​A very simple procedure that reduces the transmission of the influenza virus consists of hand washing.

The name seems very technical and pompous, but its application is simple and, when mechanized, anyone can do it. Do you remember the leaflets posted by the DGS, in public bathrooms or public places, with pictures of how to wash your hands? Well, surgical hand washing is that! The intention, at the time, was to reduce the spread with influenza A (H1N1).

The fuss over influenza A has passed, but one of the intentions of this hand-washing campaign was to create this habit in the general population. Frequent handwashing, coupled with some specific products for the purpose, according to need (such as Promanum and Softaskin), reduces the transmission of any other type of influenza virus or of transmitting microorganisms of the most varied diseases.

Then find a block of answers, scientifically very noticeable, to very interesting questions about the flu.

 

1. What is the agent responsible for the flu?

The disease is caused by influenza viruses that are RNA viruses belonging to the Orthomyxoviridae family.

 

2. What is the viral genome of the influenza virus?

The viral genome consists of 8 single-stranded RNA (single stranded RNA) segments of negative polarity and which are associated with several proteins.

 

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Image source: http://www.virology.ws/2009/04/30/structure-of-influenza-virus/

The most abundant of them is the nucleoprotein (NP), which supports the helical structure of ribonucleoproteins. In much smaller quantities than NP, are the polymerases (PB1, PB2 and PA), that constitute the viral enzymatic complex in charge of the synthesis of the RNA. The genome, i.e. the viral RNA, has negative polarity and is therefore not infectious, since it can not act directly as messenger RNA in the synthesis of proteins. Fragmentation of the genome explains genetic lability and the emergence of gene exchange recombination (when two different viruses infect the same cell). This is the aspect that determines the epidemiological behavior of the disease.

 

3. What are the family and gender / type of influenza virus?

Influenza viruses are part of the Orthomyxoviridae family, which includes the very similar biologically similar types A, B and C viruses. However, while B and C viruses are micro-organisms that predominantly infect humans, A viruses are able to naturally infect numerous species of animals belonging to the Mammal and Bird classes.

 

4. What are the major subtypes of A virus?

The variation within type A is so large that it can be classified into subtypes which are defined based on their membrane antigens HA and NA. To date, 9 NA and 16 different HAs have been identified which can give rise to numerous combinations or subtypes.

 

5. What is the name of the flu virus?

The manner of naming influenza viruses is very descriptive and takes into account the reservoir / host of origin (except for humans), place, laboratory number and year of virus isolation. In the particular case of influenza caused by virus A, the characteristics of HA and NA are taken into account:

  • A/new Caledonia/20/99 (H1N1) *Human
  • A/ California/7/04 (H3N2) * Human
  • A/Peru/Iowa/13/85 (H5N9) * Animal
  • B/Hong Kong/361/2002 *Human
  • C/California/78 *Human

 

6. Why does the influenza virus have a high mutating capacity?

This is a characteristic of viruses that have an RNA genome. In the case of influenza viruses, in which it is a segmented genome, there are still other possibilities of variation.

Two types of fundamental mechanisms have been identified that can give rise to all the variations observed in influenza viruses; these changes are classified into two types:

  • Antigenic Drift.
  • Antigenic Shift.

 

7. What is antigenic variation due to?

The antigenic variation is due to the gradual accumulation of point mutations in the antigenic regions of surface glycoproteins that originate mutant viruses that are gradually separated from those that circulated until that moment. The three types of influenza viruses, viruses A, B and C exhibit this type of variation, which results in the emergence of genetically heterogeneous populations, known as "almost" species.

 

8. Can antigenic variations occur in all types of viruses?

The major antigenic variation (Antigenic Shift) only occurs in Type A viruses and is responsible for the appearance of the different subtypes of HA and Na due to the introduction of new viruses into an animal species, or the exchange of genes between different viruses that co-infect the same host.

 

9. What is bird flu?

Bird flu is a very contagious infection that affects most birds and is often manifested by epidemic outbreaks, especially on poultry farms (private or industrial). It is likely that major epizootics both in East Asia, Europe and Africa have been caused by the spread of poultry by migratory birds. Although, after the initial outbreaks, the poultry trade may also have played an important role in the spread of the disease.

 

10. What is the gateway to the flu virus in our body?

 

The virus reaches the respiratory mucosa by air, where it can be neutralized by local antibodies from previous infections; Nonspecific inhibitors in the mucus and mucociliary system also contribute to our body's defense.

 

11. When does virus infection begin?

Infection begins when the virus is fixed to the mucoprotein receptors of the respiratory columnar epithelium cells, where intense replication occurs for the next 49-72 hours and for a longer period in children.

