater benefit, in the first 2 months of age, also
finding that the greater antibodies titers at birth are correlated with
delayed RSV infection, thus suggesting the benefits of maternal
vaccination during pregnancy. 28
Likewise, in 2017, Jans et al, also correlated the levels of antibodies
against the RSV G protein and the presence of severity markers such as
oxygen therapy need, tachypnea, oxygen saturation, admission to the
intensive care unit and days of hospitalization, finding that the
avidity of RSV-specific IgG antibodies was lower in vitro in infected
infants than in uninfected controls, though, they found no relationship
between the titers of these antibodies and the severity data.10 However, Falsey, Koval, DeVincenzo and Walsh
(2017), demonstrated that high titers of neutralizing antibodies against
RSV bring benefits in the survival of immunocompromised patients
infected with this virus 7 also Nyiroet al. (2016),
reported the association between high titers of neutralizing antibodies
against RSV, measured in the umbilical cord of pediatric patients with
severe infection and the decrease in the probability of acquiring the
infection over time in controls. 18 However, they
mention a wide variation in antibody levels, which is why further
studies will follow in this regard. 10,7, 18
These investigations support that, the greater the number of specific
antibodies against the respiratory syncytial virus, (both IgG and IgA),
the clinical data on the severity of said infection in pediatric
populations will be lower.
Previous research regarding RSV antibody levels are all measured in
serum, Vissers, Ahout, de Jonge and Ferwerda (2016), supported that
elevated levels of IgG in infected infants mucosa are correlated with a
lower viral load than plasma IgG levels, suggesting focusing humoral
immunity studies on mucosae of patients affected by this virus,
corroborating in this study what was stated by these authors.27
Likewise, there was also found a relationship between the presence of
clinical signs of repetitive respiratory tract infections in pediatric
patients whose RSV-specific immunoglobulin A titers were lower.
Jounai et al. (2017), examined the responses of total IgG antibodies,
subclasses and antibodies against the neutralizing epitopes of patients
in acute and convalescent stages of RSV infection, also evaluated the
serum neutralizing activity, finding that children antibody responses
against RSV matured over time in terms of titer, neutralization levels,
increased affinity, and increased overall IgG response in repeat virus
infections (Jounai et al., 2017). (12)
On the other hand, another of the results obtained in this research
indicates that there is a relationship between breastfeeding for 6
months and the decrease in the presence of clinical severity data in RSV
infection, such as low oxygenation index, presence of crackles and
wheezes on physical examination. This is recently supported by what was
published in January of this year in Nepal by scientists who carried out
a clinical study where the concentration of immunoglobulins A and G
against RSV F fusion protein was measured in breast milk, finding that
patients with active RSV infection had lower IgG concentrations than
controls, ,being the comparison of means statistically significant. This
supports the important role played by the antibodies present in breast
milk as a protective measure against infections and symptoms of this
virus. 17
In regard to the clinical characteristics epidemiology of Mexican
pediatric patients, data that are not updated in Mexico, it was found
that there was a predominance of males, the median age was 12 months,
this in contrast to what was reported by RodrÃguez-Auadetal., in 2012,
where it is mentioned that the median age in their study population was
22 months. Most of the patients presented incomplete vaccination
schedule, which, at present, represents a real public health problem,
probably due to the social stereotypes focused on vaccination, a
situation which, focused on the infection context by RSV, predisposes to
situations of co-infections, increased mortality and risk of RSV
infection, making visible the lack of optimization of vaccination tools
and strategies. 11,22
Also, it was documented in this investigation that the patients
presented as important pathological personal history, exposure to
tobacco smoke, repeated respiratory tract infections, previous wheezing,
gastroesophageal reflux disease and asthma. 18 patients who had some
underlying disease were treated in the intensive care unit and
mechanically intervened for breathing, data that is consistent with that
published by Vissers, Ahout, de Jonge, and Ferwerda (2016), who also
mention the predominance of these conditions in patients younger than 6
months of age. 27
This study showed that the main coinfections identified among the
included patients were essentially viral, with Rhinovirus being the main
responsible agent, followed by seasonal influenza and Parainfluenza 1
virus, this coinciding with what was reported by Robledo-Acevedo et at
., last year. 22 A high exposure to cigarette smoke
was also found in the population of patients included in this research,
as was also found by these authors. About the coinfections found,
Pneumococcus was the most frequently isolated bacterium in this
population, as well as the H1N1 influenza virus, whose association
RSV-Influenza H1N1 was already reported by Taylor et al. (2017).26 Finally Aspergillus spp. it was the only isolated
fungus considered as a fungal coinfection in this study.
The clinical relevance of the findings in this research lies in the
importance of promoting breastfeeding as a preventive method to avoid
severe RSV infections in pediatric patients, since currently there is no
effective vaccine or treatment. and standardized to prevent and treat
such infection. Likewise, the medical importance of the information
produced by this research updates the epidemiological data of the
population affected by this infection and its clinical characteristics
and outcomes.
The limitations of this research are related to the methodological
procedure for measuring specific immunoglobulin A against RSV, since
when trying to measure these levels in a poorly studied medium
(nasopharyngeal exudate), it is a priority to standardize this process
and to indicate by means of ROC curves, the cut points of said
concentrations, opening a chain of subsequent investigations that can
determine specific concentrations of specific IgA and even propose it as
a diagnostic or monitoring method in infected patients.