Influenza a Virus (H1N1)

Epidemiology

Disease surveillance is done through two sentinel groups, the Gripal Syndrome (GS), which reports cases of individuals with fever, accompanied by cough or pain relief with onset of symptoms around seven days, and the Severe Acute Respiratory Syndrome (SARS), which are individuals hospitalized in an Intensive Care Unit (ICU) with fever, cough or sore throat, dyspnea and respiratory distress. Sentinel groups collect five weekly samples per unit. So far, 13,775 samples were collected by GS sentinels, of which 74.3% were processed and 11.8% positive for influenza, of which 79.2% were predominantly influenza A (H1N1), 12.2% were positive for influenza B, 7% were non-sub typed influenza A and 1.5% were influenza A (H3N2). The regions most affected by H1N1 are the South and Southeast and the most affected age group corresponds to individuals from 10 years of age. The SRAG Sentinel Group has at the moment collected 2,366 samples, of which 82.1% have been processed and updated, 18.16% have been positive for influenza, 85% of which correspond to influenza A (H1N1), 10.7% for influenza A Non-sub typed, 3.2% for influenza B and 1.2% presented positive for influenza A (H3N2). However, the epidemiology through compulsory notifications in Brazil presents about 47,500 cases of SARS, where 78.2% of the samples collected in hospitals were processed. From the samples processed, 29.8% were positive for influenza, presenting 89.6% of cases positive for influenza A (H1N1), 6.4% for non-sub typed influenza A, 3.6% for influenza B and 0.4% of cases related to influenza A (H3N2). In these cases the median age was 40 years, presenting a Southeast region with the highest number of cases of SARS caused by Influenza virus. These data correspond to the five weekly samples obtained since the first week of 2016.

The beginning of the pandemic observed by the Ministry of Health in Brazil was on June 15, 2009, when there was a virus contamination abroad or through direct contact with a host. The World Health Organization (WHO) has created a national preventive program for vaccination against the virus. Virus prevention is divided into two phases, the containment phase, where there are surveillance actions at airports, border crossing points and a phase of mitigation or promotion of products with the aim of reducing the intensity of the disease [7]. The Ministry of Health has developed a course of preparation of professionals, with the purpose of making them multipliers in knowledge in their territories, knowledge about the disease [7]. The year 2016 was an atypical year due to an anticipation of viral infections caused by the H1N1 virus. Therefore, vaccination campaigns occurred at the end of May, obeying the immunological window of 15 days until the immunized individuals actually presented defense against the pathogen, although there were no cases of claims and emerging nations. The Oswaldo Cruz Institute - FIOCRUZ is currently responsible for the diagnosis of H1N1. It receives biological samples from all over the country and continues to provide support to society on strategies of combat and prevention, course on clinical management of the disease, symptoms and recent data of the anticipated outbreak of 2016. Brazil has been on alert for a possible influenza A (H1N1) epidemic. According to the Ministry of Health, only in these first months of 2016 were registered 444 cases of severe acute respiratory syndrome (SARS) caused by Influenza A (H1N1). Of the 76 deaths recorded, three were children under the age of two. Oseltamivir phosphate is the most suitable for treating the disease [11].

Diagnosis and Symptoms

The Ministry of Health in 2009 found that influenza A virus is transmitted from person to person through coughing, sneezing and by contact with respiratory secretions by infected patients. It is noteworthy that the most susceptible groups are the elderly, children, immunosuppressed, and pregnant women, cardiac and pneumatic patients [7]. In the United States, a report of 642 confirmed cases reported fever (94%), coughs (92%), sore throat (66%), diarrhea (25%), vomiting (25%) and 2 patient’s death.

The Ministry of Health reported other symptoms such as: headache, muscle pain, joint pain and breathing difficulties. The figure 1 describes the symptoms of H1N1 and those of the common flu [10]. Tests for confirmation of infection with influenza A (H1N1) virus may be by means of Real Time-PCR (Q-PCR), or by viral culture, which is virus isolation. Nevertheless in Brazil suspicious cases are submitted to collection of clinical samples such as: respiratory secretions, these must be collected within the first seven days at the onset of symptoms. Blood collection is also used to monitor the clinical evolution of the patient [12]. Both adult and pediatric treatments are with the use of oseltamivir phosphate granted by the National Agency of Sanitary Surveillance (ANVISA) and produced by the Institute of Drug Technology, beyond hygienic care and adequate food. However, prevention is the best cost- benefit (Table 1).