 

12. How can the influenza virus spread from an infected person?

The influenza virus is eliminated in large infective doses mainly by droplets (Pflugge droplets), which are emitted into the environment by speaking, sneezing or coughing. There is also some resistance to the virus in the environment, favored by the conditions of high humidity and low temperature, concentration of virus in the respiratory secretions and size of the formed droplets / aerosols.

 

13. What is the most common clinical condition?

The most common clinical presentation is uncomplicated influenza or influenza syndrome, a benign, self-limiting disease produced by influenza A or B viruses. Type C virus causes mild upper airway respiratory symptoms without systemic repercussion. The most common signs and symptoms are:

  • Myalgia (muscle pain)
  • Headache (headache)
  • Rough start
  • Uneasiness
  • Cough
  • Fever

 

14. What are the basic flu symptoms? Fever, headache (headache), general malaise and respiratory symptoms. The onset of influenza is almost always sudden and even abrupt. During the first days, the systemic manifestations predominate over the respiratory ones, which gradually install themselves. It should be borne in mind that symptoms may change depending on the age, habits of the person, previous flu processes, virulence of the strains involved and medical history.

 

15. What are the main complications of influenza?

The complications of influenza vary with the age of the patients; for example, otitis is more frequent in children and pneumonia is more frequent in the elderly, but there are other complications, the appearance of which depends on the existence of chronic airway processes (asthma, chronic obstructive pulmonary disease, cystic fibrosis, among others) and from other chronic processes involving distinct organs and systems.

 

16. What other complications can occur?

Myocarditis, pericarditis, acute post-influenza myositis, central nervous system disorder (myelitis and encephalitis) and Reye's syndrome (which has been especially associated with virus B).

 

17. What are the clinical characteristics of influenza in adults?

Influenza is characterized by a sudden onset, after a short incubation period (24-48h), which in some cases allows us to “identify” the source of contagion between contacts. The patient begins a clinical condition with high fever and chills that usually force him to stay in bed. Fever is usually the most common sign among laboratory-confirmed cases and is usually between 38ºC and 39.5ºC. Headaches are usually severe and later than the onset of fever. Usually the cough is not productive and there may be nasal congestion in the first three days, with occasional hoarseness or retrosternal pain. Pulmonary auscultation shows, in some cases, snoring and wheezing that reveal bronchial impairment.

 

18. What are the clinical characteristics of influenza in children?

Children and adolescents are the most affected in influenza epidemics and influenza infection causes a fever that tends to be very high. Newborns and infants often have unspecific symptoms such as refusal to eat, and croup-like bronchiolitis. In almost half of children under the age of four, a significant degree of sleepiness and lethargy is observed. Abdominal pain, vomiting and diarrhea may be seen less frequently in older children. Influenza syndrome can be especially intense and prostate in young children, with slightly elevated CPK and SGOT values, reflecting enzymatic manifestations of muscle impairment. The frequency of complications and their severity in children is related to the lower responsiveness to infection and the absence of previous flu episodes.

 

19. What is the transmission mechanism of influenza?

Influenza is transmitted from person to person through respiratory secretions. Its transmissibility period extends from 24-48 hours before the onset of symptoms to 5-6 days later and may be longer in children. Transmission occurs in a variety of ways, but above all through infected droplets and direct or indirect contact with newly infected respiratory secretions. Transmission by inhalation of aerosols and finer droplets may also occur. This would explain the occurrence of outbreaks with high attack rates in populations where there was no personal contact between those affected. There are no latent infections. The short incubation period (1 to 5 days) and the explosive nature of epidemics and pandemics, as well as the simultaneous onset in several communities, suggest that a single person may transmit the infection to a large number of susceptible individuals. The importance of transmission through photites (object or material that can house an infectious agent and allow its transmission). It is not well evaluated, although outbreaks have been described in which transmission occurs through the hands or photites.

 

20. What is influenza control and surveillance today?

In an interpandemic period such as the present, influenza control is solely based on administering the vaccine to different groups of the population, with a higher risk of complications from the disease. However, due to the constant antigenic mutation of influenza viruses, the influenza vaccine is modified annually, thus adapting it to the estimated strains circulating that year. It is precisely here that international influenza surveillance plays an important role, with the fundamental objective of adequately characterizing circulating viruses and their spread among the population. To ensure rapid identification of circulating virus strains, the World Health Organization (WHO) has created an international network of laboratories that currently spans 80 countries through the collaboration of National Flu Centers and 4 Reference Centers. This network is the basis for WHO's recommendations each year on the antigenic composition of the influenza vaccine, and is undoubtedly a major achievement. However, knowledge of how the disease behaves is only possible with its integrated surveillance, gathering epidemiological, clinical and laboratory data from the same population.

