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Common cold

  1. Jun 19, 2005 #1
    I have a wierd question here :biggrin:. What exactly causes common cold? I'm aware it is caused due to viruses but why do doctors prescribe anti-biotics for common cold which are supposed to fight bacterial infection?
    Do the following cause common cold:
    *Eating ice-creams
    *Wet hair
    *Hot weather
    *sudden temperature change

    Looking forward for your responses...:smile:
  2. jcsd
  3. Jun 19, 2005 #2
    eating candys can sick too,,
    mostly peple sick because they dunt pay attention,
  4. Jun 19, 2005 #3
    The common cold is caused by rhinoviruses, coxsackieviruses, echoviruses, paramyxoviruses, and some others. They infect the upper respiratory system.

    Doctors give anti-biotics to deal with symptoms of the cold, a stupid reason, as the cold is not caused by bacteria but a virus. Virus are impervious to essentially all treatment due to their nature. They are essentially RNA or DNA wrapped in a protein coat that enter cells and cause replication of the virus and then cell death. Antibiotics have no effect.

    Doctors mainly give them because their patients EXPECT to be gien something (more of a stupid reason!). This is also stupid as it aids bacteria in the body to (due to natural selection) eventually become immune to antibiotics! Not good!

  5. Jun 19, 2005 #4
    However, antibiotics do treat pneumonia which can develop in association with colds.. especially in the elderly or immune depressed.

    The number 1 biggest factor in transmission of the common cold: Lack of sunlight!

    Not because you've been skinny dipping in 0 degree weather, not because you've left your hair wet, nor because of temperature! Low sunlight means there is less UV radiation to destroy the virus when it is airbourne, which is why there is rarely any colds/flus during summer.

    The effect also occurs in train stations. Strangely enough, you would think stations would be a breeding ground for transmission of air bourne diseases - but it's not! It's because of all the reactive oxides (pollution) caused by the electricity lines fill the air and steralise it. Paradoxically, its the pollution which is protecting you :surprised

    Read all this years ago: never forgot it!
    Last edited: Jun 19, 2005
  6. Jun 19, 2005 #5
    Not all pneumonia is bacterial so antibiotics may not be effective although most of the time they are.

    I somehow find the idea that a Lack of sunlight causes an increase in colds spreading a bit silly, as to my knowledge, the sun is still shining -and more UV radiation is getting through the Ozone layer :P! I presume therefore you mean that people spend too much time inside?!

    Oh and the pollution at stations is leading to bronchitis, emphazemia and other illnesses - I wouldn't mind a cold :P!

  7. Jun 19, 2005 #6
    Haha yes the sun is still shining, but at a reduced intensity during winter... which I'm guessing is why we have winter? But I suppose it's true.. with more people staying indoors (for work, travel) away from the sun's cleansing rays, means that one can catch colds during summer. But who knows! That book I read might have been 15 years old haha
  8. Jun 19, 2005 #7


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    My understanding of the biggest factor in transmitting the cold virus is putting your hands to your nose. This comes from a leading investigator in studying influenza.
  9. Jun 20, 2005 #8


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    Any time I've been presribed antibiotics when ill with a cold, I've been told that its due to a secondary bacterial infection, not the cold itself. Bacterial infections are a reasonably common side effect of colds.
  10. Jun 20, 2005 #9
    a more interesting question: if they prescribe antibiotics for bacterial infections, why don't they prescribe antivirals for viral infections?
  11. Jun 20, 2005 #10


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    Let me guess. I'm not a medical professional so I can stand to be corrected. Antiviral agents are extremely toxic. I mean, they anti the virus by interferring with DNA replication. Jesus. I'd rather have the flu.

    Edit: Let me qualify that statement: I'm relatively young and very healthy. My body can survive the flu.

