Colds and flu
Infections are part of the human condition and have coexisted with us since the dawn of time. The positive side of this equation is their essential role in the development of our immune system; the negative side is that they can make us very ill and at times be life-threatening.
How we respond to infection (how ill we become) depends on how virulent the organism is; the strength of our immune systems and the portal of entry of the organism (for example, the skin, the nose or the mouth) and how effective the barrier mechanisms are at these sites; and how effective are the various components of our blood-borne immunity.
If the organism is particularly virulent, the immune system can be overwhelmed but, if the immune system is healthy, the person may suffer only mild symptoms (if any) while at the same time developing antibodies to—and, therefore, future protection from—that particular organism.
Colds and influenza have adversely affected humans since antiquity. Even the ancient Egyptians had a specific hieroglyph for the disease and Hippocrates the Greek physician described the disease in the 5th century BC. The term cold probably derived from the ancient physicians who described “cold” conditions and “warm” conditions. Despite all our medical knowledge today, treatments have barely advanced since ancient times and today respiratory infections are the leading causes of death for children under the age of five and complications from them are a significant cause of death in the elderly.
The cold is the commonest infectious disease that humans contract and it is today an economic as well as health nightmare. Respiratory disease results in significant losses to the economy in lost workdays and school attendance and the medical costs are huge. In Australia, costs to business were calculated from January to September in 2017 (with the flu season not yet over for the year) at $114.6 million in lost productivity.
Colds and flu are the leading cause of doctor visits in Australia annually and influenza infections are the leading cause of morbidity and mortality: 13,500 hospitalisations and more than 3000 deaths per year among Australians over 50 years of age, which is double the number of deaths from motor vehicle accidents.
Colds and influenza: similar but different
While there is a significant overlap in the diagnosis and symptoms of colds and flu, both are caused by viral infections—albeit different viruses. The most common initial symptoms of a cold are headache, sneezing, chilliness and sore throat, followed later by nasal discharge and/or obstruction, sinus pain, coughs (if the infection spreads to the lungs or a secondary infection develops because of the lowered immunity) and general malaise.
The severity of symptoms increases quickly over two to three days after the initial infection, lasting about seven to 10 days with some symptoms persisting for more than three weeks. A lingering cough is the largest single cause of medical consultations.
At least one third of the annual visits to a medical doctor to treat colds and flu result in a prescription for antibiotics even though they have no effect on viral infections and can lead to the development of antibiotic resistance.
Viral infections
Cold
The common cold—or acute viral nasopharyngitis—is usually