Current Vaccine and the Excipient Thimerosal

The vaccine is produced every six months, starting with the selection of the circulating strains until the final product for distribution. Campaigns take place in the spring, so that the immune system is activated with the vaccine formulation. Then, in the winter, the society would be protected due to increased dissemination in rainy times [13]. The work realized by the global influenza surveillance network updates the composition of the seasonal vaccines each year. The effect of vaccination on reducing the occurrence of influenza depends on the composition of the viral subtypes contained in the vaccine and the circulating viruses of the population in the coinciding period. Seasonal influenza vaccines, both live attenuated and inactive virus, make up the trivalent vaccines, as they present both influenza B, A (H1N1) and A (H3N2) viruses [14]. The vaccine contraindications are evident for those who are allergic to eggs, because the virus is incubated in proteins of chicken eggs. Care is also taken of patients who have already presented Guillain-Barré syndrome, since they must be vaccinated with the medical consent [13]. The commercial name of the vaccine in Brazil is influenza A (H1N1) and it is manufactured in the laboratory Sanofi Pasteur, where the Butantan Institute has affiliation for the production of the vaccine in the country, since [15]. The side effects, through the killed virus are basically tolerated, with only pain and inflammation at the site injected [13]. In vaccines with the authorized use in Brazil, ANVISA allows the addition of excipients such as Thimerosal, which is not allowed in other countries because it contains in its organic composition mercury, called ethyl mercury (EtHg). Ethyl mercury in small amounts does not present health risks according to the Food and Drug Administration (FDA). However, as well as those obtained in formulations of vaccines associated with food, especially fish containing methyl mercury (MeHg), this in turn neurotoxic, the body becomes a reservoir of mercury and this combination, are associated with negative responses in neurological development, especially in early childhood [16, 17]. Marques, et al. studied 1,139 children (6-24 months of age plus prenatal period) from the Western Amazon based on combined exposure (low, intermediate and high) for chronic MeHg through fish and acute consumption through vaccines containing Thimerosal (EtHg) [18]. Several parameters in the development of children with analysis and the outcome of the study reported several neurological problems and delays in the development of these children, which were dosed through the hair and breast milk. Children with low exposure had a more positive score on the Mental Development Index (MDI). Another study developed by Geier DA, et al. in the United States of America assessed through medical records between 1991-1994 of Safety Data link Vaccine (VSD) the relationship between exposures to EtHg of Thimerosal present in hepatitis B vaccines administered at specific intervals in the first 6 months of life and specific delays in development [19]. Several studies have shown that Thimerosal interferes with the neurological development of children. In 2001, the use of this excipient in vaccine formulations was banned in the USA. However, in Brazil the use is allowed and assured by the World Health Organization, the Ministry of Health and ANVISA.

Final Considerations

The virus of Influenza A is very diverse and has two lines that have great spread among humans, H1N1 and H2N3. The virus has been distributed worldwide and since 1918 has been causing countless deaths. In Brazil, in 2009 we had the onset of the H1N1 outbreak and since then preventive measures have been taken to avoid further deaths. Sentinels distributed throughout Brazil make collections to verify the frequency of H1N1 in cases of virus. The symptoms of H1N1 are different from the common flu and it is important to pass on the information to the greater knowledge of the population. Butantan Institute produces the vaccine against the virus specifically in the spring, with the vaccination campaign in the fall. Its purpose is to guarantee protection for society, which will be susceptible in the winter. The Brazilian government has doses for the groups of risks and the other groups can acquire in private companies. Further studies in Brazil are needed on the excipient used in question, Thimerosal. However, several studies already report their relation with low development in early childhood, an important point to be considered by ANVISA. In this context, it can be concluded that due to constant mutations in the Influenza A virus, annual vaccinations are of great importance for the protection of the population and the dissemination of relevant information about the symptoms; diagnoses are highly considerable for a society to be conscious about a Pathology [20, 21].