Viral respiratory infections

Definition

Viral respiratory infections are group of illnesses caused by viruses, affecting the upper, the lower or both parts of the respiratory tract.

They are generally classified as clinical syndromes such as:

  • Common cold
  • Bronchiolitis
  • Croup
  • Influenza-like illness
  • Pneumonia

Viral respiratory tract infections are typically divided into:

  • Upper respiratory tract infections: Symptoms occur mainly in the nose and throat. Viral upper respiratory tract infections may occur at any age and include the common cold and influenza.
  • Lower respiratory tract infections: Symptoms occur in the windpipe, airways, and lungs. Viral lower respiratory tract infections are more common among children and include croup, bronchiolitis, and pneumonia.

Children sometimes have infections involving both the upper and lower respiratory tracts.

More than 200 types of viruses can cause respiratory infections

Although specific viruses commonly exhibit their own characteristic clinical manifestations, each can cause many of the viral respiratory syndromes

Common cold definition

An acute, self-limiting inflammation of the upper respiratory tract mucosa that may involve any or all of the nose, throat, sinuses, and larynx. The condition is rarely characterised by a discrete set of specific symptoms, with the illness varying according to individual and causative pathogen. Occasionally, there is spread to the lower respiratory tract. Symptoms include sore throat, sneezing, blocked, and/or runny nose, headache, cough, malaise, and low-grade fever. The condition is associated with more than 200 virus subtypes.

Epidemiology

The common cold is the most common acute illness in humans. A US study found that 23.6% of adults had experienced a cold in the previous 4 weeks. [3] Upper respiratory tract infections, nasal congestion, throat complaints, and cough are responsible for 11% of general practice consultations in other western countries. [4] Each year, children suffer approximately 5 such infections and adults 2 to 3 infections. [4] [5] [6] [7] Adults who are in contact with children suffer from more colds than adults not in contact with children. [8] It has also been suggested that children may act as ‘carriers’ of the infection.

There are no major gender or ethnicity differences in incidence. Most infections occur in the winter period. It is also thought that different viruses may be responsible for summer and winter colds. [8] The condition is highly contagious and is responsible for considerable absenteeism from school and work, though it is unclear whether the main mechanism of spread is by hand-to-hand contact, aerosol between people, or contamination of surfaces by aerosol that then transfers the infective pathogen to buccal mucous membranes (e.g. when eating).

Associated mortality/morbidity is rare, although common colds are responsible for considerable discomfort, absenteeism from school and work, and healthcare costs. [3]

Aetiology

The majority of common colds are caused by rhinoviruses (up to 50%), of which there are many. [2] [9] Other known pathogens include coronavirus (10% to 15%), influenza (5% to 15%), parainfluenza (5%), respiratory syncytial virus (5%), and metapneumovirus. [2] Often, no infecting organisms are identified. Re-infection can occur after re-exposure to the same viral sub-type, but the illness is typically milder and of shorter duration. There is an association between adenoviruses and enteroviruses and the common cold. Pharyngitis is commonly due to adenoviruses, which can also cause lower respiratory tract infections. Common respiratory tract bacteria (Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis) may be associated with the common cold. [10] However, this has limited implications in terms of antibiotic treatment for the typical common cold.

 

Step-by-step treatment approach for common cold

Plenty of rest is the key to treating a cold. You may find you need 12 hours of sleep each night, so don’t set that alarm. You’ll be most comfortable in a warm, humid environment. It’s also important to stay hydrated by drinking lots of water and avoiding alcohol and caffeine. This helps mucus to flow more freely and relieves congestion.

No specific treatment exists for the virus that is causing your cold, but a symptomatic treatment can provide relief.

Advice should be given about limiting spread to others and hygiene measures. No additional harm is caused if symptomatic treatment is declined, although such treatment may shorten absenteeism and reduce discomfort.

Additional medicines play a limited role, with most benefit coming from rest and maintaining fluid intake. A systematic review of combination therapies containing antihistamines, decongestants, and/or analgesics found that they have some general benefit in treating cold symptoms in adults and older children, but not in young children. [30][ ] However, the risk of adverse effects should be considered.

There appears to be a connection between the severity and duration of symptoms and what the patient believes and feels about the treatment received, [31] and empathetic treatment, as perceived by the patient, is associated with improvement in symptoms and biochemical markers. [32] [33]

Fever and pain

Paracetamol is used to treat the common cold with pain and/or fever. Evidence suggests that it may help with nasal congestion and rhinorrhoea, but not a sore throat, malaise, sneezing, or cough. [34] Despite this, it is still one of the most widely used analgesic-antipyretic agents, and is a first choice for many clinicians for the management of pain and fever. [35]

A review of non-steroidal anti-inflammatory drugs (NSAIDs) found benefit for reducing discomfort, but found no benefit in terms of easing respiratory symptoms. Possible adverse effects need to be considered. [36][ ] Studies of aspirin have found it to be effective for pain and fever, without serious gastrointestinal side effects with short-term use, [37] although a small increased risk of dyspepsia has been reported. [38] Aspirin should be avoided in children under 18 years because of the risk of Reye’s syndrome.

