Essay Example on the Influenza Viruses: Structure and Classification

Introduction

The influenza viruses belong to a group of viruses that have single strands of segmented RNA (Fukuyama & Kawaoka, 2011). The viruses can be classified into several types, including A, B, and C. Influenza types B and C affect human beings while type A affects a range of birds and mammals. The influenza virion takes a spherical shape (Fukuyama & Kawaoka, 2011). The virus is enveloped such that its outer layer is a lipid membrane taken from the host cell (Fukuyama & Kawaoka, 2011). Influenza is a non-spore forming gram-negative coccobacillus. Given the small size of the influenza virus, an electron microscope is used to visualize the virus. Negative staining is used in electron microscopy to view an enveloped virus. This staining method is useful in determining the size as well as the arrangement of the viruses.

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Virulence Factors

Virulence factors refer to molecules released by viruses such as influenza which assist them in infecting host cells. One of the virulence factors in influenza is hemagglutinin (HA). Hemagglutinin is synthesized by host cells in a form known as HA0 and later converted to HA. The conversion to HA is either intracellular or extracellular. HA contains amino acid substitutions that affect the preference of receptor binding in the host cell. HA is processed by proteases on the cell membranes of host cells to allow the influenza virus to envelop the host cell.

Immunity

Influenza infection leads to the systemic production of antibodies to the glycoproteins HA and neuraminidase (NA). The antibodies concentration peaks 4-7 weeks after infection. A steady decline follows this (Medina & Garcia-Sastre, 2011). The anti-HA antibodies protect against both disease and infection. The anti-NA antibodies reduce the rate of release of virus from infected cells (Medina & Garcia-Sastre, 2011). A cellular immune response involves lung dendritic cells that have acquired an antigen from the invading virus to travel to a draining lymph node (Medina & Garcia-Sastre, 2011). In the lymph node, the dendritic cells trigger an immune response by T cells (Medina & Garcia-Sastre, 2011). T cells then acquire effector cell functions and migrate to the lung's site of infection (Medina & Garcia-Sastre, 2011). After recovery from an infection, an individual possesses immunological memory that allows them to control any future similar infection better (Medina & Garcia-Sastre, 2011).. Overall, the immune response to the influenza infection involves reducing the viral burden, eliminating the virus, and initiating illness recovery (Medina & Garcia-Sastre, 2011).

Infectious Disease Information

Influenza causes a variety of symptoms, including cough, fever, headaches, and malaise.

The illness occurs in seasonal epidemics that are severe during the cold months such as winter. After infection, a patient experiences an incubation period of one to four days. Respiratory symptoms may mirror those of the common cold. These include sore throats, nonproductive coughs, coryza, and substernal burning (Iwasaki & Pillai, 2014). Among children, nausea, abdominal pain, as well as vomiting may appear. After about two to three days, the symptoms subside. Influenza infections primarily affect organs in the respiratory system. These include the lungs, nose, and trachea. The epithelial cells in the respiratory tract are likely to become inflamed, which may induce labored breathing. The immunological responses to influenza affect other organs, including the brain and kidneys (Cowling et al., 2010). If left unattended, influenza could result in mortality in high-risk patients such as infants and those of extreme age. Influenza weakens the respiratory system affecting the ability of the body to acquire oxygen and get rid of carbon dioxide. As a result, patients with cardiopulmonary insufficiency could see their condition worsen as a result of influenza infection. Influenza viruses result in acute infections. It results in severe symptomatic expression that doesn't last long. Influenza is an opportunistic infection. It occurs more frequently and severely among people with weakened immune systems (Iwasaki & Pillai, 2014).

