Overview

Respiratory infections, such as influenza and asthma, are serious health concerns that affect individuals worldwide. Influenza is an infectious respiratory illness that presents symptoms like fever and cough. Asthma is a long-term condition marked by narrowed airways that make breathing challenging. While these conditions have different effects on the respiratory system, understanding how they are interrelated is critical for appropriate treatment and prevention. Recognising the complex link between these two illnesses is critical for improving healthcare methods and providing better outcomes for patients.

Understanding influenza

Definition and causes

Influenza, also known as the flu, is a highly infectious viral disease that predominantly targets the respiratory system. It is typically caused by one of three viruses, with the most severe cases stemming from strains A and B. The influenza virus changes its appearance to avoid the body's defences by making small genetic modifications over time, a process called antigenic drift.¹ These changes are usually subtle enough for the immune system to recognise and fight off the virus. However, if enough changes occur, the virus may become unrecognised by the immune system, leading to potential reinfections. To combat this viral evolution, scientists develop a new flu vaccine each year. As a result, viral mutations produce seasonal epidemics and occasional pandemics.¹

Symptoms and transmission

The influenza virus normally has a latent phase of one to two days without any symptoms. When they do emerge, fever, cough, headache, sore muscles, and weakness are usually the first signs. Respiratory symptoms such as a dry cough, sore throat, and runny nose are common, and gastrointestinal problems like nausea and diarrhoea can also occur, particularly in children. The flu may produce persistent symptoms, which usually last for four to eight days.¹ Most infections affect the upper respiratory tract and are minor, but they may increase an individual's susceptibility to secondary bacterial infections such as pneumonia. Influenza spreads through respiratory droplets released by an infected person coughing, sneezing, or speaking. It may also be transmitted by contacting virus-infected surfaces and then touching one's face].^1,2

Risk factors

Children and elderly individuals are more likely to have severe influenza infections owing to variables such as limited viral exposure, age-related immunological changes, and underlying health problems. Severe disease may also be more likely to affect those who have weakened immune systems, are pregnant, or have specific genetic markers.² Further research is required to fully understand the influence of host genetics on disease severity.

Understanding asthma

Definition and causes

Asthma is a long-term respiratory disorder that affects the airways, which are responsible for controlling the inhalation and exhalation processes in the lungs. The two main issues that set it apart are the inflammation and build-up of excess mucus in the airways, as well as the tightness of the surrounding chest muscles. As a result, breathing difficulties arise for those experiencing asthma.³ Many different variables contribute to the development of asthma, including a combination of genetic predispositions and environmental influences.

Symptoms and triggers of asthma attack

Asthma causes frequent wheezing, coughing, shortness of breath, and chest tightness. Sputum, if present, may be difficult to cough up and may seem pus-like during recovery because of elevated numbers of white blood cells (particularly eosinophil). Symptoms often intensify at night, in the early morning, or after activity or exposure to cold air. While some individuals with asthma may have symptoms on occasion in reaction to triggers, others may have regular and chronic attacks.⁴ These symptoms may vary in severity and frequency, with exacerbations triggered by various factors.

Individuals with asthma have sensitive airways that respond aggressively to triggers, resulting in periods of exacerbation, often known as asthma attacks. Allergens (such as pollen, dust mites, and pet dander), respiratory illnesses, irritants (such as air pollution), physical exercise, cold weather, and stress may all induce asthma attacks.⁴ Other disorders might also be the source of the symptoms. 

Risk factors

Asthma affects people of all ages but often begins in childhood. It may persist until adulthood or develop later in life, and the severity may vary from moderate to severe. Some individuals may experience regular symptoms, but others will have prolonged periods without any symptoms.³ Improper asthma management may lead to recurrent episodes, compromised lung capacity, reduced life expectancy, and increased healthcare utilisation. Severe asthma attacks could prove deadly and demand immediate medical attention.

