What is a cold?
The common cold is an upper respiratory tract infection1.
In most cases caused by the rhinovirus, it occurs quite frequently in humans with the symptoms generally being mild2. Treatment for the common cold focuses on symptoms, with antibiotics not being effective in either children or adults1.
The viruses that cause the common cold are concentrated in nasal mucous and easily passed on through sneezing, coughing and nose blowing1. The common cold is the third most common diagnosis in American patients visiting their healthcare provider1. In South Africa, deaths related colds and flu are three times higher than in the USA3. The prevalence of HIV and TB infections in South Africa increases the risk of severe flu-related illness3. In South Africa people usually experience cold symptoms during late autumn and winter (early May to August)3.
What is the flu?
Influenza or flu is an acute viral respiratory infection of the upper and lower respiratory tract that is highly contagious and a significant cause of death wordwide2,4.
It comes on suddenly and treatment is most effective if it is initiated in the first 24 hours4. It is usually diagnosed clinically by a healthcare provider, based on symptoms and time of onset4. Flu can occur all year round, but is more common in the winter months3.
Causes
Cold
The common cold is caused by viruses1. It can be passed from person to person by inhaling viral particles or through hand contact2.
The common cold is mostly caused by human rhinoviruses (RVs), although other viruses can also cause cold symptoms, including2:
- Respiratory syncytial virus
- Influenza viruses
- Parainfluenza viruses
- Coronaviruses
- Adenoviruses.
Less frequently, cold symptoms can be caused by2:
- Enteroviruses (such as coxsackieviruses and echoviruses)
- Bocavirus
- Epstein-Barr virus
- Human metapneumovirus (hMPV).
Flu
Flu is also caused by viruses4. It is highly contagious4. Patients are contagious a day or two before they develop symptoms and for five to seven days afterwards4.
Seasonal flu occurs mainly in the colder months4. It is mainly passed from person to person when an infected person coughs or sneezes, although it can also be contracted by inhaling airborne particles or touching surfaces that have virus particles on them4.
Upper respiratory tract infections are especially prevalent in winter because people spend more time indoors and therefore in close proximity with people who may be infected2.
There are three types of influenza virus that infect humans4. These include:
- Influenza A (IAV): In addition to humans, this type of influenza virus also commonly infects other species, such as birds, pigs, and horses4. It is susceptible to genetic mutations (antigenic variation) which means people who have developed immunity to one strain will not necessarily be protected against another4,5. This makes it a cause of major pandemics4.
- Influenza B (IBV): This type of influenza virus causes local outbreaks and seasonal epidemics, along with influenza A6. It causes illness in children, teenagers and the elderly and has a higher death rate in children and teens6. It is also more likely to cause complications than influenza A and the impact is higher during the epidemic season6.
- Influenza C (ICV): This type of influenza virus is found mainly in humans, although it has also been detected in pigs, dogs, and cattle7. ICV is not as well-known as other types of influenza, although it is common7. Blood markers suggest most people are exposed to ICV at least once in childhood7. Symptoms are mild and cold-like, although it can lead to more serious illness in young children under the age of two7.
Clinical Presentation
Cold
Symptoms of the common cold include1:
- Fever
- Cough
- Runny nose
- Blocked nose
- Sore throat
- Headache
- Muscle aches and pain.
In most cases, the common cold is a mild illness and clears up on its own, but it has been linked to numerous complications, including2:
- Acute otitis media (middle ear infection)
- Sinus infection
- Loss of smell or altered sense of smell (especially in middle-aged and elderly people and especially women)
- Lower airway infections, including pneumonia.
Factors that increase the risk of developing a cold include2:
- Day-care attendance for children
- Genetic factors
- Psychological stress
- Smoking
- Intense physical training.
Flu
Symptoms of the flu usually come on suddenlyand include4:
- Fever
- Cough
- Chills or sweats
- Muscle aches and pain
- Feeling generally unwell
- Gastrointestinal symptoms, such as vomiting and diarrhoea, in children.
