What is a cold? What are the causes of a cold?

In daily life, men usually do not pay special attention to the maintenance of their bodies, so colds are the most common diseases in them. So, what is a cold and what are the causes of a cold?

What is a cold?

Upper respiratory tract infection is abbreviated as upper respiratory tract infection, also known as the common cold. It is a general term for acute inflammation of the nasal cavity, pharynx or larynx. In a broad sense, upper respiratory tract infection is not a disease diagnosis, but a group of diseases, including the common cold, viral pharyngitis, laryngitis, herpetic pharyngitis, pharyngoconjunctival fever, and bacterial pharyngitis-tonsillitis. Upper respiratory tract infection in a narrow sense is also called the common cold. It is the most common acute respiratory tract infection disease, which is mostly self-limiting, but the incidence rate is relatively high. Adults have 2 to 4 cases per year, and the incidence rate in children is higher, 6 to 8 times per year. The disease can occur throughout the year, but it is more common in winter and spring.

Causes of colds:

70% to 80% of upper respiratory tract infections are caused by viruses, including rhinovirus, coronavirus, adenovirus, influenza and parainfluenza virus, respiratory syncytial virus, echovirus, coxsackie virus, etc. Another 20% to 30% of upper respiratory tract infections are caused by bacteria. Bacterial infection can be direct infection or secondary to viral infection. Hemolytic streptococci are the most common, followed by Haemophilus influenzae, pneumococci, Staphylococci, etc., and occasionally Gram-negative bacteria.

Various factors that lead to a decrease in the systemic or local respiratory defense function, such as cold, rain, climate change, excessive fatigue, etc., can cause the virus or bacteria that already exists in the upper respiratory tract or invades from the outside to multiply rapidly, thus inducing this disease. The elderly, the young, the weak, the immune system-compromised or patients with chronic respiratory diseases are susceptible.