The link between influenza and asthma

The relationship between asthma and influenza is complex. Asthmatics are more vulnerable to influenza-induced complications due to their respiratory condition, and when infected, they typically have worsening symptoms, such as more frequent and severe episodes. This deterioration is caused by influenza-induced airway inflammation and constriction, necessitating additional medical treatment.⁵

Individuals with influenza, especially those with asthma, are more likely to have significant consequences. Asthma-related inflammation in the airways may slow the recovery from influenza, extending the illness and increasing the risk of subsequent infections such as pneumonia. Managing asthma during influenza epidemics requires careful evaluation of overlapping symptoms, which may require changes to treatment approaches to maintain optimum control while successfully managing influenza-related respiratory difficulties.^5,6

Management and prevention strategies

Given the known correlation between influenza and asthma, appropriate treatment and preventative methods are crucial for those suffering from both conditions. The following are some important techniques:

Vaccination

Immunisation against influenza is generally acknowledged as one of the best ways to prevent the virus itself as well as any potential complications. This is especially important for those with asthma since they are more susceptible to the negative effects of influenza. The yearly influenza vaccination is advised for everyone over the age of six months. However, some high-risk populations are given preference, such as kids, elderly people, pregnant women, and those with underlying health issues like asthma. Those who suffer from asthma must get the influenza vaccination.⁵ It is highly advised for individuals with asthma to receive the flu vaccine, as it can effectively decrease the occurrence of asthma attacks that are commonly triggered by the flu. It is crucial to understand that there are various types of flu vaccines accessible, such as the nasal spray option and the conventional flu shot. Getting vaccinated for the flu is essential for reducing the likelihood of contracting the virus and diminishing the severity of symptoms if an infection develops.^5,6 This is achieved by activating the immune system to generate antibodies that specifically target the strains of influenza virus contained in the vaccination.

Medications

There are several medicinal drugs available for managing asthma and influenza, in addition to vaccination.^6,7

• Controller drugs are used routinely to alleviate asthma symptoms and reduce airway inflammation. Inhaled steroids, long-lasting beta-agonists, leukotriene modifiers, and biological drugs are all possible treatments.
• Quick-relief drugs treat acute asthma symptoms during an attack. They usually include short-acting beta-agonists like albuterol that respond quickly to expand the airways and aid breathing.
• Antiviral drugs may lower the intensity and duration of influenza symptoms. These drugs are most effective when taken early in the course of the disease because they prevent the influenza virus from replicating in the body.

Lifestyle modifications

Lifestyle changes can help asthma and influenza patients manage their conditions more effectively alongside clinical interventions. These may include:

• Maintaining a healthy lifestyle means following a balanced diet, engaging in regular physical activity, effectively managing stress levels, and ensuring adequate sleep. These practices not only contribute to overall well-being but also play a significant role in supporting immune function and respiratory health.⁸
• It is important to identify and avoid triggers that can worsen asthma conditions, such as allergens like pollen and pet dander, as well as irritants like strong odours and environmental pollutants.⁵
• Practise basic hygiene habits, such as washing hands regularly, covering coughs and sneezes, and avoiding being in proximity to ill people, to help prevent the transmission of respiratory diseases like influenza.⁵

Summary

Influenza and asthma are both major respiratory health issues across the world, with independent but associated complications. Influenza, a highly infectious viral respiratory infection, is produced by small genetic changes in the virus, resulting in seasonal epidemics and atypical pandemics. Its symptoms include coughing, fever, painful muscles, and fatigue, which are often accompanied by respiratory and gastrointestinal problems. Influenza is especially dangerous for vulnerable groups, such as children, older adults, and those with compromised immune systems.

In contrast, asthma is a long-term condition marked by inflammation and narrowing of the airways, which causes breathing problems, wheezing, coughing, and tension in the chest. Due to their pre-existing respiratory disease, asthmatics are more vulnerable to influenza complications, which may worsen symptoms and require a longer recovery period.

Asthma and influenza both need different plans for management and prevention. It is recommended to vaccinate against influenza, particularly for those who have asthma, since this lowers the chance of influenza-related asthma episodes. Timely antiviral drugs for influenza and doses customised for controlling asthma are also key. To improve respiratory health and reduce the risk of episodes, lifestyle changes such as leading a healthy lifestyle, recognising triggers, and maintaining adequate hygiene are complementary to medicinal therapies. Understanding the complex correlation between influenza and asthma is essential for optimising healthcare approaches and elevating the results for impacted individuals.