What Is A Cold? What Is The Common Cold? What Causes The Common Cold?

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Main Category: Flu / Cold / SARS
Also Included In: Infectious Diseases / Bacteria / Viruses;  Respiratory / Asthma
Article Date: 07 Oct 2009 - 7:00 PDT

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The common cold is a viral infectious disease that infects the upper respiratory system. It is also known as acute viral rhinopharyngitis, or acute coryza. Being the most common infectious disease in humans, the cold is mainly caused by coronaviruses or rhinoviruses.

The human body can never build up resistance to all the viruses that can cause the common cold. That is why colds are so common and recurring. According to the CDC (Centers for Disease Control and Prevention) kindergarten children get an average of 12 colds per year, compared to adolescents and adults who catch about seven per year.

Experts say that going out when it is cold does not have any effect on the risk of catching a cold or spreading one. Antibiotics do not cure a cold or speed up recovery.

According to Medilexicon's medical dictionary, a common cold virus is "any of the numerous strains of virus etiologically associated with the common cold, chiefly the rhinoviruses, but also strains of adenovirus, coxsackievirus, echovirus, and parainfluenza virus."

What are the signs and symptoms of a cold?

A symptom is something the patient feels or reports, while a sign is something other people, including a doctor may detect. Pain could be an example of a symptom, while a rash could be a sign.

The body reacting to the cold virus is mainly what brings about the symptoms. A release of chemicals is triggered, making the blood vessels leak, causing the mucous glands to work harder. The most common symptoms of a cold are:

• Dry throat
• Sore throat
• Cough
• Mild fever
• Sneezing
• Hoarse voice
• Blocked nose
• Mild headache

The rarer symptoms are:

• Muscle aches
• Shivering
• Pink eye
• Weakness
• Reduction in appetite
• Extreme exhaustion

Approximately 25% of people do not suffer any symptoms when infected with the cold virus; perhaps because their immune system reacts differently to the virus. Sometimes bacteria can infect the ears or sinuses - this is known as a secondary bacterial infection - and can be treated with antibiotics.

What causes a cold?

The common cold can be caused by more than 200 different viruses. Up to 50% of colds are caused by rhinoviruses, other cold causing viruses are:

• Human parainfluenza virus
• Metapneumovirus
• Coronavriuses adenovirus
• Human respiratory syncytial virus
• Enteroviruses

When the viruses manage to overpower the body's immune system infection occurs. The first line of defense is mucus, which is produced in the nose and throat by the mucus glands. This mucus traps anything inhaled, such as dust, viruses and bacteria. Mucus is a slippery fluid that the membranes of the nose, mouth, throat and vagina produce.

When the mucus is penetrated by the virus which then enters a cell, the virus takes control of the element of the cell which makes protein. It uses this element to manufacture more viruses, these viruses then attack surrounding cells.

Are there any complications of the common cold?

Being infected with the common cold can lead to the following complications:

• Acute Bronchitis - This is when the bronchi in the lungs are inflamed as a result of either a bacterial or viral infection. Antibiotics can only be used to treat this if the infection is bacterial; if it is viral it is common just to treat the symptoms until the infection goes away with time. A sample of the sputum may be taken and examined under a microscope to determine what the levels of bacteria are. Symptoms include wheezing, shortness of breath, coughing and sputum.


• Pneumonia - Again this is a condition where the lungs are inflamed, but this time is due to the alveoli filling with fluid. Pneumonia can be caused by bacteria or viruses. However, the common cold virus does not cause pneumonia. If pneumonia occurred as a complication of a cold the most likely pathogen would be bacterial. The patient will be prescribed antibiotics. Symptoms include chest pain, cough, an elevated body temperature, and breathing difficulties.


• Acute Bacterial Sinusitis - This is when bacteria infect the paranasal sinuses. Nasal and oral decongestants can be used as treatment; however antibiotics are required both to treat the condition and to prevent further infection which could lead to other conditions such as bacterial meningitis. Symptoms include headache, aching of the sinuses and nasal discharge.

