Flu

Influenza (commonly shortened to ‘flu’), is a highly-infectious disease caused by a family of viruses known as Orthomyxovitidae, which attack RNA. Flu can afflict both mammals and birds, as in the recent outbreaks of bird flu (H5N1). Typical symptoms of influenza in humans include headaches, fatigue, muscular pain, sore throat and coughing. Fighting influenza weakens the immune system, and so a flu can occasionally cause pneumonia, a much more serious disease which is potentially fatal to the very young and very old. Vomiting and nausea are occasionally symptoms of flu, but more often indicate temporary gastroenteritis, otherwise known as 24 hour flu, or stomach flu.

Oftentimes confused with a common cold, flu is in fact caused by a different kind of virus and is a much more serious condition.

Influenza is potentially highly infectious disease (depending on the strain of the virus) that can be transmitted through the air often by sneezing or coughing, and in the case of bird flu by proximity to the bird’s droppings. Flu can also be passed from creature to creature by way of bodily fluids including saliva, feces and blood, and by surfaces contaminated with these things. A virus can stay active and potentially infectious for up to a week outside the body at a steady temperature of around thirty-seven degrees celsius (human body temperature). At a temperature just above freezing, the virus can last around a month, and at sub-zero temperatures it can remain infectious indefinitely. Virtually all strains of influenza virus can be destroyed by standard disinfectants or detergents.

Outbreaks of flu occur in the form of epidemics, which sweep across a large area, killing hundreds of thousands of people in a non-pandemic year, and potentially millions in a pandemic year. In the twentieth century, three flu pandemics were responsible collectively for the deaths of tens of millions of people. Flu pandemics occur when a new and highly infectious form of flu virus mutates and spreads rapidly throughout the population, often beginning from a strain of animal flu. The greatest threat to the world currently is thought to be the dreaded H5N1 virus, known as ‘bird flu’, which has not yet mutated to easily pass from human to human, but would be lethal on an enormous scale should it do so in the future.

Flu vaccines are available primarily to at-risk groups such as children and the elderly, and also to farmed poultry and poultry farmers. The trivalent flu vaccine is most commonly used, incorporating active material from three different strains of flu virus, in order to protect from as many possible mutations as is practical to do. Flu vaccines must be constantly adapted and updated, since influenza viruses mutate so rapidly that a vaccine developed one year may be completely ineffective the next. This makes large-scale vaccinations and emergency planning (in the event of a pandemic) impractical and expensive, and is one of the main reasons why flu pandemics spread so rapidly and are so devastating. Some antiviral drugs are effective against influenza, particularly neuraminidase.

Flu symptoms generally begin to manifest between 24 and 48 hours following an infection, and can appear to come on very suddenly. Chills and fever are most common, accompanied by painful aching, particularly in the leg and back area. Some flu symptoms, for example headaches, fatigue and fevers, are caused by the hugely inflated amount of chemokines and pro-inflammatory cytokines that cells infected with flu tend to produce. Flu viruses do not generally cause tissue damage, unlike the common cold virus, and so symptoms do differ. Other classic signs of influenza include - coughs and sneezing, extreme cold, watery eyes, irritated eyes, nausea, vomiting, red eye, dry and red mouth, nose and throat, and congestion of the nasal passages.

Initial treatment for flu is in the form of good, old-fashioned bed rest, as well as drinking plenty of fluids and avoiding poisonous products such as alcohol and tobacco. Painkillers, particularly paracetamol, can be effective in combating the muscular aches and fever associated with flu, but young people should avoid aspirin because of the potentially fatal risk of developing a liver disease called Reye’s syndrome. Antibiotics have no effect against the flu virus, but may be useful to combat secondary complications, particularly pneumonia. Antiviral medication may work if the particular strain of flu has not already adapted to become immune to them, which is always a distinct possibility.

Current research into the influenza family of viruses is focused around pathogenesis (how the virus causes the disease), immune response of the hosts, the structure of the virus itself at the genetic level (viral genomics) and the methods by which it spreads (epidemiology). Each of these branches of investigation is likely to yield benefits for different areas of influenza treatment or pandemic prevention. For example, studying the human body’s immune response when infected with a flu virus may help scientists to engineer a more effective vaccine, while examining the epidemiology of the viruses is likely to lead to better antiviral drugs.

Constant research into different strains of flu and ways to combat them is essential, as flu viruses evolve at an extremely rapid pace, as mentioned above, and so treatment options can rapidly become obsolete.

Influenza costs the global economy tens of billions of dollars annually, while a possible future flu pandemic could push that cost up into the hundreds of billions, or trillions of dollars. Billions of dollars have already been spent attempting to investigate and prevent the spread of the potentially catastrophic H5N1 strain of bird flu, but no definitive solution has so far been forthcoming. Another global flu pandemic in the medium term is statistically likely.

Flu