    Edit2: Alright, I'm not too sure about the DNA replication part. This is what I got off the internet:

    The antiviral activity of these medications isn’t understood very well. Amantadine (Symmetrel), oseltamivir (Tamiflu), and rimantadine (Flumadine) appear to prevent the release of infectious viral material from the influenza virus or interfere with the ability of the virus to enter a healthy (host) cell. Zanamivir (Relenza) inactivates an enzyme in the virus, which stops the growth and spread of the virus.
    Last edited: Jun 20, 2005
  12. Jun 20, 2005 #11


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    The sun shines the same, but the winter hemisphere of the Earth is tilted away from the sun (less direct sunlight = less intense sunlight reaching the ground = colder weather).
  13. Jun 20, 2005 #12


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    Just for the record:

    Four prescription medications with antiviral activity against influenza viruses are commercially available in the United States (amantadine, rimantadine, oseltamivir, zanamivir). The four drugs are classified into two categories, the adamantane derivatives and the neuraminidase inhibitors, on the basis of their chemical properties and activities against influenza viruses.

    Zanamivir and oseltamivir block the active site of the influenza viral enzyme neuraminidase, which is common to both influenza A and influenza B viruses. This effect results in viral aggregation at the host cell surface and reduces the number of viruses released from the infected cell.

    Neuraminidase is one of two membrane bound proteins found on the surface of influenza virus particles. The overall function of neuraminidase is to cleave sialic acid, which releases virus particles from the surface of host cells.

    Alright, just forget about DNA replication . . .
  14. Jun 26, 2005 #13
    Thanks for the responses everyone :smile:. So the common cold is confused with a lot of other respiratory ailments, right? I've seen people who have a temporary allergic reaction to a substance dust, pollen etc. and call it cold and simply take medicine when it is not necessary.
    Very good point!! That is the main reason new forms of anti-biotic resistant bacteria are evolving each day leading to new and dangerous forms of bacterial diseases like TB.
  15. Jun 26, 2005 #14
    I think it is really unnecessary to prescribe antibiotics in this case unless it is really needed. Even for a mild infection antibiotics are prescribed.
    At my place the sun shines almost all year round. But the maximum common cold infections are during the summer and the monsoons. I guess the humid environment is an ideal breeding ground for these viruses :wink:.
  16. Jun 26, 2005 #15


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    For the record, most doctors try not to prescribe antibiotics when a virus is suspected. Only for secondary infections that may come about (say sinusitis after weeks of mucopurulent material building up in the sinuses that get secondarily infected). In addition, in the wake of influenza, strep and staph pneumonia as a secondary bacterial infection can be common in the elderly or immunocompromised . In fact, it is these secondary infections that can cause the death of the patient, rather than the original flu virus.

    However, it may mean arguing with the patients and loosing them as clients. Thus, some doctors capitulate (to assuage angry patients who feel they did not get their money's worth making the appointment with the doctor..."Doc, I spent 50 dollars so you can just do nothing?"). Pediatricians especially are faced with the onslaught of parent's demands for antibiotics ("What do you mean the fever of 103 degrees is just caused by a virus!") So yes, despite education and teaching, antibioitics are still abused and over used.

    As for antivirals affecting DNA, I think people are talking about something like acyclovir which is used against herpes virus. Acyclovir's byproducts terminates growing chains of viral DNA by irreversibly binding to viral DNA polymerase but has virtual inactivity in uninfected human cells. (In fact you can give acyclovir during pregnancy, it is quite safe and does not seem to cause birth defects despite its actions on DNA polymerase (herpes virus).

    Correct, hand to mouth/nose transmission is the most common form of transmission of most cold viruses with the exception of the flu ( which can be transmitted in aerosolized form which is one of the reasons why it is so contagious ) but others (like the adenovirus) require hand to mouth contact.

    As for seasonal variations, with the exception of influenza (which peaks in the winter) common colds are seen throughout the year. (In fact, coxsackie virus has its highest prevalence in the summer.)
    Last edited: Jun 26, 2005
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