There are a number of agents that can cause common cold though a majority of them (66-75%) of them are caused by 200 antigenically distinct viruses. Among them, the most common are rhinoviruses (25-80%), coronaviruses (10-20%), Influenza virus (10-15%), and adenovirus (5%).

• Frequency- In the United States, most people have an average frequency of 1 episode in 1-2 years. Rhinoviruses cause up to 80% of this disease in the autumn months

• Frequency- Flu usually takes the form of an epidemic in winter months in America. The severity depends on the pathogen involved. Within a year, millions of people can suffer from this infection.

Symptoms-

1. Nasal discharge which is yellow, green of white
2. Nasal congestion
3. Frequent sneezing
4. Severe headache
5. Facial and ear pressure
6. Loss of smell
7. Loss of taste
8. Chest auscultation reveals ronchi (scrapping sound resembling sandpaper rub)

These symptoms usually last for 7 – 11 days though 25 % of the patients may suffer from it for more than 2 weeks. In case of patients suffering from asthma and chronic pulmonary disease, the symptoms can get aggravated.

Symptoms

1. Fever- it can range from 100-104˚F. As the person ages, the fever becomes more severe.
2. Tachycardia- The heart rate increases due to hypoxia, fever or both.
3. Throat infection- this can make talking and swallowing difficult.
4. Reddening of the eye with watery discharge.
5. Unlike common cold, patients usually do not have nasal discharge.
6. Drug cough.