 

21. Is influenza a disease of compulsory declaration in our country?

No. Influenza surveillance in Portugal began as a laboratory only, through the National Flu Center (CNG) and the Dr. Ricardo Jorge National Health Institute (INSA), and is currently an integrated clinical and laboratory surveillance based on two sentinel networks. surveillance: one of doctors and another institutional.

 

22. What do Flu Surveillance Sentinel Networks consist of?

The network of sentinel physicians made up of Family Medicine physicians from all over the country who participate voluntarily are responsible for notifying clinically compatible cases of influenza (clinical diagnosis according to predefined criteria) of patients on their list as well as sending biological products to be analyzed (nasopharyngeal swabs performed on a patient sample). The network of sentinel institutions is composed of emergency services, which voluntarily participate in the network, and which are responsible for sending biological products to CNG / INSA, thus helping to identify circulating viruses and identify their diffusion pattern. Portugal is also part of the European Influenza Surveillance Network (EISS).

 

23. What are the main indications for influenza vaccination?

The Directorate-General for Health (DGS), assisted by a group of experts, issues an Annual Information Circular (these Circulars are available on the website of the Directorate-General for Health www.dgs.pt) published in September. vaccination for the seasonal season of this year. Vaccination begins on October 1. The primary objective is to increase immunization coverage in (1) people aged 65 and over, (2) chronically immunosuppressed patients and (3) healthcare professionals.

In general these leaflets contain the following recommendations: 

  • The quota of vaccines for each country is limited. 
  • The prescription of the vaccine should be careful, especially to the people who benefit most from it and according to the criteria defined in the Circular. • The seasonal influenza vaccine does not protect against “bird flu” viruses. 
  • Vaccination is recommended for people considered to be at high risk of developing post-influenza complications who are (1) over the age of 65, particularly if residing in nursing homes or other institutions, (2) chronic patients, provided that ages over 6 months (including pregnant women at any stage of pregnancy and breast-feeding women) who have: (a) chronic pulmonary diseases, including asthma, or heart disease (hypertension is not considered a high risk condition per se) ; (b) chronic diseases requiring regular medical segments such as renal, liver, haematological (hemoglobinopathies), metabolic (including Diabetes mellitus) or neuromuscular (compromising respiratory function, elimination of secretions or increased risk of aspiration of secretions) ; (c) Other conditions that cause depression of the immune system due to medication (eg prolonged corticosteroid therapy or chemotherapy) or illness (eg human immunodeficiency virus infection or cancer), (3) resident or hospitalized for extended periods in healthcare institutions (eg disabled people, rehabilitation center users), provided they are older than 6 months, (4) adolescent children (6 months to 18 years) on long-term salicylate therapy and therefore risk of developing Reye's syndrome following influenza virus infection, (5) pregnant women who are in the second or third trimester of pregnancy in October not only to protect them from possible serious disease progression during pregnancy, but also , to protect your babies during the first months of life.
  • Vaccination is recommended for persons with an increased likelihood of transmitting the virus to the groups considered in the previous item: (1) health and other caregiver staff (domiciliary or institutional) and with direct contact with the persons included in the previous item, (2) cohabitants of children under 6 months of age and at high risk of developing complications. •
  • Professionals who may be involved in sanitary slaughtering of birds potentially infected with influenza viruses. This recommendation, in the current international context of avian influenza epizootic diseases, aims to reduce the theoretical risk of genetic recombination of the virus by co-infection between the avian influenza virus and the human influenza virus. The charges resulting from the vaccination of health professionals, or other services whose risk arises from their professional activity, are the responsibility of the respective employer (public or private), according to the legislation in force (Decree-Law no. 84/97, 16 April and Decree-Law No. 109/2000, 30 June), through the Occupational Safety, Hygiene and Health Services.

 

24. What are the main contraindications for influenza vaccine?

 Children under 6 Allergy to egg protein. • Allergy to thiomersal and other vaccine components • Febrile Diseases • Guilain-Barré Syndrome 25. What is the role of nurses in influenza vaccination? In addition to nurses applying the vaccine, taking into account the good practices Costa and al, they conclude in their study that nursing staff has a positive influence on compliance with influenza vaccination and is a useful element in patient recovery strategies. with negative attitudes towards vaccination. Puig-Barberá et al demonstrated that the invitation / invitation by letter or telephone, the awareness of nursing staff to vaccinate and the discussion of external evaluations were independently associated with higher rates of vaccine coverage.

 

Catarina Vilela (Nurse)