Nasal congestion, rhinorrhoea, or sneezing

There are many different formulations of decongestants and/or antihistamines available, including single-agent and combination formulations.

For decongestants there is a choice of oral (e.g. pseudoephedrine) or intranasal (e.g. oxymetazoline, ipratropium) formulations. Oxymetazoline nasal spray has been shown to have an effect in reducing airway resistance, [39] but there is limited evidence on patient-oriented benefits. [40] Further use may lead to recurrence of nasal congestion, although there are limited data on the frequency of this potential complication. [41] [42] [43] Ipratropium nasal spray has been shown to be effective in adults, although it is also used in children. A systematic review of intranasal ipratropium in children and adults with common cold symptoms found evidence to suggest that it is effective for rhinorrhoea but not for nasal congestion. Adverse effects were more frequent compared with placebo or no treatment. [30] [44] A Cochrane review found a small benefit in relief of nasal congestion from multiple doses of nasal decongestants (mainly pseudoephedrine or oxymetazoline) but it was unclear whether this was beneficial for patients. [45]

A further option for nasal congestion, for older children and adults but not for young children, is a combination antihistamine-decongestant formulation. [30] [ ] The quality of trial data for these formulations is weak. Furthermore, studies of these formulations show limited efficacy in young children. [46] [47] This should be taken into account when considering prescribing antihistamines and centrally active antitussive agents in children, as these drugs are known to have the potential to cause serious harm. Use of these formulations is subject to a general advisory warning in children under 2 years of age. [48]

Intranasal corticosteroids play no role in the treatment of common cold, based on current evidence. [49]

Cough

There are many different cough suppressants or expectorants available, including single-agent and combination formulations. They are often combined with decongestants and antihistamines.

There is no good evidence for or against the effectiveness of over-the-counter cough medicines in acute cough, particularly in young children. [46] [47] In the US, use of these formulations is subject to a general advisory warning in children under 2 years of age.

To ease cold symptoms, the essential aromatherapy oils may be rubbed on the body, inhaled with steam, diffused into the air, or poured on a cloth to be used as a compress. Try rubbing diluted eucalyptus oil on the chest as a decongestant, or inhale eucalyptus or peppermint oil to clear stuffiness. Adding lavender, cedar, or lemon to steam may also soothe the nasal passages. Inhaling menthol not only provides relief from nasal congestion, but might help inhibit infection as well. Rosemary, thyme, mint, basil, and tea tree oils can also provide relief from symptoms of a cold. Exercise caution if you have asthma, as aromatherapy can trigger an attack.

A review of inhaled corticosteroids for acute and sub-acute cough found insufficient evidence to recommend their routine use for acute respiratory tract infections in adults. However, some trials have shown benefits, suggesting the need for further high-quality, adequately supported trials. [50]

Antibiotic therapy

Antibiotics are not effective for treatment of the symptoms of the common cold and are known to cause adverse effects. [51] The US Centers for Disease Control (CDC) and the American College of Physicians do not recommend antibiotic treatments. [2] Regulatory bodies in other countries also support this recommendation. [52] [53]

This treatment is often requested by patients at consultation, but there is increasing evidence that this encourages resistant strains of bacteria and causes unnecessary harm. There is limited evidence that purulent nasal discharge suggestive of bacterial infection will not respond to antibiotics. [51] A delayed prescription for antibiotics, alongside advice on the natural history of the illness and symptomatic treatments, has been found to reduce the rate of antibiotic use (31%) compared with immediate antibiotics (93%) with similar rates of patient satisfaction. [54]

Other treatments

Good nutrition is essential for resisting and recovering from a cold. Eat a balanced diet. Take supplements as needed to ensure you are receiving the recommended dietary allowances for vitamin A, the vitamin B complex (vitamins B1, B2, B5, B6, folic acid), and vitamin C, as well as the minerals zinc and copper.

Interventions such as oral and nasally inhaled zinc, [55] [56] echinacea, [20] [55] and humidified air [57] have all been studied in placebo-controlled trials. Overall, they have shown minimal evidence of effectiveness.