Epidemiology

In temperate climates, influenza causes widespread sporadic illnesses during autumn and early winter (Das, Aramini, Ma, Krug, & Arnold, 2010). Influenza A virus causes most epidemics. Pandemics, on the other hand, are less common. Such pandemics are often localized in region or country (Das, 2010). The virus is spread by airborne droplets, contact with contaminated objects as well as contact with people. Various subsets of the population are at high risk of complications from influenza. These include children below four years of age, adults above 65 years of age, women in the third trimester of pregnancy, people with chronic medical disorders such as immunodeficiency and cardiopulmonary disease, and patients with disorders which impair the handling of respiratory secretions (Das, 2010). There are several causes of mortality and morbidity in influenza patients. These include primary influenza pneumonia, the exacerbation of an underlying illness, and acute respiratory distress syndrome.

Presentations

A patient visited with the following symptoms; fever (102 degrees Fahrenheit), fatigue, headaches, cough, sore throat, shortness of breath, and dizziness. The patient began experiencing these symptoms two days ago. A day before that, the patient had used a public transportation system. Therefore, she could have acquired influenza from coming into contact with railings that had residues of the virus. Further information can be collected. This includes carbon dioxide levels, level of hydration, and breathing rate.

Prevention

There are several approaches to preventing influenza infections. One approach includes minimizing the probability of coming into contact with the virus. Maintaining high levels of hygiene is necessary. It involves cleaning hands frequently and covering mouth and hands when coughing or sneezing. It is also essential to eat healthily and exercise to boost the immune system's robustness. There are vaccines available for both children and adults. The Center for Disease Control (CDC) recommends yearly vaccination for children above six years against the flu (TRIKHA, 2015). This vaccine is known as a flu shot and is administered intravenously. The vaccine contains a modified version of the virus, which makes the body produce antibodies that fight any infection that may arise.

Treatment

Given there is no known cure for the flu, treatments can be provided to alleviate influenza's symptoms. Analgesics are provided to relieve pain. Decongestants help in treating blocked or stuffy noses. Antihistamines treat sneezing and runny noses while cough suppressants alleviate dry coughs. Expectorants are taken to treat chesty coughs. Antiviral drugs that reduce the ability of the virus to replicate can also be administered (TRIKHA, 2015).

Clinical Relevance

The influenza virus changes its genetic makeup frequently. As such, the virus changes its characteristics frequently. The antiviral medications become ineffective against the virus due to these changes. More so, influenza vaccines also need to be developed continually to adapt to the changes occurring within the virus. The CDC routinely tests influenza viruses to assess the extent to which they have become resistant to approved antiviral medications (TRIKHA, 2015). It is necessary to collect samples of the virus both locally and globally. This increases the information available on the virus. All healthcare workers are at a higher risk of exposure to influenza virus than the general population. Given that the virus can be spread by airborne pathogens, healthcare workers are more likely to inhale these pathogens due to increased contact with infected patients (Cowling et al., 2010). It is, therefore, necessary to vaccinate these workers annually. When they are vaccinated, healthcare workers cannot pass the virus to other people they come into contact with such as family members.

References

Cowling, B. J., Chan, K. H., Fang, V. J., Lau, L. L., So, H. C., Fung, R. O., ... & Ngai, H. Y. (2010). Comparative epidemiology of pandemic and seasonal influenza A in households. New England journal of medicine, 362(23), 2175-2184.

Das, K., Aramini, J. M., Ma, L. C., Krug, R. M., & Arnold, E. (2010). Structures of influenza A proteins and insights into antiviral drug targets. Nature structural & molecular biology, 17(5), 530.

Fukuyama, S., & Kawaoka, Y. (2011). The pathogenesis of influenza virus infections: the contributions of virus and host factors. Current opinion in immunology, 23(4), 481-486.

Iwasaki, A., & Pillai, P. S. (2014). Innate immunity to influenza virus infection. Nature Reviews Immunology, 14(5), 315.

Medina, R. A., & Garcia-Sastre, A. (2011). Influenza A viruses: new research developments. Nature Reviews Microbiology, 9(8), 590.

TRIKHA, G. (2015). Something's in the Air. Infections in the Immunosuppressed Patient: An Illustrated Case-Based Approach, 236.