Influenza is a viral pathogen that attacks the human body respiratory system. The virus is introduced into the body through contact with saliva that contains the virus on the mucosal membranes around the mouth and nose. Influenza virus can also be transmitted through aerosol droplets found in the air inhaled. The virus is categorised into four major groups; A, B, C and D. Human influenza A and B are responsible for the seasonal flu (CDC, 2019). However, influenza A type causes severe flus that are often classified as global epidemics due to its ability to mutate into new strains that spread and multiplicate faster. “A(H1N1) pdm09 virus,” is an example of type A influenza that cause global pandemic flu in the spring of 2009. Influenza C causes other mild conditions in humans while D mainly causes illnesses among livestock.
Influenza virus type A is further divided into subtypes according to the two proteins in the cell wall of the virus: neuraminidase (N) and hemagglutinin (H). The two proteins have a variety of subtypes with hemagglutinin having 18 while neuraminidase has 11. Common colds caused by influenza A are mainly the combination of A(H1N1) or A(H3N2). The influenza viruses in type A can be further subdivided based on genetic clades and sub-clades of the individual strains (CDC, 2019). Unlike influenza A, type B is not divided into subtypes. Instead, it is classified into two major lineages: B/Victoria and B/Yamagata. However, the two lineages can be classified into clades and subclades like influenza A. The rate of mutation for both genetic and antigenic properties in this type of influenza is slower compared to the A virus. Therefore, influenza B is considered more manageable compared to influenza A.
Causes of influenza Flu
The influenza virus is airborne. Humid air droplets released into the atmosphere by virus positive persons through coughing, sneezing, or talking remain suspended until they come into contact with a surface (CDC, 2018). Sometimes the surface is the human body. When the infectious air molecules land on the mucus membranes of the upper respiratory system or mouth of human being they cause flu. The virus can also be obtained from surfaces contaminated with saliva droplets of infected persons. As mentioned earlier, there are different types of influenza, thus they cause different types of flu. Some are mild that they resolve without medical intervention while others are lethal.
Risk Factors
Every human being can contact influenza and develop its symptoms. However, some people are at a higher risk compared to others. An active immune system recognises foreign bodies in the system and initiates mechanisms to render them harmless. Depending on the type of pathogen, an effective immune system may clear the foreign bodies from the system before the individual realises through symptoms. In other cases, a person develops symptoms that subside without taking any medication. However, a weak immune system is easily overwhelmed during a fight with pathogens thus severe symptoms that sometimes progress and become complications. Therefore, persons with weak immunity are at higher risk of contracting the influenza virus than other members of the general population (Magdaleno, 2019) A weak or ineffective immune system could be caused by various factors including improper nutrition, medications like antihistamines, and conditions like HIV.
Persons with pre-existing respiratory conditions like chronic obstructive pulmonary disease (COPD) are at a higher risk of influenza. COPD symptoms exacerbate those of influenza thus making the individual more critical. Influenza triggers an immune reaction on the respiratory system that initiates increased production of mucus. Excessive production of mucus blocks the airways hence breathing difficulties which are a major symptom in COPD. Children below 6 years are also at a higher risk of developing flu since their immune system is still weak to form a strong resistance towards the virus (Magdaleno, 2019) Senior citizens with 65 years and above are also at a higher risk of developing the flu due to compromised immunity which occurs with advancement with age. Pregnant women or those who have recently given birth have a physiologic low immunity that makes them vulnerable for more severe symptoms of flue if the virus enters their system. Morbid obesity is another risk factor since the nutritional disorder lowers both leucocytes and cell-mediated immune response increasing chances of a pathogen thriving in the system. Other chronic conditions like kidney disease, heart disease, asthma, diabetes and liver disease are also risk factors of influenza.
Symptoms of Influenza
Flu majorly affects the respiratory system though in severe cases other systems can be impacted. Once the virus is detected in the body, th
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