Common Cold

 Common Cold

The term “common cold” refers to a mild upper respiratory viral illness. It is self-limited therefore it will go away without treatment. It is the most frequent acute illness in the United States. It is separate and a distinctly different illness than influenza, throat infection, bronchitis, sinusitis, pertussis, and allergic rhinitis. The average person has two or three colds a year. Colds are caused by many viruses, which cause similar symptoms. The same virus can cause another cold after re-exposure. However, the second illness is usually milder and lasts for a shorter period of time. Seasonal patterns may be seen for some of the viruses

Transmission: 

* Common cold viruses can be spread by three mechanisms: 

o Direct contact – colds are primarily spread from person-to-person via hands. The virus can stay alive on the skin for at least two hours. Thus, if a sick person shakes someone’s hand and that individual then touches his eye, nose, or mouth, the virus can be transmitted and later infect that person. 

o Indirect contact – viruses may survive on surfaces such as countertops for several hours thus can be transmitted from touching that surface and then touching the mouth, nose, or eyes.

  o Inhaling viral particles – droplets containing viral particles can be breathed, coughed, or sneezed into the air and transmitted to others if another person is standing close (within a few feet) and the droplet touches that person’s eye, nose, or mouth. Covering the mouth while coughing or sneezing reduces this risk. 

*  Persons with colds shed viruses the most on the second day of illness, however, low levels of viral shedding may persist for up to two weeks. 

* Saliva generally does not spread the common cold virus as most people with a cold have no detectable virus in their saliva. 

* Studies of using recirculated air in commercial airliners versus fresh air ventilation show no difference in the number of colds reported by persons after the flight.

Risk factors:

 There are some factors that can increase the risk and severity of illness with a cold. There is no scientific basis for the belief that a cold climate increases susceptibility to getting a respiratory illness. 

Increased risks of developing cold symptoms occur with: 

1. Psychological stress 

2. Lack of sleep or sleep disturbances 

3. Exposure to children in daycare settings 

Increased severity of colds is often seen with: 

1. Underlying chronic diseases 

2. Immunodeficiency disorders 

3. Malnutrition 

4. Cigarette smoking

Clinical features: 

Symptoms of the common cold are mostly due to the response of the individual to the infection, rather than to direct damage to the respiratory tract from the virus. Symptoms vary from person to person and include: 

 Rhinitis (runny nose) and congestion are the most common symptoms. 

 Sore throat, sneezing, cough, malaise (feeling ill) 

 Fever is uncommon in adults but may be present in children 

 Purulent (colored, thick drainage containing pus) drainage may be seen with the common cold. The presence of purulence does not distinguish between a cold or sinus infection. 

Incubation period/symptom duration:
 From the time of contact until onset of symptoms is generally 24 to 72 hours but can be as early as 10 to 12 hours after exposure.
 Symptoms usually last 3 to 10 days, but can last up to two weeks in some people.

Diagnosis:
The diagnosis is based on symptoms and observed signs.
 Swelling and congestion of nasal passages  Redness of the throat
 Enlarged lymph nodes in the neck
 Normal lung exam
 Chest x-rays not needed unless chest exam is abnormal Conditions that can mimic a cold include:  Allergic or seasonal rhinitis – a cough or sore throat are usually not seen with allergies.
 Bacterial throat infection or tonsillitis – nasal congestion and drainage are not generally seen with a bacterial throat infection or tonsillitis.
 Bacterial sinus infections – usually associated with significant facial pain and purulent nasal discharge.
 Influenza – usually associated with high fever, headache, and body aches.
 During flu season, obtain nasal swabs for rapid flu testing
 Pertussis – associated with prolonged coughing, sometimes associated with vomiting.

Complications:
 Acute sinus infections are a rare complication in adults with colds. Viral sinusitis occurs more frequently than secondary bacterial sinusitis. Viral sinusitis will resolve within 3 weeks without antibiotic treatment.
 Lower respiratory tract disease:    
      o RSV (respiratory syncytial virus) can cause an infection in the lungs especially in children,                  older adults, and immunocompromised patients.
      o Acute asthma attacks occur with colds thought to be due to changes in airway reactivity which            can last up to four weeks following an infection.
 Ear infections:
      o Because colds cause problems with drainage and pressure regulation of the middle ear, an acute          ear infection (otitis media) can occur.


Prevention:
 Studies have not proven that the use of alcohol gels prevent developing symptoms of a respiratory illness as the virus can be spread by inhaling droplet particles. However general hygienic measures such as hand washing has been shown to prevent the spread of respiratory viruses especially from younger children.
 Decontamination of environmental surfaces with disinfectants that kill viruses may help decrease the rate of transmission. However a study of the effectiveness of antibacterial cleaning products failed to show a difference when compared to standard cleaning products in the incidence of colds.
 Vitamins - regular supplementation with vitamins C, D, and E have not been shown to decrease the incidence of colds.
 Zinc – there have been studies that show that children taking zinc sulfate decreased the rate of development of colds, however studies have not shown this to work for adults. Zinc, especially when found in intranasal products, can lead to the loss of smell.