Influenza

Author: Alison Shieh

Editor: Helia Mansouri Dana

Overview

Influenza, otherwise known as the flu, is a respiratory disease caused by the influenza virus that affects approximately 5 to 15% of the global population every year (Dangi & Jain, 2012) and is transmitted through the inhalation of respiratory droplets (Yamauchi, 2018). The major influenza viruses that affect humans are influenza A and B, with influenza A virus infecting humans more commonly and severely, and each having their own subtypes that transmit among humans (Peteranderl et al., 2016).

Through mutations that cause minor changes in their genetic information (Ghebrehewet et al., 2016; Peteranderl et al., 2016), influenza A viruses are thereby able to avoid attacks by the human immune system, resulting in seasonal epidemics each year generally occurring during the winter seasons (Dangi & Jain, 2012). 

 

What causes Influenza?

The flu is caused by influenza viruses, namely influenza A and influenza B (Ghebrehewet et al., 2016). The virus is transmitted through respiratory droplets and infects different locations along the respiratory tract, which leads to some of the common symptoms including sore throats and coughs (Ghebrehewet et al., 2016)

 

Symptoms

  • Headache
  • Sore throat
  • Aching muscles
  • Fatigue
  • Fever
  • Nausea
  • Vomiting
  • Diarrhea 

(Minodier et al., 2015)

 

Risk Factors

  • children of ages 2 and younger
  • adults over the age of 65
  • heart or lung disease
  • diabetes

(Dangi & Jain, 2012)

 

Diagnosis

Influenza is typically diagnosed clinically through tests on respiratory samples (Ghebrehewet et al., 2016). Individuals suffering from flu-like symptoms including fever, cough, or sore throat, or battling acute pneumonia, especially those residing in a place where a flu outbreak is prevalent, should be tested for carrying the influenza virus (Jilani, Jamil & Siddiqui, 2020; Soleimani & Akbarpour, 2011).

Treatment

Patients may be treated with antiviral drugs; however, antiviral therapies are only effective during the very early stages of the illness, and the ability of the virus to change genetically makes treatment difficult (Peteranderl et al., 2016). 

Reducing the Spread of Influenza 

Non-pharmaceutical methods available to reduce influenza virus infection include community health education about the importance of social distance, and personal hygiene ( Sharma et al.2019). Biosecurity measures, regular disease surveillance and monitoring program, farm management practice including washing hands (Khanna et al. 2012, Itolikar et al. 2015, Singh et al. 2011, Scolaro et al. 2017), follow the disinfection and sanitary practices, isolating people with flu from the public places.

It is important to follow biosafety standards, such as using face masks, covering nostrils and mouth while sneezing or coughing (Dhama et al. 2012), following infection control practices, distributing correct information, and having Education and Communication (IEC) material in hospitals and schools (Mahesh et al. 2014).

 

Vaccines

Vaccination has been found to be the most effective method of preventing influenza, though the composition of influenza vaccines need to be altered every year to account for the changing nature of the virus (Peteranderl et al., 2016).

 

References

Biswas, D. K., Kaur, P., Murhekar, M., & Bhunia, R. (2012). An outbreak of pandemic influenza A (H1N1) in Kolkata, West Bengal, India, 2010. The Indian journal of medical research, 135(4), 529–533.

Dangi, T., & Jain, A. (2012). Influenza Virus: A Brief Overview. Proceedings of the National Academy of Sciences, India. Section B, 82(1), 111–121. https://doi.org/10.1007/s40011-011-0009-6.

Dhama K, Verma AK, Rajagunalan S, Deb R, Karthik K, Kapoor S, Mahima, Tiwari R, Panwar PK, Chakraborty S. Swine flu is back again: a review. Pak J Biol Sci. 2012 Nov 1;15(21):1001-9. doi: 10.3923/pjbs.2012.1001.1009. PMID: 24163942.

Ghebrehewet, S., MacPherson, P., & Ho, A. (2016). Influenza. The BMJ, 355. https://doi.org/10.1136/bmj.i6258

Hutchinson, E. C., & Yamauchi, Y. (2018). Understanding Influenza. Methods in Molecular Biology (Clifton, N.J.), 1836, 1–21. https://doi.org/10.1007/978-1-4939-8678-1_1

Itolikar S, Nadkar MY. H1N1 revisited after six years: then and now. The J Assoc Physicians India. 2015;63(4):41–43. 

Jilani, T. N., Jamil, R. T., & Siddiqui, A. H. (2020). H1N1 Influenza (Swine Flu). Stat Pearls.

Khanna M, Kumar B, Gupta A, Kumar P. Pandemic influenza A H1N1 (2009) virus: lessons from the past and implications for the future. Indian J Virol. 2012;23(1):12–17. 

Mahesh S.H.,  Kushwaha A.S., Kotwal A, Pandemic influenza: Experience in a flu OPD of a tertiary care hospital, Medical Journal Armed Forces India, Volume 70, Issue 1,2014,Pages 39-42,ISSN 0377-1237, https://doi.org/10.1016/j.mjafi.2012.06.018.

Minodier, L., Charrel, R. N., Ceccaldi, P.-E., van der Werf, S., Blanchon, T., Hanslik, T., & Falchi, A. (2015). Prevalence of gastrointestinal symptoms in patients with influenza, clinical significance, and pathophysiology of human influenza viruses in faecal samples: What do we know? Virology Journal, 12, 215. https://doi.org/10.1186/s12985-015-0448-4

Muruganandam N, Bhattacharya D, Chaaithanya IK, et al. Emergence of influenza A (H1N1) PDM09 in the remote Islands of India-A molecular approach. Indian J Med Microbiol. 2015;33(1):143–146.

Peteranderl, C., Herold, S., & Schmoldt, C. (2016). Human Influenza Virus Infections. Seminars in Respiratory and Critical Care Medicine, 37(4), 487–500. https://doi.org/10.1055/s-0036-1584801

Scolaro K.L., Handbook of Nonprescription Drugs: An Interactive Approach to Self-Care, 19th Edition. November 2017

Sharma R, Agarwal S, Mehta S, et al. Profiling the mortality due to influenza a (H1N1) pdm09 at a tertiary care hospital in jaipur during the current season-january & february 2015. J Assoc Phys India. 2015;63(4):36–39. 

Sharma J, Bhattacharyya D, Poddar K, Pavithran T.C., Thakur H, Scoping review of non-pharmacological interventions to control H1N1 in India, Clinical Epidemiology and Global Health, Volume 7, Issue 3,2019,Pages 504-508,ISSN 2213-3984,https://doi.org/10.1016/j.cegh.2018.12.001.

Sheikh Taslim Ali, Kadi A.S., Ferguson N.M., Transmission dynamics of the 2009 influenza A (H1N1) pandemic in India: The impact of holiday-related school closure, Epidemics, Volume 5, Issue 4,2013, 5(4):157-163

Singh SS, Muruganandam N, Chaaithanya IK, et al. H1N1 influenza A outbreak among the Nicobarese, an aboriginal tribe of the Andaman and Nicobar Islands. India. Publ Health. 2011;125(8):501–504. 25. CDC. Information on Swine Influenza/Variant Influenza Virus. 2009; 2009. Available from: https://www.cdc.gov/flu/swineflu/. 

Soleimani, G., & Akbarpour, M. (2011). Clinical presentation of novel influenza a (h(1)n(1)) in hospitalized children. Iranian journal of pediatrics, 21(2), 215–219.

 

 

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