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