Influenzae (flu) and the common cold: A comprehensive Guide

Introduction:

The flu, also known as influenza, is a common viral infection that affects the respiratory system. It is important for individuals to be aware of the causes, symptoms, and management of the flu to prevent its spread and ensure proper treatment. Understanding the various types of flu viruses is crucial in combating the spread of infection and implementing effective preventive measures. This essay will discuss the different types of flu viruses, their characteristics, and the implications they have on public health.

Abstract:

This Blog will discuss the causes of the flu, common symptoms that individuals may experience, and effective management strategies for dealing with the flu. By understanding this information, individuals can take necessary precautions to protect themselves and others from the flu.

Causes of the Flu:

The flu and common cold is caused by influenza viruses and other viruses that infect the nose, throat, and lungs. These viruses can spread through droplets when an infected person talks, coughs, or sneezes. Individuals can also become infected by touching surfaces contaminated with the virus and then touching their face. The flu is more common during the fall and winter months when the virus is more easily spread due to close contact in enclosed spaces. Influenza (flu) is a highly contagious respiratory illness caused by influenza viruses. There are two main types of human influenza viruses: A and B. There are also many sub-types and strains. Flu is more serious than the common cold. Severe cases can result in breathing difficulties and pneumonia.

Types of Flu Viruses:

There are three main types of influenza viruses that infect humans: influenza A, influenza B, and influenza C.

Influenza A viruses are further classified based on the specific proteins on their surface, hemagglutinin (H) and neuraminidase (N), into different subtypes. Influenza A viruses are known to infect humans and animals, including birds and pigs, and are responsible for seasonal flu outbreaks as well as pandemics.

Influenza B viruses are primarily found in humans and cause seasonal flu outbreaks. Unlike influenza A viruses, influenza B viruses do not have subtypes but are categorized into two distinct lineages: B/Yamagata and B/Victoria. Both lineages are included in the annual flu vaccine to provide protection against circulating strains.

Influenza C viruses are less common and generally cause mild respiratory illness. They do not cause seasonal flu epidemics and are not included in the flu vaccine. Influenza C viruses are typically associated with sporadic cases of respiratory illness in humans.

Implications on Public Health:

Understanding the different types of flu viruses is essential for public health officials in monitoring and controlling flu outbreaks. Surveillance systems track the circulation of influenza viruses, identify emerging strains, and inform vaccine development strategies. By identifying the predominant flu viruses in a given season, healthcare providers can tailor treatment options and public health interventions to effectively manage the spread of the infection.

The ability of influenza viruses to undergo genetic changes, such as antigenic drift and antigenic shift, poses a challenge in flu prevention and control. Antigenic drift results in minor changes in the surface proteins of the virus, leading to the emergence of new strains that may evade immunity from previous infections or vaccinations. Antigenic shift, on the other hand, occurs when different influenza viruses infect the same host and exchange genetic material, potentially giving rise to novel strains with pandemic potential.

Symptoms of the Flu:

Common symptoms of the flu include fever, chills, cough, sore throat, runny or stuffy nose, muscle aches, fatigue, and headaches. Some individuals may also experience vomiting and diarrhea, although this is more common in people than adults. Symptoms typically appear one to four days after exposure to the virus and can last for several days to a week.

When to see a doctor

If you think you have influenza, you should see a GP who may want to do a test to confirm if you have influenza. These RAT for influenzae A/B and RSV are widely available in most pharmacies across Australia.

Management of the Flu:

There are several ways to manage the flu and alleviate symptoms. Resting and staying hydrated are important for helping the body recover. Over-the-counter medications such as acetaminophen or ibuprofen can help reduce fever and relieve muscle aches. In some cases, antiviral medications may be prescribed by a healthcare provider to shorten the duration of the illness and reduce the severity of symptoms.

In addition to these treatments, individuals can take preventive measures to reduce their risk of getting the flu. Getting an annual flu vaccine is the most effective way to prevent the flu and its complications. Practicing good hand hygiene, such as washing hands frequently with soap and water, can also help prevent the spread of the virus.

Antibiotics are not helpful for influenza because antibiotics do not treat viruses. You are only prescribed antibiotics if you are suspected to also have a secondary bacterial infection. 

Influenza can be more serious in people with chronic (long-lasting) medical conditions, including:

• chronic respiratory conditions (including asthma)
• chronic heart disease
• chronic neurological or metabolic conditions
• chronic kidney or liver problems
• diabetes mellitus.

