Most people who think
they have the flu, don’t. And some people who think they have a cold, really
have the flu. So what is the difference between a cold and the flu? And does it
matter?
A
cold is a mild illness that resolves without treatment. It is a combination of
some or all of the following: sneezing, a runny and then blocked nose, a sore
or scratchy throat, cough, low-grade fever, headache and malaise. Doctors often
refer to a cold as an upper respiratory tract infection or URTI (pronounced er-tee). They are very common – on average, you can expect three per
year.
There
are at least 200 different viral subtypes that cause colds – the commonest by
far are rhinoviruses which are responsible
for at least 40%; others include coronaviruses, respiratory syncytial virus (RSV),metapneumovirus and parainfluenza viruses.
Following
a cold, the small airways in the lungs become “hyper-reactive”. This can
trigger an asthma attack and may result in the so-called “post-viral cough”
that lasts for weeks. (In this setting, whooping cough should also be considered).
A
cold may be complicated by an ear infection and sinusitis – both of which are usually viral and do not require
antibiotics.
By
definition, “the flu” is an illness caused by an influenza virus. True flu is much less common than a cold and can be a
more severe disease – the nasal symptoms are absent but sore throat may be
present. You’re likely to be much sicker and have high fever, chills, shaking,
severe muscle aches, malaise, headache and a cough.
Influenza
may progress to pneumonia and, in the elderly and
those with particular chronic conditions, the risk of death is substantial.
When a pandemic strain of influenza appears, the mortality in otherwise healthy
people may be significant.
The problem is that many
people who have some or all of the symptoms of influenza are not infected with
an influenza virus but rather with one of the cold viruses – we call these
illnesses “flu-like”. Many people who thought they had influenza in the past
will have just had a severe cold (sometimes referred to by female partners as
“man flu”).
Occasionally,
someone with symptoms of a cold will actually be infected with an influenza
virus. To add even more complexity, studies of the 2009 H1N1 influenza pandemic show that the majority
of people who were infected had no symptoms.
It is not easy to
identify the cause of your cold or flu-like illness. Current diagnostic testing
is usually limited to patients who require hospital admission. And even then,
we don’t find a definitive answer in most people.
Most colds and flus are
transmitted by touching the nasal secretions of an infected person and then
touching your own nose or eye. The incubation period is usually one to three
days and you are most infectious for about five days from the onset of
symptoms.
Frequent hand hygiene (washing with soap and water or alcohol-based hand rub) will
reduce your risk of infection. Masks, a common sight in Asia ,
have been shown to be useless at
preventing transmission.
The typical cold lasts
between three and ten days but 25% persist for more than ten days. The
persistence of symptoms often results in people inappropriately seeking
antibiotics from their doctor.
You can treat the
symptoms of a cold with nasal decongestants and drugs such as aspirin and
paracetamol but none shorten the infection.
There
are countless unproven claims for herbs, vitamins and minerals in the treatment
of colds. In a salutary lesson that “natural” is not always safer, the US Food
and Drug Administration in 2009 warned against the use of
zinc-containing products in nasal sprays, including homeopathic preparations,
because they were associated with a risk of permanent loss of smell.
There
is no vaccine for the common cold – it is impossible to make one that can cover
so many different viruses. Influenza has a seasonal vaccine that targets the most
common subtypes circulating in the community but it is not 100% protective.
The
antiviral drugs that work against influenza – Relenza (zanamivir) and Tamiflu
(oseltamivir) – reduce the duration of symptoms by just over
a day on average.
So, most of us are wrong
when we think we have the flu. But if you were to tell the boss that your
recent absence was due to “acute coryzal rhinopharyngitis”, you may get more
sympathy than by just giving her the cold facts.
There are countless unproven claims for herbs, vitamins and minerals in the treatment of colds. In a salutary lesson that “natural” is not always safer, the US Food and Drug Administration in 2009 warned against the use of zinc-containing products in nasal sprays, including homeopathic preparations, because they were associated with a risk of permanent loss of smell.
There is no vaccine for the common cold – it is impossible to make one that can cover so many different viruses. Influenza has a seasonal vaccine that targets the most common subtypes circulating in the community but it is not 100% protective.
The antiviral drugs that work against influenza – Relenza (zanamivir) and Tamiflu (oseltamivir) – reduce the duration of symptoms by just over a day on average.
So, most of us are wrong when we think we have the flu. But if you were to tell the boss that your recent absence was due to “acute coryzal rhinopharyngitis”, you may get more sympathy than by just giving her the cold facts.
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