Cold Flu

COLD AND FLUinfectious 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 orthomyxoviridaethese occur simultaneously, or one in each nostril);
family. It rapidly spreads around the world inscratchy, sore, or phlegmy throat; coughing;
seasonal epidemics. The name comes from theheadache; and tiredness. Colds typically last
old medical belief that unfavourable astrologicalbetween 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 theirinfecting 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 birdsrates greater than three infections per year per
Influenza B viruses that infect only humansperson are not uncommon in some populations.
Influenza C viruses that infect only humans The AChildren and their caretakers are at a higher risk,
type of influenza virus is the type most likely toprobably due to the high population density of
cause epidemics and pandemics. This is becauseschools and the fact that transmission to family
the influenza A virus can undergo antigenic shiftmembers or caretakers is highly efficient.
and present a new, immune target to susceptibleNinety-five percent of people exposed to a cold
people. Populations tend to have more resistancevirus become infected, although only 75% show
to influenza B and C, because they only undergosymptoms. The symptoms start 1-2 days after
antigenic drift, and have more similarity withinfection. 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 ofexpel the invader, and inflammation to attract and
flu that spreads unusually quickly, is unusuallyactivate immune cells. The virus takes advantage
virulent, or is for which the host is uncommonlyof sneezes and coughs to infect the next person
unresponsive to treatment. Thus, there is abefore it is killed by the body's immune system.
tendency to apply the term to strains whichSneezes expel a significantly larger concentration
cause epidemics or pandemics. There is no exactof 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 respiratoryhours - with part of the water droplets
tract, is transmitted from person to person byevaporating 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) Dryfor hours on surfaces, although less virus can be
cough Sore throat Nasal congestion Sneezingrecovered from porous surfaces such as wood
Irritated eyes Body aches Extreme coldnessor paper towel than non-porous surfaces such as
Fatiguea metal bar. After a common cold, a sufferer
Flu season Influenza reaches peak prevalence indevelops immunity to the particular virus
winter, and because the Northern and Southernencountered. However, because of the large
Hemisphere have winter at different times of thenumber of different cold viruses, this immunity is
year, there are actually two flu seasons eachof limited use. A person can therefore easily be
year. Hope-Simpson (1981) observed thatinfected by another cold virus to start the
influenza outbreaks are globally ubiquitous, andprocess all over again.
consistently occur six months following the timePrevention 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 vaccinethe 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 Northernthe 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 ofnext year. The flu vaccine is usually
1918 and 1919 reached peak virulence during laterecommended for anyone in a high-risk group,
spring and summer worldwide, and not untilwho would be likely to suffer complications from
October in the US. It remains unclear whyinfluenza.
outbreaks of the flu occur seasonally rather thanThe best way to avoid a cold is to avoid close
uniformly throughout the year. One possiblecontact with existing sufferers, to thoroughly
explanation is that, because people are indoorswash hands regularly, and to avoid touching the
more often during the winter, they are in closeface. Anti-bacterial soaps have no effect on the
contact more often, and this is enough to triggercold virus - it is the mechanical action of hand
the outbreak. Another is that the cold weakenswashing that removes the virus particles. In some
the immune system; however, the virus iscountries, such as China and Japan, people with
contracted in a warm indoor environment in whichthe common cold wear surgical masks out of
it can thrive.courtesy to protect others.
Common cold The common cold is a mild viral