Flu is responsible for many deaths worldwide4. A small number of people who are at high risk may experience severe illness or complications, which can affect the circulatory, musculoskeletal and nervous systems, as well as the eyes, lungs and kidneys4.
Those at higher risk include4:
- Patients with coexisting medical conditions
- Elderly patients over 65 years
- Children younger than five (and particularly younger than two)
- Residents of institutions such as nursing homes and chronic care facilities
- Pregnant women
- Postpartum women up to two weeks postpartum (including pregnancy loss).
Diagnosis
Cold
Because the common cold typically clears up on its own over time, identifying which virus is the cause is unnecessary8. It is diagnosed by examination and differentiated from other, more serious viral infections (such as the flu) by comparing symptoms8. Only in rare cases are laboratory tests required8.
Flu
Flu is also usually diagnosed via examination, based on the patient’s symptoms or if they have a possible flu-related complication, such as pneumonia, severe muscle damage (called rhabdomyolysis) or a chronic disease that has worsened4. Testing is an option when the results could influence how the patient is treated or when the patient is hospitalised4. It can also be considered to avoid unnecessary antibiotic prescription or in cases where high-risk household members could benefit from prophylactic treatment4.
Treatment
Cold
Colds clear up on their own and usually last about 10 days1. For this reason, the focus is usually on symptom relief, rather than treating the infection1.
Flu
Patients with flu can be treated with anti-influenza medication4., Anti-influenza medication can decrease the length of illness by about a day when treatment is initiated within 36 hours of symptom onset, and lower the risk of developing serious complications4.
Treatment Principles
Antibiotics are ineffective against viruses and do not work for treating colds and flu9. Anti-influenza medication is only an option within 48 hours of developing symptoms and is most beneficial within the first 24 hours of symptom onset4. In patients who are at high risk of complications, treatment should be started even if the 48-hour window has passed4. Cough suppressants are not recommended for children under four years1.
Treatment Options
Cold
Treatment of the common cold focuses on relieving symptoms2. Medication options include2:
- Non-steroidal anti-inflammatory drugs (NSAIDs) and paracetamol for pain and feeling unwell
- First-generation antihistamines for runny nose and sneezing (although not for children)
- Decongestants in combination with first-generation antihistamines (however side effects may include drowsiness, dry mouth, sleeplessness, or dizziness)
- Zinc to reduce the duration of a cold, although not the severity, if the patient starts taking it within 24 hours of developing symptoms
- Vitamin D to support the body’s immune response.
Flu
There are anti-influenza medications available. These are aimed at suppressing the influenza virus and are only available on prescription. Consult with your healthcare provider for more information3.
Prevention
Washing hands frequently reduces the spread of respiratory viruses in people of all ages1.
Benzalkonium chloride-based sanitisers, which foam and leave a residue on the hands protect against colds1. Alcohol-based hand sanitisers are not as effective1.
Cold
Some therapies, used preventatively, can reduce the symptoms of the common cold in children, including1:
- Vitamin C
- Zinc sulfate
- Nasal saline rinse
- Probiotics.
Flu
There are a number of flu vaccines available and annual vaccination is recommended for anyone aged six months and older who does not have contraindications3. For those concerned about egg allergy, there are egg-free vaccines available3.
Certain vitamin and mineral supplements can help reduce the risk and duration of acute respiratory tract infections, including flu9, in adults. These include9:
- Vitamin D: Reduces risk and symptom duration
- Vitamin C: Reduces risk and symptom duration
- Zinc: Reduces symptom duration
- Multivitamin: Reduces risk.
Helpful Tools
The number of times people get a common cold per year typically declines with age2. Adults usually get between one and three colds a year, while children tend to get many more2.
Typical number of colds per year in children per age group is8:
- Pre-school children: 6 – 10 episodes
- Primary school children: 7 – 12 episodes
- Teenagers: 2 – 4 episodes.