It can also be more serious in people who are immunocompromised (have a weakened immune system because of medicines or illness). If you have any of these conditions and show signs of influenza, see your doctor or book a consultation with one of our doctors.

Antiviral medications (such as Tamiflu) are sometimes given to people with chronic medical conditions or who have developed severe symptoms. These medicines are not given to otherwise fit and healthy people who have influenza, because the medicines do not usually make a difference to the duration of the illness. They also have little effect if given more than 48 hours into the illness.

Risk factors for severe disease – consider treatment

• Severe chronic disease, particularly:
• neurological
• respiratory
• cardiac
• haematological eg sickle cell disease
• Genetic condition eg trisomy 21
• Premature infant
• Immunosuppression

Clinical features at presentation - indications for treatment

Severe respiratory (eg pneumonia), neurological (eg encephalitis), cardiac (eg myocarditis, pericarditis), muscle (eg rhabdomyolysis) or multi-organ failure.

Antiviral treatment

Oseltamivir, zanamivir and peramivir are neuraminidase inhibitors that reduce influenza virus replication

• Oseltamivir is usually first line therapy (oral or nasogastric)
• Treatment may have a modest effect in terms of reducing duration of symptoms (1 day on average) and may prevent more severe disease
• Treatment is most effective if started within 48 hours of onset of illness
• Neuraminidase inhibitors have no role in treating other viral infections

Oseltamivir

• Oral capsule 30 mg, 45 mg, 75 mg or oral suspension 6 mg/mL
• Capsule contents may be dissolved in water (for use immediately)
• Side effects:
• headache
• nausea and vomiting (reduce by giving with food), twice as likely to have vomiting (from 4% to 8% of unwell people)
• For use in renal impairment – seek advice

Complications of severe influenza

• Pneumonia
• Secondary bacterial infection especially S. aureus and S. pneumoniae
• Respiratory failure
• Neurological complications
• Encephalopathy / encephalitis
• Aseptic meningitis
• Guillain-Barre Syndrome
• Cerebellar ataxia
• Myositis and rhabdomyolysis
• Myocarditis and pericarditis
• Reye syndrome (associated with aspirin use) 
• 
  

Management

Immunization status does not affect the management of people with suspected influenza

Additional notes

Influenza vaccine

• The best available preventative measure against influenza
• Recommended for all people aged >6 months annually
• Strongly recommended and funded for people ≥6 months and <5 years
• Strongly recommended and funded for all people with Aboriginal or Torres Strait Islander background, people with risk factors for severe influenza and pregnant women
• More information is available from the Australian Immunisation Handbook and the ATAGI annual position statement.

Prophylaxis of contacts

In hospital contact:

• significant exposure is classified as being within 1 metre >15 mins without personal protective equipment

After significant exposure, suggest oseltamivir (prophylaxis) for people and family members if:

• they have risk factors
• household contacts have risk factors
• household contacts are:
• aged ≥65 years 
• women who are pregnant or within 2 weeks after delivery

Know when to get help 

If you get any of the following symptoms call Triple Zero (000) immediately and tell the ambulance staff you could have flu:

·        shortness of breath or rapid breathing​

·        chest pain or pressure lasting longer than ten minutes

·        confusion or sudden dizziness

·        persistent vomiting. ​

If you have flu and have health questions that are not a medical emergency, contact us www.aussiescripts.com.au and speak to one of our doctors. 

Conclusion:

In conclusion, understanding the causes, symptoms, and management of the flu is essential for individuals to protect themselves and others from this common viral infection. By taking preventive measures, seeking appropriate treatment, and practicing good hygiene, individuals can reduce the spread of the flu and minimize its impact on their health. Stay informed and take necessary precautions to stay healthy during flu season.

The classification of influenza viruses into different types and subtypes plays a crucial role in understanding the diversity of flu strains and their impact on public health. By monitoring flu viruses, implementing preventive measures such as vaccination, and staying informed about emerging strains, individuals and communities can effectively combat the spread of the flu and minimize its burden on healthcare.

References:

1.     https://www.rch.org.au/clinicalguide/guideline_index/Influenza/

2.     https://www.health.nsw.gov.au/Infectious/factsheets/

AUSSIESCRIPTS HEALTH TIP: Stay vigilant, get vaccinated, and practice good hygiene to protect yourself and others from the flu.