Other complications that the common cold can lead to are:

• Bronchiolitis
• Croup
• Otitis media
• Strep throat

People with the following conditions can be vulnerable to the common cold and should take measures to avoid catching it as it can worsen their condition:

• Chronic obstructive pulmonary disease (COPD) - This includes both emphysema and chronic bronchitis. The Common Cold can exacerbate emphysema or chronic bronchitis symptoms, leading to increased coughing and shortness of breath. Sometimes a bacterial infection can occur which can lead to fever, and the patient will be prescribed antibiotics.


• Asthma - Asthma attacks can be caused by a cold, especially in children.

How can a cold be prevented?

As there are so many cold causing viruses, it has been difficult for scientists to develop a vaccine. However there are some precautions that can be taken to help avoid catching the common cold, these are:

• Avoid close contact with someone infected with a cold.


• Eat lots of vitamin-rich fruit and vegetables regularly so that your immune system remains strong.


• When sneezing or coughing make sure it is done into a tissue. Discard the tissue carefully and wash your hands.


• If you sneeze into your hands make sure you wash them with soap and water immediately.


• If you have no tissues or a handkerchief cough into the inside (crook) of your elbow rather than your hands.


• Wash your hands regularly; cold viruses can be transmitted from one person to another by touch.


• Keep surfaces in your home clean - especially in the kitchen or bathroom.


• Avoid touching your face especially your nose and mouth.

How is a cold treated?

Unfortunately, both antibiotics and antiviral medications are ineffective against most viruses that cause the common cold. A cold normally lasts up to ten days; however some symptoms do stay as long as three weeks. Although there is no real way of treating or curing the common cold, the following measures may help ease the symptoms:

• Drink plenty of fluids and keep well hydrated, being dehydrated when infected with a cold can make you feel worse.


• Get plenty of bed rest, it is important to get as much sleep/rest as possible when infected as the body's immune system is fighting off the virus.


• Take aspirin, paracetamol or ibuprofen to relieve headache or fever. Do not give aspirin to children under the age of 16.


• Some people find that inhaling steam helps ease the symptoms of nasal congestion.

What is the difference between a cold and flu?

As symptoms can sometimes be quite similar, it may be difficult to know whether you have the flu or a bad cold. Generally, flu symptoms are felt sooner than cold symptoms. Flu symptoms are also more intense. People with the flu feel weak and tired for up to two or three weeks. As the fever comes and goes they will have periods of chills and sweats (cold sweats). Their muscles will ache, and they will have a runny or bunged-up nose, headache and sore throat.

Below is a list of symptoms that can or cannot be experienced when being infected with the common cold or flu:

• Flu symptoms
  
  
  • Headache - common flu symptom, can be quite severe.
  • Tiredness and weakness - common and can last a few weeks.
  • Extreme tiredness - common early on, and can be severe.
  • Aches and pains - yes and usually severe.
  • Temperature/Fever - yes ranging from 39⁰C/102⁰F to 40⁰C/104⁰F
  • Sneezing - occasionally
  • Stuffed up / runny nose - quite common.
  • Coughing - quite typical of flu, can be harsh.
  • Dry/Sore Throat - frequent.
  
  Treatment is often with antivirals. Immunization (flu shot, or flu mist) is available to aid in prevention. Please see "What is Flu? What is Influenza? What are the Symptoms of Flu?" for further information.


• Cold Symptoms
  
  
  • Headache - uncommon, but possible.
  • Tiredness and weakness - occasionally, but milder than with flu.
  • Extreme tiredness - uncommon.
  • Aches and pains - much milder than with flu.
  • Temperature/Fever - unusual.
  • Sneezing - a common cold symptom
  • Stuffed up/runny nose - quite common.
  • Coughing - occasionally, but not as severe as with flu.
  • Dry/Sore Throat - common
  
  Treatment only provides temporary relief of symptoms, and good hygiene is the best prevention.

Written by Mike Paddock
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today

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