Zinc administered within 24 hours of onset of symptoms reduces the duration of common cold symptoms in healthy people, but some caution is needed due to the heterogeneity of the data. The optimal dosage for zinc requires further study. Zinc lozenges have been widely studied, with a significant reduction in the duration of cold symptoms at a dose greater than or equal to 75 mg/day. For those considering zinc supplementation, it would be best to use it at this dose throughout the cold. However, no firm recommendations can be made with regard to prophylactic zinc supplementation because of insufficient data. When using zinc lozenges (not as syrup or tablets), the likely benefit has to be balanced against side effects. Intranasal zinc has significant adverse effects and it has been reported to cause occasional anosmia, which may be permanent. [58] For this reason intranasal zinc should not be used.

After much research, vitamin C is believed to have a small effect in preventing colds, and no benefit in treating a cold. There have been several large studies in adults and in children, but the results have been inconclusive. Taking large amounts of vitamin C over a long period of time can be harmful. {70}

To ease cold symptoms, the essential aromatherapy oils may be rubbed on the body, inhaled with steam, diffused into the air, or poured on a cloth to be used as a compress. Try rubbing diluted eucalyptus oil on the chest as a decongestant, or inhale eucalyptus or peppermint oil to clear stuffiness. Adding lavender, cedar, or lemon to steam may also soothe the nasal passages. Inhaling menthol not only provides relief from nasal congestion, but might help inhibit infection as well. Rosemary, thyme, mint, basil, and tea tree oils can also provide relief from symptoms of a cold. Exercise caution if you have asthma, since aromatherapy can trigger an attack. [72]

Commercial inhalant products are popular, although evidence from clinical trial data to support efficacy is limited. A combination of intranasal and inhaled sodium cromoglicate from company studies found inconclusive evidence of effectiveness. [59] [60] There is some evidence for the effectiveness of vapour rubs in providing symptomatic relief. [61]

Treatments for which there is evidence of benefit from a single trial or from poor-quality trials include green tea,[62] garlic, [63] [64] various Chinese herbal medicines, [65] [66] and Pelargonium sidoides (also known as umckaloabo). [67] There is limited evidence that sea buckthorn has no effect. [68] Nasal irrigation may have benefits in relieving symptoms of acute URTIs, although the evidence is weak. [69]

How to Feel Better in-home environment

General Advice

For upper respiratory infections, such as sore throats, ear infections, sinus infections, colds, and bronchitis, try the following:

  • Get plenty of rest
  • Drink plenty of fluids
  • Use a clean humidifier or cool mist vaporizer
  • Avoid smoking, second-hand smoke, and other pollutants (airborne chemicals or irritants)
  • Take acetaminophen, ibuprofen or naproxen to relieve pain or fever (read about what is safe to give your child)
  • Use saline nasal spray or drops

Sore Throat

Try the following tips if you or your child has a sore throat:

  • Soothe a sore throat with ice chips, sore throat spray, popsicles, or lozenges (do not give lozenges to young children)
  • Use a clean humidifier or cool mist vaporizer
  • Gargle with salt water
  • Drink warm beverages
  • Take acetaminophen, ibuprofen or naproxen to relieve pain or fever (read about what is safe to give your child)

Ear Pain

The following tips can be used to help ease the pain from earaches:

  • Put a warm moist cloth over the ear that hurts
  • Take acetaminophen, ibuprofen or naproxen to relieve pain or fever (read about what is safe to give your child)

Runny Nose

Stop a runny nose in its tracks by trying the following tips:

  • Get plenty of rest
  • Increase fluid intake
  • Use a decongestant or saline nasal spray to help relieve nasal symptoms (read about what is safe to give your child)

Sinus Pain/Pressure

Try the following tips to help with sinus pain and pressure:

  • Put a warm compress over the nose and forehead to help relieve sinus pressure
  • Use a decongestant or saline nasal spray
  • Breathe in steam from a bowl of hot water or shower
  • Take acetaminophen, ibuprofen or naproxen to relieve pain or fever (read about what is safe to give your child)

Cough

The following tips can be used to help with coughing:

  • Use a clean humidifier or cool mist vaporizer
  • Breathe in steam from a bowl of hot water or shower
  • Use non-medicated lozenges (do not give lozenges to young children)
  • Use honey if your child is at least 1 year old (read about what is safe to give your child)

Prognosis

The majority of patients recover after 2 weeks. In a study of children aged 6 months to 12 years, 26% still had symptoms 7 days from onset and 6% after 14 days. [76] Cough is the most common persistent symptom, lasting from 15.3 to 28.6 days. [77] It is important to advise patients of this so as to reduce their expectations of a quick improvement and pre-empt a visit wanting more treatment and/or antibiotics. Recurrence is common, although it is not clear whether the causative pathogen is the same virus, a sub-type, or a different pathogen altogether.

The above text has been adapted from BMJ Best Practice Common Cold review and BMJ Learning does not endorse Agovirax, nor are they making usage recommendations. The information mentioned in the text is for learning purpose.