| COLD AND FLU | | | | infectious disease of the nose and throat; the |
| Influenza Influenza (or as it is commonly known, | | | | upper respiratory system. Symptoms include |
| the flu or the grippe) is a contagious disease, | | | | sneezing, sniffling, running/blocked nose (often |
| caused by an RNA virus of the orthomyxoviridae | | | | these occur simultaneously, or one in each nostril); |
| family. It rapidly spreads around the world in | | | | scratchy, sore, or phlegmy throat; coughing; |
| seasonal epidemics. The name comes from the | | | | headache; and tiredness. Colds typically last |
| old medical belief that unfavourable astrological | | | | between three to five days, with residual coughing |
| influences cause the disease. | | | | lasting up to three weeks. As its name implies, it |
| Types There are three types of the virus, | | | | is the most common of all human diseases, |
| identified by antigenic differences in their | | | | infecting subjects at an average rate of slightly |
| nucleoprotein and matrix protein: | | | | over one infection per year per person. Infection |
| Influenza A viruses that infect mammals and birds | | | | rates greater than three infections per year per |
| Influenza B viruses that infect only humans | | | | person are not uncommon in some populations. |
| Influenza C viruses that infect only humans The A | | | | Children and their caretakers are at a higher risk, |
| type of influenza virus is the type most likely to | | | | probably due to the high population density of |
| cause epidemics and pandemics. This is because | | | | schools and the fact that transmission to family |
| the influenza A virus can undergo antigenic shift | | | | members or caretakers is highly efficient. |
| and present a new, immune target to susceptible | | | | Ninety-five percent of people exposed to a cold |
| people. Populations tend to have more resistance | | | | virus become infected, although only 75% show |
| to influenza B and C, because they only undergo | | | | symptoms. The symptoms start 1-2 days after |
| antigenic drift, and have more similarity with | | | | infection. They are a result of the body's defense |
| previous strains. | | | | mechanisms: sneezes, runny nose and coughs to |
| The term superflu is used to refer to a strain of | | | | expel the invader, and inflammation to attract and |
| flu that spreads unusually quickly, is unusually | | | | activate immune cells. The virus takes advantage |
| virulent, or is for which the host is uncommonly | | | | of sneezes and coughs to infect the next person |
| unresponsive to treatment. Thus, there is a | | | | before it is killed by the body's immune system. |
| tendency to apply the term to strains which | | | | Sneezes expel a significantly larger concentration |
| cause epidemics or pandemics. There is no exact | | | | of virus "cloud" than coughing. The "cloud" is partly |
| scientific definition of a superflu. | | | | invisible and falls at a rate slow enough to last for |
| Symptoms The virus attacks the respiratory | | | | hours - with part of the water droplets |
| tract, is transmitted from person to person by | | | | evaporating and leaving much smaller and invisible |
| saliva droplets expelled by coughing, and causes | | | | "droplet nuclei" in the air. Droplets from turbulent |
| the following symptoms: | | | | sneezing or coughing or hand contact can also last |
| Fever Headache Tiredness (can be extreme) Dry | | | | for hours on surfaces, although less virus can be |
| cough Sore throat Nasal congestion Sneezing | | | | recovered from porous surfaces such as wood |
| Irritated eyes Body aches Extreme coldness | | | | or paper towel than non-porous surfaces such as |
| Fatigue | | | | a metal bar. After a common cold, a sufferer |
| Flu season Influenza reaches peak prevalence in | | | | develops immunity to the particular virus |
| winter, and because the Northern and Southern | | | | encountered. However, because of the large |
| Hemisphere have winter at different times of the | | | | number of different cold viruses, this immunity is |
| year, there are actually two flu seasons each | | | | of limited use. A person can therefore easily be |
| year. Hope-Simpson (1981) observed that | | | | infected by another cold virus to start the |
| influenza outbreaks are globally ubiquitous, and | | | | process all over again. |
| consistently occur six months following the time | | | | Prevention It is possible to get vaccinated against |
| of maximum solar radiation in an area. Therefore, | | | | influenza. However, due to the high mutability of |
| the World Health Organization makes two vaccine | | | | the virus, a particular flu vaccine formulation |
| formulations every year; one for the Northern, | | | | usually only works for about a year. The World |
| and one for the Southern Hemisphere. | | | | Health Organization co-ordinates the contents of |
| While most influenza outbreaks in the Northern | | | | the vaccine each year, to contain the most likely |
| Hemisphere tend to peak in January or February, | | | | strains of the virus which probably will attack the |
| not all do. For example, the influenza pandemic of | | | | next year. The flu vaccine is usually |
| 1918 and 1919 reached peak virulence during late | | | | recommended for anyone in a high-risk group, |
| spring and summer worldwide, and not until | | | | who would be likely to suffer complications from |
| October in the US. It remains unclear why | | | | influenza. |
| outbreaks of the flu occur seasonally rather than | | | | The best way to avoid a cold is to avoid close |
| uniformly throughout the year. One possible | | | | contact with existing sufferers, to thoroughly |
| explanation is that, because people are indoors | | | | wash hands regularly, and to avoid touching the |
| more often during the winter, they are in close | | | | face. Anti-bacterial soaps have no effect on the |
| contact more often, and this is enough to trigger | | | | cold virus - it is the mechanical action of hand |
| the outbreak. Another is that the cold weakens | | | | washing that removes the virus particles. In some |
| the immune system; however, the virus is | | | | countries, such as China and Japan, people with |
| contracted in a warm indoor environment in which | | | | the common cold wear surgical masks out of |
| it can thrive. | | | | courtesy to protect others. |
| Common cold The common cold is a mild viral | | | | |